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Developmental, Stem Cell & Regenerative biology > Lecture 8 - Growth > Flashcards

Lecture 8 - Growth Flashcards

1
Q

Why must tissue growth be regulated?

A

To maintain the correct proportions to drive morphogenesis

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2
Q

What are the 3 types of tissue growth?

A
  • cell proliferation
  • cell enlargement (cellular hypertrophy)
  • growth by accretion - cells can be instructed to produce more extracellular matrix
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3
Q

What are the 4 stages of the cell cycle

A
  • M phase
  • G1
  • S phase
  • G2
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4
Q

In what stage of the cell cycle is the cell in most of the time?

A

G1 - making material (transcribing genes)

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5
Q

What is the purpose of checkpoints in the cell cycle?

A

to make sure everything is in order before mitosis & cytokinesis

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6
Q

Why are checkpoint genes often mutated in tumours?

A

to allow cell proliferation

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7
Q

What molecule can be found at the start checkpoint (between G1 & S)?

A

FGF

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8
Q

Why is tissue regulation important in setting the adult growth size?

A

different cell tissues grow at different rates. As a result, growth rate is carefully regulated

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9
Q

What 3 signals control body size?

A

IGF - insulin-like growth factor
GH - growth hormone
GHRH - growth hormone-releasing hormone

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10
Q

Where is growth hormone made?

A

pituitary

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11
Q

Where is GHRH (growth hormone releasing hormone) kept?

A

deep in brain in hypothalamus

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12
Q

Describe what occurs when there is too much Growth Hormone present?

A

Too much GH - increase in somatostatin (secreted from hypothalamus) - leading to inhibition of GH production.

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13
Q

Describe what occurs when there is a lack of Growth Hormone present?

A

Low levels of GH - stimulates GHRH from hypothalamus, leading to the upregulation of GH

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14
Q

How does GH actually regulate tissue growth?

A

Regulates production of IGF1 in the liver & bone.

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15
Q

Where is GH found?

A

found in circulation - as is IGF1

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16
Q

What produces IGF1?

A

Liver is the main producer - bone also produces it locally.

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17
Q

What is genetic ablation?

A

the production of toxin or destruction of components to regulate an organisms size - carried out by themselves

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18
Q

What are the 2 pathways to regulate organ size?

A

TOR pathway
Hippo pathway

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19
Q

How does the TOR pathway regulate organ size?

A

increase in cell size

20
Q

How does the Hippo pathway regulate organ size?

A

Reduces cell size by blocking cell proliferation & by inducing cellular death.

21
Q

What can occur if there’s a mutation in the Hippo pathway?

A

can cause organ hypertrophy - due to increased proliferation

22
Q

What is apoptosis?

A

Deliberate suicide if an unneeded cell. This involves the careful coordination of the shut down cell - followed by engulfment of the remnants by other cells. Apoptosis is caused by stress. In adult tissue it is used for homeostasis (e.g. mammary glands) & health (e.g. get rid of infected (viral) or genetically compromised (tumour) cells.

23
Q

What is necrosis?

A

can be caused by injury, infection, cancer, infarction and inflammation.
- disorderly, dying-off of cells without any signal to or from the neighbouring cells
- cells just split open & empty their contents into the surrounding tissue

24
Q

How does muscle growth regulate itself?

A

Myostatin (signaling molecule) is secreted by muscle fibres. It provides negative feedback on muscle growth.

25
Q

How does mutations affecting myostatin activity affect muscle mass?

A

It increases muscle mass

26
Q

How does myostatin regulate muscle growth?

A
  • It reduces myoblast proliferation (through Rb)
  • It reduces muscle differentiation (through MyoD)
27
Q

What occurs if there is a removal of part of the kidney?

A

there will be an increase in the size of the remaining kidney

28
Q

Why does the remaining kidney grow if a part has been removed?

A

in response to a rise in the concentration of creatinine in circulation

29
Q

What is creatinine?

A

a waste product which signals the need to increase kidney function - an increase can be due to cell enlargement

30
Q

What produces and regulates bile acid levels?

A

liver

31
Q

How can you artificially cause the liver to grow?

A

artificially increasing bile acid in circulation, which leads to cell proliferation. This will eventually lead to bile levels reducing due to liver absorption.

32
Q

What drives body growth as a whole?

A

skeletal growth

33
Q

What does the skeleton form from?

A

cartilage in the embryo

34
Q

What is the process by which the cartilage template turns to bone?

A

ossification

35
Q

What is a chondrocyte?

A

cartilage cell

36
Q

What is an osteoblast?

A

bone cell

37
Q

Where does cartilage reside after ossification?

A

cartilage remains in the joint areas

38
Q

What colour does the bone matrix go when treated with Alizarin Red?

A

red

39
Q

What colour does the cartilage matrix go when treated with Alician Blue?

A

Blue

40
Q

What drives postnatal growth in long bones?

A

chondrocytes

41
Q

What are growth plates made of?

A

proliferating chondrocytes

42
Q

What happens to growth plates at the end of puberty?

A

they close

43
Q

What is found where the cartilage meets the bone?

A

growth plate

44
Q

What 3 events occur in the cell plate?

A
  • cell division
  • hypertrophy
  • apoptosis (chondrocytes) & ossification
45
Q

What does high levels of androgens (e.g. testosterone) in the ring finger in the embryo lead to?

A

Promotes growth

46
Q

What does high levels of estrogens (e.g. testosterone) in the ring finger in the embryo lead to?

A

Repressed growth

47
Q
A

Developmental, Stem Cell & Regenerative biology (15 decks)

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