4-2Membranes



Chapter 4. IntroductionObjectivesList the four main types of tissuesDefine the function and location of tissuesDefine the function and location of membranesDefine an organ and organ systemRelate various organs to their respective systemsDescribe the processes involved in the two types of tissue repairDefine the key words that relate to this chapterKey Wordsadipose tissueaponeurosesareolar tissuebactericidalcalcify?cardiac muscle?cartilage?collagen?connective tissueelastin?epithelial tissuefasciaegastric mucosagraftgranulationhyalineintestinal mucosa?ligament?membrane?mucosa4-1TissuesMulticellular organisms are composed of many different types of cells. Each of these cells performs a special function. These millions of cells are grouped according to their similarity in shape, size, structure, intercellular materials, and function. Cells so grouped are called?tissues. There are four main types of tissue:(1)Epithelial tissue?(ep-ih-THEE-lee-al)?protects the body by covering internal and external surfaces. Epithelial tissue in the lining of the small intestine absorbs nutrients. All glands are made of epithelial tissue. The endocrine glands secrete hormones, mucous glands secrete mucus, and the intestinal glands secrete enzymes. Epithelial tissue also excretes sweat. The epithelial tissue is named according to its structure.(2)Connective tissue?connects organs and tissues. Connective tissue allows for movement and provides support for other types of tissue. Connective tissue is classified into subgroups:?adipose tissue,?areolar tissue, dense fibrous tissue, and supportive tissue.(3)Muscle tissue?contains cell material that has the ability to contract and move the body.(4)Nervous tissue?contains cells that react to stimuli and conduct an impulse.Nervous tissue controls and coordinates body activities, controls our emotions, and allows us to learn through the memory process. Nervous tissue includes the special senses of sight, taste, touch, smell, and hearing.Specialization of cells can be seen in a study of the epithelial cells that make up epithelial tissue. Epithelial cells that cover the body's external and internal surfaces have a typical shape—squamous, cuboidal, or columnar. This variation is necessary so the epithelial cells can fit together smoothly in order to line and protect the body's surface. Muscle cells making up muscle tissue are long and spindlelike so they can contract.Some tissues consist of both living cells and various nonliving substances which the cells build up around themselves. The variations, functions, and locations of each type are described in?Table 4-1.Table?4-1Different Kinds of Human TissueType of TissueFunctionCharacteristics and LocationMorphologyI. EpithelialCells form a continuous layer covering internal and external body surfaces, provide protection, produce secretions (digestive juices, hormones, perspiration), and regulate the passage of materials across themselves.A. Covering and Lining TissueThese cells can be stratified (layered), ciliated, or keratinized (hard, nonliving substance).1. Squamous Epithelial CellsThese are flat, irregularly shaped cells. They line the heart, blood and lymphatic vessels, body cavities, and alveoli (air sacs) of the lungs. The outer layer of the skin consists of stratified and keratinized squamous epithelial cells. The stratified squamous epithelial cells on the outer skin layer protect the body against microbial invasion.? Cengage Learning 20142. Cuboidal Epithelial CellsThese cube-shaped cells line the kidney tubules and cover the ovaries and secretory parts of certain glands.? Cengage Learning 20143. Columnar Epithelial CellsThese cells are elongated, with the nucleus generally near the bottom and often ciliated on the outer surface. They line the ducts, digestive tract (especially the intestinal and stomach lining), parts of the respiratory tract, and glands.? Cengage Learning 2014B. Glandular or Secretory TissueThese cells are specialized to secrete materials such as digestive juices, hormones, milk, perspiration, and wax. They are columnar or cuboidal shaped.1.?Endocrine Gland CellsThese cells form ductless glands that secrete their substances (hormones) directly into the bloodstream. For instance, the thyroid gland secretes thyroxin, and adrenal glands secrete adrenaline.2.?Exocrine Gland CellsThese cells secrete their substances into ducts. The mammary glands, sweat glands, and salivary glands are examples.? Cengage Learning 2014II. ConnectiveCells whose intercellular secretions (matrix) support and connect the organs and tissues of the body.A. Adipose TissueThis tissue stores lipid (fat), acts as filler tissue, cushions, supports, and insulates the body.Connective