A&P Chapter 4 - The Tissue Level of Organization
Made from the Brady book Anatomy & Physiology for Emergency Care 2nd edition by Martini, Bartholomew, and Bledsloe
Terms in this set (108)
How many different types of cells are there?
collections of specialized cells and cell products that perform a limited number of functions.
the study of tissue.
Four basic types of tissue
epithelial, connective, muscle, and neural
includes epithelia and glands.
layers of cells that vocer internal or external surfaces.
composed of secreting cells derived from epithelia.
Characteristics of epithelia
*Cells that are bound closely together. In other tissue types, the cells are often widely seperated by extracellular materials.
*A free (apical) surface exposed to the environment or to some internal chamber or passageway.
*Attachment to underlying connective tissue by a basement membrane
*The absence of blood vessels (avascular). Because of this these cells must obtain nutrients across their attached surface from a deeper tissue or across their exposed surface.
*Epithelial cells that are damaged or lost at the exposed surface are continuously replaced or regenerated.
Where is epithelia located?
covers the skin, line internal passageways that communicate with the outside world, such as the digestive, respiratory, reproductive, and urinary tracts. These form selective barriers that separate the deep tissues of the body from external environment.
line internal cavities and passageways, such as the chest cavity; the fluid-filled chambers of the eye, brain, and inner ear, and the inner surfaces of the blood vessels and heart. These prevent friction, regulate the fluid composition of internal cavities, and restrict the fluid communication between the blood and tissue fluids.
What are the functions of epithelia?
1. Provide physical protection from abrasion, dehydration, and destruction by chemical or biological agents.
2. Control permeability. Any substance entering or leaving the body must pass through epithelium. Some epithelia are relatively impermeable while others are easily crossed by compounds as large as proteins.
3. Provide sensation. Can detect changes in environment and rely info about it to the nervous system.
4. Produce specialized secretions. The cells that do this are called gland cells.
In these cells most or all of the cells actively produce secretions. These secretions are classified according to where they are discharged.
Secretions are discharged onto the surface of the epithelium. Examples include enzymes within the digestive tract, perspiration of the skin, and mild produced by mammary glands.
Secretions are released into the surrounding tissue fluid and blood. These are produced in organs such as the pancreas, thyroid and pituitary gland.
Endocrine secretions that act as chemical messengers and regulate or coordinate the activities of other tissues, organs, and organ systems.
Cell adhesion molecules
"CAMs" specialized transmembrane proteins that hold together the epithelial cell membranes which causes and effective barrier.
intrercellular connection where lipid bilayers of adjacent cell membranes are tightly bound together by interlocking membrane proteins. These prevent the passage of water and solutes between cells. common between epithelial cells exposed to harsh chemicals or enzymes.
Rapid intercellular connection communication where two cells are held together by embedded membrane proteins. They are channel proteins and form a narrow passageway that lets small molecules and ions pass from cell to cell. Most abundant in cardiac muscle and smooth muscle tissue, where they are essential to the coordination of muscle contractions.
Durable interconnection where the cell membrane of two cells are locked together by intercellular cement and by membrane proteins connected to a network of intermediate filaments. Are abundant between cells in the superficial layers of hte skin, with is why damaged skin cells are usually lost in sheets rather than as individual cells. Skin peels rather than comes off as powders
desmosomes that form a small disc
resemble half a button desmosome and attach a cell to the basement membrane.
microvilli and cilia on epithelia tissue
Many epithelia that line internal passageways have microvilli on their exposed surfaces which are abundant on epithelial surfaces where absorption and secretion take place. A cell with microvilli has at least 20 Xs the surface area of a cell without. There greater the surface area of the cell membrane, the more transport proteins are exposed to the extracellular environment.
Some contain cilia on their exposed surfaces. A ciliated epithelium has roughly 250 cilia that beat in a coordinated fashion to move materials across the epithelial surface. EX. where it lines the respiratory tract the cilia moves mucus-trapped irritants away from the longs and towards the throat.
