A&P 1 Chapter 4

subserous fascia

-between serous membranes and deep fascia -areolar tissue the layer between the deep fascia and the serous membranes that line the body cavities

4-4 connective tissue has varied roles in the body that reflect the physical properties of its three main types

List the specific functions of connective tissue and describe the three main categories of connective tissues.

supporting connective tissues: cartilage lacunae

Fluid cavities that contain chondrocytes, and reside in lamellae

3 useful characteristics: the relationship between the ducts and the glandular areas

a gland is branched if several secretory areas share a duct, be they tubular or acinar. the branching refers to the glandular areas, not the duct.

abscess

a localized collection of pus in the body from infection.

dense regular connective tissues: aponeurosis

a tendinous sheet that attaches a broad, flat muscle to another muscle or to several bones of the skeleton. it can stabilize positions of tendons and ligaments. associated with skull muscles, lower back and abdominal muscles, and tendons and ligaments of palms of hands and soles of feet.

4-2 Epithelia tissue covers body surfaces, lines internal surfaces, and serves other essential functions

by the end of this section: discuss the types and functions of epithelial tissue. Identify the four essential functions, list the five important characteristics of epithelial tissue, identify the various types of epithelial cell junctions and be able to answer these questions; what is the probable function of an epithelium whose cells bear microvilli? what is the functional significance of gap junctions?

types of secretions: mixed exocrine glands

contain more than one type of gland cell. submandibular salivary glands.

connective tissue fibers: reticular fibers

contain the same protein subunits as do collagen fibers, but are arranged differently. they form a branching interwoven framework that's flexible, tough, and thinner fibers than collagen. this network is called a stroma. the stroma stabilizes relative positions of functional cells, which are called the parenchyma.

blood

contains plasma which has blood cells and fragments of cell sknown as formed elements, of which there are three types, including red blood cells, white blood cells, and platelets.

connective tissue fibers: elastic fibers

contains the protein elastin. these fibers are branched and wavy and return to original length after stretching. elastic ligaments are filled with these, and are rare but have important functions, like interconnecting vertebrae.

4-7 the supporting connective tissues cartilage and bone provide a strong framework.

describe how cartilage and bone function as supporting connective tissues.

glandular epithelia

epithelia that contain gland cells that are specialized for secretion.

connective tissue

fills internal spaces, provides structural support, stores energy.

basolateral surfaces

include both the base (basal surface). where the cell attaches to underlying epithelial cells or deeper tissues, and the sides (lateral surfaces), where the cell contacts neighbors.

three major subdivisions of extracellular fluid

interstitial fluid, plasma, and lymph

methods of secretion: apocrine secretion

involves the loss of cytoplasm as well as the secretory product. apical part of cytoplasm gets packed with secretory vesicles and is shed. this happens with milk production.

3 useful characteristics: the structure of a duct

its simple if it has a single duct that doesn't split on its way to the gland cells. if it does, it's compound.

macrophages

large phagocytic cells throughout the matrix that eat damaged cells and when stimulated, release chemicals that activate the immune system and attract large numbers of additional macrophages and other cells involved in defense. they are either fixed (stay in a tissue) or free (migrate through tissues). frontline of defense.

nervous tissue

propagates electrical impulses and carries information.

serous membrane: pericardium

protective sac enclosing the heart composed of two layers with fluid between. secretes serous fluid.

functions of epithelial tissue

provide physical protection, control permeability, provide sensation and produce specialized secretions

4 common signs of inflammation

redness, heat, swelling, and pain.

stratified columnar epithilia

relatively rare, providing protection along portions of the pharynx, epiglottis, anus. and urethra, as well as along a few large excretory ducts. The epithelium has either two layers or multiple layers the latter case only the superficial cells are columnar. This is shown in figure 4-5.

exocrine glands

release their secretions directly onto an epithelial surface or into tubular passageways called ducts that open onto an epithelial surface. they are classified by three ways, which are explored in the next cards.

endocrine glands

release their secretions into the blood. their secretions are called hormones. these regulate or coordinate activities of various tissues, organs, and organ systems. these are often called ductless glands. thyroid, thymus, and pituitary glands are examples.

cubidal epithilia

resemble hexagonal boxes from their apical surfaces, and square in sectional views.

mesenchymal cells

stem cells present in many connective tissues that respond to injury by making daughter cells that turn into other connective tissue cells.

histology

study of tissues.

fasciae

superficial and deep and subserous

plasma

the colorless fluid part of blood, lymph, or milk, in which corpuscles or fat globules are suspended.