tissue is found almost everywhere within the body: bones, cartilage, mucous membranes, muscles, nerves, skin, and all internal organs.Adipose tissue is a type of loose, connective tissue composed of saclike adipose cells; they are specialized for the storage of fat. Adipose cells are found throughout the body: in the subcutaneous skin layer, around the kidneys, within padding around joints, and in the marrow of long bones.? Cengage Learning 2014B. Areolar (Loose Connective) TissueThis tissue surrounds various organs and supports both nerve cells and blood vessels that transport nutrient materials (to cells) and waste (away from cells). Areolar tissue also temporarily stores glucose, salts, and water. Areolar tissue easily stretches and resists tearing.Areolar tissue is composed of a large, semifluid matrix, with many different types of cells and fibers embedded in it. These include fibroblasts (fibrocytes), plasma cells, macrophages, mast cells, and various white blood cells. The fibers are bundles of strong, flexible, white fibrous protein called?collagen, and elastic single fibers of?elastin. Areolar tissue is found in the epidermis of the skin and in the subcutaneous layer with adipose cells.? Cengage Learning 2014C. Dense Fibrous TissueThis tissue forms ligaments, tendons, aponeuroses, and fasciae.?Ligaments?are strong, flexible bands (or cords) that hold bones firmly together at the joints.?Tendons?are white, glistening bands that attach skeletal muscles to the bones.?Aponeuroses?are flat, wide bands of tissue that hold one muscle to another or to the periosteum (bone covering).?Fasciae?are fibrous connective tissue sheets that wrap around muscle bundles to hold them in place.Dense fibrous tissue is also called white fibrous tissue, because it is made from closely packed white collagen fibers. Fibrous tissue is flexible, but not elastic. This type of tissue has a poor blood supply and heals slowly.? Cengage Learning 2014D. Supportive Tissue1.?Osseous (bone) tissueComprises the skeleton of the body, which supports and protects underlying soft tissue parts and organs and also serves as attachment points for skeletal muscles.This connective tissue's intercellular matrix is?calcified?by the deposition of mineral salts (like calcium carbonate and calcium phosphate). Calcification of bone imparts great strength. The entire skeleton is composed of bone tissue.? Cengage Learning 20142.?CartilageProvides firm but flexible support for the embryonic skeleton and part of the adult skeleton.a.?HyalineForms the skeleton of the embryo.Hyaline cartilage is found on articular bone surfaces, and also at the nose tip, bronchi, and bronchial tubes. Ribs are joined to the sternum (breastbone) by the costal cartilage. It is also found in the larynx and in the rings of the trachea.? Cengage Learning 2014b. Fibro cartilage?A strong, flexible, supportive substance, found between bones and wherever great strength (and a degree of rigidity) is needed.Fibro cartilage is located within intervertebral discs and symphysis pubis between the pubic bones.? Cengage Learning 2014c. Elastic cartilageThe intercellular matrix is embedded with a network of elastic fibers and is firm but flexible.Elastic cartilage is located inside the auditory ear tube, external ear, epiglottis, and larynx.? Cengage Learning 2014E. Vascular (Liquid Blood Tissue)1. BloodTransports nutrient and oxygen molecules to cells, and metabolic wastes away from cells (can be considered as a liquid tissue). Contains cells that function in the body's defense and in blood clotting.Blood consists of two major parts: a liquid called plasma, and a solid cellular portion known as blood cells (or corpuscles). The plasma suspends corpuscles, of which there are two major types: red blood cells (erythrocytes) and white blood cells (leukocytes). The types of leukocytes are lymphocytes, monocytes, neutrophils, basophils, and eosinophils. A third cellular component (actually a cell fragment) is platelets (thrombocytes). Blood circulates within the blood vessels (arteries, veins, and capillaries) and through the heart and lungs.? Cengage Learning 20142. LymphTransports tissue fluid, proteins, fats, and other materials from the tissues to the circulatory system. This occurs through a series of tubes called the lymphatic vessels.Lymph fluid consists of water, glucose, protein, fats, and salt. The cellular components are lymphocytes and granulocytes. These components flow in tubes called lymphatic vessels, which closely parallel the veins and bathe the tissue spaces between cells.? Cengage Learning 2014III. MuscleA. Cardiac MuscleThese cells have the ability to contract to enable the heart to pump blood throughout and out of the