Tissues: Epithelium Flashcards Preview

Biology 210 > Tissues: Epithelium > Flashcards

Flashcards in Tissues: Epithelium Deck (29):
1

Tissue

group of specialized cells

2

Four primary Tissues

Epithelium, Connective, Muscle, Nerve

3

Ematopoisis

formation of blood cells

4

*Epethilium*

sheet of tissues that covers a body surface or lines body cavity
-basal surface attached to basement membrane
-always connected to connective tissue
-avascular and inervative
-rapid regeneration (GOOD- are prone to lots of friction)

5

Two types of epithelium

covering/lining
glandular (protection, lubrication, chemical signaling)

6

Apical Surface

surface that is either on the outside or inside a lumen

7

Basement membrane

seperates the epethilium from the connective tissue

8

Functions of Epithelial Tissue

protection
barrier
permeability
sensation
absorption

9

Classification : Cell Layers

simple = one cell layer
stratified = more than one layer
pesuedostratified = really simple columnar

10

Classification : Cell Shape

Squamous = flat
Cuboidal = square
Columnar = tall

11

*Squamous Epithelium*

*Simple Squamous*
thin and flat
- 1 layer thick (delicate)
- found in linings of blood vessels and lungs (absorption)
*Stratified squamous*
- forms many layers thick (against physical and chem attacks)
- found on outside of body (epidermis, dermis)

12

Keratinized stratified squamous epithelium

apical layers of skin cells (tough and water resistant)
- packed with fibrous protein keratin

13

Nonkeratinized stratified squamous epithelium

resists abrasions but dries out (must be well lubricated)
- found in vaginal and oral cavities

14

*Cuboidal Epithelium*

*Simple cubodial*
occurs where secretion or absorption takes place (lining of kidney tubules)
*Stratified cubodial*
RARE, but found in ducts of sweat and mammary glands

15

*Transitional Epithelium*

tolerate repeated cycles of stretching without damage (urinary bladder)
- called transitional because cell layers change appearance (from stratified to more as they stretch)

16

*Columnar Epithelium*

*Simple columnar*
found where absorption or secretion occur (stomach small intestine, large intestine)
*Pseudostratified columnar*
cilia bearing cells found in portions of respiratory tract (nasal, trachea, bronchi)
*Stratified columnar*
RARE, but protect portions of pharynx, epiglottis, anus and urethra

17

Glands

typically multicellular and specialized for secretion
-goblet cells secrete mucus (trachea and parts of digestive tract)

18

Endocrine Glands

release hormonal secretions into interstitial fluid which then moves to blood (thyroid and pituitary gland)
NO DUCTS

19

Exocrine Glands

release secretion into ducts that carry it to an epithelial surface (skin)
HAVE DUCTS

20

Classification of Exocrine Glands (NTK! 86 & 87)

Merorcrine secretion: exocytosis (sweating)
Apocrine secretion: cell pinches off secretion (mammary glands but also exocytosis)
Holocrine secretion: fills a gland and bursts; no repair (sebum- gland that produces oil) ==> have to have a population of stem cells behind the gland to produce more cells

21

DUCTS

1 ducts = simple tubular glands and simple alveolar gland
Branching ducts = compound tubular glands and alveolar

22

Cell Connections

Tight Junctions
Gap Junctions
Desmosomes

23

(A) Gap Junctions

-cells held together by channel proteins
-allows free diffusion of ions and small molecules between cells (cardiac muscle- contractions)

24

(B) Tight Junctions

- close; prevent water and solutes between cells (permeability)
- lipid plasma membranes fused together with proteins in membrane

25

(C) Desmosomes

- strongest; allows cell to bend and twist without seperating
- like cable connection (one cell to another)

26

Ability of epithelial tissue to maintain and repair itself

(1) epithelium exposed to toxins, chemicals, pathogens, abrasions
(2) rapid regeneration (miotic life cycle)
(3) stratified epithelium, new cells arise from stem cells located in basal layer of tissue

27

Differentiation

non specialized cells (stem cells: hemocytoblasts) undergo genetically guided changes to become more specialized cells

28

First Body TIssues

Ectoderm
Mesoderm
Endoderm

29

Goblets

only type of unicellular gland in the body