The basement membrane
lies between the epithelium and underlying connective tissues. Consists of a network of protein fibers. Contains no cells. Epithelial cells adjacent to the basement membrane are firmly attached to these protein fibers by hemidesmosomes. This provides strength and resists distortion, and provides a barrier that restricts the movement of protein and other large molecules from the underlying connective tissue into the epithelium.
"germinative cells" Found in the deepest layers of epithelium, near the basement membrane. The only way the epithelium can contain its structure over time is through the continuous division of these cells.
consists of a single layer of cells that covers the basement membrane. These are thin, fragile, and cannot provide much mechanical protection. Line internal compartments and passageways, including the ventral body cavities, they heart chambers, and blood vessels. Also found where secretion and absorption occurs, such as lining of digestive tract, and gas-exchange surfaces of the lungs. In these cases thinness is an advantage b/c it reduces the diffusion time for materials to cross the epithelial barrier
provides greater degree of protection b/c it has several layers of cells above the basement membrane. usually found in areas subject to mechanical or chemical stresses, such as the surface of the skin and linings of the the mouth and anus.
the cells are thin and flat, and the nucleus occupies the thickest portion of each cell. Viewed from the surface, the cells look like fried eggs laid side by side.
Resemble little hexagonal boxes when seen in 3D, but in 2D they appear square. The nuclei lie near the center of each cell, and they form a neat row.
the cells are also hexagonal but taller and more slender. Nuclei are crowded into a narrow band close to the basement membrane, and the height of the epithelium is several times the distance between the nuclei.
Simple Squamous epithelium
Locations: epithelia lining ventral body cavities; lining of heart and blood vessels, portions of kidney tubules (thin secretions of loops of Henle), inner lining of cornea, alveoli (air sacs) of lungs.
Functions: Reduces friction, controls vessel permeability, performs absorption and secretion.
Simple cuboidal epithelium
Locations: Glands, ducts, portions of kidney tubules, thyroid gland
Functions: limited protection, secretion, absorption
Simple columnar epithelium
Locations: Lining of stomach, intestines, gallbladder, uterine tubes, and collecting ducts of kidneys
Functions: Protection, secretion, and absorption.
Pseudostratified Ciliated columnar epithelium
Locations: Lining of nasal cavity, trachea, and bronchi; portions of male reproductive tract
Functions: Protection, secretion
Locations: Urinary bladder, renal pelvis of kidneys, ureters
Functions: Permits expansion and recoil after stretching
Stratified squamous epithelium
Locations: surface of the skin, lining of mouth, throat, esophagus, rectum, anus, and vagina
Functions: Provides physical protection against abrasion, pathogens, and chemical attack.
produced by exocrine glands, which discharge their products through a duct, or tube, onto some external or internal surface. Can be categorized as unicellular glands (called goblet cells) or as multicellular glands.
"hormones" are produced by ductless glands and released into blood or tissue fluids.
Exocrine glands different modes of secretion
merocrine secretion, apocrine secretion, and holocrine secretion.
The most common mode of secretion, the product is released from secretory vesicles by exocytosis. One type of this is mucin, mixes with water to form mucus, which is an effective lubricant, a protective barrier, and a sticky trap for foreign particles and microorganisms. Examples: Saliva from salivary glands, perspiration on skin, milk in breasts
a mode of secretion occurs through loss of cytoplasm that contains secretory product. The outermost portion of the cytoplasm becomes packed with secretory vesicles before it is shed. EX: Milk in breasts, viscous underarm perspiration
a mode of secretion occurs through loss of entire cell that contains secretory product. The entire cell becomes packed with secretions then bursts apart and dies. EX: Skin oils and waxy coating or hair (produced by sebaceous glands of the skin)
a type of secretion that secretes a watery solution that contains enzymes. Ex: Secretions of parotid salivary gland
a type of secretion that secrets a thick, slippery mucus. Ex: Secretions of sublingual salivary gland
contain more than one type of gland cell and may produce two different exocrine secretions, one serous and the other mucous. Ex: Secretions of submandibular salivary gland (serous and mucous)
most diverse dissues of the body. Bone, blood, and fat are connective tissue. Distributed throughout the body but is never exposed to outside environment. Is high vascular and contains receptors that provide pain, pressure, temperature, and other sensations.