neurons

the long, thin cells of nerve tissue along which messages travel to and from the brain. they are the longest cells in your body, many being as long as a meter. most can't divide under normal circumstance, so self repair is limited. has a large body with a nucleus and a nucleolus, with dendrites extending from it and an axon to connect the cell to another.

columnar epithelia

these cells appear rectangular, but in reality are hexagonal; taller and more slender than cuboidal epithelium cells. they have elongated nuclei jthat create a narrow band close to the basement membrane.

apical surface

where the cell is exposed to an internal or external environment.

pus

yellowish liquid product of inflammation or infection liquid product of inflammation containing various proteins and leukocytes.

specializations of epithelial cells

(1) the movement of fluids over the epithelial surface, providing protection and lubrication; (2) the movement of fluids through the epithelium, to control permeability; or (3) the production of secretions that provide physical section or act as chemical messengers.

synovial fluid

Secretion of synovial membranes that lubricates joints and nourishes articular cartilage.

mesothelium

Special names have been given to the simple squamous epithelia that line chambers and passageways that do not communicate with the outside world. pleura, pericardium, and peritoneum each contain a superficial layer of this.

characteristics of epithelial tissue: avascularity

They lack blood vessels. get nutrients by diffusion or absorption.

characteristics of epithelial tissue: attachment

. The basement membrane adheres to the basal surface and to the underlying tissues to establish the cell's border and resist stretching. This basement membrane is formed from the fusion of several successive (the basal lamina and reticular lamina), a collagen , and proteoglycans (intercellular cement).

lymph

A clear, watery, sometimes faintly yellowish fluid derived from body tissues that contains white blood cells and circulates throughout the lymphatic system, returning to the venous bloodstream through the thoracic duct. forms as interstitial fluid enters lymphatic vessels where cells in immune system (lymphocytes) monitor for composition and signs of injury or infection, returning lymph to veins near heart. This process is essential to homeostasis because it eliminates local differences in levels of nutrients, wastes, or toxins, maintains blood volume, and alerts the immune system to infections that could be underway in peripheral tissues.

mucous membrane: lamina propria

A layer of loose areolar connective tissue underlying a mucous membranes just deep to the basement membrane. underlying a mucous membrane.

skeletal muscle

Voluntary, multi-nucleated striated muscle that moves bones, works in pairs and is attached to bones by tendons. incapable of dividing. new muscle fibers are produced through divisions of myosatellite cells, which are stem cells that persist into adult skeletal muscle tissue, allowing for tissue repair. a muscle contains all four types of body tissue; the fibers are tied with collagen and elastic fibers that blend into attached tendon or aponerosis, which conducts the force of contraction to a bone of the skeleton, which are pulled with each contraction to make movement.

supporting connective tissues: cartilage chondrocytes

a cell that has secreted the matrix of cartilage and become embedded in it. they are the only cells in the cartilage matrix and occupy small chambers called lacunae.

pseudostratified columnar epithelium

a columnar epithelium that includes several types of cells with varying shapes and functions. the distances between the cell nuclei and the exposed surface vary, making the epithelium layered or stratified. it isn't truly stratified because every epithelial cell still contacts the basement membrane. these cells typically have cilia.

necrosis

abnormal condition of tissue death or happens after cells have been damaged. begins several hours after original injury as lysosomal enzymes cause the damage, destroying the injured cells and some surrounding tissues, possibly resuling in pus.

functions of connective tissues

Establishing a structural framework for the body. Transporting fluids and dissolved materials. Protecting delicate organs. Supporting, surrounding, and interconnecting other types of tissue. storing energy, especially in the form of triglycerides. Defending the body from invading microorganisms.

capillaries

Microscopic vessel through which exchanges take place between the blood and cells of the body. blood pressure forces water and small solutes out of the bloodstream across the walls of these.

4-9 The three types of muscle tissue are skeletal, cardiac, and smooth

Identify the three types of muscle tissue in the body. Which type of muscle tissue has small, tapering cells with single nuclei and no obvious striations? If skeletal muscle cells in adults are incapable of dividing, how is skeletal muscle repaired?

fibroblasts

In connective tissue, cells that secrete the proteins of the fibers. always present in connective tissue proper. secrete hyaluronan and proteins (hyaluronan helps lock epithelial cells together). these two things interact with extracellular fluid to make proteoglycans that form ground substance viscous. these fibroblasts also make protein subunits to make large extracellular fibers.

keratinized

On exposed body surfaces where mechanical stress and i are potential problems, superficial layers of epithelial cells are packed with filaments of the protein keratin, creating layers that are. both tough and water resistant.

mast cells

circulate in the blood in an immature form before migrating to other vascularized areas to undergo maturation. cytoplasm is filled with granules inside mast cells, containing histamine and heparin.

glands

collection of epithelial cells that produce secretions. range from scattered cells to complex glandular organs. 2 main types classified by where they deliver their secretion: endocrine glands and exocrine glands. Most glands in the body only produce one or the other, but the pancreas and digestive tract produce both.

tissues

collections of specialized cells and cell products that carry out a limited number of functions.

