Anatomy Lecture Notes Update 2015



Human Anatomy (Biology 4)To KnowUpdated January 2017 Professor: Julie GallagherChapter 1 The Human Body: An Orientation Terms Anatomy: the study of body structure and relationships among structures Physiology: the study of body function Levels of Organization Chemical level atoms and molecules Cells the basic unit of all living things Tissues cells join together to perform a particular function Organs tissues join together to perform a particular function Organ system organs join together to perform a particular function Organismal the whole body Organ Systems Anatomical Position Regional Names Axial region head neck trunk thorax abdomen pelvis perineum Appendicular region limbs Directional Terms Superior (above) vs. Inferior (below) Anterior (toward the front) vs. Posterior (toward the back)(Dorsal vs. Ventral) Medial (toward the midline) vs. Lateral (away from the midline) Intermediate (between a more medial and a more lateral structure) Proximal (closer to the point of origin) vs. Distal (farther from the point of origin) Superficial (toward the surface) vs. Deep (away from the surface) Planes and Sections divide the body or organ Frontal or coronal divides into anterior/posterior Sagittal divides into right and left halves includes midsagittal and parasagittal Transverse or cross-sectional divides into superior/inferior Body Cavities Dorsal cranial cavity vertebral cavity Ventral lined with serous membrane viscera (organs) covered by serous membrane thoracic cavity two pleural cavities contain the lungs pericardial cavity contains heart the cavities are defined by serous membrane mediastinum is the area between the pleurae, includes everything in thoracic cavity except lungs abdominopelvic cavity abdominal cavity is lined by peritoneum (serous membrane), which also covers organs pelvic cavity has reproductive organs, bladder, portions of large intestine regions and quadrants Chapter 4 Tissues Four major tissue types Epithelial (epithelium) covers and lines body parts (sheets of cells) glandular epithelium two major types endocrine glands secrete hormones to blood (no ducts) exocrine secrete products into ducts that open to skin or lumen of organ structural classification of exocrine glands multicellular - form a distinctive structure or organ (e.g., sweat, salivary) unicellular - have no ducts but still considered exocrine (e.g., goblet cells) functional classification of exocrine glands holocrine - cell accumulates product, cell dies, bursts open and substance secreted (e.g., sebaceous) merocrine - secrete by exocytosis (most glands) epithelial sheets - special characteristics continuous sheets of closely packed, tightly joined cells have apical (free) and basal surface attached to 2-layered basement membrane basal lamina - proteins and polysaccharides secreted by epithelial cells reticular lamina - protein fibers and glycoproteins secreted by underlying connective tissue avascular - exchanges occur by diffusion from blood supply of underlying connective tissue have nerve supply high capacity for regeneration (lots of mitosis) basic functions - protection, secretion, absorption Connective tissue special characteristics made up of living cells plus non-living extracellular matrix -blasts are immature cells that secrete matrix (e.g., fibroblasts, chondroblasts, osteoblasts) -cytes are mature cells that help maintain matrix (e.g., chondrocytes, osteocytes) other cell types include macrophages, plasma cells (secrete antibodies), mast cells (store chemicals that help fight invaders) matrix consists of protein fibers embedded in ground substance (polysaccharides and proteins); supports cells structurally and functionally fibers include collagen (strong, flexible), elastin (strong, very stretchy), reticular fibers (collagen with coating of glycoprotein, forms branching networks that support tissues and organs) has nerve supply, except cartilage most highly vascular, except cartilage which is avascular, and tendons/ligaments which have a low supply functions - support, protection, binding Muscle tissue generates force, movement, generates heat three types - skeletal, cardiac, smooth Nervous tissue initiates and transmits electrical signals neurons and neuroglia (support cells) Cell Junctions Tight junctions adjacent plasma membranes are fused forms barrier that prevents leakage common in epithelial sheets Gap junctions cells linked by protein tunnels called connexons allow small molecules to pass between cells important in conducting electrical signals (e.g., cardiac muscle) Desmosomes scattered over membrane surface found all over body, but more common in tissues that experience stretching (e.g., skin, digestive tract) Membranes Most are epithelial membranes epithelium with underlying CT Cutaneous membrane covers body surface (skin) Mucous membranes (mucosa) line body cavities open to the exterior in respiratory, digestive, reproductive and urinary systems form a barrier to invaders, important in body defense tight junctions prevent leakage secretes mucus, which moistens, lubricates, traps dust and invaders underlying CT layer called lamina propria formed from different kinds of epithelium Serous membranes (serosa) lines body cavities not open to exterior, covers organs simple squamous epithelium with areolar CT two layers parietal - attached to cavity wall visceral - covers organs between layers is serous fluid secreted by the epithelial cells includes pleurae, pericardium, peritoneum Synovial membranes line cavities of synovial joints no epithelium areolar CT with elastic fibers and fat secretes synovial fluid to lubricate joint Chapter 5 Integumentary System Epidermis Keratinized stratified squamous epithelium keratinocytes (90% of cells) produce fibrous protein keratin (as intermediate filaments of cytoskeleton) help provide protective properties of skin melanocytes (8%) produce pigment melanin that protects from UV light have projections that extend between keratinocytes, keratinocytes phagocytize projections to take in melanin Langerhans cells produced in red bone marrow important in immune response projections form a network in some layers Merkel cells associated with nerve endings (Merkel discs) important in sense of touch Thickness ranges from .1 mm – 2 mm Layers of epidermis (strata, from deep → superficial) Stratum basale one row of mainly cuboidal or columnar keratinocytes melanocytes and Merkel cells scattered among keratinocytes divide often, older cells push upward and become parts of other layers (accumulate more keratin) also known as stratum germinativum Stratum spinosum 8 - 10 cells thick, more superficial keratinocytes are flatter some keratinocytes can still divide Langerhans cells and projections of melanocytes Stratum granulosum 3 - 5 cells thick, flattened keratinocytes nuclei and organelles degenerate, lots of keratin (many cells dead) cells contain keratohyaline granules (no membrane, bundles together keratin filaments) also lamellar granules (membrane, lots of lipids, forms waterproof barrier between this and superficial layers) Stratum lucidum only in thicker skin (palms and soles) 3 - 5 cells thick, very flat, dead keratinocytes lots of keratin and keratohyaline Stratum corneum 25 - 30 cells thick, very flat, dead keratinocytes lots of keratin, keratohyaline and lipids from lamellar granules waterproof barrier that protects from light, heat, chemicals and invaders constantly shed Dermis Connective tissue with other embedded structures cells include fibroblasts, macrophages contains blood vessels and nerves glands and hair follicles are embedded Regions of dermis papillary region areolar CT with elastic fibers projects into epidermis as dermal papillae loops of capillaries touch receptors cause ridges in epidermis (fingerprints) reticular region dense irregular CT with lots of collagen and some elastin contains bits of adipose, hair follicles, nerves, oil and sweat glands differs in thickness in different body areas (up to 2 mm) Hypodermis Attaches dermis to underlying structures areolar and adipose Also known as subcutaneous layer or superficial fascia Contains blood vessels and nerves Functions of Integumentary System Temperature regulation evaporation of sweat decreases body T changes in blood flow (more blood → lose heat, less blood → conserve heat) Protection physical barrier to invasion, dehydration and UV radiation contains cells of immune system Sensation nerve cells with receptors for pain, touch, pressure, temperature Excretion water and dissolved substances in sweat Acts as a blood reservoir flow can be shifted to hard-working muscles if needed Vitamin D synthesis epidermis makes inactive form of vitamin D upon exposure to UV important in absorption of calcium Derivatives of the Epidermis (skin appendages) - Hair dead, keratinized cells shaft projects from surface of skin root is beneath skin surface surrounded by hair follicle (from epidermis) root plexus consists of nerve endings that contribute to sense of touch 4. arrector pili smooth muscle can make hair "stand up" with cold or emotional stress 5. functions protect from light decrease heat loss protect eyes and nose from foreign particles sense of touch hold chemical signals (pheromones) Sebaceous (oil) glands holocrine glands ducts usually open to hair follicle secrete sebum mix of fats, cholesterol, proteins, salts, pheromones coats hairs holds moisture in the skin inhibits most bacterial growth Sudoriferous (sweat) glands eccrine sweat glands (functionally merocrine) on most skin ducts open to skin surface secrete sweat water, salt, some wastes (urea, ammonia) mainly for cooling body, some excretion, acidity protects from bacteria apocrine sweat glands (functionally merocrine) axillary, genital and anal