Epithelium Flashcards Preview

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Flashcards in Epithelium Deck (44):
1

How often does cancer arise from epithelium?

75% of the tim; MAJORITY

2

Tissues

Group of cells closely associated in structure and function

3

Histology

The study of tissues

4

What are the four major types of tissue?

1. Epithelium
2. Connective
3. Muscle
4. Nervous

5

Where are epithelia located?

They COVER or LINE:
a. free surfaces (skin)
b. lining of open cavities (digestive, respiratory systems)
c. lining of closed cavities (ventral body cavity)
d. lining of blood vessels and heart (parietal pericardium (lines heart WALL) visceral pericardium (lines organ itself))}

6

Epithelial Gland

Skin dips down and make something in it when there is a gland
ex. gland in ear makes ear wax

7

What are the 4 main function of Epithelia?

1. Protection- against bacterial infections, injury, etc.
2. Absorption- ex. lining of digestive tract; absorbs food into blood vessels that takes food in
3. Filtration- ex: renal-kidney; make urine, some goes out, some stays
4. Secretion- ex. glandular epithelium

*Or any COMBO of the 4

8

What are the features of epithelial tissue?

-Tightly packed/little extracellular space
- exists as sheets: tight junctions and desmosomes

9

Apical

Top part of cell; often contain microvilli

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Basal

Bottom part of cell; always attached to basement membrane

11

Desmosome

Anchoring junction; anchors cells together

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Tight junction

Keeps in in tact so it doesn't fall apart

13

Microvilli

Highly folded EXTENSIONS of the plasma membrane (it IS the membrane) that increases absorption area; brush border

14

Cilia

-Beat in/out; stroke to push things away
EX: filter (beat out) mucous out of mouth and catch particles while its going up. (move substances over surfaces)
-not part of the membrane; they go through the cell membrane and ANCHOR in the cytoplasm

15

What is the structure of cilia?

Core 9+2 microtubule doublets

Basal body (centriole)= 9 microtubule triplets

16

Flagella

longer projections from basal body in cilia; cell propels itself

17

Goblet cell

Musinagen inside them that will become mucous; not cilia covering where goblet cell is bc once it makes mucous, it pushes it out of cell

18

What does it mean if epithelia doesn't sit on basement membrane?

cancer

19

Polarity of epithelia

cell is different all around

20

Basement membrane

-only epithelia have this
-two layers: basal lamina and reticular lamina

21

Is epithelia vascular or avascular?

Avascular; no blood vessels

22

Basal Lamina

-Thin layer; closest to epithelium (secreted BY epithelium)
-non-cellular adhesive layer
-selective filter of materials from blood
-template for wound repair

23

Reticular lamina

-Below the basal lamina
-Extracellular network of collagen fibers

24

Lamina means...

layer

25

How does food get from connective tissue to epithelia if there are no blood vessels in epithelia?

Simple diffusion through capillaries: Blood vessels in connective tissue ----> epithelium; skin is fed from bottom, up

26

Avascularity

Epithelia:
-No blood vessels
-Nutrients by diffusion
-IS innervated (supplied by nerves)

27

Regeneration

Epithelia:
-High mitotic index; one of highest in body

28

Simple epithelium

One layer of cells; contains all 3 shapes

29

Stratified

multiple layers; may have different shapes but nomenclature (naming) is based upon the cell shape of the free (apical) surface

30

3 epithelium shapes

-squamous; flattened
-cuboidal; height=width
-columnar; height>width

31

Pseudostratified

Looks stratified but really not; one layer of cells but different heights
pseudo= false

32

Simple Squamous

-Little protection; good for filtration (allows things to diffuse through them; form/function)
-Lines blood vessels/capillaries
-serosal membrane (ex: mesothelium- inside lining of lung)

33

How does oxygen get to simple squamous epithelia?

O2 gets absorbed by alveoli in lungs, diffused into capillaries, and since simple squamous is only one cell thick, it absorbs it quickly

34

What are the most common gasses in air?

N2, O2 (20%), CO2 (1%)

35

Simple cuboidal

One layer thick of cubes; absorption in kidney (many microvilli)

36

Simple columnar

-Sometimes have cilia, sometimes not; goblet cells for mucous production (mucous=sugar)
-digestive tract, urine tubes, pancreatic duct, oviduct

37

What kinda of epithelium is in the trachea?

Psuedostratified ciliated columnar epithelia

38

Stratified squamous epithelium

-MOST COMMON type of stratified epithelium
-protection vs. abrasion
-high mitotic index
-cells shed from apical region
- different layers may have different shapes but name is based off of the free apical (top) surface
-Basal layers: usually not squamous, site of new cell generation

39

Example of stratified squamous

SKIN

40

Keratin

On apical surface of stratified squamous; water insoluble protein (extra layer on top of skin; NOT in places with moisture like nose, mouth, vagina, etc.)

41

Why do we need moisture in our noses?

Function is to warm air; warmer it is the faster it diffuses so we humidify it with moisture

42

Stratified columnar

-Very RARE
-Urethra of male
-some large organ ducts of glands

43

Stratified cuboidal

-RARE
-2 to 3 cells deep
-Largest ducts of: sweat glands, mammary glands, salivary glands, surrounding eggs

44

Transitional Epithelium

(Stratified)
-Urinary bladder *
-Cuboidal on top, columnar on bottom
-Stretches out when bladder is full