4-5 Connective tissue proper includes loose connective tissues that fill internal spaces and dense connective tissues that contribute to the internal framework of the body.

compare the structures and functions of the various types of connective tissue proper, and the layers of connective tissue called fasciae. Identify the cells found in connective tissue proper. Lack of vitamin C in the diet interferes with the ability of fibroblasts to produce collagen. What effect might this interference have on connective tissue? Many allergy sufferers take antihistamines to relieve their allergy symptoms. Which cells produce the substance that this medication blocks? Which type of connective tissue contains primarily triglycerides? Name the three layers of fascia and their types of connective tissue

neuroglia aka glial cells

connective tissue holding nervous tissue together.

three general categories of connective tissues

connective tissue proper, fluid connective tissue, and supporting connective tissues .

dense regular connective tissues: tendons

cords of dense regular connective tissue that attach skeletal muscles to bones. they run longitudinally along the tendon and transfer the pull of the contracting muscle to the bone. collagen fibers run longitudinally along tendon, pulling the contracting muscle.

loose connective tissues: adopose tissue: liposuction

cosmetic surgical procedure to remove excess adipose tissue. temporary solution, risky. adipose tissue can regenerate through differentiation of mesenchymal cells.

epithelial tissue

covers exposed surfaces, lines internal passageways and chambers, produces glandular secretions. 4 functions: provide physical protection, control permeability, provide sensation, and produce specialized secretions

elastic tissue

dense regular connective tissue made up of mainly elastic fibers. elastic ligaments are almost completely dominated by thees fibers as they help stabilize the positions of the vertebrae of the spinal column.

4-12 with advancing age, tissue regeneration decreases and cancer rates increase

describe how aging affects the tissues of the body. identify some age-related factors that affect tissue and structure. what would account for the observed increase in cancer rates with age?

4-11 The response to tissue injury involves inflammation and regeneration

describe how injuries affect the tissues of the body. Identify the two phases in the response to tissue injury and list the four common signs of inflammation.

4-6 blood and lymph are fluid connective tissues that transport cells and dissolved materials

describe the fluid connective tissues blood and lymph, and explain their relationship with interstitial fluid in maintaining homeostasis. which two types of connective tissue have a fluid matrix? Describe the recirculation of fluid in the body.

4-3 cell shape and number of layers determine the classification of epithelia

describe the relationship between structure and function for each type of epithelium. identify three cell shapes characteristic of epithelial cells. when classifying epithelial tissues, know the name of a single layer of cells vs multiple layers of cells. is tissue viewed through a light microscope as simple squamous epithelium part of the skins surface? why or why not? why do the pharynx, esophagus, anus, and vagina have a similar stratified epithelial organization? name two primary types of glandular epithelia. the secretory cells of sebaceous glands fill with vesicles and then rupture, releasing their contents in this method of secretion: ____. the type of gland that releases its secretions directly into the interstitial fluid is called _____.

supporting connective tissues.

differ from connective tissue proper in having a less diverse cell population and a matrix containing much more densely packed fibers. they protea soft tissues and support the weight of part or all of the body. The two types of supporting connective tissues are cartilage and bone.

4-10 Nervous tissue responds to stimuli and propagates electrical impulses throughout the body

discuss the basic structure and role of nervous tissue. A tissue contains irregularly shaped cells with many fibrous projections, some several centimeters long. These are probably which type of cell?

serous membrane: pleura

double-layered membrane surrounding each lung. secretes serous fluid.

fibrocartilage

durable and thought due to lack of ground substance and dominating presence of densely interwoven collagen fibers. this is found in the intervertebral discs that lie between vertebrae, and around tendons/with and around joints.

connexons

embedded transmembrane proteins, each one composed of 6 connexin proteins that form a cylinder with a central pore. Two together create a narrow passageway for small molecules and ions to pass from cell to cell. Common in epithelial cells where ion movement coordinates beating of cilia. common in cardiac muscle tissue and smooth muscle tissue to coordinate muscle contractions.

intercellular connections: tight junctions

encircle the apical regions of epithelial cells. at this junction, the lipid portions of the two plasma membranes tightly bound together by interlocking membrane proteins. Inferior (under) these junctions lies a continuous adhesion belt that forms a band encircling the cells, binding them to neighbors. This band is attached to the microfilaments of the terminal web. these junctions prevent water and solutes from going between cells.

