Lecture 4: Epithelium

Question 1

Tissue

Answer 1

An aggregation of cells and extracellular substances

Question 2

Epithelium

Answer 2

A tissue composed of closely aggregated cells with very little extracellular substance

Question 3

4 basic types of tissue

Answer 3

Epithelial tissue
Connective tissue
Muscular tissue
Nervous tissue

Question 4

3 categories of the epithelium

Answer 4

1. Surface/Lining epithelia
2. Glandular epithelia
3. Special epithelia

Question 5

Surface or lining epithelia

Answer 5

Form sheets that cover body surface and line luminal organs, tubular structures, and body cavities

Question 6

Glandular epithelia

Answer 6

Secretory

Their functions are to synthesize, store, and release it’s product

Question 7

Special epithelia

Answer 7

Receptors for taste and hearing (sensory for smell and vision have modified neurons)

Question 8

7 functions of epithelial tissue

Answer 8

1. Protection
2. Secretion
3. Absorption
4. Diffusion
5. Friction Reduction
6. Cleaning
7. Sensation

Question 9

Protection

Answer 9

Protects underlying tissue from mechanical abrasion/injury, harmful chemicals, invading microbes, and from excessive loss of water

Question 10

Secretion

Answer 10

In glands, specialized to secrete specific chemical substances such as enzymes, hormones, and lubricating fluids

Question 11

Absorption

Answer 11

Those lining the small intestine absorb nutrients from the digestion of food. Second largest absorbing area are of kidney tubules

Question 12

Diffusion

Answer 12

Simple squamous (square) epithelium promotes the diffusion of gases, liquids, and nutrients (ex. endothelium of capillaries and lungs)

Question 13

Friction reduction

Answer 13

the smooth, tightly-interlocking endothelial cells that line the entire circulatory system reduce friction between the blood and walls of the blood vessels

Question 14

Cleaning

Answer 14

Ciliated respiratory epithelium assists in removing dust particles/foreign bodies from air passages

Question 15

Sensation

Answer 15

Specialized epi. tissue containing sensory nerve endings is found in the skin, ears, and on the tongue

Question 16

Three germ layers in the developing embryo

Answer 16

1. Ectoderm
2. Mesoderm
3. Endoderm

Question 17

Ectoderm

Answer 17

Epidermis of the skin and its derivatives

Question 18

2 parts of the mesoderm

Answer 18

Mesothelium

Endothelium

Question 19

Mesothelium

Answer 19

Epitthelium lining three serious body cavities (peritoneal, pleural, and pericardial)

Question 20

Endothelium

Answer 20

Epithelium lining blood and lymphatic vessels and heart chambers

Question 21

Endoderm

Answer 21

Epithelial lining and glands for most of the GI tract, respiratory system, liver, pancreas, and urinary bladder

Question 22

Epithelium has ____ cellular density

Answer 22

High

Question 23

Endothelium has little _____cellular subastance

Answer 23

inter

Question 24

Epithelial cell structure

Answer 24

polarized, cohesive, and closely associated to supporting connective tissue

Question 25

Three surfaces of epithelial cells

Answer 25

Apical Lateral Basal

Question 26

Where is the extracellular basal lamina

Answer 26

Lies at the interface of epithelial and connective tissue

Question 27

Small blood capillaries never enter an epithelium across

Answer 27

a basal lamina

Question 28

When components of a basal lamina are distinguishable in light microscopy, it is called

Answer 28

a basement membrane

Question 29

Basal lamina

Answer 29

- Extracellular material, formed by the epithelial cells, separating epithelium from underlying connective tissue and acting as a selective barrier. - Provides structural support

Question 30

Basal lamina is visible in EM...

Answer 30

Only as a dense layer up to 100 nm thick

Question 31

Basement membrane

Answer 31

- Basal lamina when it is visible with light microscopy | - Semi-permeable barrier (ex. blood-urine in placenta)

Question 32

Basement membrane stain

Answer 32

PAS

Question 33

Epithelial cells that are subject to pressure and traction have marked

Answer 33

Intercellular adhesion

Question 34

Cohesiveness is due to (3)

Answer 34

- Transmembrane glycoproteins - E-Cadherins - Folds of plasma membrane between neighboring cells from intercellular adhesions

Question 35

Three types of intercellular junctions

Answer 35

- Tight junctions - Desmosomes - Gap junctions

Question 36

Tight junctions

Answer 36

- The membranes of neighboring cells are bound together by specific proteins - Form continuous hermetic seals around the cell - Prevent leakage of fluid across a layer of epithelial cells

Question 37

Desmosomes

Answer 37

- Function like rivets, fastening cells together into strong sheets - Intermediate filaments made of sturdy keratin proteins anchor desmosomes in place - Adhere epithelial cells of the skin

Question 38

Gap junctions

Answer 38

-Provide cytoplasmic channels or tunnels from one cell to adjacent cell

Question 39

Gap junctions consist of

Answer 39

special membrane proteins that surround a pore through which ions, sugars, amino acids, and other small molecules may pass

Question 40

Gap junctions are necessary for

Answer 40

communication (chemical and electrical signals) between cells in many types of tissue (ex. heart muscle)