Epithelial tissue
form surface layer of body, line body cavities and hollow organs, constitute gland tissue
Features of epithelia
1) free apical surface
2) fixed basal surface
3) specialized intercellular junctions
4) basement membrane
4) avascular
5) have many sensory nerve endings
6) fast regeneration
functions of epithelia
1) resist dehydration and injury
2) regulate permeability
3) secretion
4) monitor environment through sensory input to nervous system
classifications of epithelial tissue
determined by number of cell layers (simple vs stratified) and apical cell shape (squamous vs
cuboidal vs columnar)
simple cuboidal epithelium
found in kidney tubules, ducts of glands
as tall as they are wide (so CUBE), central spherical nucleus
function: absorption and secretion
,transitional epithelium
a stratified epithelium that gives the impression of transitioning from cuboidal (when relaxed) to
squamous (when stretched)
-found in urinary tract
pseudostratified epithelium
simple epithelium where all cells contact basal lamina but not all cells reach apical surface
-nuclei are at different positions which gives impression of stratification
apical cell membrane specializations
1) cilia: finger like motile projections
-help with movement
2) microvilli: serve to increase surface area
-found in epithelial cells involved in absorption
3) keratin: protein that protects epithelial cells from damage or stress
-key structural material to our skin
simple cuboidal epithelium pic
,simple squamous epithelium
simple columnar epithelium
psuedostratified epithelium
ocular micrometer
measuring guide placed in one of the oculars of microscope
-used to measure heights of different types of epithelial cells
measuring heights of simple cuboidal and simple columnar
measure cells from basal surface to apical surface
measuring height of simple squamous
need to find simple squamous cell in cross section and then measure it
functions of connective tissue
1) structural support
2) binding organs of the body
3) fat storage
4) exchange of nutrients and metabolic waste
5) defense and protection
general components of connective tissue
1) cells
2) protein fibers
3) ground substance
, extracellular matrix in connective tissue
made up of protein fibers and ground substance
3 major types of connective tissue
1) connective tissue proper
2) supporting connective tissue
3) fluid connective tissue
2 types of connective tissue proper
1) loose connective tissue
2) dense connective tissue
loose connective tissue and its 3 types
1) abundant ground substance
2)scattered cells and loosely arranged protein fibers
types:
areolar, adipose and reticular
dense connective tissue and 3 types
1) abundant tightly packed fibers with few cells
2) less ground substance
types:
Regular
Irregular
Elastic
areolar connective tissue
found in subcutaneous layer and around organs
1) gel like ground substance
2) numerous blood vessel
3) scattered fibroblasts
adipose connective tissue