Specialized Tissues, Stem Cells and Tissue Renewal I

Question 1

What are the characteristics of stem cells?

Answer 1

not terminally differentiated
can divide without limit
ability to renew themselves
when divide each new cell has ability to remain a stem cell or become differentiated into a different cell type 
undergo cell division

Question 2

What is totipotency?

Answer 2

ability of a cell to give rise to all cells of an organism, including embryonic and extra embryonic tissue

Question 3

A zygote is what type of cell?

Answer 3

totipotent cell

Question 4

What is pluripotency?

Answer 4

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

Question 5

Embryonic stem cells are what type of cell?

Answer 5

pluripotent cell

Question 6

What is multi potency?

Answer 6

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

Question 7

adult stem cells are what type of cells?

Answer 7

multipotent

Question 8

A steady pool of stem cell population maintained by:

Answer 8

asymmetric division

independent choice

Question 9

What is asymmetric division?

Answer 9

creates 2 cells, one with stem cell characteristics and another with the ability to differentiate

Question 10

What is independent choice?

Answer 10

division makes 2 identical cells but the outcome is stochastic and/or influenced by environment

Question 11

What is a drawback to asymmetric division?

Answer 11

cannot explain how existing stem cells rapidly increase their numbers

Question 12

Why is the independent choice more flexible?

Answer 12

explains the sharp increase in stem cell numbers when needed to repair

Question 13

If the adult organ needs to be renewed, founder stem cells can divide give rise to what?

Answer 13

one daughter cell that remains a stem cell and a set of cells that have a set number of transit amplifying divisions

Question 14

Do transit amplifying stem cells divide frequently?

Answer 14

yes

Question 15

Adult stem cells are ______ specific

Answer 15

tissue

Question 16

Describe the epidermis

Answer 16

• forms the outer covering of skin
• creates a water barrier
• made of epithelial cells
• continously repaired and renewed

Question 17

What is the dermis?

Answer 17

second layer, rich in collagen, provides toughness

Question 18

What is the hypodermic?

Answer 18

fatty subcutaneous layer

Question 19

the extracellular matrix of the skin is secreted by ______ that provide _____

Answer 19

fibroblasts, mechanical support

Question 20

Epidermis is a stratified layer made of ______

Answer 20

keratinocytes

Question 21

describe prickle cells

Answer 21

have numerous desmosomes that attach tufts of keratin filaments

Question 22

granular cells are sealed together to form a ______ barrier

Answer 22

waterproof

Question 23

What boundary does the granule cell layer form?

Answer 23

inner metabolically active strata and outer dead epidermis cells

Question 24

What is the outermost layer the epidermis called?

Answer 24

squame

Question 25

What is the squame?

Answer 25

flattened dead cells densely packed with keratin but with no organelles

Question 26

proliferative potential of stem cells directly correlates with expression of what?

Answer 26

B1 subunit of integrin

Question 27

What are the factors that govern renewal of epidermis?

Answer 27

- rate of stem cell division - probability that one of the daughter cell will remain a stem cell - rate of division of transit amplifying cells - timing of exit from basal layer and the time the cell takes to differentiate and be sloughed away from surface

Question 28

_____ signaling mediates epidermis renewal

Answer 28

integrin

Question 29

Over activation of hedgehog pathway makes what happen?

Answer 29

makes cells continue to divide even after exit from basal layer

Question 30

What happens when there is a deficit of hedgehog signal?

Answer 30

loss of sebaceous glands

Question 31

What happens when there is an up regulation of Wnt signaling?

Answer 31

extra hair follicles to develop and give rise to tumors

Question 32

Loss of Wnt signaling leads to what?

Answer 32

failure of hair follicle development

Question 33

What does notch signaling restrict?

Answer 33

size of stem cell population

Question 34

What does lateral inhibition cause?

Answer 34

neighbors of stem cells to become transit amplifying cells

Question 35

TGF beta plays a key role in what?

Answer 35

repair of skin wounds promoting formation of collagen rich scar tissue