heart.Cardiac muscle?is a striated (having a cross-banding pattern), involuntary (not under conscious control) muscle. It makes up the walls of the heart.? Cengage Learning 2014B. Skeletal (Striated Voluntary) MuscleThese muscles are attached to the movable parts of the skeleton. They are capable of rapid, powerful contractions and long states of partially sustained contractions, allowing for voluntary movement.Skeletal muscle?is striated (having transverse bands that run down the length of muscle fiber), voluntary because the muscle is under conscious control, and skeletal because these muscles attach to the skeleton (bones, tendons, and other muscles).? Cengage Learning 2014C. Smooth (Nonstriated Involuntary) MuscleThese muscles provide for involuntary movement. Examples include the movement of materials along the digestive tract, and control of the diameter of blood vessels and the size of the pupil of the eye.Smooth muscle is nonstriated because it lacks the striations (bands) of skeletal muscles; its movement is involuntary. It makes up the walls of the digestive tract, genitourinary tract, respiratory tract, blood vessels, and lymphatic vessels.? Cengage Learning 2014IV. NerveA. Neurons (Nerve Cells)These cells have the ability to react to stimuli.1.?IrritabilityAbility of nervous tissue to respond to environmental changes.2.?ConductivityAbility to carry a nerve impulse (message).Nerve tissue consists of neurons (nerve cells). Neurons have branches through which various parts of the body are connected and their activities coordinated. They are found in the brain, spinal cord, and nerves.? Cengage Learning 2014??Cengage Learning?20144-2MembranesA?membrane?is formed by putting two thin layers of tissue together. The cells in the membrane may secrete a fluid. Membranes are classified as epithelial or connective.4-2aEpithelial MembranesEpithelial membranes are classified as either?mucous?or?serous membranes, depending on the type of secretions produced,?Figure 4-1.Figure?4-1Mucous and serous membranes? Cengage Learning 2014Mucous MembranesThe Effects of Aging on TissueAging changes are found in all of the body's cells, tissues, and organs and, as such, they affect the functioning of the body systems. As an individual ages, the cells become larger and are less able to divide and reproduce. There is an increase in pigments and fatty substances (lipids) inside the cell. Waste products accumulate in the tissue with aging. A fatty brown pigment called lipofuscin collects in many tissues. Connective tissue becomes progressively stiff. This makes the organs, tissues, and airways more rigid. The cell membranes change, resulting in many tissues having difficulty receiving oxygen and nutrients and getting rid of carbon dioxide and wastes. Many tissues lose mass and atrophy.??Cengage Learning?2014Mucous membranes line surfaces and spaces that lead to the outside of the body; they line the respiratory, digestive, reproductive, and urinary systems. The mucous membrane produces a substance called mucus, which lubricates and protects the lining. For example, the mucus in the digestive tract protects the lining of the stomach and small intestines from the digestive?juices. The term?mucosa?is used for the following specific mucous membranes (Figure 4-1).Respiratory mucosa?lines the respiratory passages.Gastric mucosa?lines the stomach.Intestinal mucosa?lines the small and large intestines.Serous MembranesThe serous membrane is a double-walled membrane that produces a watery fluid and lines closed body cavities. The fluid produced is called?serous fluid. The outer part of the membrane that lines the cavity is known as the?parietal membrane?(pah-RYE-eh-tal). The part that covers the organs within is known as the?visceral membrane?(VIS-er-al). The fluid produced allows the organs within to move freely and prevents friction. The name?serosa?is given to the specific serous membranes, all beginning with the letter p. The serous membranes are as follows (Figure 4-1):Pleural membrane?lines the thoracic or chest cavity and protects the lungs. The fluid is called pleural fluid.Pericardial membrane?lines the heart cavity and protects the heart. The fluid is called pericardial fluid.Peritoneal membrane?(pehr?-ih-toh-NEE-al)?lines the abdominal cavity and protects the abdominal organs. The fluid is called peritoneal fluid.Cutaneous Membrane (Skin)The cutaneous?(kyou-TAY-nee-ous)?membrane is a specialized type of epithelial membrane. See?Chapter 5?for a complete discussion.4-2bConnective MembranesConnective membranes consist of two layers of connective tissue. In this classification is the?synovial membrane?