Jaringan Epitel
Epithelial Tissues
Tissues – Introduction
a group of similar cells specialized to carry on a particular function
tissue = cells + extracellular matrix
– nonliving portion of a tissue that supports cells
4 types
– epithelial = protection, secretion, absorption – connective = support soft body parts and bind
structures together – muscle = movement
– nervous = conducts impulses used to help control and coordinate body activities
Epithelial Tissues Characteristics
free surface open to the outside or an open internal space
basement membrane anchors
epithelium to underlying connective tissue
lack blood vessels
readily divide (ex. skin healing)
tightly packed with little extracellular space
Epithelial Classifications
classified based on shape and # of cell layers
shape
– squamous = thin, flat cells – cuboidal = cube-shaped cells – columnar = tall, elongated cells
number
– simple = single layer
– stratified = 2 or more layers
Epithelial Locations
cover body surfaces, cover and line internal organs, and compose glands
– skin cells, cells that line the stomach and small intestine, inside of your mouth
Simple squamous epithelium
a single layer of thin, flattened cells
– look like a fried egg
easily damaged
common at sites of filtration, diffusion, osmosis; cover surfaces
air sacs of the lungs, walls of
capillaries, linings of blood and lymph vessels
Simple cuboidal epithelium
single layer of cube-shaped cells
– centrally located nucleus
secretion and absorption
surface of ovaries, linings of kidney
tubules, and linings of ducts of certain glands
Simple columnar epithelium
single layer of cells that are longer than they are wide
– nucleus located near basement mem.
ciliated or nonciliated
some have microvilli
goblet cells = secrete mucus
absorption, secretion, protection
linings of the uterus, stomach, and intestine
Pseudostratified
columnar epithelium
appear stratified b/c nuclei are at 2 or more levels
– NOT stratified b/c all cells touch basement mem.
ciliated
goblet cells
protection, secretion, movement of mucus
linings of respiratory system
Stratified squamous epithelium
many layers of flattened cells
named based on appearance of top layer of cells
protection
outer layers of skin, linings of oral cavity, throat, vagina, and anal canal
Stratified cuboidal epithelium
2 or 3 layers of cuboidal cells
protection
linings of larger ducts of mammary
glands, sweat glands, salivary glands, and pancreas
Stratified columnar epithelium
protection and secretion
vas deferens, part of the male urethra, parts of the pharynx (throat)
Transitional epithelium
can stretch
distensibility (stretching), protection
inner lining of urinary bladder and linings of the ureters and part of urethra
Glandular epithelium
cells that are specialized to produce and secrete substances into ducts or into body fluids
gland = 1 or more cuboidal or columnar cell
secretion
salivary glands, sweat glands, endocrine glands
Exocrine vs. Endocrine
exocrine = secrete sub. into ducts that open onto surfaces
– skin or linings of digestive tract
endocrine = secrete sub. into tissue fluid or blood
– hormones
Exocrine glands
merocrine = release watery, protein- rich fluid by exocytosis
– salivary glands, sweat glands
apocrine = lose small portions of their cell body during secretion
– mammary glands, ear wax
holocrine = entire cell lysis (breaks apart) during secretion
– sebaceous glands of the skin
Serous vs. Mucous
serous = typically watery with lots of enzymes
– lubrication
mucous = mucus
– digestive and respiratory systems – protection