regions ducts open to hair follicles secrete sweat, fats and proteins may function in sexual signaling (pheromones) Nails hard, keratinized cells nail body is visible root is under skin functions - grasp and manipulate objects, scratching Chapter 6 Bones and Skeletal Tissues Functions of bone Support soft tissues Protection of internal organs Movement points of muscle attachment form joints Mineral storage mainly calcium and phosphorous Production of blood cells red marrow in some bones Energy storage yellow marrow is mostly fat Types of Bones Long bones longer than they are wide (e.g., most bones of limbs) Short bones roughly cube shaped (e.g., bones of wrist and ankle) sesamoid bones- in tendons, provide support (e.g., patella) Flat bones flat and curved (e.g., cranial bones, ribs, sternum, scapula) Irregular bones complex shapes (e.g., vertebrae and hip bones) Basic structure of a long bone Diaphysis long part of bone (shaft) Epiphyses ends of the bone Articular cartilage hyaline cartilage covering ends of bone decreases friction and absorbs shock Periosteum white fibrous membrane covering surfaces not covered by articular cartilage outer fibrous layer dense irregular CT blood and lymphatic vessels, nerves inner osteogenic layer elastic fibers, blood vessels, bone cells functions bone growth in thickness repair of fractures protects and nourishes point of attachment for ligaments and tendons Medullary cavity cavity in diaphysis containing yellow marrow Endosteum lining of marrow cavities delicate CT with bone cells Histology Cells osteoblasts secrete collagen and other parts of bone tissue on inner and outer bone surfaces become osteocytes osteocytes main cells of bone tissue in cavities within bone called lacunae exchange nutrients and wastes with blood osteoclasts may come from circulating WBCs on inner and outer bone surfaces break down bone (resorption) Matrix 25% water 25% protein fibers collagen gives bones flexibility and strength 50% mineral salts mainly calcium phosphate and calcium carbonate (hydroxyapatite = mineral salts) b. gives bone hardness Compact bone makes up outer portion of all bones and diaphyses of long bones made up of osteons (Haversian systems) with interstitial lamellae in between blood and lymphatic vessels and nerves run through canals matrix arranged in lamella osteocytes in lacunae lacunae connected to one another by canaliculi (filled with ECF) Spongy bone makes up most of bone tissue in short, flat and irregular bones, and epiphyses of long bones site of red marrow in adults (axial skeleton, girdles, proximal epiphyses of humerus and femur) no true osteons lamellae arranged in trabeculae Ossification (formation of bone) Intramembranous bone forms within a CT membrane most bones of skull, clavicles basic steps mesenchyme (embryonic CT) develops into osteoblasts at center of ossification, matrix is secreted osteoblasts are now osteocytes in lacunae matrix hardens as minerals deposited trabeculae develop (woven bone) outer layers replaced by compact bone Endochondral bone replaces cartilage (most bone formed this way) basic steps hyaline cartilage model surrounded by perichondrium periosteum develops, bone collar forms cartilage in center of diaphysis calcifies primary ossification center forms secondary ossification centers form in epiphyses Bone Growth Growth in length of long bones cartilage at epiphyseal plate grows toward epiphyseal end other side of epiphyseal plate ossifies continues until growth completed in early adulthood eventually the whole plate ossifies and becomes epiphyseal line Appositional growth (growth in diameter) osteoclasts in endosteum destroy inner portion of bone osteoblasts in periosteum produce new bone on outer surface Bone Remodeling Bone is constantly being broken down and reformed particularly in areas where bone is stressed Repair of Fractures Hematoma formation due to broken blood vessels, hematoma forms (mass of clotted blood) bone cells deprived of nutrition die fracture site become swollen and painful capillaries grow into hematoma, osteoclasts and macrophages remove dead tissue and debris Fibrocartilage callus fibroblasts and osteoblasts migrate from periosteal and endosteal membranes fibroblasts make collagen that connects the broken bone ends chondroblasts secrete cartilage matrix osteoblasts form spongy bone this callus "splints" the bone Bony callus osteoclasts and osteoblasts break down fibrocartilage callus and form bony callus Remodeling occurs until bone completely healed Chapter 9 Joints Structural Classification Based on whether there is a joint cavity and the type of CT fibrous joint no cavity fibrous CT holds bones together cartilaginous joint no cavity cartilage holds bones together synovial joint has synovial cavity articular capsule and ligaments hold bones together Functional Classification Based on movement allowed synarthroses are immovable amphiarthroses are partially movable diarthroses are freely movable Fibrous Joints Sutures in skull dense fibrous CT functionally synarthrotic other sutures (synostoses) complete fusion of bone functionally synarthrotic Syndesmoses more CT than a suture (longer fibers) dense regular CT forms ligament or interosseous membrane functionally amphiarthrotic (depends on length of fibers) Gomphoses peg fits into a socket functionally synarthrotic Cartilaginous Joints Synchondroses hyaline cartilage epiphyseal plate is functionally synarthrosis, later becomes synostosis 3. sternum and rib 1 is synarthrosis Symphyses fibrocartilage functionally amphiarthrotic Synovial Joints Basic structure ends of bones covered with articular cartilage (hyaline), which reduces friction and absorbs shock joint surrounded by articular capsule fibrous capsule is outer layer mostly dense irregular CT helps stabilize joint synovial membrane is inner layer areolar CT, elastic fibers, adipose secretes synovial fluid into synovial cavity, which lubricates (hyaluronic acid), supplies nutrients to articular cartilage and removes wastes (fluid is derived from plasma, coming from the blood vessels in the synovial membrane) accessory ligaments some are intracapsular (part of articular capsule) some are extracapsular help stabilize joint articular discs (menisci) fibrocartilage allow better fit of bone surfaces found in temporomandibular, knee, sternoclavicular, distal radioulnar rich nerve supply same nerves that supply skeletal muscles that cause movement at that joint sensory nerves for pain and body position rich blood supply bursae sacs of CT lined with synovial membrane provide extra cushioning between bones, tendons, ligaments, muscles and skin tendon sheaths like bursae, but wrap around tendons where there's lots of friction around tendon of biceps at shoulder, at wrist and ankle Movements at synovial joints gliding flat bone surfaces move back & forth, side to side example: intercarpal 2. angular change in angle between bones flexion (decrease in angle), example: bending elbow extension (increase in angle), example: straightening elbow; hyperextension is continuing beyond anatomical position abduction (moving bone away from midline), example: moving arm laterally adduction (moving bone toward midline), example: moving arm medially circumduction (moving in a circle, involving b-e), example: move arm in circle at shoulder 3. rotation movement of bone around its own longitudinal axis example: turning head 4. special movements occur only at specific joints elevation (upward motion), examples: closing mouth, shrugging shoulders depression (downward motion), examples: opening mouth protraction (anterior movement), examples: moving jaw forward, move clavicles forward retraction (moving back from protracted position) inversion (move soles of feet medially) eversion (move soles of feet laterally) dorsiflexion (move dorsum of foot toward tibia) plantar flexion (move sole of foot to "point the toe") supination (turning palm anteriorly or superiorly) pronation (turning palm posteriorly or inferiorly) opposition (move thumb toward fingertips) Types of synovial joints gliding or plane articulating surfaces usually flat allows gliding movement nonaxial (does not involve movement around an axis) hinge convex surface fits into concave surface allows flexion and extension monaxial (allows movement in a single axis) pivot rounded or pointed surface articulates with a ring of bone and ligament allows rotation monaxial condyloid oval shaped projection fits into oval shaped depression allows abduction, adduction, flexion, extension, circumduction biaxial saddle modified condyloid with more freedom of motion allows abduction, adduction, flexion, extension, circumduction biaxial ball & socket ball shaped surface fits into a cup allows abduction, adduction, flexion, extension, circumduction, and rotation c. triaxial Chapter 10 Muscle Tissue Muscle Basics Three types (cells are long and thin, called fibers) skeletal striated voluntary control many nuclei per cell longest fibers (extend the length of the whole muscle cardiac striated involuntary control one nucleus per cell smooth not striated involuntary control one nucleus per cell Functions movement of whole body or body parts (skeletal) of substances within body (cardiac - pumps blood, smooth - substances move through hollow organs) heat production (mostly skeletal) maintain posture and stabilize joints (skeletal) Characteristics excitability - respond to stimuli like neurotransmitters (from neurons) or hormones with electrical signals contractility - ability to develop tension (muscle fiber may shorten) extensibility - can stretch elasticity – assumes original length after stretching Skeletal Muscle Associated Connective Tissue superficial fascia (subcutaneous layer or hypodermis) areolar & adipose stores water