histology: connective tissue

Question 1

connective tissue is embryonically derived from?

Answer 1

mesenchyme

Question 2

what do all connective tissues have in common?

Answer 2

tend to have low cell:ECM ratio

Question 3

ECM is comprised of which prime constituents of fibrous connective tissue?

Answer 3

collagen fibers and ground substance

Question 4

what kind of cells secrete collagen and ground substance?

Answer 4

fibroblasts

Question 5

is the overlying epithelium avascular?

Answer 5

yes; it relies on the superficial vasculature of the dermis to meet its metabollic needs.

Question 6

what does collagen do?

Answer 6

collagen is a fibrillar protein that:

1) very strong and provides scaffolding for cells
2) provide substrate for cells to adhere to and crawl across
3) form scars after tissue is damaged
4) provide framework for other supporting tissues to build upon or travel inside.

Question 7

what do the different types of collagen do? I,II,III, IV

Answer 7

I- most common (skin, bones, organs, etc.)

II- cartilage

III-reticular fibers

IV- basement membrane

Question 8

what are type III reticular fibers?

Answer 8

short, branched type of collagen fiber that results in a spongy tissue

Question 9

what are elastic fibers?

Answer 9

in addition to collagen, some tisues will have elastic fibers that are comprised of a protein called **elastin. ** allows stretching

Question 10

Collagen disorder: Scurvy- what is it? what causes it?

Answer 10

deficiency in vitamin C -> impairs collagen formation

1) vit c is required for hydroxylation of procollagen (precursor molecule for collagen, without hydroxylation, cannot form the final helical shape and is more easily degraded by enzymes)
2) rate at which procollagen is synthesized is inhibited.

as a result: wounds heal poorly, gums bleed easily

Question 11

Elhers-Danlos

Answer 11

genetic disorder that affects transcription, assembly or modification of collagen.

result: strecheable skin, hypermobile joints, poorly healing wounds, increased risk of aneurism and rupture of colon

Question 12

what is ground substance? what macromolecules make it? what does it do?

Answer 12

“stuff” that exists outside cells other than collagen that helps maintain the extracellular environment.

made up of: glycosaminoglycans (GAG) and proteoglycans

absorbs a large amount of water which allows biomolecules to dissolve, creating a gel-like substance that allows biochemical reactions to occur.

serves as a reservoir of nutrients

repository for cell waste products

shock absorber

Question 13

as the density of connective tissue increases, there are fewer/more lymphatic and vascular structures

Answer 13

fewer

Question 14

what is this?

Answer 14

a mast cell- it has a frothy granular appearance.

cell cytoplasm is packed with granules

the granules stain dark so they obscure the nucleus

release histamine, initiating an inflammatory reaction

also responsible for allergic rxn

Question 15

what kind of cell is this?

Answer 15

plasma cell:

differentiated B cells

primary source of immunoglobulins

constituitive secretors - Abs are synthesized and released immediately rather than stored for later use

wagon wheel or clock faced nucleus

Question 16

how do mast cells and plasma cells interact?

Answer 16

plasma cells secrete IgE

when a B cell is sensitive to a certain allergen and exposed to it, it can become activated and differentiate into a plasma cell.

mast cells have IgE receptors , and can become primed ** once they take up the IgE and display it on their cell surface.

if mast cells encounter the allergen again, it will degranulate