3.9 specialized tissues, stem cells

Question 1

What are stem cells?

Answer 1

unspecialized cells

Question 2

why are stem cells important?

Answer 2

potential to develop into many dif cell types in the body

Question 3

Stem cells can also serve as what to many tissues?

Answer 3

internal repair system.

Question 4

What are 5 characteristics of stem cells?

Answer 4

can divide without limit. Can renew themselves. Not terminally differentiated. Can remain a stem cell or become differentiated. Undergo slow division

Question 5

What is totipotency?

Answer 5

ability of a cell to give rise to all cells of an organism. Embryonic and extra embryonic tissues

Question 6

What is an example of totiplotency?

Answer 6

zygote

Question 7

What is pluripotency?

Answer 7

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

Question 8

What is an ex of pluripotency?

Answer 8

embryonic stem cells

Question 9

What is multipotency?

Answer 9

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

Question 10

What is an ex of multipotency?

Answer 10

adult stem cells

Question 11

What two ways are stem cells maintained?

Answer 11

asymmetric division and independent choice

Question 12

What is asymmetric division?

Answer 12

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

Question 13

What is independent choice?

Answer 13

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

Question 14

Which of the two (asymmetric or independent choice) is a better option?

Answer 14

independent choice

Question 15

Differentiation of stem cells depends on what two types of signals?

Answer 15

internal and external signals

Question 16

How are internal signals controlled by?

Answer 16

cells genes

Question 17

How are the external signals controlled by?

Answer 17

cells micro environment.

Question 18

Each organ/tissue has a fixed number what?

Answer 18

founder cell populations and fixed number of divisions

Question 19

How are founder stem cells controlled?

Answer 19

by short range signals.

Question 20

Pertaining to founder stem cells, if the adult organ needs to be renewed, founder stem cells can what?

Answer 20

can divide, having one daughter cell that remains a stem cell and a set of cells that have a set number of transit amplifying divisions.

Question 21

What are transit amplifying cells?

Answer 21

cells that divide frequently and are mixed with stem cells

Question 22

Transit amplifying cells are programmed to divide for how many times?

Answer 22

limited number of times

Question 23

Adult stem cells are specific to what?

Answer 23

tissue

Question 24

What is the architecture of the skin? 3 layers

Answer 24

Epidermis, Dermis and hypodermis

Question 25

What does the epidermis do?

Answer 25

forms the outer covering of skin, creates a water barrier. continuously repaired and renewed.

Question 26

What is the Dermis?

Answer 26

second layer of skin, rich in collagen, provides toughness

Question 27

What is the hypodermis?

Answer 27

fatty layer

Question 28

The epidermis is stratified layer made of what?

Answer 28

keratinocytes

Question 29

the basal cell layer is attached to what?

Answer 29

basal lamina

Question 30

prickle cells have what?

Answer 30

numerous desmosomes that attach tufts of keratin filaments

Question 31

Granular cells form what type of barrier?

Answer 31

water proof

Question 32

What is the squame?

Answer 32

outermost layer of the epidermis with flattened dead cells densely packed with keratin but no organelles.

Question 33

Name the multilayered structure of the epidermis from outest layer to most inner.

Answer 33

Squame, Granular, Prickle, Basal lamina.

Question 34

How does the epidermis renew?

Answer 34

with basal cells that move through the prickle then the granule cell layer.

Question 35

Where do stem cells come from for the renewal of the epidermis?

Answer 35

basal layer

Question 36

how are epidermal stem cells regulated?

Answer 36

By contact with basal lamina

Question 37

How does contact with basal lamina control the number of stem cells in the epidermis?

Answer 37

Maintenance of contact preserves stem cell potential, loss of contact triggers terminal differentiation.

Question 38

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

Answer 38

Beta 1 subunit of integrin

Question 39

Intregrin signaling pertaining to epidermis stem cell renewal helps to control what?

Answer 39

size of stem cell population

Question 40

What factors govern renewal of epidermis?

Answer 40

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.

Question 41

Where does hair grow upward from?

Answer 41

Dermal papilla

Question 42

Sebaceous glands secret oily liquid called

Answer 42

sebum

Question 43

Overactivation of hedgehog pathway makes cells do what?

Answer 43

cells to continue to divide even after exit from basal layer

Question 44

What happens with a deficit of hedgehog signal?

Answer 44

loss of sebaceous glands

Question 45

What causes extra hair follicles to develop?

Answer 45

up regulation of Wnt signaling

Question 46

What signaling restricts size of stem cell population?

Answer 46

notch signaling.

Question 47

What plays a key role in repiar of skin wounds?

Answer 47

TGFb