Exam II Flashcards
histology
the study of tissues
epithelial
sheet of cells covering or lining a body surface/cavity
nervous
specialized cells generate and conduct nerve impulses to control body
muscle
highly cellular and vascularized tissues responsible for most body movement
connective
the most abundant and widely distributed tissue found through out the body composed of several variations in cell composition
polarity
all epithelia exhibit apicalbassal polarity. this means that the regions of cells near the basal surface differ from apical cells in their structure and function. their locations are maintained by the cytoskeleton of epithelial cells
specialized contacts
with the exception of glandular epithelia, the epithelial cells fit together snuggly (by means of tight junctions or desmosomes) in order to form continuous sheets of tissue
connective tissue support
connective tissue supports and lies beneath all sheets of epithelial tissue. this is done by two laminae that make up the basement membrane
vascularity
the epithelium in innervated (supplied by nerve fibers), but is avascular and holds not blood vessels. they receive their nutrients by diffusing substances from blood vessels in underlying connective tissues
regeneration
exposure to friction and “wear and tear” the epithelial cells have a high regeneration capacity. they can rapidly reproduce themselves by cell division when the apical basal polarity and lateral contacts are destroyed as long as they have adequate nutrition
simple epithelia
single cell layer; simplest of all epithelium
simple squamous
- laterally flattened
- disc-shaped central nuclei
- sparse cytoplasm
simple squamous functions
- filtration
- diffusion
- secretion
simple squamous locations
- kidney’s glomeruli
- air sacs in lungs
- heart linings
- blood vessels
- lymphatic vessels
- lining of ventral body cavity
simple columnar
- tall cells
- round to oval nuclei
- some cells have goblet glands (unicellular and mucus-secreting)
simple columnar functions
- absorption
- secretion of mucus, enzymes and other substances
- ciliary action propels mucus
simple columnar locations
- most of digestive tract; stomach to anal canal (nonciliated type)
- gallbladder
- excretory ducts of some glands
- small bronchi, uterine tubes, regions of uterus (ciliated type)
simple cubodial
- tall and wide
- spherical nuclei that stain darkly
simple cubodial functions
- secretion
- absorption
simple cubodial locations
- kidney tubles
- ducts
- secretory portions of mall glands
- ovary surface
pseudostratified
- differing heights (some don’t reach free surface)
- nuclei seen at different levels
- may contain goblet cells and bear cilia
pseudostratified functions
- secretion (particularly mucus)
- ciliary action propels mucus
pseudostratified locations
- male’s sperm-carrying ducts & ducts of large glands(non ciliated)
- trachea & most of upper respiratory (ciliated)
stratified epithelia
- very similar to simple epithelia; mostly same tissue types just multiple layers
- function generally the same but function vary in intensity (stratified squamous nonkeratinzed)
- several layers to protect surface of skin, whereas, simple squamous does not have protective function
stratified squamous
- stratifies squamous nonkeratinized (lacks surface layer of dead cells)
- stratified squamous keratinized (compact dead cells)
stratified squamous functions
protection against abrasion and pathogen invasion
stratified squamous locations
- nonkeratinized - oral cavity, esophagus, vagina, and rectum
- keratinized - only in epidermis
stratified cuboidal
- very rare in body
- typically two layers
stratified cuboidal functions
- secretes sweat and ovarian hormones
- produces sperm
stratified cuboidal locations
- sweat glands/ducts
- mammary glands/ducts
- ovarian follicles
- seminiferous tubules
stratified columnar
very rare in body
stratified columnar functions
absorption secretion
stratified columnar locations
- pharynx
- male urethra
- glandular duct linings
transitional epithelium
- cells of basal layer are cuboidal or columnar
- apical cells vary in appearance (depending on degree of stretching)
- resembles stratified squamous/cuboidal
- surface cells dome shaped or squamous-like depending on degree of stretch
transitions epithelium functions
- allow vessels they line to stretch
- example: when stretched, bladder transitional cells thin from sex layers to three layers
transitions epithelium locations
lining of hollow urinary organs
glandular epithelia
- one or more cells that produce and secret product
- secretions - fluid (water, lipid, or steroid-rich) generally consisting of proteins
endocrine glands
- “ductless” glands
- internally secreting (directly into blood)
endocrine gland functions
produce hormones
endocrine gland locations
- thyroid gland
- pituitary gland
exocrine glands
- numerous-secrete products onto body surface or into cavities
- familiar products
- 2 types: unicellular and multicellular
unicellular exocrine gland functions
- produce mucin - complex glycoprotein that dissolves in water when secreted and turns into…
- mucus - a slimy coating that protects and lubricates surfices
unicellular exocrine gland locations
goblet cells (sprinkled throughout intestinal and respiratory tracts amid columnar cells
multicellular exocrine gland functions
- structurally more complex than unicellular
- merocrine (eccrine) glands secret their products as they are produced
- holocrine glands accumulate their products within them until they rupture
multicellular exocrine gland locations
merocrine (eccrine)
- pancreas
- sweat glands (most)
- salivary glands
holocrine
- sebaceous glands
- apocrine glands (some scientists disagree that humans as well as animals have this gland)
locations of nervous tissue
- brain
- spinal cord
- nerves
- ganglia
- in centras nervous system
- branches throughout body in the peripheral nervous system
neurons (nerve cell)
- highly specialized brached cells with cytoplasmic processes
- respond to stimuli in order to generate and conduct impulses
neuroglia (glial cells)
- much smaller cells that appear circular, but at a closer look, they appear starburst-like
- these cells protect and aid in assistance of the neurons sending signals
neurosoma
the cell body that is usually round, ovoid, or stellate in shape. it houses the nucleus and most other organelles, and is the cells center of genetic control and protein synthesis
dendrites
signal receptors and transmits messages to neurosoma
axon/nerve fiber
singe long fiber which sends outgoing signals
myelin sheath (schwann cells/oligodendrocytes)
material that forms an electrically insulating protection usually around the axon. it increases the speed of electrical impulses by allowing the signal to jump over the next site of exposed axon (node of rangier)
