Epithelium

Question 1

4 basic types of tissues

Answer 1

Epithelial

Connective

Muscle

Nervous

Question 2

Location of Epithelium

Answer 2

Covers surfaces

Extends into all complex invaginations

Mostly cells

Question 3

Parenchyma vs. Stroma

Answer 3

Parenchyma: Essential/Functional

Stroma: non-essential (connective tissue, blood vessels, ducts)

Question 4

Functions of epithelium

Answer 4

Protection (chemical and mechanical)

Control of transport (absorption and secretion)

Question 5

Epithelium Characteristics

Answer 5

Uninterrupted layer of cells

avascular (no vessels)

Polarized

Apical
⇅
Basal

*Basal layer undergoes mitosis

Question 6

Where is the basement membrane? What is it also called?

Answer 6

Basement membrane (aka Basal Lamina )

Between epithelium and connective tissue

Question 7

Basal cell layer of epithelium

Answer 7

Stem cells that reside closest to the basal lamina (undifferentiated)

Mitosis (renewal/turnover)

Progenitor cells (division)

Question 8

Metaplasia

Answer 8

Adaptation of mature tissue to physical or chemical stress

Stem cells alteration

✰Can lead to cancer (neoplasia)

Question 9

Paracellular vs. Transcellular transport

Answer 9

Paracellular - Between two cells

Transcellular - Through a singular cell

Question 10

Junctions of epithelium

Answer 10

*Tight: Seal
- proteins: occludens, claudins, ZO proteins

*Adherens: Anchor
- proteins: actin filaments and cadherins.

*Desmosomes: anchor (velcro) mechanical stress
- proteins: Desmogleins, desmoplakin, plakoglobin

*Gap junctions: communication
- protein: Connexin.

*hemidesmosomes: anchor to basal lamina
- proteins: integrins/laminins
*blistering disorder

Question 11

Classification: epithelial types

Answer 11

Simple (single layer) vs. Stratifies (multi-layered)

Cuboidal, columnar, squamous (low)

keratinized vs non-keratinized

Pseudostratifies columnar

Urothelium (kidneys, ureters, bladder, urethra)
-stratified
-Stretch and leak prevention

Question 12

T/F: Mast cells are resident cells of connective tissue that contain many granules rich in histamine and heparin.

Answer 12

TRUE

mast cells are key players in the inflammatory response.

Question 13

eosinophils are associated with… and …

Answer 13

eosinophils are associated with INFLAMMATORY RESPONSE and ASTHMA

Question 14

fibroblasts secrete most of the ___

Answer 14

ECM

Question 15

adipocytes store energy and regulate ____

Answer 15

metabolism

Question 16

aquaporins

Answer 16

channels that allow water transport when they are inserted in the cell membranes

Question 17

tight junctions

Answer 17

control paracellular transport

Question 18

gap junctions

Answer 18

cell to cell communication

Question 19

which connective tissue component is located in the ECM but not in the ground substance?

Answer 19

Collagen bundles!

ECM: ground substance and collagen fibers

Ground substance: fills space with fibers (collagen fibers), water, organic molecules (GAGS), proteoglycans, and glycoproteins (fibronectin, laminin).

Question 20

what cell type produces hormones important for metabolism and stores energy?

Answer 20

adipocytes

adipocytes store energy in the form of lipid molecules

adipocytes have important endocrine and metabolic roles
- secreting hormones (adipokines- regulate energy balance)
- food intake and satiety
- inflammatory response
- metabolism of steroid hormones

Question 21

what cell is involved in adhesion to the basement membrane?

Answer 21

Integrins

Integrins are receptors

Fibrilin and laminin are ligands (bind with integrins)

Question 22

desmoplakin

Answer 22

component of desmosomes which mediate cell to cell attachment

Question 23

cadherins

Answer 23

component of adherens junctions which mediate cell to cell attachment

Question 24

fibrillin

Answer 24

component of elastic fibers

glycoprotein

secreted by fibroblasts

Question 25

occludens

Answer 25

proteins associated with tight junctions

Question 26

T/F: all epithelia will have some attachment to a basal lamina and express desmosomes

Answer 26

TRUE

Question 27

what structural feature of the epithelial cells contributes to selective permeability and surface specialization?

Answer 27

polarity apical and basal surfaces

Question 28

macrophages defend against infection via ____

Answer 28

phagocytosis and presenting antigen to T cells secrete cytokines and chemokines to recruit immune cells, promote inflammation, tissue repair/healing, clear dead cells/debris

Question 28

what characteristic of epithelia cells gives the protective function?

Answer 28

tight junctions between cells that create a continuous barrier

Question 29

junctions and their protein(s)

Answer 29

tight junctions: occludens, claudins, ZO proteins adheren junctions: cadherins and actin filaments desmosomes: desmogleins and desmoplakin hemidesmosomes: integrins and laminins gaps junctions: connexin

Question 30

how do molecules pass the epithelial membrane?

Answer 30