(sih-NOH-vee-al), which lines joint cavities. Synovial membranes secrete synovial fluid, which prevents friction inside the joint cavity.4-3Organs and SystemsAn organ is a structure made up of several types of tissues grouped together to perform a single function. For instance, the stomach is an organ consisting of highly specialized vascular, connective, epithelial, muscular, and nervous tissues. These tissues function together to enable the stomach to perform digestion and absorption.The skin that covers our bodies is no mere simple tissue, but a complex organ of connective, epithelial, muscular, and nervous tissues. These tissues enable the skin to protect the body and remove its wastes (water and inorganic salts).The various organs of the human body do not function separately. Instead, they coordinate their activities to form a complete, functional organism. A group of organs that acts together to perform a specific, related function is called an?organ system?(Figure 4-2). For example, the digestive system has the special function of processing solid food into liquid for absorption into the bloodstream. This organ system includes the mouth, salivary glands, esophagus, stomach, small intestine, liver, pancreas, gallbladder, and large intestine. The circulatory system transports materials to and from cells. It consists of the heart, arteries, veins, and capillaries.Figure?4-2The formation of the human organism progresses from simple to complex? Cengage Learning 2014Each organ system is highly specialized to perform a specific function; together they coordinate their functions to form a whole, live, functioning organism.The systems of the body are the integumentary, skeletal, muscular, nervous, endocrine, circulatory, lymphatic, respiratory, digestive, urinary, and reproductive.The functions and organs of each system are shown in?Table 4-2.Table?4-2Body SystemsBody SystemsMajor StructuresMajor FunctionsIntegumentary SystemChapter 5Epidermis, dermis, sweat glands, oil glands, nails, and hairHelps regulate body temperature, protects the body against invasion by bacteria, synthesizes vitamin D, and has nerve receptors for temperature, pressure, and pain.Skeletal SystemChapter 6Bones, joints, and cartilageSupports and shapes the body, protects the internal organs, forms some blood cells, and stores minerals.Muscular SystemChapter 7Muscles, fascia, and tendonsMakes movement possible. Moves body fluids and generates heat.Nervous SystemChapters 8?and?9Nerves, brain, and spinal cordCommunicates and coordinates body activities.Special SensesChapter 10Eyes, ears, nose, and tongueReceives visual, auditory, taste, and smell information and transmits it to the brain.Endocrine SystemChapter 11Adrenal glands, gonads, pancreas, parathyroids, pineal, pituitary, thymus, and thyroidManufactures hormones to regulate body activities.Circulatory SystemChapters 12,?13, and?14Heart, arteries, veins, capillaries, and bloodBlood circulates to all parts of the body carrying oxygen and nutrients to the cells and carrying away waste products from the cells.Lymphatic SystemChapter 15Lymph, lymphatic vessels, and lymph nodeRemoves and transports waste products from the fluid between the cells. Fluid is filtered through the lymph nodes and harmful substances are removed. Returns the filtered lymph to the blood stream where it becomes plasma again.Respiratory SystemChapter 17Nose, pharynx, larynx, trachea, bronchi, alveoli, and lungs.Brings oxygen into the body for transportation to the cells. Removes carbon dioxide and some water waste from the body.Digestive SystemChapter 18Mouth, salivary glands, teeth, pharynx, esophagus, stomach, intestines, liver, gallbladder, and pancreasPrepares food for absorption and use by the body through physical and chemical means. Eliminates solid waste from the body.Urinary SystemChapter 20Kidneys, ureters, bladder, and urethraFilters blood to eliminate waste products of metabolism. Maintains the fluid and electrolyte balance in the body.Reproductive SystemChapter 21Male: testes, epididymis, vas deferens, seminal vesicles, ejaculatory duct, prostate gland, Cowper's glands, penis, and urethraFemale: ovaries, fallopian tubes, uterus, vagina, external genitalia, and breastsReproduces new life.Manufactures hormones necessary for development of reproductive organs and secondary sex characteristics.??Cengage Learning?20144-4Disease and Injury to TissueTissue can be affected by infection or inflammation. Inflammation is a protective response to an injury or irritant. Inflammation will result in pain, swelling, redness, and loss of motion. Infection refers to the invasion of a microorganism causing disease. Infection usually results in inflammation (see?Chapter 12).Trauma resulting from an external force will cause tissue damage and injury. A