and fat decreases heat loss protects underlying tissues deep fascia dense irregular holds together functional groups of muscle allows free movement of muscles packs spaces between muscles, nerves and blood vessels pass through less coarse CT layers protect and support muscle cells, reinforce whole muscle, provide elasticity epimysium - dense irregular CT, wraps whole muscle perimysium - dense irregular CT, wraps bundles of fibers called fascicles endomysium - similar to areolar CT, lots of reticular fibers, wraps each fiber all the CT layers are continuous with one another and with the tendons that attach the muscle to the periosteum of bone tendons are dense regular CT a flattened tendon is called an aponeurosis (may attach to bone, skin or another muscle) Skeletal muscle cells very large 10 - 100 ?m in diameter, may be many cm long plasma membrane called sarcolemma cytoplasm called sarcoplasm lots of glycogen (stored form of glucose) and myoglobin (a protein that binds O2) contains the usual organelles plus some modified ones myofibrils specialized organelles that run the length of the cell (100s-1000s/cell) made up of contractile units called sarcomeres sarcomeres are made up of myofilaments the arrangement of myofilaments causes the striations myofilaments thick filaments- made of the protein myosin, often called cross-bridges because they can bind with the thin filaments thin filaments- made of the proteins actin (where myosin binds), tropomyosin and troponin sarcoplasmic reticulum specialized smooth ER that stores calcium and releases it when signaled by a nerve impulse (an electrical signal from a neuron) T tubules the sarcolemma penetrates into deeper parts of the cell, forming hollow tubes surrounding all the myofibrils conducts electrical signals throughout the cell so all myofibrils contract at once Sliding Filament Theory when a nerve impulse signals the muscle cell, calcium is released from the SR this allows myosin to bind to actin and pull the thin filaments toward the center of the sarcomeres ATP required Blood supply lots of blood needed to supply oxygen and carry away wastes from these very active cells vessels penetrate CT layers, lot of capillaries in endomysium Nerve supply (see Chapter 14) each muscle served by at least one motor nerve containing 100s of motor neurons a motor unit is one motor neuron plus all the muscle fibers it innervates a motor unit may have only a few muscle fibers or 1000+ fewer muscle fibers per motor unit where fine, delicate control needed (eyes, fingers) more muscle fibers per motor unit where more power needed (limbs) activating more motor units at one time means a more powerful contraction neuromuscular junction area where a neuron meets a muscle fiber separated by a gap called synaptic cleft when an electrical signal (action potential) travels to the end of a neuron, the neuron releases a chemical message called a neurotransmitter (specifically, acetylcholine at the neuromuscular junction, also known as ACh) the ACh binds to the muscle cell, and initiates an electrical signal (action potential) there this ultimately results in the muscle fiber contracting Muscle tone small groups of motor units are periodically activated involuntarily this keeps the muscle ready to contract Fiber types 2. red slow twitch (a.k.a. slow oxidative) small contract slowly (use ATP at a slow rate), have lots of mitochondria, myoglobin, good capillary supply (for using O2 to make ATP) resist fatigue, good for low intensity endurance activity postural muscles in back and lower limbs have lots 2. white fast twitch (a.k.a. fast glycolytic) large contract quickly, with lots of power (use ATP at a fast rate) fewer oxygen use components (generate most ATP anaerobically - without O2) fatigue quickly, good for high intensity activity lots in arms for lifting 3. intermediate fast twitch (a.k.a. fast oxidative) medium sized contract quickly, with lots of power (like white fast twitch) have component for making ATP with oxygen (like red slow twitch) fatigue resistant, good for intermediate activities muscles used for walking have lots each muscle has a mix of the three types, but has a greater proportion of the type used most often exercise can change fiber types endurance activities(e.g., running long distances): white fast twitch → intermediate fast twitch intense activities (e.g., weight lifting): intermediate fast twitch → white fast twitch changes occur in size of fiber, blood supply, number of mitochondria, etc. generally cannot convert between slow and fast fibers (depends on nerve supply) Cardiac Muscle 100 ?m long, 15 ?m diameter Basically the same set-up of myofilaments, etc. - Cells connected by intercalated discs desmosomes and gap junctions cells contract as a unit Main electrical stimulation from specialized cells that spontaneously activate (autorhythmicity) Use oxygen to make ATP Smooth Muscle 30 - 200 ?m long, 2 - 10 ?m diameter at middle Arranged in sheets Has thick and thin filaments, but not in the same pattern as other muscle types - Two basic types multiunit groups of cells function independently innervated by autonomic (involuntary) nervous system found in large blood vessels, large airways, eye (for adjusting lens and iris), arrector pili single unit (visceral) cells electrically linked by gap junctions and contract as a unit clusters of cells are self-excitable pass electrical signal to other cells also influenced by ANS most smooth muscle in the body is this type (hollow organs) uses oxygen to make ATP can be influenced by local metabolic changes or hormones Chapter 11 Muscles Lever Systems A lever is a rigid bar that moves on a fixed point (the fulcrum) when a force is applied to it; the force (effort) applied is used to move a resistance (load) bones = levers joints = fulcrum muscles provide the effort Levers operate in one of two ways mechanical advantage load is closer to fulcrum, effort farther from fulcrum little effort moves a large load over a small distance mechanical disadvantage load is farther from fulcrum, effort is closer to fulcrum lots of effort moves a load rapidly over a large distance Types of levers first-class fulcrum between load and effort seesaws, scissors, lifting head off chest can be mechanical advantage or disadvantage second-class levers load between fulcrum and effort wheelbarrow, standing on toes mechanical advantage third-class levers (most muscles in the body are set up this way) effort between load and fulcrum tweezers, lifting using biceps mechanical disadvantage Arrangement of Fascicles Influences range of motion and power longer fibers can shorten more and have greater range of motion a greater number of shorter fibers means more power Types of arrangements parallel (tend to be less powerful) fusiform (nearly parallel) circular convergent pennate (tend to be the most powerful) Group Actions Functional types of muscles prime mover/agonist: the muscle that has the main responsibility for a particular movement antagonist: opposes the action of the agonist synergist: helps the agonist add extra force stabilize joint and prevent undesired movement 4. fixator: stabilizes prime mover One muscle may act as any of the functional types Origin and Insertion Origin: the attachment point on the more stationary (less movable) bone, usually proximal Insertion: the attachment point on the more movable bone, usually distal The insertion moves toward the origin when the muscle shortens Naming Muscles Names may be based on... location shape relative size direction of fascicles and fibers location of attachments number of origins action Selected Skeletal Muscles (see handouts) Chapter 14 Nervous Tissue Organization of the Nervous System Central nervous system (CNS) brain and spinal cord integrating and command center - Peripheral nervous system (PNS) 1. cranial nerves a. carry electrical signals to and from brain spinal nerves carry electrical signals to and from the spinal cord two main functional divisions sensory (afferent) division carries signals toward CNS, from skin, muscles and joints (somatic), and from visceral organs (visceral) motor (efferent) division carries signals away from CNS to effector organs somatic division (to skeletal muscle, voluntary control) autonomic division (to smooth and cardiac muscle, glands; involuntary control; further divided into sympathetic division ("fight or flight") and parasympathetic division ("resting and digesting") Histology Nervous tissue made up of... neurons cells that receive and transmit electrical signals neuroglia (glial cells) supporting cells of CNS and PNS Neuroglia in CNS astrocytes hold neurons together repair of injury and scar formation induce changes in blood vessels to form the blood-brain barrier hold neurons together take up and break down some neurotransmitters (chemical signal molecules) maintain ion concentrations microglia defense cells ependymal cells line cavities in brain and spinal cord help form and circulate cerebrospinal fluid oligodendrocytes send out extensions that wrap neurons, forming myelin sheaths in PNS Schwann cells make myelin sheaths satellite cells support clusters of neuron cell bodies (in ganglia) Neurons (nerve cells) highly specialized to conduct electrical signals can vary in structure but all have some common features common features cell body (soma) nucleus and other organelles well developed rough ER (Nissl bodies) plasma membrane has receptors for neurotransmitters (receives chemical signals) 4) clusters in CNS called nuclei, in PNS called ganglia dendrites relatively short, highly branched projections from cell body plasma membrane has receptors for neurotransmitters (receives chemical signals) 3) conducts electrical signals toward cell body axon (nerve fiber) one long projection