Specialized Tissues, Stem Cells And Tissue Renewal I Flashcards Preview

Molecular Biology Exam 3 > Specialized Tissues, Stem Cells And Tissue Renewal I > Flashcards

Flashcards in Specialized Tissues, Stem Cells And Tissue Renewal I Deck (38):
1

Asymmetric Division

- Creates 2 cells

- One with stem cell Characteristics

- One with the ability to DIFFERENTIATE

2

TGF-Beta on Epidermis Renewal

- Plays a key role on REPAIR of Skin wounds

- Promotes. The formation of COLLAGEN rich SCAR tissue

3

Regulation of Epidermal Stem Cells

- CONTACT with Basal Lamina Controls number of Stem cells

- Maintenance of contact preserves Stem Cell Potential

- Loss of contact triggers terminal differentiation

4

Characteristics of the Prickle Cell Layer

- Has DESMOSOMES

- Attaches to Keratin filaments

5

Characteristics of Founder stem cells

- Proportion of the parts of a body are determined EARLY in development

- Each organ/tissue has a FIXED number of Founder cells

- Programmed to have fixed number of divisions

6

Layers of the Epidermis from Outermost to Innermost

1. Basal Cell layer

2. Prickle Cell

3. Granular Cell

4. Squame

7

Factors governing Renewal of Epidermis

1. Rate of Stem cell Division

2. % that one daughter will remain a Stem cell

3. Rate of Division of Transit Amplifying Cells

4. Timing of Exit from Basal Layer and the time the cell takes to differentiate and be sloughed away

8

Characteristics of Stem cells

- Not terminally differentiated

- Can divide w/o limit

- Ability to renew themselves

- Undergo Slow Division

9

Characteristics of Multipotent stem cells

- Ability to give rise to different cell types of a given LINEAGE

- Adult stem cells

10

Characteristics of the Basal Cell Layer

- Attached to Basal Lamina

- The Only DIVIDING cells in the Epidermis

- Has STEM cells

11

Characteristics of the Squame Cell Layer

- Flattened Dead cells

- Densely packed with Keratin

- NO ORGANELLES

12

A steady pool of Stem cells are maintained by what?

- Asymmetric Division

- Independent Choice

13

Characteristics of Adult stem cells

- Tissue Specific

- Serves an internal REPAIR system in many tissues

- Replace cells with rapid turnover

- Needs specialized environment

14

Overactive Hedgehog Pathway in Epidermis Renewal

- Makes cells continue to divide

- Even after exit from the Basal Layer

15

The Ectoderm lineage gives rise to what systems?

- Skin

- Neurons (CNS)

16

Characteristics of Pluripotent cells

- Ability to give rise to ALL cells of the Embryo
(NOT Extra Embryonic)

- Gives rise to adult tissues

-Ex: Embryonic stem cells

17

Characteristics of the Granular Cell Layer

- Sealed together to form a WATERPROOF Barrier

- Forms boundary b/w INNER (active) strata and OUTER (dead) cells

18

Fibroblast on skin composition

- Secrete ECM

- Provide Mechanical support

19

Architecture of the Skin

1. Epidermis
- Continuously repaired and renewed

2. Dermis
- Rich in collagen and provides toughness

3. Hypodermis
- FATTY subcutaneous layer

20

Upregulation vs Loss of Wnt on Epidermis Renewal

Upregulation
- Causes extra HAIR follicles to develop
- Gives rise to tumors


Loss of Fxn
- Leads to failure of HAIR follicle development

21

The Mesoderm lineage gives rise to what systems?

- Muscles

- Blood

22

Developmental Capacity of stem cells: Most to Least

1. TOTI-Potent

2. PLURI-Potent

3. MULTI-Potent

23

Characteristics of Transit Amplifying cells

- Transit from a Stem cell to a Differentiated cell

- Programmed to divide a LIMITED # of times

- Part of growth control

24

Deficit in Hedgehog in Epidermis Renewal

Leads to loss of SEBACEOUS gland

25

Which is more flexible? Asymmetric Division or Ind. Choice?

Independent Choice
- Explains the SHARP increase in Stem Cell # when needed for REPAIR

26

Examples of Adult stem cells

1. Skin

2. Intestinal

3. Blood

4. Neurons

27

Renewal Process of Epidermis

- Some Basal Cells divide and maintain that layer

- Others move up to other layers

- Change GENE EXPRESSION at each step of differentiation

- Cells will eventually lose organelles

28

Time of Birth of a Basal Cell Layer to Shedding from Surface?

1 month

29

The Endoderm lineage gives rise to what systems?

- Lung

- Pancreas

30

The Epidermis is a ________ layer made of ________.

1. Stratified

2. Keratinocytes

31

Proliferative potential of stem cells are directly correlated with expression of what?

- Beta 1 Subunit of INTEGRIN

- Helps mediate Adhesion to Basal Lamina

32

Drawback of Asymmetric Division

Cannot explain how existing stem cells rapidly increase their numbers

33

3 lineages of Pluripotent stem cells

1. Endoderm

2. Mesoderm

3. Ectoderm

34

What happens to a founder cell when an adult organ needs to be renewed?

- Founder cells divides to make
1. One daughter stem cell
2. Differentiated cell

Differentiated cells have a SET number of transit amplifying divisions

35

Independent Choice

- Division makes 2 IDENTICAL cells

- The outcome is Randomly Determined

Or

- Influenced by environment
(Does not have to be 50:50 for every division)

36

Notch Signaling on Epidermis Renewal

Restricts the SIZE of Stem cell population

37

Characteristics of Totipotent cells

- Ability to give rise to ALL cells of an organism
(Can produce a new being)

- Embryonic and Extra embryonic

- Ex: Zygote

38

What are the two fates of stem cell division?

1. Can remain a stem cell

Or

2. Become a DIFFERENTIATED cell type