cartilage growth: interstitial

enlarges the cartilage from within due to the chondrocytes int he cartilage matrix dividing and the daughter cells creating extra matrix for growth. most important during developent.

characteristics of epithelial tissue: cellularity

epithelia are made almost entirely of cells bound closely together by interconnections known as cell junctions.

epithelial tissue: provide physical protection

epithelia protect exposed and internal surfaces from abrasion, dehydration, and destruction by chemical or biological agents.

maintaining integrity of epithelia: attachment to the basement membrane

epithelial cells must be attached to other cells or they will die. the basement membrane has a basal lamina and a reticular lamina.

4-1: The four tissue types

epithelial, connective, muscle, and nervous.Tissues are structures with discrete structural and functional properties, which combine to form organs. By the end of this section: Identify these and describe their roles.

adipocytes

fat cells. have lipids. nucleus, organells and cytoplasm are squezed to one side, forming a class ring looking thingy, but without the hollowed out part for a finger to go through.

supporting connective tissues: bone. periosteum

fibrous membrane surrounding bones; rich in blood vessels and nerve tissue. Covers a fibrous outer layer and a cellular inner layer. attaches a bone to surrounding tissues and to associated tendons and ligament. helps with bone growth and repairs after injury.

ground substance qualities

fills spaces between cells, surrounds connective tissue fibers. clear, colorless, viscous, contains proteoglycans and glycoproteins, and is viscous enough that pathogens move incredibly slowly through it and are much more often caught by phagocytes.

supporting connective tissues: cartilage

firm gel containing polysacharide derivatives called chondroitin sulfates, that form complexes with proteins in the ground substance, creating proteoglycans.

loose connective tissues: embryonic connective tissues, aka mesenchyme

first connective tissue to appear in a developing embryo, containing an abundance of star shaped stem cellsseparated by a matrix with fibe protein filaments. these produce other connective tissues. mucous connective tissue is included in this

gland structure

first method of classifying exocrine glands. unicellular vs multicellular.

multicellular glands

include glandular epithelia and aggregations of gland cells that produce exocrine or endocrine secretions. the simplest is a secretory sheet, where gland cells form an epithelium that releases secretions into an inner compartment, like the mucin-secreting stomach lining cells that protect the organ from its own enzymes and acids. these secretions go through 1+ ducts to get to the surface.

loose connective tissues

include mucous connective tissue in embyos and areolar tissue, adipose tissue, and reticular tissue in adults.

connective tissue fibers

includes collagen, reticular, and elastic fibers, all of which are formed by fibroblasts that secret protein subunits that interact in the matrix and are maintained by the fibrocytes.

connective tissue proper cell populations

includes fibroblasts, fibrocytes, adipocytes, and mesenchymal cells, all permanently residents of the connective tissue, to function in local maintanence, repair, and energy storage. the mobile cells defend and repair damaged tissues and include macrophages, mast cells, lymphocytes, plasma cells and microphages, none of which are permanent residents of the connective tissue.

maintaining integrity of epithelia: intercellular connections

includes gap junctions, tight junctions, and desmosomes, bound by cell adhesion molecules. the types of junctions allow certain specific features shared by the cells joined by them.

supporting connective tissues: types of cartilage

includes hyaline cartilage, elastic cartilage, and fibrocartilage.

connective tissue proper

includes those connective tis> with many types of cells and extracellular fibers in a viscous (syrupy) ground substance. This broad category contains a variety of connective tissues that are grouped into loose connective tissues and dense connective tissues. These groupings are based on the number of cell types present, and on the relative properties and proportions of fibers and ground substance.

nervous tissue

includes two types of cells: neurons and neuroglia.

to maintain integrity of epithelia

intercellular connections, attachment to the basement membrane, and epithelial maintenance and repair

cardiac muscle

involuntary muscle that is branched, striated, single nucleated. found only in the heart. thinner and shorter than skeletal muscle cell. centrally portioned nucleus or nuclei. consists fo interconnected branching network of cardiac muscle cells connected at specialized regions called intercalated discs. limited ability to self repair, meaning heart function is lost with damage.

four types of physical barriers of tissue membranes: synovial membrane

lines the joint cavity, excreting synovial fluid into a fibrous capsule surrounding the joint and ends of the articulating bones. has 2 layers; areolar tissue and atypical or unusual epithelium. (1) It develops within a connective tissue; (2) no basement membrane is present; (3) gaps of up to 1 mm may separate adjacent cells; and (4) fluid and solutes are continuously exchanged between the synovial fluid and capillaries in the underlying connective tissue.

