Chapter 5 Flashcards
four types of tissues
epithelial, connective, muscle, nervous
stem cells
cells without a name or specific job that differentiate into a specific cell. maintain cell populations in tissue
epithelia tissue
covers body surfaces, lines body cavities, forms glands
epithelium
composed of one or more layers of closely packed cells with little extracellular matrix and avascular.
cellularity
composed almost entirely of tightly packed cells
polarity
has apical surface exposed to external environment, lateral surface w/ intercellular junctions, and basal surface where epithelium attaches to connective tissue
basement membrane
complex structure produced by epithelium and connective tissue and consists of 3 layers: lamina lucida, lamina densa, reticular lamina. contains collagen fibers and proteins and carbs. forms a selective barrier between epithelium and connective tissue.
avascularity
nutrients obtained across apical surface or from basal surface, no blood vessels
extensive innervation
detects changes in environment in that region (pain, temp, pressure)
high regeneration capacity
apical surface exposed to environment so they continually get replaced due to frequent mitosis of deep epithelial cells
physical protection
skin protects from dehydration, abrasion, destruction
selective permeability
relative impermeable to some substances but promotes passage of others
secretions
some epithelium specialized to secrete
sensations
skin contains nerve endings
tight junctions
cells completely attached to neighbors in a fused plasma membrane to prevent substances from passing between epithelial cells
desmosomes
hold cells together at a single point. found in cells exposed to stress
gap junctions
form tiny, fluid-filled tunnels to allow direct passage of substances between cells (flow of ions b/w cardiac muscle cells)
glands
composed of epithelial tissue and secretes substances for use or elimination. May secrete: mucin, electrolytes, hormones, enzymes, urea
endocrine glands
no ducts; secretes hormones directly into body fluids that act as chemical messengers and influence cell activity anywhere
exocrine glands
formed from folded epithelium within connective tissue. connects with epithelial surface (sweat glands, mammary, salivary)
merocrine glands
uses vesicles and exocytosis. lacrimal, salivary, sweat, pancreas, and stomach
apocrine glands
pinching of cytoplasm, contains secretory product, exocytosis. Mammary, some sweat glands, axillary, pubic regions
holocrine glands
accumulation and then sudden cell disintegration. Happens in sebaceous glands
functions of connective tissue
physical protection, support and framework, binding of structures, storage, transport, immune protection.
body membranes
formed from epithelial tissue bound to underlying connective tissue. lines body cavities and external surfaces.
serous membrane
internal membrane that covers organs and lines wall of body cavities (pleura, pericardium). made of simple squamous termed mesothelium and produces serous fluid developed from plasma
mucous membrane
also called mucosa; lines passageways the open to outside. absorptive, protective, and secretory. formed from epithelium and underlying connective tissue (lamina propria) often covered in mucus. found in body tracts
cutaneous membrane
skin; composed of keratinized stratified squamous epithelium. protects and prevents water loss
synovial
lines some joints in the body. composed of areolar connective tissue and covered by squamous epithelium without a basement membrane. secretes synovial fluid that reduces friction and gives nutrients to cartilage
metaplasia
change of mature epithelium to a different form as it adapts. (smokers trachea epithelium changes from pseudostratified ciliated columnar to nonkeratinized stratified squamous. and in chronic acid reflux
hypertrophy
increase in size of existing cells of a tissue
hyperplasia
increase in number of cells of a tissue
neoplasia
tissue growth proceeding out of control; develops tumor
atrophy
shrinkage of tissue by decrease in cell number or size from aging and lack of use
necrosis
term for tissue death, irreversible tissue damage with inflammatory response to damage. (gangrene)
gangrene
necrosis of soft tissue due to diminished blood flow. complication of diabetes and can happen in intestines
dry gangrene
area is shriveled and desiccated; due to extreme cold
wet gangrene
caused by bacterial infection with loss of blood supply. ruptured dying cells with fluid release
gas gangrene
bacteria invading necrotic tissue, bacteria producing gas bubbles
changes to aging skin
support, maintence, and replacement of cells is less efficient, structure and chemical composition is altered (thin epithelial), less collagen, brittle bones, delayed tissue repair, atrophy