wide variety of traumatic events can occur, but the most frequent cause of serious injury is motor vehicle collisions. Emergency management of trauma is necessary to prevent complications such as shock, hemorrhage, and infection.Abnormal growth of cells can also alter tissue and cause tissue damage and trauma. These types of growth patterns were discussed in an earlier chapter.Birth defects can also impair tissue. This can result from a change in structure or function of tissue at the chromosomal level or as a result of environmental factors.4-5Degree of Tissue RepairRepair of damaged tissues occurs continually during the everyday activities of living. Depending on the type and location of injury, some tissue is quickly repaired. Muscle tissue heals slowly and bone tissue repairs are slow because broken bone ends must be kept aligned and immobilized until the repair is done4-6Process of Epithelial Tissue RepairTissue Repair animationWatch the animation to learn how our bodies heal after a laceration.Volume 90%?? Cengage LearningThere are two types of epithelial tissue repair:?primary repair?and?secondary repair.4-6aPrimary Repair of a Clean WoundA?clean wound?is a cut or incision on the skin where infection is not present. In a simple skin injury, the deep layer of stratified squamous epithelium divides. The new stratified squamous epithelial cells “push” themselves upward toward the surface of the skin. The damage or wound is quickly and completely restored?to normal. However, if the damage is over a larger area, then the underlying connective tissue cells and fibroblasts are also involved.Primary Repair over a Large Skin AreaIf a large area of skin is damaged, fluid will escape from the broken capillaries. This capillary fluid dries and seals the wound, and the typical?scab?forms. The scab formation prevents pathogens from entering the site. Epithelial cells multiply at the edges of the scab and continue to grow over the damaged area until it is covered. If a great or deep area of skin is destroyed, skin?grafts?may be needed to help in wound healing.Medical Highlights?4-1Tissue and Organ TransplantOrgan transplants are proven therapy for a variety of serious diseases. In 2011, more than 28,000 organ transplants were done, but more than 100,000 people are on waiting lists for organs (statistics from? HYPERLINK "" \t "_blank" ).Thousands of people have received a blood transfusion, which is a tissue transplant. Successful tissue transplants include heart valves, veins (to improve circulation), corneas, blood, and bone. Skin tissue is used to promote healing and prevent infection in critically burned individuals.?Tissue transplants are not subject to rejection and do not require long-term therapy.Major organ transplants include kidney, heart, lung, liver, pancreas, and intestines. Bone marrow transplants differ from other transplants and are discussed in the chapter on blood (Chapter 12). The organ transplant may be from a deceased donor or a genetically compatible living donor. Timing is critical in doing an organ transplant. The shorter the time between when a donated organ becomes available and its subsequent surgical implantation, the better the chance for success. Ideally, a lung transplant should be done within 2 to 4 hours, a heart within 4 to 6 hours, a liver within 12 hours, and a kidney within 24 hours.After an organ has been successfully transplanted, the recipient must continue medical treatment for the rest of his or her life. This is due to the response of the immune system to a new organ. A transplanted organ is made of cells foreign to the body, which means the body's immune system will attack the organ if left to its own devices. Even with a good match between the donor and recipient's blood types, the body will see the organ as foreign and act to reject it. The most common type of rejection is acute rejection. This is the type for which immunosuppressive drugs are given. The drugs used to prevent rejection also suppress parts of the immune system that are necessary to fight infection and disease. Suppressing the immune system is a balancing act; the optimal result weakens the immune system just enough to prevent organ rejection, but leaves it strong enough to fight infection and disease.Living with a transplant is a continuing challenge; however, in most cases it does enable the recipient to live a full and active life. The goal of researchers is to coax the immune system into accepting an organ transplant without the lifelong need for immune-suppressing drugs.A major issue today is the concern that there has been a decline in the number of living donor organs available for transplants during the past 5 years. According to Dr. Andrew