nerve fibers

made up of axons and dendrites. mostly refers to axons in this book.

melanocytes

make and store melanin. present in eye and dermis.

extracellular protein fibers

make up part of the matrix, which accounts for most of the volume of connective tissues.

ground substance

make up part of the matrix, which accounts for most of the volume of connective tissues.

specialized cells

make up part of the matrix, which accounts for most of the volume of connective tissues.

deep fascia

may be referred to more specifically as muscular fascia, parietal fascia or visceral fascia, depending on location. fibers organized like sheet of plywood in that the fibers all run the same direction but are oriented differently from layer to layer. tough capsules are bound to this layer of fascia.

methods of secretion

merocrine secretion, apocrine secretion, holocrine secretion

lymphocytes

migrate throughout the body traveling through connective tissues and other tissues, increasing in numbers wherever tissue damage happens. some of these develop into plasma cells that produce antibodies that defend the body against disease.

connective tissue fibers: collagen fibers

most common fibers in connective tissue proper. long, straight, unbranched. consists of a bundle fo fibrous protein subunits wound together like a rope strand. It's flexible, but when pulled tight is stronger than steel. includes tendons and ligaments.

hyaline cartilage

most common type of cartilage. Surrounded by perichondrium except inside joint cavities. Connections between ribs and sternum is a good example. Includes articular cartilages, which cover opposing bone surfaces within many joints like the elbow and knee.

intercellular connections: desmosomes

most of these cells experience mechanical stresses like stretching, bending, twisting or compression, so the durable interconnections for these are called __________, at which CAMs and proteoglycans link opposing plasma membranes. this junction forms from two cells. each cell has a dense area connected to the cytoskeleton, which gives the desmosome and epithelium its strength, explaining why damaged cells are lost in sheets. there are two types: spot desmosomes and hemidesmosomes.

epithelial tissue: provide sensation

most of these tissues are extremely sensitive to stimulation due to large sensory nerve supply, thanks to the neuroepithelium, which is specialized to perform a particular sensory function.

maintaining integrity of epithelia: attachment to the basement membrane. more on the reticular lamina

mostly consists of reticular fibers and ground substance, both of which are discussed later on page 130. these attachments between fibers of basal lamina and reticular lamina hold the two layers together and hemidesmosomes attach these epithelial cells to the composite basement membrane. this is all a lot more clear in the diagrams on 4-3.

cartilage growth

occurs by two mechanisms: interstitial growth and appositional growth

dense connective tissues

often called collagenous tissues due to dominant fiber type of collagen. two types: dense regular connective tissue (which includes elastic tissue) and dense irregular connective tissue.

motile cilia

on ciliated epithelium. A typical ciliated cell contains bout 250 cilia that beat in a coordinated manner. The synchronized beating of the cilia moves substances over the epithelial surface. moves mucus up from the lungs and toward the throat. via the respiratory tract, trapping foreign pathogens and particles in its goop.

intercellular connections: gap junctions

permit the free diffusion of ions and small molecules between two cells. held together via connexons

microphages

phagocytic blood cells that move through connective tissues and are attracted to site of an infection or injury by chemical signals released via macrophages and mast cells.

characteristics of epithelial tissue

polarity, cellularity, attachment, avascularity and regeneration

methods of secretion: merocrine secretion

product released from an exocrine ell by secretory vesicles through exocytosis, and is the most common method of exocrine secretion.

simple cuboidal epithelium

provides limited protection and occurs where secretion or absorption takes place. these make up glands and lines portions of kidney tubules.

characteristics of epithelial tissue: polarity

refers to the presence of structural and functional differences between the exposed and attached surfaces. An epithelium consisting of a single layer of cells has an exposed apical surface and an attached basal surface. Often, apical surface has microvilli; sometimes it has cilia. It's also evident at times based on where the concentration of organelles lies within the cell (usually towards basal end).

superficial fascia

refers to the subcutaneous layer of areolar and adipose tissue that separates the skin from the underlying tissues and organs, and also provides padding and insulation.

stratified cuboidal epithelia

relatively rare, located along ducts of sweat glands and in larger ducts of mammary glands.

hemidesmosomes

resemble half of a spot desmosome. RatH' i attaching one cell to another, a hemidesmosome attaches a cell to extracellular filaments in the basement membrane, stabilizing the position of the epithelial cell and anchors it to underlying tissues.

dense regular connective tissues: ligaments

resemble tendons but connect bone to another or stabilize the positions of internal organs.

elastic cartilage

resilient and flexible due to all the elastic fibers. yellowish color. forms external flap of outer ear and epiglottis of throat.

