Introduction to the Human Body



Unit 1 Introduction to the Human Body

Anatomy

The branch of science dealing with the form and structure of body parts

Physiology

The branch of science pertaining to the study of body functions

Levels of Organization

Arranged from Smallest to Largest

Atom → Molecule → Cell → Tissue → Organ → Organ System → Organism

Homeostasis

State of balance in which the body's internal environment remains within a normal range despite changing external circumstances

Mechanisms that help maintain homeostasis are called homeostatic mechanisms and include temperature control, blood sugar control, blood pressure regulation, and water balance among other things

Anatomical Position

Refers to an individual standing erect with their face forward, upper limbs hanging to their sides with the palms of their hands facing forward, thumbs pointing outward, and feet pointing straight ahead

What are cavities?

Large internal spaces within the body

What are viscera?

Organs within the cavities of the body

Major Cavities of the Human Body

Cranial cavity

Spinal cavity

Thoracic cavity

Abdominal cavity

Pelvic cavity

Common Anatomical Terms

Superior – toward the head

Inferior – away from the head

Anterior – toward the front of the body

Posterior – toward the backside of the body

Medial – toward the body's midline

Lateral – toward the body's peripheral edges or away from the midline

Intermediate – area in between the medial and lateral regions

Proximal – closer to the point of attachment

Distal – away or further from the point of attachment

Superficial – toward the surface of the body

Deep – away from the surface of the body; located internally

11 Major Organ Systems and a Brief Description of Their Functions

There are 11 major systems in the human body. All are important for survival and play an essential role in maintaining homeostasis, or equilibrium. They are as follows:

Circulatory

Structure: The circulatory system consists of the heart, arteries (carry blood away from the heart), veins (carry blood to the heart), capillaries (where nutrient and gas exchange occurs with tissue), and blood.

Function: The function of the circulatory system is to transport blood to every part of the body. In the blood are all of the necessary gases, nutrients, and waste products; which are all transported to the necessary parts of the body.

2. Digestive

Structure: The digestive system begins with the mouth. It continues with the esophagus, stomach, small intestine, large intestine, and ends with the rectum. There are several organs that are associated with the digestion process. The liver, among other functions, produces bile (a digestive enzyme). The gall bladder stores the bile. The pancreas also secretes digestive enzymes and hormones.

Function: The function of the digestive system is to digest food and provide vital nutrients to the body. It also helps to regulate metabolism, as well as eliminate wastes.

3. Nervous

Structure: The nervous system is broken down into two parts: the central nervous system and the peripheral nervous system. The brain and spinal cord combine to create the central nervous system (acts as the body’s control center and coordinates body’s activities). The nerves that carry messages to and from the central nervous system to the entire body makes up the peripheral nervous system.

Function: The nervous system controls all bodily activities.

4. Endocrine

Structure: The endocrine system consists of a network of glands including the pituitary, thyroid, thymus, pancreas, testes, ovaries, adrenal, and parathyroid glands.

Function: The endocrine system consists of glands that secrete hormones that play a key role in the regulation of digestion, metabolism, and homeostasis.

5. Reproductive

Structure: The male reproductive system consists of the testis (produce sperm), vas deferens (tube to transport sperm), urethra (continuation of vas deferens), and the penis. The female reproductive system consists of the ovary (produces eggs), the uterus, and the vagina.

Function: The function of the reproductive systems in males and females is to perpetuate the species through reproduction.

6. Integumentary

Structure: The skin is composed of two parts, the epidermis and the dermis. The epidermis is the outer, thinner portion of the skin. The dermis is the inner, thicker portion of the skin. Also associated with the skin are melanin (pigment in the skin), keratin (dead, waterproofing cells), and hair follicles.

Function: The skin has several vital roles in maintaining equilibrium within the body. The skin is responsible for regulating your body temperature. It also serves as a protective layer to the underlying tissues.

7. Skeletal

Structure: The skeleton is comprised of two parts, the axial skeleton, and the appendicular skeleton. The axial skeleton is made up of the skull, the vertebral column, the ribs, and the sternum. The appendicular skeleton are the bones of the arms and legs, including the shoulders and pelvic girdle. Joints, ligaments (connects bones to bones), and tendons (connects muscles to bones) are also associated with the skeletal system.

Function: The skeletal system provides a framework for the tissue of the body. It also protects the upper organs. Muscles are anchored to the bones to allow for movement. Bones also produce blood cells, and store vital minerals.

Respiratory


Structure: The first part of the respiratory system is the trachea, this is the passageway of air from the mouth or nasal cavity. The trachea then divides into two bronchi, with are the tubes that lead to the lungs, which then branch into bronchioles that lead to the tiny air sacs called alveoli, where gas exchange occurs with the blood.

Function: The purpose of the respiratory system is to provide the body with oxygen, and also to dispel carbon dioxide from the body.