from cell body, begins at axon hillock may be up to a few feet long may have branches called collaterals ends in many branches called axon terminals carries electrical signals away from the cell body (signal called depolarization or action potential or nerve impulse) when AP reaches terminals, neurotransmitters are released myelin sheath many neurons have their axons covered in myelin sheaths (helps conduct electrical signals faster) connect to other neurons at synapses Bundles of Axons Called a nerve in PNS wrapped in CT coverings (as in skeletal muscle) endoneurium wraps each fiber perineurium wraps groups of axons called fascicles epineurium wraps entire nerve Called a tract in CNS Structural classification of neurons Multipolar neurons many dendrites, one axon most neurons of the brain and spinal cord Bipolar neurons one dendrite, one axon in retina of eye, inner ear, olfactory (smell) neurons Unipolar neurons one short process from cell body branches into two processes sensory neurons peripheral process has sensory receptor 2. central process enters CNS Functional Classification of Neurons Sensory (afferent) neurons conduct signals toward CNS from skin, sensory organs, muscles, joints, viscera 2. unipolar 3. cell bodies in ganglia Motor (efferent) neurons conduct signals away from CNS to muscles and glands multipolar cell bodies usually in CNS Association neurons (interneurons) between sensory and motor neurons, and throughout brain multipolar contained entirely within CNS about 99% of neurons in the body thousands of types Gray matter and white matter of CNS Gray matter nerve cell bodies and dendrites axon terminals unmyelinated axons neuroglia White matter bundles of myelinated axons Chapter 15 The Brain and Cranial Nerves Major Parts of the Brain Cerebrum two cerebral hemispheres Diencephalon thalamus hypothalamus epithalamus Brain stem midbrain pons medulla oblongata Cerebellum two cerebellar hemispheres Protection and Coverings Cranial meninges continuous with the spinal meninges, same basic parts dura mater tough outer layer dense irregular CT arachnoid mater middle layer collagen and elastin fibers subdural space is between dura mater and arachnoid mater, contains a little fluid c. pia mater inner layer delicate CT covering brain subarachnoid space is between arachnoid mater and pia mater, contains cerebrospinal fluid dura mater has 2 layers in cranial meninges periosteal layer (outer) periosteum of cranial bones meningeal layer (inner) corresponds to spinal dura mater between layers are dural sinuses extensions of dura mater separate parts of the brain falx cerebri- between cerebral hemispheres falx cerebelli- between cerebellar hemispheres tentorium cerebelli- between cerebrum and cerebellum Cerebrospinal fluid (CSF) similar to plasma circulates through subarachnoid space functions cushions CNS d. maintained at optimal chemical levels (ions, nutrients, etc.) the ventricles are cavities within the brain that contain CSF all ventricles are interconnected to one another, the subarachnoid space, and the central canal of the spinal cord lined with ependymal cells four ventricles two lateral- each within a cerebral hemisphere, separated by a thin membrane called septum pellucidum third ventricle- between the lateral ventricles, connected to lateral ventricles by interventricular foramina (foramina of Monro) fourth ventricle- between brain stem and cerebellum, connected to third ventricle by cerebral aqueduct CSF formed at choroid plexuses capillaries covered by ependymal cells, in all ventricles CSF reabsorbed into venous circulation through arachnoid villi (extensions of arachnoid mater projecting into dural sinuses) circulation of CSF Blood-brain barrier brain capillary cells are joined by tight junctions only things that can get through the lipid bilayer of capillary cells can pass easily (e.g., O2, CO2), and some things are specially transported (glucose, amino acids) protects brain from harmful substances Cerebrum Gyri are the ridges Sulci are the grooves (deepest grooves called fissures) Paired lobes (frontal, parietal, temporal, occipital) Made up of... gray matter (cortex) allows us to perceive, understand, communicate, remember, do voluntary movements divided into many "functional areas" (but there is lots of overlap, and no one area acts alone) three major kinds of functional areas motor areas- control voluntary motor function sensory areas- conscious awareness of sensation association areas- integrate diverse information each hemisphere specializes in functions on the opposite side of the body (contralateral) hemispheres not equal in function left side generally more involved in logical, analytical tasks like language and math 2) right side generally more involved in spatial perception, art, music white matter provides for communication between all areas of CNS and PNS three main types of fibers association fibers- transmit signals between gyri in the same hemisphere commissural fibers- transmit signals from gyri in one hemisphere to the corresponding gyri in the other hemisphere (corpus callosum, anterior and posterior commissures) projection fibers- form ascending and descending tracts, transmit signals from cerebrum and other parts of brain to and from spinal cord basal nuclei (basal ganglia) groups of gray matter embedded in white matter corpus striatum (caudate nucleus and lentiform nucleus, which consists of putamen and globus pallidus) amygdala (functionally part of limbic system) mostly important in motor pathways (communicate with cortex) Diencephalon Epithalamus 1. pineal gland part of endocrine system produced melatonin, which helps regulate the biological clock Thalamus masses of gray matter and tracts of white matter two sides connected by intermediate mass made up of several nuclei, each with a functional specialty major functions preliminary processing of sensory input - screens out unimportant stimuli and passes on significant input to the appropriate area of cortex crude awareness of sensation some degree of consciousness Hypothalamus many functionally grouped nuclei integrating center for homeostasis, links the ANS and endocrine system regulates body temperature (monitors temperature of blood) regulates water balance through urine output and has "thirst center" (contains osmoreceptors that sense concentration of body fluids) regulates food intake (monitors blood levels of nutrients and hormones) controls endocrine functioning (produces hormones, regulates pituitary) plays a role in emotional and behavioral patterns (part of limbic system) controls ANS centers in brain stem (cardiovascular, respiratory) contains biological clock pituitary connected by infundibulum pituitary has two lobes anterior lobe is glandular tissue, produces and secretes hormones in response to hormones released from the hypothalamus posterior lobe is nervous tissue, stores hormones produced by the hypothalamus and releases them in response to electrical signals from hypothalamus Brain Stem Midbrain cerebral peduncles- motor and sensory fiber tracts superior cerebellar peduncles- carry info from cerebellum toward cortex reflex centers superior colliculi- visual reflexes, like eyes tracking an object inferior colliculi- auditory reflexes, like turning toward a loud noise other nuclei substantia nigra and red nucleus- involved in motor pathways, interact with basal nuclei b. nuclei for cranial nerves III and IV periaqueductal gray matter- sympathetic responses like increased heart rate and blood pressure and pain suppression Pons motor and sensory fiber tracts middle cerebellar peduncles- carry info from cortex to cerebellum nuclei for cranial nerves V, VI and VII respiratory centers- smooth out inspirations and expirations Medulla oblongata connects to spinal cord at foramen magnum motor and sensory fiber tracts pyramids - formed by pyramidal tracts, most fibers cross over here, "decussation of the pyramids" inferior cerebellar peduncles- carry info on equilibrium from vestibular nuclei and info on proprioception from spinal cord to cerebellum (olives are nuclei acting as relay stations) nuclei for cranial nerves VIII-XII ANS nuclei cardiovascular centers- regulate rate and force of heartbeat, blood pressure respiratory center- regulates basic rhythm of respiration centers for vomiting, sneezing, coughing, hiccuping, swallowing Functional Brain Areas - Reticular formation an area of gray and white matter running through the core of the brain stem motor and sensory functions important in maintaining consciousness and overall alertness of cortex (reticular activating system, RAS) Limbic System parts of cortex, basal nuclei, thalamus, hypothalamus deals with all aspects of emotion and physical expression of emotion (e.g., anger, fear, crying, laughing, gestures) Cerebellum Consists of vermis and cerebellar hemispheres with lobes (anterior, posterior, flocculonodular) Has gray and white matter (white matter forms "arbor vitae") Cerebellar peduncles connect it to brain stem Receives sensory information, especially from proprioceptors Sends information to motor areas of brain coordinates movements adjusts posture to maintain equilibrium Cranial Nerves Mnemonic device- Oh, Oh, Oh, To Touch And Feel Very Good Velvet, AH 1 I OLFACTORY 2 II OPTIC 3 III OCULOMOTOR 4 IV TROCHLEAR 5 V TRIGEMINAL 6 VI ABDUCENS 7 VII FACIAL 8 VIII VESTIBULOCOCHLEAR 9 IX GLOSSOPHARYNGEAL 10 X VAGUS 11 XI ACCESSORY 12 XII HYPOGLOSSAL Chapters 16 The Spinal Cord and Spinal Nerves Protection and coverings Vertebral column the spinal cord is in a canal formed by the vertebral foramina vertebral ligaments also protect Fat in the epidural space between wall of vertebral canal and meninges Meninges (spinal meninges), cover cord and spinal nerves until they exit