types of secretions: serous glands

secrete a watery solution with enzymes. salvatory glands = example.

goblet cells

secrete mucin in unicellular exocrine glands, which mixes with water to form mucus. They are goblet cells if they are scattered among the absorptive cells in the columnar epithelium of the small and large intestines, but they are considered mucous cells if they're along other epithelial tissues.

types of secretions: mucous glands

secrete mucins that hydrate to form mucus. sublingual salvary glands.

types of secretions

serous glands, mucous glands, mixed exocrine glands.

stratified epithilium

several layers of these cover the basement membrane. they are located in areas exposed to mechanical or chemical stresses. surface of skin and lining of mouth are examples.

spot desmosomes

small discs connected to bands of intermediate filaments that stabilize the shape of the cell.

smooth: nonstriated involuntary muscle

smooth muscle- the nervous system does not voluntarily control smooth muscle contractions. actin and myosin filaments are organized differently from those of skeletal and cardiac muscles. they have no striations.

cell junctions

specialized areas of the plasma membrane that attach a cell to another cell or to extracellular materials. The three most common types of cell junctions are gap junctions. junctions, and desmosomes.

all connective tissues share these characteristics

specialized cells, extracellular protein fibers and a fluid known as ground substance are the three basic components shared by all connective tissues.

cardiac: intercalated discs

specialized connections between myocardial cells containing gap junctions and desmosomes. Structures in muscle cells that connect heart tissue to ensure a smooth and rapid contraction.

muscle tissue

specialized tissue for contraction to produce movement. three types; skeletal, cardiac and smooth.

simple squamous epithelium

te body s most delicate type of epithelium. in protected regions where absorption or diffusion takes place, or where a slick, slippery surface reduces friction. {alveoli} of the lungs. lining of the heart and blood vessels.

dense connective tissues: regular

tendons, ligaments, aponeurosis.

aging has these two important effects on tissues

the body's ability to repair damage to tissues decreases and cancer is more likely to occur.

inflammation

the inflammatory response; a process that isolates the injured area while damaged cells, tissue components, and any dangerous microorganisms, which could cause infection, are cleaned up.

loose connective tissues: areolar tissue

the least specialized connective tissue in adults. It may contain all the cells and fibers of any connective tissue proper in a very loosely organized array. A viscous ground substance provides most of its volume and absorbs shocks. fibers are loosely organized in an open framework and areolar tissue returns to its original shape after external pressure is relieved. underneath it has an extensive blood supply. common durig injection site. capillaries deliver oxygen and nutrients and remove carbon dioxide and waste products in areolar tissues.

smooth muscles

the muscles found in organs, blood vessels, and glands.

body

the nucleus-containing central part of a neuron exclusive of its axons and dendrites that is the major structural element of the gray matter of the brain and spinal cord, the ganglia, and the retina

regeneration

the repair process that restore normal function after inflammation has subsided.

fibrocytes

the second most abundant cell in connective tissue proper. They differentiate i fibroblasts. Fibrocytes are spindle-shaped cells that maintain the connective tissue fibers of connective tissue proper.

endothelium

the simple squamous epithelium lining the inner surface of the heart and all blood vessels

four types of physical barriers of tissue membranes: cutaneous membrane

the skin; composed of epidermal and dermal layers. consists of keratinized stratified squamous epithelium and a layer of areolar tissue reinforced by underlying dense irregular connective tissue. it's thick and relatively waterproof and usually dry.

four types of physical barriers of tissue membranes: mucous membranes

the specialized epithelial tissues that line the respiratory, digestive, reproductive, and urinary systems. must be kept moist to reduce friction so it can help to also occasionally facilitate absorption or secretion. areolar tissue component of this membrane is the lamina propria. simple epithelia help perform absorptive or secretary functions, but occasionally other types can be involved as well, like the stratified squamous epithelium part of this membrane of the mouth.

3 useful characteristics of the structure of multicellular exocrine glands

the structure of a duct, the shape of the secretory portion of the gland, and the relationship between the ducts and the glandular areas.

microvilli

these are especially abundant on epithelial surfaces where absorption and secretion take place, such as along portions of the digestive system and kidneys. transport specialists. 20 times more surface area per cell thanks to these.

simple epithelium

these are necessarily thin, making them fragile. These are located only in protected areas inside the body to line internal compartments and passageways like the pleural, pericardial and peritoneal cavities, heart chambers, and blood vessels .this type of epithelia has regions in which secretion or absorption occurs, like gas exchange in lungs.

epithelial tissue: produce specialized secretions via gland cells

these are scattered among other cell types in the epithelium. the glandular epithelium either discharge their secretions onto the surface of the epithelium as protection or temp regulation, or release them into the surrounding interstitial fluid and blood as chemical messengers.

