Exam I | Epithelia

Question 1

What are the 4 tissue types?

Answer 1

• epithelial
• connective
• muscle
• nervous

Question 2

Where is epithelium found?

Answer 2

• internal cavities
• GI, GU, and reproductive tract
• exocrine glands

Question 3

What are the 3 functions of epithelium?

Answer 3

1) protective barrier against pathogens, toxins
2) limits or regulates fluid loss in some regions
3) secretion, absorption, and excretion

Question 4

6 characteristics of epithelium

Answer 4

• contains little, if any, matrix (ground substance)
• linked by cell junctions
• typically have apical (lumenal) and basolateral surfaces
• largely avascular
• highly mitotic
• may be derived from all 3 germ layers

Question 5

What is the basal lamina, and what is it made up of?

Answer 5

• is the “bed” for overlying epithelial cells and is part of anchoring membrane
• superficial portion of basement membrane
• made up of lamina lucida and lamina densa

Question 6

What is endothelium?

Answer 6

a type of epithelium that lines blood vessels, serous membranes, etc.

Question 7

What makes up basement membrane?

Answer 7

• basal lamina (lamina lucida and lamia densa)

- reticular lamina

Question 8

What are the three main types of cell junctions?

Answer 8

• tight junctions
• gap junctions
• anchoring junctions

Question 9

What are the 3 types of anchoring junctions?

Answer 9

• desmosomes
• hemidesmosomes
• adherens junctions

Question 10

What 4 important proteins make up tight junctions?

Answer 10

1) e-cadherins
2) occludin
3) catenins
4) caludin-1

Question 11

What are the functions of tight junctions?

Answer 11

• separate cell into apical and basalolateral compartments

- prevent passage of substances between adjacent cells

Question 12

what cytoskeletal components are associated with tight junctions?

Answer 12

actin filaments

Question 13

What are two other names for tight junctions?

Answer 13

• zonula occludens

- blocking zones

Question 14

What are two other names for gap junctions?

Answer 14

• connexons

- electrical junctions

Question 15

What are gap junctions made up of?

Answer 15

connexins

Question 16

What is the function of gap junctions?

Answer 16

• facilitate rapid cell-to-cell communication. Can transmit action potentials (depolarization)
• allow small proteins, sugars, and ions to pass from one cell to another

Question 17

Name 5 areas where gap junctions can be found.

Answer 17

• epithelia
• cardiac muscle
• some types of smooth muscle
• certain types of neuron
• osteocytes

Question 18

What is the difference between desmosomes and hemidesmosomes?

Answer 18

• desmosomes tie together 2 epithelial cells

- hemidesmosomes bind epithelial cells to basement membrane

Question 19

what are CAMs? Give 3 examples

Answer 19

• cell adhesion molecules

- cadherins and catenins

Question 20

What are desmosomes made up of?

Answer 20

cadherins

Question 21

How do desmosomes function?

Answer 21

link intermediate filaments of adjacent cells

Question 22

which cell junctions aggregate into “plaques” along the cell membrane?

Answer 22

desmosomes

Question 23

What do hemidesmosomes do?

Answer 23

link cells to extracellular matrix (basal lamina)

Question 24

What are hemidesmosomes made up of?

Answer 24

integrins

Question 25

where are tight junctions found?

Answer 25

proximal to apical membrane

Question 26

What cytoskeletal filaments are hemidesmosomes associated with?

Answer 26

Intermediate filaments

Question 27

what are the functions of adherens junctions?

Answer 27

- use cadherins or integrins to link actin filaments - provide points linking cytoskeletons of adjacent cells - strengthens and stabilized nearby tight junctions

Question 28

what are adherens junctions essential to?

Answer 28

cell morphology

Question 29

Name 3 ways epithelia can be classified by shape.

Answer 29

- squamous (flat, thin) - cuboidal (square) - columnar (rectangular)

Question 30

Name 3 ways epithelia can be classified by number of layers.

Answer 30

- simple (one layer) - stratified (multiple layers) - pseudostratified (appearance of multiple layers)

Question 31

What are 3 ways, besides number of layers and shape, that epithelia can be classified?

Answer 31

- function - appearance - presence of cilia

Question 32

structure of simple squamous epithelia

Answer 32

- single, thin layer of flat cells | - little or no intracellular matrix

Question 33

simple squamous epithelia function

Answer 33

- gas exchange - diffusion - filtration

Question 34

What 3 places can simple squamous epithelia be found?

Answer 34

- alveoli - endothelia of capillaries - renal corpuscle

Question 35

Where can you find stratified squamous epithelium?

Answer 35

- epidermis | - cornea of eye

Question 36

What is the function of stratified squamous epithelium?

Answer 36

protection

Question 37

simple cuboidal epithelium is usually involved in what?

Answer 37

- glandular secretion | - absorption

Question 38

What 4 places can simple cuboidal epithelium found?

Answer 38

- ovary - kidney tubules - glandular tissue of thyroid (thyroid follicles) - pancreas

Question 39

Where are 3 places stratified cuboidal can be found?

Answer 39

- uncommon - mamillary glands - salivary glands - some sweat glands

Question 40

What are the functions of simple columnar epithelia?

Answer 40

- secretion and absorption | - some protection

Question 41

what 2 places can simple columnar be found?

Answer 41

- GI tract (villi) | - reproductive tract

Question 42

what are 2 places pseudostratified epithelium can be found?

Answer 42

- respiratory tract | - portions of reproductive tract

Question 43

describe the structure of pseudostratified epithelium.

Answer 43

- typically ciliated - simple, but appears stratified - columnar cells extend to basement membrane, but not all cells reach lumen. Cells are of different heights - heterogeneous arrangement of nuclei

Question 44

What is the function of Goblet cells, and where are they found?

Answer 44

- secrete mucus - in stratified squamous, columnar epithelia, and pseudostratified epithelia - in GI and GU tract epithelium

Question 45

What are the three types of epithelial secretion?

Answer 45

- merocrine - apocrine - holocrine

Question 46

What is merocrine secretion and where does it occur?

Answer 46

- relatively common (e.g. some sweat glands) | - vesicles leave Golgi, merge with plasma membrane (EXOCYTOSIS), and secrete contents

Question 47

What is apocrine secretion, and where does it occur?

Answer 47

- apical portion of cell is pinched off and released during secretion (blebbing) - occurs in sweat glands of axillary and pubic region

Question 48

What is holocrine secretion, and where does it occur?

Answer 48

- cell undergoes lysis and disintegrates | - sebaceous glands

Question 49

Where is glycocalyx found?

Answer 49

- slime on fish and eels - ubiquitous in all human tissues - respiratory tract - protective lining in blood vessels - lining of skeletal muscle

Question 50

Glycocalyx functions (the proven ones)

Answer 50

- mediates interactions between epithelium and underlying connective tissue - mediates interactions between lumen of a tract and what flows through it - mediates flow of blood through vessels - protective lining of blood vessels

Question 51

what is the composition of the glycocalyx?

Answer 51

gel-like matrix of glycolipids, glycoproteins, and negatively charged molecules