Body Tissues. Tissues - groups of cells that are similar in structure and function Four tissue types...
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Transcript of Body Tissues. Tissues - groups of cells that are similar in structure and function Four tissue types...
Body Tissues
Tissues - groups of cells that are similar in structure and function
Four tissue types and general function:
*EPITHELIUM - covering
*CONNECTIVE - support
MUSCLE - movement
NERVOUS - control
epithelial tissue (epithelium)
the lining, covering, and glandular tissue of the body
protection (skin, respiratory tract), absorption (stomach, small intestine), filtration (kidneys), and secretion (glands-sweat, oil, digestive enzymes, mucus)
special characteristics of epitheliumform continuous sheets, joined by desmosomes and tight junctions
apical surface= free surface or edge exposed to body’s exterior or cavity of internal organ
basement membrane =lower surface of epithelium, secreted by cells
no blood supply, depend on diffusion from capillaries for food and oxygen
regenerate themselves easily
classification of epithelium
by cell arrangement (simple, stratified) and cell shape (squamous, cuboidal, columnar)
simple = one cell layer
stratified = more than one cell layer
squamous = flattened like fish scales
cuboidal = cube-shaped like dice
columnar = shaped like columns
simple epitheliasimple squamous - single layer, filtration, rapid diffusion (alveoli, capillaries, serous membranes)
simple cuboidal - single layer on basement membrane (glands and ducts, kidney tubules and surface of ovaries)
simple columnar - single layer, tall close together (lines digestive tract from stomach to anus)
pseudostratified (ciliated) columnar - appear at different heights above basement membrane, absorption, secretion (lines respiratory tract)
stratified epitheliastratified squamous - several layers, receives frequent friction (esophagus, mouth, outer skin)
stratified cuboidal/columnar - two cell layers, cuboidal at surface, fairly rare (ducts of large glands) *not in table
transitional - modified stratified squamous, change shape, subject to stretching (urinary bladder, ureters)
types of epithelium (picture pg 80)
glandular epitheliumgland=one or more cells that secrete a product
duct = channel leading from a gland to epithelial surface
endocrine gland - ductless, secrete hormones directly into blood vessels (thyroid, adrenals, pituitary)
exocrine glands - have ducts, excrete product to internal or external surface (sweat, oil, liver, pancreas)
glands (picture)
connective tissuemost abundant and widely distributed tissue
most are well vascularized (good blood supply)
tendons and ligaments have a poor blood supply
cartilages are avascular
made up of many cell types plus nonliving substances called the extracellular matrix
extracellular matrixMade of two elements in varying amounts:
ground substance - water, adhesion proteins, large polysaccaride molecules
fibers - collagen, elastic, reticular
types of connective tissuebone (osseous tissue) - rocklike hardness, calcium salt matrix, protection, support (skull, bones)
hyaline cartilage - collagen fibers, rubbery matrix (larynx, attaches ribs to sternum, ends of bones, fetus skeleton)
fibrocartilage - chondrocytes and collagen fibers, highly compressible (between vertebrae)
elastic cartilage - elasticity (supports external ear)
connective tissuesdense connective (dense fibrous) -collagen fibers, fibroblasts, ropelike (tendons-muscle to bone, ligaments-bone to bone, lower layer of skin/dermis)
areolar - soft, pliable, “cobweb”, cushions and protects, soaks up fluid during inflammation, swelling/puffiness known as edema (widely distributed, holds organs together, underlies mucous membranes lamina propria)
adipose (fat) - areolar tissues in which fat cells predominate (subcutaneous tissue, protects kidneys, eyeballs, hips, breasts)
reticular - interwoven reticular fibers, support free blood cells (lymph nodes, spleen, bone marrow)
blood - blood cells and plasma, transports nutrients, gases, and wastes (in blood vessels)
connective tissues (pictures pg 83-84)
muscle tissue
Three types:
skeletal - striated (stripes), multinucleated, voluntary movements (attached to skeletal bones)
smooth - no striations, uninucleate, spindle-shaped, involuntary (walls of stomach, bladder, uterus, and blood vessels)
cardiac - striated, uninucleate, branching cells, intercalated disks (gap junctions that conduct electrical impulse, involuntary (heart)
muscle tissue (picture pg 157)
nervous tissue
neurons and supporting cells - cytoplasm drawn out into long extensions, electrochemical impulses (brain, spinal cord, nerves)
nervous tissue (picture pg 199)
tissue repair (wound healing)
Two major ways:
regeneration = replacement of destroyed tissue by same kind of cell
fibrosis = repair by dense (fibrous) connective tissue, the formation of scar tissue; strong but lacks flexibility
Which type used depends on type of tissue and severity. Clean cuts generally heal much more successfully than ragged tears of tissue.
Epithelia and connective tissues regenerate well. Mature cardiac muscle and nervous tissue are amitotic and are repaired by fibrosis.
At the clinic
Three patients in an intensive care unit are examined by the resident doctor. One patient has brain damage from a stroke, another had a heart attack that severely damaged his heart muscle, and the third has a severely damaged liver (a gland) from a crushing injury in a car accident.
All three patients have stabilized and will survive, but only one will have full functional recovery through regeneration. Which one and why?