vertebral column Dura mater forms sac from foramen magnum to second sacral vertebra extended thickened portions of pia mater called denticulate ligaments fuse with arachnoid mater and dura mater to hold cord in place laterally External Anatomy Extends from brain to second lumbar vertebra Two thickened areas 1. cervical enlargement a. nerves to and from upper limbs arise from this area 2. lumbar enlargement nerves to and from lower limbs arise from this area Two grooves anterior median fissure posterior median sulcus Conus medullaris end of cord tapers to a cone shape Filum terminale extension of pia mater attaches cord to coccyx Cauda equina some nerves exit the spinal cord and continue down the vertebral column to exit farther down Dorsal and ventral roots fuse to form spinal nerves Internal Anatomy Gray matter has two sides, connected by gray commissure central canal is in center, extends the length of the spinal cord (contains CSF) anterior (ventral) horns - contain cell bodies of motor neurons supplying skeletal muscle posterior (dorsal) horns- contain cell bodies of interneurons, axon terminals of sensory neurons lateral horns- contain cell bodies for autonomic motor neurons which supply smooth/cardiac muscle and glands, only in thoracic, lumbar and sacral segments function: receives and integrates incoming and outgoing signals White matter anterior (ventral) white columns, posterior (dorsal) white columns, lateral white columns ascending (sensory) tracts- carry signals to brain descending (motor) tracts- carry signals away from brain function: transmitting electrical signals ascending tracts spinothalamic (anterior and lateral) carry info on pain, temperature, deep pressure, crude touch (poorly localized) posterior column tracts (fasciculus gracilis, fasciculus cuneatus) carry info on proprioception (sense of body position, comes from muscles, tendons, joints), fine touch, pressure spinocerebellar tracts (anterior and posterior) subconscious aspects of proprioception descending tracts corticospinal tracts (anterior and lateral, a.k.a. pyramidal tracts) precise voluntary movements all other tracts (tectospinal, vestibulospinal, rubrospinal, reticulospinal) 1) subconscious movement like posture Reflexes Rapid, predictable motor response to a stimulus - Many are unlearned and involuntary all spinal reflexes are unlearned and involuntary integrating center is the spinal cord no brain involvement necessary, but brain is informed of what happened learned (acquired) reflexes integrating center is brain e.g., typing, playing a sport, driving most reflexes can be modified with conscious effort Reflex arcs receptor - receives stimulus sensory neuron - electrical signal travels to... integrating center - the part of the CNS that decides on response, brain stem or spinal cord for unlearned reflexes motor neuron - signal sent to... effector - the part of the body that responds (skeletal muscle or gland) Spinal Nerves 31 pairs named and numbered by where they exit the vertebral column 8 cervical (C1-C8, C1 exits between atlas and occipital bone) 12 thoracic (T1-T12) 5 lumbar (L1-L5) 5 sacral (S1-S5) 1 coccygeal (Co) all are "mixed" nerves, meaning they carry both sensory and motor info 3. after exiting the vertebral column, they branch into... dorsal rami, which serve the posterior body trunk ventral rami, which serve the rest of the trunk and limbs meningeal branch, which serves the meninges, vertebrae and blood vessels rami communicantes, which branch from thoracic ventral rami and contain ANS fibers 4. intercostal (thoracic) nerves serve the thorax and abdominal wall Plexuses the ventral rami of all the spinal nerves (except thoracic) branch into networks cervical plexus (from C1-C4) mostly serves skin and muscles of head, neck, shoulders, upper chest phrenic nerve serves diaphragm (for breathing) brachial plexus (from C5-T1) serves upper limbs lumbar plexus (from L1-L4) serves abdomen, lower limbs sacral plexus (from L4-S4) serves lower limbs Dermatomes A segment of skin served by cutaneous branches of a particular spinal nerve (all except C1) Some areas overlap (trunk tends to have lots of overlap, less on limbs) Chapter 19General Senses Basics Sensation: conscious or subconscious awareness of internal or external stimuli Perception: conscious awareness and interpretation of sensation Components of sensation stimulus a change in the environment capable of activating sensory neurons transduction sensory receptor or sense organ transduces stimulus into a nerve impulse conduction nerve impulse conducted to CNS by afferent fibers translation CNS receives and interprets information Sensory Receptors Display selectivity respond to a particular kind of stimulus Classification by location exteroceptors near surface of body sense the external environment touch, pressure, vibration, temperature, pain, taste, smell, hearing, vision interoceptors in blood vessels and viscera sense internal environment stretch, chemical change, pain proprioceptors in muscles, tendons, joints, inner ear sense body position and movement Classification by stimulus type mechanoreceptors sense mechanical pressure or stretching touch, pressure, vibration, proprioception, hearing, blood pressure thermoreceptors sense temperature chemoreceptors sense chemicals taste, smell, changes in body fluids photoreceptors sense light nociceptors sense pain Structural classification free dendritic endings mostly sense pain and temperature, itch Merkel discs are a modified type in the epidermis, sense light touch (adapt slowly) root hair plexuses sense movement of hairs (adapt quickly) encapsulated dendritic endings are enclosed in a CT capsule Meissner's corpuscles - in dermal papillae of hairless skin; sense light pressure, discriminative touch, vibration Pacinian corpuscles - mainly subcutaneous, some more internal; sense deep pressure, stretch, vibration (adapt quickly) Ruffini's corpuscles - deep skin layers, joint capsules; deep pressure and stretch (adapt slowly) Proprioceptors - muscle spindles and Golgi tendon organs sense stretch; joint kinesthetic receptors in joint capsules sense stretch and pain (includes Pacinian and Ruffini's corpuscles, Golgi tendon organs, free dendritic endings) Sensory (Ascending) Pathways Signals are carried to reticular formation, cortex, and cerebellum first-order neurons have sensory receptor carry signals to brain stem (along cranial nerves) or to spinal cord (along spinal nerves) c. synapse with... 2. 3. second-order neurons carry signals from spinal cord and brain stem to thalamus fibers cross over (decussate) in cord or brain stem synapse with... 4. third-order neurons a. signals go to primary somatosensory cortex (postcentral gyrus) Chapter 19Special Senses Olfactory Sensations: Smell Types of cells receptors lie in nasal epithelium of superior portion of nasal cavity bipolar neurons distal end is a dendrite with olfactory cilia (hairs), which generate impulses in response to odor molecules axon synapses with another neuron in the olfactory bulb supporting cells columnar epithelial cells, secrete mucus basal cells between supporting cells stem cells that replace old receptor cells about every month olfactory (Bowman's) glands produce mucus that empties onto the olfactory epithelium by ducts (odor molecules must dissolve in mucus to be sensed) Olfactory pathway olfactory bulb neurons receive signals from receptors sends signals along olfactory tract to olfactory area on medial surface of temporal lobe, limbic system and part of frontal lobe Gustatory Sensations: Taste Taste buds mostly on tongue, some on soft palate, cheeks and pharynx in papillae (elevations on tongue) vallate papillae are on back of tongue fungiform papillae are scattered over tongue surface filiform papillae cover the surface of the tongue but do not have taste buds three kinds of epithelial cells gustatory cells are the receptor cells (have microvilli with receptors, substance to be tasted must be dissolved in saliva in a taste pore); they synapse with sensory nerve fibers b. supporting cells c. basal cells, which can differentiate into other cell types five primary taste sensations sweet, sour, salty, bitter, savory each tends to be sensed on certain areas of tongue, but an individual receptor may respond to more than one kind of taste Gustatory pathways fibers leading from taste buds are in... facial nerves (from anterior 2/3 of tongue) glossopharyngeal nerves (from posterior 1/3) vagus (from throat and epiglottis) The three cranial nerves end in the medulla, from there fibers project to gustatory area in parietal lobe via the thalamus Visual Sensations and the Eye Accessory structures of the eye eyebrows shade eyes from sunlight, protect from perspiration eyelashes protective, when disturbed trigger reflex blinking eyelids (palpebrae) upper and lower lids separated by palpebral fissure, they meet at medial and lateral canthi (medial canthus contains lacrimal caruncle with sebaceous and sweat glands) tarsal plates - fold of connective tissue that supports lids, contains tarsal glands that produce an oily secretion to lubricate lids and prevent sticking together conjuctiva stratified columnar mucous membrane lubricates eye with mucus, has palpebral and ocular layer lacrimal apparatus lacrimal glands secrete lacrimal fluid (tears) blinking spreads tears to lacrimal canals, which drain to lacrimal sac and nasolacrimal duct, and empties into nasal cavity tears clean, protect and lubricate (contain mucus, antibodies, lysozyme) extrinsic eye muscles allow movement origins are in bones of orbit, insert into outer surface of eyeball Eyeball structure 1. fibrous tunic outer part of eye wall dense CT, mostly collagen fibers sclera - opaque, white; protects and shapes the eye, muscles