maintaining integrity of epithelia: epithelial maintenance and repair

these cells are consistently exposed to enzymes, toxic chemicals, pathogenic bacteria, physical distortion, and mechanical abrasion. the epithelial cells are exposed to a variety of enzymes and abraded by partially digested food in the lining of your small intestine, so it only lasts a day before its shed or destroyed, making continual division of stem cells an absolute necessity for maintaining the overall tissue health.

functions of layers of connective tissue proper

these layers provide strength and stability, maintain the relative positions of internal organs, and supply a route for the distribution of blood vessels, lymphatic vessels, and nerves. The fasciae

4-8 Tissue membranes made from epithelia and connective tissue make up four types of physical barriers

these tissue membranes consists of an epithelium supported by connective tissue. types = mucous membranes, serous membranes, cutaneous membrane, and synovial membranes. which cavities in the body are lined by serous membranes? Which type of tissue membrane typically lines body passageways (such as the urinary tract) that open to the exterior?

3 useful characteristics: the shape of the secretory portion of the gland

they are tubular if the glandular cells form straight or coiled tubes, as they are in mucous glands of the mouth, bulbo-urethral glands in the male reproductive system and testes. . they are alveolar or acinar if they form blind pockets like mammary glands. they are tubulo-alveolar or tubulo-acinar if they form both tubes and pockets, as they do in salivary glands, the glands of respiratory passages and the pancreas.

squamous epithelia

thin, flat, and somewhat irregular in shape, like pieces of a jigsaw puzzle < from the surface the cells resemble fried eggs laid side by side. In sectional view, the disc-shaped nucleus occupies the thickest portion of each cell.

methods of secretion: holocrine secretion

this destroys the gland cell. a superficial cell in a stratified glandular epithelium becomes packed with secretory vesicles and then bursts, releasing the secretion and killing the cell. this happens with sebaceous glands.

matrix

this is made up of extracellular fibers and ground substance that surrounds the cells and makes up most off the volume of connective tissues.

structure of tissue proper

this tissue contains a varied cell population containing a matrix of extracellular fibers and viscous ground substance. We must look at the connective tissue proper cell populations, the fibers, and the ground substance.

four types of physical barriers of tissue membranes: serous membranes

three types: peritoneum, pleura, pericardium. they are sealed, internal cavities of the trunk that aren't open to the exterior. consists of mesothelium supported by areolar tissue. very thin, with primary function being minimizing friction. divided into parietal portion and visceral portion. parietal portion lines inner surface of cavity and visceral portion covers the outer surfaces of the visceral organs. excretes serous fluid out of the mesothelium. volume of this fluid is called transudate.

interstitial fluid

tissue fluid is a solution that bathes and surrounds the tissue cells of multicellular animals. It is the main component of the extracellular fluid, which also includes plasma and lymph.

loose connective tissues: reticular tissue

tissue in which reticular fibers make a stroma that supports the functional cells of these organs (liver, kidney, and spleen). this is also found in lymph nodes and bone marrow.

aging and tissue structure

tissues regeneration abilities decrease with age as the rate of energy consumption decreases with age. This is seen in hormonal alterations alongside reduced physical activity. this chages the structure and chemical composition of many tissues, causing bones to become more brittle, bruises to form more easily, and organs in which cells aren't normally replaced show more and more signs of wear and tear. The chondrocytes produce a different, thinner and less resilient cartilage component via a different form of proteoglycans than present in youth. Degeneration of tissues can be slowed or reversed, as is the case with osteoporosis.

transitional epithelia

unusual stratified epithelium because its cells can change between being squamous and cuboidal in shape, and it tolerates repeated cycles of stretching without damage. found in urinary bladder. full bladder flattens epithelium, forming stratified squamous epithelium, where as an emptied bladder would appear more plump and cuboidal.

supporting connective tissues: bone, aka osseous tissue

very little ground substance. 2/3rds of matrix of bone is calcified (mostly calcium phosphate and a bit of calcium carbonate). lacunae in matrix has osteocytes. Collagen in bones act like steel reinforcing rods and the mineralized matrix acts like concrete.

lumen

when epithelium lines a tube, the passageway is called this. the contents are prevented from reaching the basolateral surfaces of the cell, preventing enzymes and acids from digesting or damaging the underlying tissues and organs.

aging and cancer incidence

cancer rates increase with age (25% of peeps in the USA get it in their lives) mostly caused by chemical exposure, environmental factors, a combination of the two. 40% of those cancers are caused by cigarette smoke.