Klein, director of the Cedars-Sinai Medical Center Comprehensive Transplant Center, the single largest factor is that solid organ transplants have been so successful it is has encouraged physicians and their patients to opt for transplantation as a method of treatment.??Cengage Learning?2014Primary Repair of Deep TissueWhen damage occurs to deep tissues, the edges of the wound must be brought (sewn) together with?sutures. For example, operative incisions or wounds have a tremendous amount of serous fluid that leaks out onto the wound. This helps to form a coagulation (clot) that seals the wound. The coagulum contains tissue fragments and white blood cells. In 24 to 36 hours, the epithelial cells lining the capillaries (endothelium) and fibroblasts of connective tissue degenerate rapidly. The newly formed cells remain along the edges of the wound. On the third day following injury, new vascular tissue starts to form. This multiplies across the wound, along with connective tissue formation.On the fourth or fifth day, fibroblast cells become very active in making new collagen fibers. In addition, capillaries grow and “reach” across the wound, holding the edges firmly together. Toward the end of the healing process, the collagenous fibers shorten, reducing scar tissue to a minimum. Scar tissue is strong but lacks the flexibility and elasticity of most normal tissue. Scar tissue cannot perform the functions of the normal tissue it has replaced.4-6bSecondary RepairDuring secondary repair, a process called?granulation?occurs in a large open wound with small or large tissue loss. The granulation process will form new vertically upstanding blood vessels. These new blood vessels are surrounded by young connective tissue and wandering cells of different types. Granulation causes the surface area to have a pebbly texture. Fibroblasts will be quite active in the production of new collagenous fibers. The activity of this repair causes the large open wound to eventually heal. As granulation occurs, a fluid also is secreted. This fluid has strong?bactericidal?(bacteria-destructing) properties, which help reduce the risk of infection during wound healing.As in any type of tissue repair, a certain amount of scar tissue will form. The amount of tissue formed depends on the extent of tissue damage. Careful attention must be given to patients whose body or body parts are undergoing massive tissue repair (e.g., victims of burns). These areas?must?be kept in alignment and immobile at the beginning; however, later active movement should be encouraged so that, as new tissue forms, pulling from scar tissue will not occur. It is the role of the health care professional to help prevent or minimize excessive scar tissue formation that can lead to disfigurement.A health care professional should also be mindful that proper nutrition plays an important part in healing. Newly growing tissues require lots of protein for repair; thus, the need for protein-rich foods is important.Vitamins also play an essential role in wound repair (see?Chapter 19). They help the patient develop resistance to infections.?Table 4-3?lists vitamins that are needed in tissue repair.Table?4-3Vitamins Favorable to Tissue RepairVitaminFunctionVitamin AAids in repair of epithelial tissue, especially the epithelial cells lining the respiratory tract.Vitamin B (thiamine, nicotinic acid, and riboflavin)Helps to promote the general well-being of the individual. Specifically helps to promote appetite, metabolism, vigor, and pain relief in some cases.Vitamin CHelps in the normal production and maintenance of collagen fibers and other connective tissue substances.Vitamin DNeeded for the normal absorption of calcium from the intestine. Possibly helps in the repair of bone fractures.Vitamin KHelps in the process of blood coagulation.Vitamin EHelps healing of tissues by acting as an antioxidant protector. It prevents important molecules and structures in the cell from reacting with oxygen. (When delicate components of living protoplasm are attacked by oxygen, they are literally “burned.”)??Cengage Learning?2014Medical Terminologyadiposfatty-epertaining toadipos/epertaining to fattybacteriasingle-cell microorganisms-cidalto kill or destroybacteri/cidalto destroy rod-shaped microorganismscardiheart-acpertaining tocardi/acpertaining to heartmucslime-ouspertaining tomucouspertaining to a slimy substanceparietwall-alpertaining topariet/alpertaining to the wall of a body cavityperiaroundperi/cardi/alpertaining to around the heartserwatery-ouspertaining toser/ouspertaining to a watery substanceviscerguts or internal organsviscer/alpertaining to the internal organs ................
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