Components of connective tissue
1. specialized cells
2. protein fibers
3. a fluid known as ground substance
extracellular protein fibers and ground substance for this that surrounds the cells. Where epithelial tissue consists almost entirely of cells, the extracellular matrix accounts for most of the volume of connective tissues
Functions of connective tissue
*Support and protection -the minerals and fibers produced by connective tissue cells establish a bony structural framework for the body, protect delicate organs, and surround and interconnect other tissue types.
*Transportation of materials - Fluid connective tissues provide an efficient means of moving dissolved materials from one region of the body to another
*Storage of energy reserves- fats are stored in connective tissue cells call adipose cells until needed
*Defense of the body- specialized connective tissue cells respond to invasions by microorganisms through cell-to-cell interactions and production of antibodies.
Connective tissue proper
consists of many types of cells and fibers within a matrix that contains a syrupy ground substance. Ex: the tissue that underlies the skin, fatty tissue, and tendons and ligaments. Some of these cells are "permanent residents" others are not always present b/c they leave to defend and repair areas of injured tissue.
Fluid connective tissues
Have a distinctive population of cells suspended in a matrix of water ground substance that contains dissolved proteins. The two fluid connective tissues are blood and lymph.
Supporting connective tissue
have a less diverse cell population than connective tissue proper, and a matrix of dense ground substance and closely packed fibers. The body contains two supporting connective tissues, cartilage and bone. The fibrous matrix of bone is said to be calcified because it contains mineral deposits (primarily calcium salts) that give the bone strength and rigidity.
most abundant cells in connective tissue proper. These permanent residents are responsible for producing and maintaining the connective tissue fibers and ground substance. they secrete protein subunits called collagen, elastic, and reticular fibers
scattered throughout the matrix. These "big eaters" cells engulf, or phagocytize, damaged cells or pathogens that enter the tissues; they also release chemicals that mobilize the immune system, and attract additional macrophages and other cells involved in tissue defense.
spend long periods of time in connective tissue
when an infection occurs, migrating (free) macrophages are drawn to the affected area.
"adipose cells" "adipocytes" are permanent residents. Contains such a large droplet of lipid that the nucleus and other organelles are squeezed to one side of the cell.
small, mobile connective tissue cells often found near blood vessels. The cytoplasm is packed with vesicles filled with chemicals that are released to begin the body's defensive activities after an injury or infection.
White blood cells
may move through connective tissue proper. #s increase remarkedly if tissue is damaged, as does the production of antibodies, which are proteins that destroy invading microorganisms or foreign substances.
respond to local injury by dividing to produce daughter cells that differentiate into fibroblasts, macrophages, or other connective tissue cells.
long, straight, unbranched and flexible. most common fibers in connective tissue proper
contain the protein elastin. They are branched and wavy and after stretching will return to their original length.
(reticulum, a network) the lease common of the fibers, thinner and form a branching, interwoven framework in various organs.
fills the spaces between cells and surrounds the connective tissue fibers. clear, colorless, and similar in consistency to maple syrup. It slows the movement of bacteria and other pathogens, which makes them easier prey for phagocytes.