cardiac: striated involuntary muscle

cardiac muscles contract without a conscious effort to do so. pacemaker cells set a regular rate of contraction, and those cells can be altered by the nervous system to increase or decrease the rate.

classification of epithelia

categories based on cell shape and number of layers between basement membrane and exposed surface of epithelium. Three basic shapes: squamous, cuboidal, and columnar. 1 layer = simple, more = stratified.

characteristics of epithelial tissue: regeneration

cells that are damaged/lost are continuously replaced through stem cell divisions in the epithelium.

axon

A threadlike extension of a neuron that carries nerve impulses away from the cell body.

supporting connective tissues: cartilage perichondrium

Dense irregular connective tissue membrane covering cartilage. has two distinct layers; outer fibrous region of dense irregular connective tissue, and inner cellular layer. fibrous layer gives it support and protection and attaches the cartilage to other structures.

serous membranes: peritoneum

Double-layered membrane surrounding the abdominal organs. secretes serous fluid.

supporting connective tissues: bone. canaliculi

Hairlike canals that connect lacunae to each other so that osteocytes can communicate with blood vessels and with one another via cytoplasmic interactions that run through these passageways.

nonkeritinized

Nonkeratinized stratified squamous epithelia are found in the oral cavity, pharynx, pharynx, anus and vagina because they resist abrasion, but will dry out and deteriorate unless kept moist.

loose connective tissues: adipose tissue

adipocytes accound for most of the olume fo this, but only a fraction of the volume of areolar tissue. it provides padding and acts as an insulator. most adipose is white fat. brown fat is in infants and young children and is highly vascularized, each adipocyte containing multiple mitochondria and when stimulated by the nervous system speed up the breakdown of lipids.

loose connective tissues: embryonic connective tissues: mucous connective tissue

aka wharton's jelly, is a loose connective tissue found in many parts of the embryo, including the umbilical cord. adults don't have this.

maintaining integrity of epithelia: attachment to the basement membrane. more on the basal lamina

an amorphous, ill-organized layer thought to function as a filter. it's secreted by the adjacent layer of epithelial cells, and it restricts movement of proteins and other large molecules from underlying connective tissue into the epithelium.

epithelial tissue: control permeability

any substance that enters or leaves your body must cross this. it's relatively impermeable for some and easily permeable for other compounds, even large ones. they absorb or secrete specific substances and regulate/modify in response to certain stimuli, like hormones affecting ion and nutrient transport.

two functional regions

apical surface and basolateral surfaces

cell adhesion molecules (CAMs)

bind cells via transmembrane proteins of extracellular materials on large areas of opposing plasma membranes. These CAMs bind to each other and other extracellular materials (in the basolateral surface of the epithelium, for example)

arteries

blood vessels that carry blood away from the heart. red.

veins

blood vessels that carry blood back to the heart. blue.

dendrites

branching extensions of neuron that receives messages from neighboring neurons

classifying exocrine glands

by structure, by how they secrete their products and by what products they secrete.

unicellular glands

in epithelia that have independent, scattered gland cells, the individual secretory cells are called ______ _____. these consist of single cells called goblet cells, specialized for secretion.

chondroitin sulfates

form complexes with proteins in the ground substance, producing proteoglycans in cartilage.

dense connective tissues: irregular

form interwoven meshwork in no consistent pattern. Gives the dermis its strength. forms a capsule that surrounds internal organs and encloses cavities of joints. At joints, these tissues also form a sheath around cartilages (perichondrium) and bones (periosteum).

supporting connective tissues: bone. osteocytes

former osteoblasts that have become trapped in the matrix they deposited to become mature.

simple columnar epithelium

found where absorbtion or secretion takes place, like small intestine. protect against chemical stresses.

synovial joint

freely movable joint containing a cavity filled with synovial fluid.if its immobilized for long periods, it undergoes degenerative changes in the synovial membrane and articular cartilages.

stratified squamous epithelium

generally located where mechanical stresses are severe. form a series of layers (surface of the skin and the lining of the mouth, esophagus, and anus). can be either keratinized or nonkeratinized

cartilage growth: appositional

gradually increases size of cartilage by adding to its outer surface by the repeated division of the inner layer of the perichondrium creating chondroblasts (immature chondrocytes) which begin producing cartilage matrix as they become surrounded by it and embedded in it to differentiate and mature into cartilage. occurs during development or after damage to cartilage or stimulation by a growth hormone directed by the pituitary gland.

fluid connective tissues

have distinctive populations cells suspended in a watery matrix that contains dissolved proteins. The only two types are blood and lymph.

mast cells: histamine and heparin

histamine stimulates inflammation and heparin is an anticoagulant.