9. Muscular

Structure: There are three types of muscles: smooth, cardiac, and skeletal. Smooth muscle is found in internal organs and blood vessels. Cardiac muscle is found in the heart. Skeletal muscles are attached to bones. Muscles are also voluntary (skeletal muscle) or involuntary (smooth and cardiac).

Function: Smooth muscle allows for the contraction of organs (moves food along the intestines) and blood vessels (pushes blood through). Cardiac muscle is responsible for the pumping of the heart. Skeletal muscle allows for all movement of the body.

10. Excretory/Urinary

Structure: The excretory system consists of the kidneys (filters the blood), the ureters (tubes that lead from kidneys to urinary bladder), the urinary bladder (where urine is stored), and the urethra (tubes that lead from the urinary bladder to the outside of the body).

Function: The function of the excretory system is to filter the blood and remove major waste products such as ammonia and urea. It is also responsible for regulating the pH (acidity level) of the blood.

11. Immune/Lymphatic

Structure: The immune system consists of a variety of structures found throughout the body. The lymph nodes and lymph vessels are found throughout the body and help to filter out antigens (disease causing microorganisms). The tonsils, thymus gland, spleen, and bone marrow are also involved in the immune system.

Function: The function of the immune system is to protect the body from infections and antigens.

Planes of the body

Frontal – divides the body into anterior (ventral) and posterior (dorsal) portions

Sagittal – divides the body lengthwise into right and left portions

Transverse – divides the body horizontally into upper (superior) and lower (inferior) portions

Body Landmarks

Abdominal

Acromial

Antecubital

Axillary

Brachial

Buccal

Carpal

Cervical

Coxal

Crural

Digital

Femoral

Fibular

Inguinal

Nasal

Oral

Orbital

Patellar

Pelvic

Pubic

Sternal

Tarsal

Thoracic

Umbilical

Cephalic

Deltoid

Gluteal

Lumbar

Occipital

Popliteal

Sacral

Scapular

Sural

Vertebral

Unit 2 Tissues and Membranes

Tissues

A group of specialized cells that work together in order to perform a specific function

Stem Cells

Adult Stem Cells

Also referred to as somatic stem cells; An adult stem cell is a multipotent stem cell in adult humans that is used to replace cells that have died or lost function. It is an undifferentiated cell present in differentiated tissue. It renews itself and can specialize to yield all cell types present in the tissue from which it originated. So far, adult stem cells have been identified for many different tissue types such as hematopoetic (blood), neural, endothelial, muscle, mesenchymal, gastrointestinal, and epidermal cells.

Multipotent

These are less plastic and more differentiated stem cells. They give rise to a limited range of cells within a tissue type. The offspring of the pluripotent cells become the progenitors of such cell lines as blood cells, skin cells and nerve cells. At this stage, they are multipotent. They can become one of several types of cells within a given organ. For example, multipotent blood stem cells can develop into red blood cells, white blood cells or platelets.

Pluripotent

These cells are like totipotent stem cells in that they can give rise to all tissue types. Unlike totipotent stem cells, however, they cannot give rise to an entire organism. On the fourth day of development, the embryo forms into two layers, an an outer layer which will become the placenta, and an inner mass which will form the tissues of the developing human body. These inner cells, though they can form nearly any human tissue, cannot do so without the outer layer; so are not totipotent, but pluripotent. As these pluripotent stem cells continue to divide, they begin to specialize further.

Totipotent

These are the most versatile of the stem cell types. When a sperm cell and an egg cell unite, they form a one-celled fertilized egg. This cell is totipotent, meaning it has the potential to give rise to any and all human cells, such as brain, liver, blood or heart cells. It can even give rise to an entire functional organism. The first few cell divisions in embryonic development produce more totipotent cells. After four days of embryonic cell division, the cells begin to specialize into pluripotent stem cells.

Epithelium

basement membrane

Region of nonliving material that anchors epithelial tissue to underlying connective tissue

simple squamous

Structure, function, location → See previous notes (online)

stratified squamous

Structure, function, location → See previous notes (online)

simple cuboidal

Structure, function, location → See previous notes (online)

simple columnar

Structure, function, location → See previous notes (online)

pseudostratified ciliated columnar

Structure, function, location → See previous notes (online)

transitional

Structure, function, location → See previous notes (online)

Where do you find simple squamous epithelium?

Air sacs of the lungs; Lining of the heart, blood vessels, and lymphatic vessels; Lining of closed, ventral body cavities (serosa)

Where do you find simple columnar epithelium?

Lining of the digestive tract (non-ciliated); Lining of bronchi and regions of the respiratory system (ciliated); Lining of uterine tubes and some parts of the uterus (ciliated)

What type of tissue withstands friction well?

Stratified epithelial tissue; more specifically, stratified squamous epithelium

Endocrine glands

Secrete hormones directly into the blood stream; the circulatory system then carries the hormones to their target locations

Exocrine glands

Secrete substances into ducts, or tiny tubes

What type of tissue lines glands?