Loose connective tissue
"areorlar tissue" the packing material of the body. they fill spaces between organs, provide cushioning, and support epithelia, they anchor blood vessels and nerves, store lipids, and provide a route for diffusion of materials. Found beneath dermis of skin, digestive tract, respiratory tract, and urinary tract; between muscles, around blood vessels, nerves and joints.
loose connective tissue becomes adipose tissue when it becomes dominated by fat cells. It provides padding and cushions shocks, insulates (reduces heat loss) and stores energy reserves
Dense connective tissue
consists mostly of collagen fibers; also called fibrous, or collagenous tissues. Provides firm attachment, conducts pull of muscles, reduces friction between muscles, stabilizes relative positions of bones, helps prevent over-expansion of some organs such as bladder. Located between skeletal muscles and skeleton (tendons), between bones (ligaments), covering skeletal muscles, capsules of internal organs
dense regular connective tissue
collagen fibers are parallel to each other, tightly packed, and aligned with forces applied to the tissue
cords of dense regular connective tissue that attaches skeletal muscle to bones. Their collagen fibers run along the length of the tendon and transfer the pull of the contracting muscle to the bone
resemble tendons but connect one bone to another. Often contain elastic fibers as well as collagen figers and can tolerate a modest amount of stretching.
Dense irregular connective tissue
contains an interwoven meshwork of collagen fibers. This pater provides support to areas subjected to stresses from many directions and is what gives skin its strength.
watery matrix in blood. Confined to the blood vessels of the cardiovascular system is kept in constant motion by contractions of the heart.
red blood cell
a single cell type, accounts for almost half the volume of blood. transport oxygen in the blood.
white blood cell
important components of the immune system
cell fragments that function in blood clotting
What constitutes most of the extracellular fluid in the body?
plasma, lymph, and interstitial fluid.
a firm gel that contains embedded proteins. Avascular, limited repair capabilities b/c of lack of blood vessels.
the only cells found within the matrix, live in small pockets known as lacunae. must obtain nutrients and eliminate wastes by diffusion through the matrix. produces a chemical that discourages the formation of blood vessels.
contains an inner cellular layer and an outer fibrous layer. It covers cartilage and sets apart from surround tissues
most common type of cartilage. Matrix contains closely packed collagen fibers, which make it tough but somewhat flexible. It reduces friction between bony surfaces and is located between tips of ribs and bones of sternum; covering bone surfaces at synovial joints, supporting larynx (voice box), trachea, and bronchi, forming part of nasal septum.
provides support but tolerates distortion without damage and returns to original shape. located in the auricle of external ear, epiglottis, acoustic canal, cuneiform cartilages of larynx.
has little ground substance, its matrix is dominated by collagen fibers. densely interwoven which makes it tough and durable. they resist compression, prevents bone to bone contact, limits relative movement. located in the pads within the knee joint, between pubic bones of pelvis, intervertebral discs separating vertebrae.
What are the differences between cartilage and bone?
Volume of ground substance in bone is very small. Bone is strong and shatter resistant. Overall properties can compete with the best steel-reinforced concrete. Bone is constantly being remodeled throughout life.
Diffusion cannot occur through bony matrix so they obtain nutrients through cytoplasmic extensions that reach blood vessels and other osteocytes
cytoplasmic extentions that run through a branching network within the bony matrix.
Each bone is surrounded by this, except in joint cavities where opposing surfaces are covered by hyaline cartilage.
"mucosae" lines cavities that communicate with the exterior, including the digestive, respiratory, reproductive, and urinary tracts. The epithelial surfaces are kept moist at all times, by mucous secretions or by exposure to fluids such as urine or semen. The connective tissue portion is called lamina propria.
line the sealed, internal subdivisions of the ventral body cavity. Three types described next. Functions is to minimize friction between the opposing parietal and visceral surfaces when an organ moves or changes shape. Friction is reduced by a water, serous fluid formed by fluids that diffuse from underlying tissues (surfactant?)
consists of a simple epithelium supported by loose connective tissue, lines the pleural cavities and covers the lungs.
consists of a simple epithelium supported by loose connective tissue, lines the peritoneal (abdominal) cavity and covers the surfaces of enclosed organs such as the liver and stomach.
consists of a simple epithelium supported by loose connective tissue that lines the pericardial cavity and covers the heart.
"skin" covers the surface of the body. consists of stratified squamous epithelium and the underlying dense connective tissues. is thick, waterproof, and usually dry.