insert cornea - transparent; allows light to enter the eye and bends light; covered by epithelium (outer surface is a protective stratified squamous, inner surface simple squamous) 2. vascular tunic middle layer choroid nourishes the tunics (has blood vessels) contains melanin that absorbs light and prevents scattering ciliary body connects with choroid and retina at ora serrata mostly smooth muscle that controls shape of lens ciliary processes secrete fluid called the aqueous humor suspensory ligament (a.k.a. ciliary zonule) extends from ciliary body to lens iris colored portion of eye, continuous with ciliary body posteriorly pupil is the opening made up of smooth muscle 3. sensory tunic (retina) pigmented layer prevents reflection and scattering of light within the eye (melanocytes) neural layer contains photoreceptors rods - used in dim light, allow us to perceive shades of gray, shapes, movement cones - used in bright light, different types allow us to perceive color and have sharp vision (red, green, blue) macula lutea contains mostly cones, and in the center of it is the fovea centralis which has only cones (sharpest vision when light hits here) optic disc is where the optic nerve exits the eye, called the blind spot because it has no photoreceptors 4. lens transparent fibrous proteins covered by simple cuboidal epithelium changes shape to allow focusing of light on retina 5. internal chambers and fluids a. anterior segment filled with aqueous humor secreted by ciliary processes (drains into scleral venous sinus) nourishes lens and cornea, maintains shape of eye b. posterior segment 1) contains vitreous humor, a gel that maintains pressure in the eye and holds the retina in place Visual pathway light hits rods and cones, which send signals to bipolar cells, then ganglion cells signal travels along optic nerve to thalamus, synapses with neurons to visual cortex in the occipital lobes; also goes to nuclei in midbrain which mediate pupillary light reflexes and control extrinsic eye muscles, biological clock Auditory Sensations and the Ear External ear auricle (a.k.a. pinna) elastic cartilage covered with skin directs sound into ear external auditory canal (meatus) cartilage and temporal bone lined with skin hairs, sebaceous glands, ceruminous glands (produce cerumin, a.k.a. wax, that is sticky and traps foreign material) tympanic membrane thin CT membrane with skin on outer surface and mucosa on internal surface vibrates when hit by sound waves, transferring vibrations to the bones of the middle ear Middle ear lined with mucosa and filled with air medial end has oval window and round window pharyngotympanic tube connects to pharynx (allows air pressure to equalize to tympanic membrane can vibrate freely ossicles are the bones that transmit vibration to the inner ear malleus, incus, stapes Inner ear the bony labyrinth is a cavity in the bone, filled with fluid (perilymph) that conducts vibrations the membranous labyrinth is a series of interconnecting sacs and ducts floating in the perilymph (contains endolymph that conducts vibrations) the cochlea contains the structures for hearing when sound waves strike the tympanic membrane vibration is transmitted through the ossicles to the fluid in the cochlea the structures inside vibrate and hair cells are stimulated, resulting in nerve impulses being sent along the cochlear branch of the vestibulocochlear nerve, to the medulla where most fibers cross over, to thalamus where they synapse with fibers heading to primary auditory cortex on the temporal lobe 5. vestibular apparatus contains the structures for equilibrium a. vestibule contains sacs called saccule and utricle each contains a macula which senses static equilibrium (head position) and linear acceleration semicircular canals contain cristae which sense rotational acceleration when hair cells are stimulated by changes in body position or movement, they send signals along the vestibular branch of the vestibulocochlear nerve, to the vestibular nuclei in the medulla, then on to nuclei that control eye/head/neck movements and to cerebellum Chapter 20 Endocrine System ? Basics Many interactions among endocrine glands Interacts with nervous system Acts via hormones chemical secreted into the blood that acts on target cells elsewhere in the body (only target cells have receptors for a particular hormone) function at very low concentrations prolonged effects includes neurohormones tropic hormones regulate hormone secretion of other glands General functions regulate metabolism water and electrolyte balance coping with stress growth and development reproduction RBC production digestion/absorption Glands Hypothalamus/Pituitary (anterior and posterior) Thyroid Parathyroid Adrenal (cortex and medulla) Pancreas Pineal Ovaries and Testes Thymus Other organs have endocrine function Chapter 22 The Heart Basics Found in mediastinum Enclosed in pericardium 1. fibrous pericardium attached to diaphragm, fused to vessels going to/from heart dense irregular CT protects heart, attaches it to surrounding structures, prevents over-filling 2. serous pericardium parietal layer lines inside of fibrous pericardium visceral layer (epicardium) both layers are simple squamous epithelium and areolar CT pericardial cavity lies between layers and contains serous fluid (a.k.a. pericardial fluid) which decreases friction for the beating heart -Cardiac muscle cells lots of mitochondria, uses oxygen to make ATP contraction triggered by electrical signals signal spreads to all cells and heart contracts as a unit some cells are autorhythmic (they generate their own electrical activity), but can also be influenced by ANS Layers of the heart epicardium myocardium mostly cardiac muscle fibrous skeleton dense CT fibers that reinforce myocardium and support valves limits spread of electrical activity endocardium endothelium (simple squamous epith/areolar CT) lines chambers, covers valves continuous with lining of blood vessels Anatomy of Heart Know all structures from figs. 19.5bde Pathway of blood through the heart Pulmonary circuit heart to lungs and back gas exchange occurs in lungs (picks up O2, drops off CO2) right side of heart is pump short distance, low pressure circulation Systemic circuit heart to body tissues and back gas exchange at tissues (drops off O2, picks up CO2) left side of heart is pump long distance, high resistance pathway Heart Valves Keep blood flowing in one direction only Atrioventricular valves CT covered with endothelium attached to chordae tendinae (collagen cords) which attach to... papillary muscles anchor valves, prevent opening backwards Semilunar valves CT covered with endothelium shaped like cups so won't open backwards Coronary Circulation Heart receives its blood supply from right and left coronary arteries branches from ascending aorta capillaries bring blood to tissues veins carry blood back to the circulation via coronary sinus, which empties into right atrium Most blood delivered to heart when ventricles are relaxed Intrinsic Conduction System Sets basic rhythm of heart beats Autorhythmic cells noncontractile specialized to initiate and distribute electrical signals Located in... sinoatrial (SA) node (the pacemaker) atrioventricular (AV) node atrioventricular bundle (AV bundle or bundle of His) right and left bundle branches Purkinje fibers Extrinsic Innervation Modifies basic rhythm as needed ANS sympathetic division increases rate and force parasympathetic slows rate Cardiac cycle All the events associated with blood flow during one complete heartbeat Systole is contraction phase Diastole is relaxation phase Heart sounds Described as lub-dup Caused by blood turbulence when valves close "lub" - closing of AV valves "dup" - closing of semilunar valves Chapter 23Blood Vessels General Pattern heart → arteries → arterioles → capillaries → venules → veins → heart Basic Structure Three tunics surrounding a lumen tunica intima endothelium- slick surface reduces friction basement membrane elastic lamina tunica media smooth muscle and elastin sheets regulates circulation by vasoconstriction or vasodilation tunica externa collagen and elastin fibers protect vessel and anchor it to other structures larger vessels have their own blood vessels to supply outer tissues (called vasa vasorum) Arteries Carry blood away from heart Withstand high pressure Three groups elastic arteries (conducting) aorta and major branches large (1 - 2.5 cm in diameter) lots of elastin allows expansion and recoil (recoil keeps blood moving between heartbeats) muscular arteries deliver blood to specific body organs .3 mm – 1 cm in diameter more smooth muscle, less elastin active in vasoconstriction arterioles 10 ?m - .3 mm in diameter larger ones have all three tunics smaller ones are just smooth muscle surrounding endothelium Anastomoses most tissues receive blood from more than one artery anastomoses are branches between arteries also occur between veins called collateral circulation (allows alternate pathways for blood flow) Capillaries Smallest vessels, 3 – 10 ?m in diameter Thin tunica intima only Allow exchanges between blood and tissues Near almost all cells (epithelial sheets, cartilage, some parts of eye have none) Varying distribution based on need e.g., muscles, liver, kidneys, lungs, and nervous system have lots Types 1. continuous tight junctions small gaps called intercellular clefts allow fluids and small solutes to pass most common type fenestrated some cells have "windows" covered with a thin membrane greater permeability to fluids and solutes found where absorption or filtration needed (small intestine, endocrine glands, kidney) sinusoidal very "leaky" with fenestrations and large intercellular clefts allows relatively large molecules to pass found in