Glandular epithelium; Essentially, simple cuboidal epithelium wrapped in a tube

Extracellular matrix

Material that surrounds individual cells; Responsible for making each of the different kinds of connective tissue so different from one another

Loose connective tissue

Structure, function, location → See previous notes (online)

Tissue that acts as insulation

Adipose tissue

What type of tissue are tendons and ligaments made from?

Connective tissue

Tendon

Cord or band-like mass of connective tissue that connects muscle to bone

Ligament

Cord or sheet of connective tissue that binds two or more bones at a joint or articulation

Where within the body can you find...

hyaline cartilage? Fetal skeleton, Covers the ends of long bones in articulations (i.e. articular cartilage), Cartilage within the nose, trachea, larynx, and ribcage

elastic cartilage? External ear, Epiglottis

fibrocartilage? Intervertebral discs, Pubic symphysis, Disc of knee joint

Osseous tissue

Osteocytes

Osteoblasts

Osteoclasts

Nervous tissue

Structure, function, location → See previous notes (online)

Regeneration

Replacement of tissues by cells that are identical to the original cells; Occurs only in tissues that undergo mitosis, such as the skin

Fibrosis

Replacement of injured tissue by the formation of fibrous connective tissue, or scar tissue; Damaged skeletal muscle, cardiac muscle, and nervous tissue do not undergo mitosis and must be replaced by scar tissue

Mucous membranes

Line all body cavities that open to the outside of the body; Secrete mucus that lines the membrane to it keep it lubricated; Found in the digestive, urinary, respiratory, and reproductive tracts

Serous membranes

Line all body cavities that do not open to the outside of the body; Secrete a thin, watery substance that allows membranes to slide past one another with little to no friction; Found in thoracic and abdominal cavities

Skeletal muscle

Structure, function, location → See previous notes (online)

Smooth muscle

Structure, function, location → See previous notes (online)

Cardiac muscle

Structure, function, location → See previous notes (online)

Adipose

Structure, function, location → See previous notes (online)

Blood

Structure, function, location → See previous notes (online)

Reticular connective tissue

Made up of finely interwoven reticular fibers and reticular cells; Reticular connective tissue forms a scaffolding for other cells in several organs, such as lymph nodes and bone marrow. You will never see reticular connective tissue alone - there will always be other cells scattered among the reticular cells and reticular fibers; Provides support in walls of blood vessels and form a strong, supporting network aroudn fat cells, nerve fibers, and skeletal and smooth muscle fibers; Help form the basement membranes and the framework of many soft organs

1 Unit 3 Integumentary System

Functions of Integumentary System

Structures that Compose the Integumentary System

Epidermis

Dermis

Subcutaneous layer

Stratum corneum

Stratum basale

Melanocytes

UVA & UVB

Both UVA and UVB, however, penetrate the atmosphere and play an important role in conditions such as premature skin aging, eye damage (including cataracts), and skin cancers. They also suppress the immune system, reducing your ability to fight off these and other maladies.

UVA Rays

Most of us are exposed to large amounts of UVA throughout our lifetime. UVA rays account for up to 95 percent of the UV radiation reaching the Earth's surface. Although they are less intense than UVB, UVA rays are 30 to 50 times more prevalent. They are present with relatively equal intensity during all daylight hours throughout the year, and can penetrate clouds and glass.

UVA, which penetrates the skin more deeply than UVB, has long been known to play a major part in skin aging and wrinkling (photoaging), but until recently scientists believed it did not cause significant damage in areas of the epidermis (outermost skin layer) where most skin cancers occur. Studies over the past two decades, however, show that UVA damages skin cells called keratinocytes in the basal layer of the epidermis, where most skin cancers occur. (Basal and squamous cells are types of keratinocytes.) UVA contributes to and may even initiate the development of skin cancers.

UVB Rays

UVB, the chief cause of skin reddening and sunburn, tends to damage the skin's more superficial epidermal layers. It plays a key role in the development of skin cancer and a contributory role in tanning and photoaging. Its intensity varies by season, location, and time of day. The most significant amount of UVB hits the U.S. between 10 AM and 4 PM from April to October. However, UVB rays can burn and damage your skin year-round, especially at high altitudes and on reflective surfaces such as snow or ice, which bounce back up to 80 percent of the rays so that they hit the skin twice. UVB rays do not significantly penetrate glass.

Malignant melanoma

Arrector pili

Sebaceous glands

Sudoriferous glands

Eccrine glands

Apocrine glands

Acne

Classification of Burns (1st, 2nd, and 3rd Degree)

When are burns considered critical?

Unit 4 Skeletal System

What makes up the skeletal system?

Functions of the Skeletal System

Red bone marrow

Yellow marrow

Osseous tissue

Osteon or Haversian System

Osteocytes

Osteoblasts

Osteoclasts

Epiphyseal disk (or Growth Plate)

Identify Components of a Long Bone

Spongy bone

Compact bone

Periosteum

Articulations

Types of Bone Fractures

Osteoporosis

Why females are shorter than males?

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