"grease between joints" Joints that allow free movement are surrounded by a fibrous capsule that contain a joint cavity lined by this. Consists of primarily loose connective tissue and an incomplete layer of epithelial tissue. Synovial fluid helps lubricate the joint and permits smooth movement.
where bones contact one another at joints
specialized for contraction. involves interaction between filaments of myosin and actin, which are proteins found in the cytoskeletons of many cells. The filaments are more numerous and arranged so that their interaction produces a contraction of the entire cell.
Skeletal Muscle tissue
contains large, multinucleated cells, they are relatively long and slender and are usually called muscle fibers. they are incapable to dividing, but new ones are produced through the division of stem cells in adult skeletal muscle tissue. as a result, as least partial repairs can occur after injury. Fibers will not contract unless stimulated by nerves. Described as striated voluntary muscle because the nervous system provides voluntary control over its activities. functions moves or stabilizes the position of the skeleton, guards entrances and exits to the digestive, respiratory, and urinary tract, generates heat, protects internal organs
Cardiac Muscle Tissue
found only in the heart. is striated but each muscle cell is much small than a skeletal muscle fiber and has only a single nucleus. Has very limited ability to repair itself. Stem cells are lacking. This tissue does not rely on nerve activity to start a contraction.nervous system doesnt provide voluntary control over these cells. also called "striated involuntary muscle" its functions are to circulate blood and maintain blood (hydrostatic) pressure.
specialized attachment sites that contain gap junctions and desmosomes. Cardiac muscle cells are interconnected at this.
specialized cells in cardiac muscle tissue that establish a regular rate of contraction.
Smooth Muscle tissue
found in the walls of blood vessels, around hallow organs, and in layers around the respiratory, circulatory, digestive, and reproductive tracts. The functions are to move food, urine, and reproductive tract secretions, controls diameter of respiratory passageways, regulates diameter of blood vessels. Have no striations, can divide so it can regenerate after injury. may contract on their own or may be triggered by neural activity. Nervous system does not provide voluntary control over contractions so its known as nonstriated involuntary muscles.
"nervous tissue" "nerve tissue" specialized for the conduction of electrical impulses from one region of the body to another. 98% is concentrated in the brain and spinal cord which are the control centers for the nervous system.
Longest cell in the body. a cell in neural tissue specialized for intercellular communication by changes in membrane potential and synaptic connections. Our conscious and unconscious thought processes reflect communication amount these. cannot divide so limited ability to repair itself.
Cells of the CNS and PNS that support and protect the neurons. provides physical support for neural tissue, maintain the chemical composition of tissue fluids, supply nutrients to neurons, and defend the tissue from infections
part of neuron that contains a large nucleus
part of neuron that has numerous branching projections
part of neuron that carry the information from the dendrites to other cells. are very long and slender, are also called nerve fibers. Ends at synaptic terminals, where the neuron communicates with other cells.
What processes helps restore homeostasis with tissues
inflammation and regeneration.
"inflammatory response" 1st phase following injury, phase which coordinates the activities of several tissues, produces indications including swelling, warmth, redness, and pain. can also result from an infection. When stimuli kill cells, damage fibers, or injure tissues they trigger this response by stimulating connective tissue cells called mast cells. They release chemicals (histamine and heparin) that cause local blood vessels to dilate (enlarge in diameter) and become more permeable. Increased blood flow to injured region makes it red and warm the diffusion of blood plasma causes it to swell. pain is caused by stimulation of the nerve endings. These circulatory changes increase the delivery of nutrients, oxygen, phagocytic white blood cells, and blood clotting proteins, and they speed up the removal of waste products and toxins. This generally succeeds in eliminating the inflammatory stimulus over a period of hrs or days.
The second phase following injury, the damaged tissues are replaced or repaired to restore normal function. Fibroblasts produce a dense network of collagen fibers known as scar tissue or fibrous tissue. Over time scar tissue is usually remodeled and slowly appears normal.
damage to the heart is replaced by fibrous connective tissue. Such permanent replacement of normal issues is called this. This may occur in muscle and other tissues in response to injury, disease, or aging.
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