Unit 2 Flashcards
(34 cards)
Histology
The study of tissues, specialized group of cells that perform a specific function.
Epithelial
Closely spaced cells in layers that cover surfaces and organs, line cavities and ducts, form glands.
Connective
More extracellular matrix than cell volume
Muscle
Long excitable cells that generate force to move structures of the body.
Nervous
Excitable cells that transmit pulses of information.
4 functions of epithelial tissue
Physical protection, permeability barriers, innervations, glandular secretions.
Structure of epithelial tissues
Located throughout the body forming the outer layer of skin, inner lining of body cavities, tubes, and ducts, covering over the viscera.
5 characteristics of epithelial tissue
Polarity - specific surfaces and uneven distribution of cell organelles: apical, lateral, basal, basal lamina.
Cellularity - cells connected and fit tightest together at cell junctions.
Attachment - attached to underlying basal lamina.
Avascularity - no blood vessels
Regeneration
Tight junction
Interlocking zipper-like adhesion belt fastens between cells that are impermeable. Keeps enzymes, acids, and wastes in the intestine.
Gap junction
Plasma membrane channels join; ions, sugars, and other small molecules can pass from cell to cell, held together by connexons,
essential for muscle cell contraction in cardiac and smooth muscle.
Desmosone
Dense areas, very strong and resist mechanical stress such as stretching and twisting.
Abundant in superficial layers of skin which shed in sheets not individual cells.
Protein filaments stitch cells together.
Hemidesmosomes
Connects epithelial cells to the basal lamina.
Apical surface
Exposed to the exterior of the body or into a body cavity, or the interior/lumen of an organ.
May have cilia or microvilli.
Lateral surface
Faces the neighboring cells, connections to other cells.
Basal surface
Adheres to the basement membrane or basal lamina
Basal lamina
Layer of glycoproteins and fibers that joints epithelial cells to connective tissue.
Have a border which helps make the free end of the cell easy to identify.
simple squamous
thin, flat, fried egg shaped, nucleus flattened, very thin layer.
rapid diffusion or transport of substances, secretion of lubricating fluid.
LOCATION - air sacs of lungs, inner lining of heart and blood vessels, serous membranes of stomach, intestines, other.
PROTECTION, REDUCES FRICTION WITHIN BODY CAVITIES, DIFFUSION.
Stratified squamous
multiple layers of cells that get flatter as they reach the surface - thick.
keratinized - lack nuclei, dead, contain keratin and slows water loss.
nonkeratinized - no keratin, surface cells alive, in moist ares.
PROTECT FROM ABRASION AND PENETRATION.
simple cuboidal
square, nucleus round and located toward the center of the cell.
LOCATION - thyroid, mammary glands, salivary glands, kidney tubules.
PRODUCTION OF MUCOUS, HORMONES, AND FLUIDS SUCH AS SALIVA AND MILK.
stratified cuboidal
two or more layers of cuboidal cells, RARE.
LOCATION - ducts of sweat glands and mammary glands.
SECRETION
Simple columnar
tall, narrow cells, nucleus located near bottom of cell, may have microvilli or cilia on the apical surface.
LOCATION - intestines, uterus, uterine tubules.
ABSORPTION AND SECRETION, MOVEMENT OF EGG AND ZYGOTE, SECRETION OF MUCOUS.
pseudostratified columnar
all cells attached to the basement membrane but not all cells are tall enough to reach the free surface.
LOCATION - respiratory tract from nasal cavity to bronchi, male reproductive tract.
SECRETES AND PROPELS MUCOUS.
transitional epithelia
tolerates cycles of stretching and recoiling, ranging from cuboidal (empty bladder) to squamous (full bladder).
LOCATION - urinary bladder.
PERMITS EXPANSION FOR URINE STORAGE.
Glands
a collections of epithelia cells that produce secretion. 2 kinds. endocrine and exocrine.