liver, bone marrow, lymphoid tissues, some endocrine glands Capillary beds network of capillaries that feeds tissues parts terminal arteriole feeds bed metarteriole true capillaries (have precapillary sphincters that regulate blood flow) thoroughfare channel postcapillary venule Veins Venules smallest are mostly endothelium (8 – 100 ?m diameter) larger ones have 3 tunics Veins have 3 tunics lumens larger and walls thinner than corresponding arteries not much smooth muscle or elastin valves folds of tunica intima prevent backflow due to gravity (mostly in limbs) venous sinuses specialized, flattened veins with endothelium surrounded by dense CT receive blood draining from certain areas of body (e.g., brain, heart) Circulatory Routes The "vascular tree" is constructed so all organs get a fresh supply of blood Systemic circulation all systemic arteries branch from the aorta elastic arteries are the aorta, brachiocephalic, common carotid, subclavian, vertebral, common iliac all other named arteries are muscular all systemic veins drain into one of the following: superior vena cava (head, neck, chest, upper limbs) inferior vena cava (lower parts of body) coronary sinus (coronary vessels) Pulmonary circulation Special Circulations Hepatic portal circulation picks up nutrients absorbed from digestive tract and brings them to liver liver processes and stores nutrients breaks down toxins Fetal circulation fetal respiratory organ is the placenta gets nutrients and oxygen from mother's blood does not need to send much blood through pulmonary circuit must send blood to and from placenta two umbilical arteries branch from internal iliac arteries carry blood to placenta one umbilical vein brings blood from placenta to fetus some blood goes to hepatic portal vein so liver can process most diverted to a shunt called ductus venosus eventually goes to inferior vena cava then heart two shunts divert blood away from the pulmonary circuit foramen ovale hole in interatrial septum with a valve (blood goes from right atrium → left atrium) a bit less than half the blood entering the heart is diverted this way ductus arteriosus a branch from the pulmonary trunk to the aorta blood flows to the rest of the body postnatal changes (begin immediately) umbilical arteries → medial umbilical ligaments umbilical vein → ligamentum teres (round ligament) ductus venosus → ligamentum venosum foramen ovale → fossa ovalis ductus arteriosus → ligamentum arteriosum with first breaths, ductus arteriosus constricts, more blood in left atrium raises pressure and keeps foramen ovale closed until completely fused at about one year Chapter 24Lymphatic System Lymphatic Vessels and Lymph Collect excess fluid in tissues and return it to bloodstream Lymph is basically the same as interstitial fluid (once in lymphatic vessels, it's called lymph) Lymphatic vessels (lymphatics) begin at lymphatic capillaries (initial lymphatics) closed-ended vessels found most anywhere capillary beds are (not in avascular tissues, not in CNS, red bone marrow, parts of spleen) very permeable constructed with overlapping cells that act as one-way valves cells of lymphatic capillaries are attached to tissues by anchoring filaments; when excess interstitial fluid accumulates (edema) these pull on the cells and make the openings even bigger allow any leaked plasma proteins to return to blood lymphatic collecting vessels lymph in lymphatic capillaries flows into larger vessels have 3 tunics, but very thin walls have valves similar to the ones in veins flow maintained mainly by squeezing from surrounding skeletal muscles (also smooth muscle of vessels, also breathing - the lymph flows toward low pressure of thoracic region) lymph nodes filters lymph, catches invaders lymphatic trunks drain large areas of body lymphatic ducts thoracic duct main collecting duct for lymph receives lymph from left side of upper body, entire body inferior to ribs begins at cisterna chyli empties into subclavian vein right lymphatic duct receives lymph from upper right side of body empties into right subclavian vein Lymphoid Organs and Tissues Lymph nodes found throughout body lots in neck, axillary region and groin structure capsule made of dense fibrous CT extends into node as trabeculae, which form compartments inner portions supported by reticular tissue cortex lymph sinuses (filter lymph) lymphoid tissue - has lots of lymphocytes and other defense cells, has germinal center where B lymphocytes reproduce during an immune response medulla has lymphocytes and other defense cells lymph flows in through afferent lymphatic vessels, through sinuses, exits through efferent lymphatic vessels catch foreign particles in lymph (trapped in reticular fibers) macrophages destroy particles immune responses are activated, lymphocytes can leave node and move around the body Red bone marrow produces blood cells reticular tissue and cells Thymus gland T lymphocytes migrate here and go through a maturing process signaled by thymic hormones posterior to sternum reticular tissue and cells Spleen has capsule with trabeculae, reticular tissue, lots of fibroblasts other cells include RBCs, macrophages, lymphocytes and other WBCs functions houses defense cells and immune responses are activated breaks down old blood cells (RBCs, WBCs, platelets) stores platelets Lymphoid nodules concentrations of lymphatic tissue, no capsule in lamina propria of mucous membranes (mucosa-associated lymphoid tissue or MALT) gastrointestinal tract (gut-associated lymphoid tissue or GALT) respiratory tract urinary tract reproductive tract tonsils houses defense cells and destroys invaders Appendix piece of the first part of the large intestine similar to lymphoid nodules Chapter 25Respiratory System Basics Two zones conducting zone (air passages) respiratory zone (site of gas exchange) Function gas exchange (O2 in, CO2 out) other functions such as acid/base balance, route for water and heat loss Four major processes pulmonary ventilation (breathing) external respiration gas exchange between lung air sacs and blood gas transport cardiovascular system carries O2 to tissues and CO2 back to lungs internal respiration gas exchange between blood and tissues Nose Functions airway moistens, warms and filters air External nose bone and hyaline cartilage Nasal cavity air enters by external nares (nostrils) divided by nasal septum (cartilage and bone) contains olfactory mucosa and respiratory mucosa respiratory mucosa is pseudostratified ciliated columnar epithelium debris is trapped in mucus and can be swallowed or spit out nasal conchae projections in cavity (soft tissue and bone) allow air to bounce around, so most debris is caught by mucosa 5. internal nares (posterior nasal aperture) open to throat Pharynx (throat) Air passageway Three parts nasopharynx pseudostratified ciliated columnar epithelium pharyngeal tonsils (adenoids) in posterior walls uvula closes it off during swallowing oropharynx also a food passageway stratified squamous epithelium palatine and lingual tonsils laryngopharynx also a food passageway stratified squamous epithelium Larynx (voice box) Air passageway Made up of cartilages, ligaments, muscles Epiglottis elastic cartilage flap that prevents food from entering trachea Glottis contains the vocal folds elastic fibers running between cartilages under the mucosa vibrate as air passes by space between called rima glottidis Mucosa above vocal folds is stratified squamous, below is pseudostratified ciliated columnar Trachea Air passageway Three layers mucosa pseudostratified ciliated columnar, lots of goblet cells submucosa areolar CT, seromucous glands adventitia CT with rings of hyaline cartilage cartilage keeps trachea open Bronchi and bronchial tree Right and left primary bronchi Secondary bronchi are branches that supply each lobe of lung (3 right, 2 left) Tertiary (segmental) bronchi are further branches Branches finally lead to bronchioles which are <1 mm in diameter Terminal bronchioles (<.5 mm diameter) lead to air sacs of lungs Walls of bronchi past primary bronchi cartilage rings become irregular plates of cartilage (no cartilage in smallest bronchioles) whole tree surrounded with elastic fibers smooth muscle becomes more important as the tree branches epithelium changes to columnar and cuboidal in terminal bronchioles no cilia in smallest bronchioles, macrophages take on role of debris removal Lungs Three right lobes, two left Covered by plurae visceral and parietal layers, pleural fluid between decreases friction Terminal bronchioles lead to alveoli (air sacs) Respiratory membrane is a thin layer for gas exchange, includes capillary walls Cells in alveoli simple squamous epithelium (type I cells) with thin basal lamina scattered type II cells secrete surfactant, which helps alveoli stay open 3. macrophages Chapter 26Digestive System Basics Two groups of organs alimentary canal (gastrointestinal or GI tract is a continuous tube with openings at mouth and anus) accessory organs (teeth, tongue, gallbladder, salivary glands, liver, pancreas) Digestive processes ingestion (eating) motility (propulsion and mixing) digestion (breaking down food into smaller pieces) mechanical - teeth, stomach, small intestine chemical - enzymes break down large molecules absorption (small molecules absorbed into blood and lymph) defecation (eliminating wastes) Peritoneum covers most organs below diaphragm visceral layer parietal layer peritoneal cavity with serous fluid mesenteries fused sheets of peritoneum that connect organs to abdominal wall and to each other mesentery proper - small intestine to posterior abdominal wall mesocolon - large intestine to posterior abdominal wall falciform ligament - liver to anterior abdominal wall lesser omentum - stomach to liver greater omentum - stomach to posterior abdominal wall some organs are retroperitoneal (parts of intestines, pancreas, kidneys) Tunics mucosa epithelium stratified squamous in mouth, esophagus, anal canal simple columnar in stomach and intestines lamina propria areolar connective tissue, lots of capillaries and lymphatic vessels, lymphatic nodules c. muscularis mucosae 1) thin layer of smooth muscle creates folds submucosa areolar connective tissue, lots of vessels and nerve fibers muscularis externa thicker layers of smooth muscle circular, longitudinal layers nerve fibers serosa (visceral peritoneum) intrinsic nerve plexuses (enteric nervous system) network of nerves in digestive tract wall that regulate and coordinate (submucosal and myenteric) influenced by extrinsic autonomic fibers Mouth Vestibule - area between teeth and lips Oral cavity proper - area enclosed by teeth and gums Palate hard (maxillae and palatine bones) soft (muscle) Tongue mixes food with saliva, sense of taste Salivary glands cleanse mouth and moisten food begin digestion of carbohydrates parotid, mandibular, sublingual Pharynx Oropharynx and laryngopharynx are food passageways Esophagus Food passageway Deglutition (swallowing) accomplished by muscles in mouth, pharynx and esophagus Submucosa contains mucus producing esophageal glands Muscularis externa contains some skeletal muscle Outer tunic called adventitia (fibrous CT) Joins with stomach at gastroesophageal sphincter Stomach Consists of fundus, body and antrum Functions mixing and storing food (makes chyme) begins protein digestion Has an extra layer of muscle (oblique) Joins with small intestine at pyloric sphincter Large folds of mucosa called rugae Mucosa has gastric pits which lead to gastric glands which secrete gastric juice surface epithelial cells secrete protective mucus mucous neck cells secrete mucus and reproduce/differentiate into other cell types parietal cells secrete HCl to activate enzymes secrete intrinsic factor for absorbing vitamin B12 chief cells secrete inactive enzyme pepsinogen (becomes the active pepsin) enteroendocrine cells G cells - make hormone gastrin Small Intestine The major digestive organ (most chemical digestion, nearly all absorption) Three parts duodenum retroperitoneal receives ducts from pancreas and liver most digestion & absorption occurs here jejunum ileum joins to large intestine at ileocecal valve/sphincter Mucosa modifications increase surface area available for absorption plicae circulares (circular folds) are deep folds of mucosa and submucosa villi are large projections of mucosa between villi are intestinal crypts microvilli are projections of mucosal cells (brush border, contains enzymes) mucus producing cells and enteroendocrine cells Pancreas Acinar cells secrete digestive enzymes (for protein, carbohydrates, fat) Duct cells secrete alkaline fluid to neutralize acidity of chyme Pancreatic duct and accessory duct lead to duodenum Liver Four lobes (right, left, caudate, quadrate) Made up of lobules hexagonal arrangement of hepatocytes around a central vein bile ducts carry bile to larger ducts which eventually fuse to form the common hepatic duct Kupffer cells are macrophages Bile duct joins with pancreatic duct at hepatopancreatic ampulla (empties into duodenum) Bile is stored in gall bladder Function of bile emulsify fats (break it up into small droplets to increase surface area available to digestive enzymes) make products of fat digestion soluble in intestine so they can be absorbed Large intestine Parts cecum (appendix attached) colon (ascending, transverse, descending, sigmoid) rectum anal canal Contains lots of goblet cells, little muscle muscle arranged in bands forms sacs called haustra Functions absorbs water, electrolytes, vitamins made by bacteria 2. elimination of wastes Chapter 27 Urinary System Kidneys Functions main excretory organ regulates blood volume and pressure regulates chemical makeup of blood (water/solutes, acid/base) RBC production (makes erythropoietin) Retroperitoneal Renal hilus is cleft on medial surface other structures enter and leave here Supporting tissue 1. renal capsule a. fibrous CT on surface adds protection 2. adipose tissue and renal fascia holds kidney in place, cushions, protects Internal anatomy cortex (outer layer) medulla (made up of medullary pyramids) renal columns (cortex extends between pyramids) sinus (space made by the hilus) contains vessels contains renal pelvis which drains collecting ducts (pelvis is continuous with ureter and has major and minor calyces) Blood and nerve supply renal arteries deliver about 25% of cardiac output renal veins renal plexus - network of nerve fibers Nephron functional unit of kidney (about 1 million/kidney) made up of renal corpuscle (including glomerulus) and renal tubule glomerulus and parts of tubule glomerulus knot of capillaries surrounded by Bowman's capsule (together called renal corpuscle) 2) filters blood 3) fluid in tubule called filtrate proximal convoluted tubule (PCT) begins cuboidal epithelium lots of microvilli for reabsorption and secretion loop of Henle important in ability to concentrate urine and thus conserve water squamous and cuboidal epithelium distal convoluted tubule (DCT) some microvilli collecting duct each drains several nephrons to the renal pelvis most nephrons are cortical (lie mainly in the cortex) and some are juxtamedullary (loops dip to the end of the medulla, which is called the papilla) microvasculature glomerulus has afferent and efferent arterioles, and pressure forces fluid into the nephron peritubular capillaries branch from efferent arteriole and supply kidney tissue with blood juxtaglomerular apparatus specialized cells of DCT and arterioles that regulate kidney function Ureters Continuous with renal pelvis Carry urine to bladder Three layers mucosa (transitional epithelium) muscularis (circular and longitudinal layers) adventitia Bladder Muscular sac that stores urine Trigone area between ureters and urethra Three layers mucosa (transitional epithelium) muscularis (called detrusor muscle, has longitudinal, circular, longitudinal layers) adventitia Urethra Drains urine from bladder Mucosal epithelium changes along length transitional stratified/pseudostratified columnar (in males) stratified squamous Two sphincter muscles control the flow of urine internal urethral sphincter (smooth muscle, involuntary) external urethral sphincter (skeletal muscle, voluntary) Chapter 28 Reproductive System Basics Gonads are the primary sex organs and produce gametes in typical female ovaries produce eggs in typical male testes produce sperm gonads also secrete sex hormones Accessory reproductive organs Biological sex Genetic (chromosomal) Internal and External Structures Intersex and other differences from typical Typical Male Scrotum sac of skin with superficial fascia two compartments dartos muscle (wrinkles skin) and cremaster muscle (elevates testes) control temperature for sperm production Testes outer serous membrane is tunica vaginalis inner fibrous layer is tunica albuginea divides each testis into a few hundred lobules contain seminiferous tubules which produce sperm sustentacular (Sertoli) cells support developing sperm interstitial (Leydig) cells produce testosterone Spermatic cord contains nerves, blood vessels, ducts Duct system epididymis sperm mature and are stored ductus (vas) deferens runs through spermatic cord into pelvic cavity transports sperm urethra transports sperm out of body three regions - prostatic, membranous, penile Accessory glands seminal vesicles - produce most of the semen (about 70%) prostate - produces about 30% of semen bulbourethral glands - produce mucus (pre-ejaculate) semen contains alkaline fluid to neutralize the acidity of the female reproductive tract, and fructose to provide sperm with an energy source Penis delivers sperm to female tract contains spongy CT and smooth muscle filled with vascular spaces corpus spongiosum and corpora cavernosa - fill with blood during erection Typical Female Ovaries supported by ligaments surrounded by tunica albuginea covered with cuboidal cells cortex has follicles with gametes medulla has blood vessels and nerves Uterine tubes (Fallopian tubes or oviducts) receive ovulated oocyte site of fertilization open end is infundibulum (ciliated fimbriae sweep oocyte into tube) walls have smooth muscle and thick folded mucosa (simple ciliated columnar, cilia move oocyte toward uterus) Uterus receives, retains and nourishes fertilized egg cervix opens to vagina cervical glands in mucosa secrete mucus that covers os (opening) three layers perimetrium (visceral peritoneum) myometrium (smooth muscle - longitudinal, circular, oblique) endometrium (mucosa - simple columnar) fertilized egg implants here functional layer has cyclic changes basal layer forms a new functional layer each cycle uterine glands are invaginations from lumen down to myometrium Vagina passageway for baby and menstrual flow receives semen three layers mucosa (stratified squamous) has rugae muscularis (circular and longitudinal layers) adventitia hymen extension of vaginal mucosa at external opening External genitalia (vulva) mons pubis labia majora labia minora vestibule - contains vaginal and urethral openings clitoris - fills with blood during arousal Breasts fat mammary glands Meiosis Basics most cells in the body are diploid have two copies of each chromosome (2 sets) one set from mom, one from dad indicated by "2n" gametes are haploid only one set of chromosomes indicated by "n" fertilization → back to 2n key differences from mitosis two parts- meiosis I and meiosis II the amount of genetic material is cut in half because homologous chromosomes pair ................
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