epithelial tissue lecture

Question 1

what are the four major classes of tissues?

Answer 1

connective epithelial nervous muscle

Question 2

an “organ” must contain at least how many different tissue types?

Answer 2

at least 2 types
usually a mix of all 4 tissue types

Question 3

where is epithelial tissue located in general?

Answer 3

1. skin
2. lining body surfaces that open to outside
3. covering organs
4. glands

Question 4

what are several general functions of epithelial tissue?

Answer 4

1. protection
2. absorption and filtration
3. secretion
4. gas exchange

Question 5

describe the general structure of epithelial tissue.

Answer 5

1. cells fit tightly together
2. on lower surface, EPI cells are attached and supported by an adhesive basement membrane
3. one free surface- apical surface

Question 6

what is the function of stem cells?

Answer 6

to regenerate as any type of cell

Question 7

what do goblet cells do?

Answer 7

produce mucus

Question 8

what’s the major difference between endocrine and exocrine glands?

Answer 8

exocrine glands- have ducts through which their secretions travel to apical surface

endocrine glands- ductless and hormone diffuse outward to extracellular fluid

Question 9

list the 3 types of simple epithelial tissue.

Answer 9

1. simple cuboidal
2. simple squamous
3. simple columnar

Question 10

for each of these 3 types of simple, what is its function and where can it be found?

Answer 10

simple squamous- flat shape makes it ideal for the rapid diffusion of substances and provides smooth surface to reduce friction. location- body cavities, lining of blood vessels, gas exchange sites for lungs

simple cuboidal- absorption and protection. located in kidney tubules, and certain glands (thyroid)

simple columnar- absorption, secretion, movement of egg. located in lining of small intestines, oviducts

Question 11

list the 3 types of stratified epithelial tissue.

Answer 11

1. stratified squamous
2. stratified cuboidal
3. stratified columnar

Question 12

for each of these 3 types of stratified EPI, what is its function and where can it be
found?

Answer 12

stratified squamous- protection from abrasion and pathogens. location- skin, cornea, body cavities that open to outside

stratified cuboidal- secretion and some protection. located on sweet and salivary glands

stratified columnar- secretion and protection. located larynx, mammary gland ducts, and parts of male urethra

Question 13

what are the last two remaining types of epithelial tissue called? What is the function
and location of each

Answer 13

pseudostratified columnar- secretion and movement of mucus. located in lining of nasal cavity trachea, and upper respiratory tract

transitional epithealium (urothelium)- allows structures to stretch as they are filled with urine and protection from chemicals in urine. located in bladders and urethra

Question 14

what are three specialized junctions that may occur between epithelial cells?

Answer 14

1. gap junctions
2. tight junctions
3. desmosomes

Question 15

for each type of junction, what is its major function?

Answer 15

gap junctions- cells that are held together by interlocking proteins called connexons. the connexons have a hollow space through center

desmosomes-cells held together by proteins and glue, the proteins are anchored to dense areas which attach to cell’s skeleton. very strong

tight junctions- long stretch of interlocking proteins tightly connects the two cell membranes

Question 16

for each type of junction, what is an example where it is found?

Answer 16

gap junctions- cardiac muscle, lens of eye
desmosomes- cervix of uterus
tight junctions- intestinal cells

Question 17

do these junctions ever occur in any of the other non-epithelial tissues?

Answer 17

yes