Zaidi tissues 1

Question 1

Describe the basic characteristics of stem cells

Answer 1

1. not terminally differentiated
2. can divide without limit
3. can renew
4. can retain a stem cell or become differentiated
5. slow division

Question 2

Define totipotentcy

Answer 2

ability of a cell to give rise to all cells of an organism

Question 3

Define pluripotency

Answer 3

ability of a cell to give rise to all cells of an embryo and adult tissues

Question 4

Define multi potency

Answer 4

ability of a cell to give rise to difference cell types of a different lineage

Question 5

Describe the difference between asymmetric division and independent choice

Answer 5

asymmetric- creates 2 cells; one with stem cell characteristics and the other with the ability to differentiate

independent choice- makes 2 identical cells but the outcome is stochastic and influenced by the env; more flexible

Question 6

Describe founder stem cells

Answer 6

each cell has a fixed number of founder cells that are programmed to have a fixed number of divisions

Question 7

Describe transit amplifying cells

Answer 7

divide frequently; programmed to divide for a limited number of times

Question 8

Describe skin

Answer 8

Epidermis–> loose CT dermis –> dense CT dermis–> fatty connective tissue hypodermis

has different cell types: 
fibroblasts are mechanical support 
blood vessels do nutrients 
macrophages protect 
lymphocytes are immune response 
nerve fibers are sensory info

Question 9

Describe the epidermis

Answer 9

stratified layer of keratinocytes with a basal cell layer (only dividing cells)
have prickle cells with desmosomes that attach keratin

granular cells waterproof everything and provide a boundary between the inner metabolically active strata and the outer dead epidermis

squame- outermost layer

Question 10

What is the order of the epidermis structure from the bottom to the top

Answer 10

• dermis
• basal lamina
• basal cell layer
• prickle cell layer
• granule cell layer
• keratinized squames
• squames

Question 11

Describe the renewal of the epidermis by the stem cells

Answer 11

SELF RENEWING
-basal layer has stem cells that divide to both maintain the basal layer and to move to the other layers changing gene expression to acquire the phenotype of cell for that layer

supplied an indefinite supply of fresh cells

Question 12

What are the factors that govern the renewal of the epidermis?

Answer 12

1. Rate of stem cell division
2. probability that one of the daughter cells will be a stem cell
3. rate of division of transit amplifying cells
4. timing of exit

Question 13

What happens in the event of the over activation of the hedgehog pathway?

Answer 13

cells continue to divide after exiting the basal layer; lose sebaceous glands

Question 14

What happens with the up regulation of Wnt signaling?

Answer 14

hair follicles into tumors

Question 15

What happens with the loss of Wnt?

Answer 15

failure of hair follicle development

Question 16

What plays a role in the repair of skin wounds promoting collagen rich scar tissue?

Answer 16

TGFB