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AHS 1 > Cell survival and uncontrolled growth Wk 4 > Flashcards

Cell survival and uncontrolled growth Wk 4 Flashcards

1
Q

What are the hormonal pathways of the hypothalamus, pituitary and liver controlling animal growth in development?

A

Hypothalamus produces GHRH which acts on the pituitary to release GH which acts on the liver which releases IGF-1 which stimulates growth and survival of tissue cells (muscle, bone & fat).

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2
Q

What role does nutrition and amino acids play in cell growth?

A

Nutrition controls cell growth, amino acids activate mTORC1.

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3
Q

Where is phosphatidylserine usually? When and why does it move?

A

On the inside of the phosphoid lipid bylayer; It moves to signal phagocytosis of apoptotic cells during apoptosis.

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4
Q

What is mammary gland regression? When does it happen and how is it controlled?

A

After peak lactation (mammogenesis), mammary gland cells which have proliferated during pregnancy, undergo controlled apoptosis (involution).

Controlled by BOVINE GROWTH HOROMONE (somatostatin) which inhibits involution.

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5
Q

Why does GHD dwarfism not exist today?

A

Children are injected with GH in childhood as GHD is understood (whereas it wasn’t when the Wizard of Oz was made re. Munchkin Town and Karl Slover - I’ve put this in for you, Chrissy).

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6
Q

What controls the size of an individual animals?

A

Hormones.

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7
Q

What controls the size of an individual animals?

A

Hormones (GHRH, GH & IGF-1).

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8
Q

Why are tiny dogs so small?

A

Mutations in IGF-1 (proportionate growth).

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9
Q

How does IGF-1 function as a growth signal for cells?

A
  1. Binds to IGF-1 receptors at surface of cell.
  2. Triggers confrontational change, activating the receptor
  3. Akt protein is activated
  4. Akt activates mTORC1 (major controller of cell growth).
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10
Q

What cells are post-miotic, what does it mean?

A

Neuron. Never divide again.

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11
Q

What cells are post-miotic, what does it mean?

A

Neuron. Muscles. Heart.

Never divide again.

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12
Q

What cells are quiescent cells? Where?

A

Resting (G0) such as Liver.

Can re-enter cell cycle by circulation factor mitogen, putting them back into cell cycle to proliferate again.

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13
Q

What are circulating cell survival factors?

A

Factors promoting continued life of the cell.

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14
Q

What are circulating cell death factors?

A

Factors promoting death of the cell.

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15
Q

What effects the size of a cell?

A

Growth Factor

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16
Q

What is increased cell size called?

A

hypertrophy

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17
Q

What is decrease cell size called?

A

hyperplasia

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18
Q

What does the activation of mTORC1 do?

A

Cell starts producing the raw materials required for growth.

19
Q

Other than hormonal control, what else leads to growth?

A

Mechanical loading (exercise) also causes activation of mTORC1.

20
Q

What is an example of equine hypertrophy?

A

Over training and over loading can lead to hypertrophy of the left ventricle heart wall in race horses.

21
Q

What does the hormone myostatin do?

A

Binds to myostatin receptors on muscle cells stopping the IGF-1 pathway by inhibiting Akt and mTORC1.

22
Q

Why do belgian blue and piedmontese cattle have double muscle?

A

Mutation to myostatin gene; less myostatin produced thus more muscle growth.

23
Q

Why do belgian blue and piedmontese cattle have double muscle?

A

Mutation to myostatin gene; less myostatin produced thus more muscle growth. Cells are larger, rather than double the amount of cells.

24
Q

What two things does cell growth require?

A

Amino acids and growth factor hormones

25
Q

What does reduced admino acid in development lead to?

A

Reduced body size.

26
Q

What two things does full potential of cell growth require?

A

Amino acids and growth factor hormones

27
Q

What does reduced admino acid in development lead to? What’s the classic experiment proving this?

A

Reduced body size (classic fruit fly experiment).

28
Q

How does maternal nutrition affect body size of child?

A

Mother’s childhood nutrition leads to inherited epigenetic changes for one or two generations.

29
Q

What is apoptosis?

A

Regulated cell death

30
Q

During development some cells must die to sculpt tissues and organs; give an example

A

webbing of digits, tadpole tail, retina blood vessels after birth for efficiency

31
Q

When does apoptosis occur in adults?

A

Cancer and faulty cells

32
Q

What happens to apoptotic cells?

A

Removed by phagocytosis

33
Q

What is the first stage of apoptosis?

A

Proteases called capases digest key protein contents of cell, triggering key changes

34
Q

What happens to the nucleus during apoptocis?

A

Fragmented into apoptotic bodies containing DNA

35
Q

What happens to the plasma membrane?

A

The plasma membrane forms blebs containing DNA fragments.

36
Q

How do blebs signal to phagocytes?

A

Plasma membrane flips the lipid phosphatidyslerine to the outside, signalling “eat me” to phagocytes.

37
Q

What does phagocytosis of apoptotic fragments prevent?

A

Inflammation: fibrosis and scaring of the tissue

Autoimmune reactions: developing antibodies against DNA

38
Q

What is involution and mammogensis?

A

Expansion and regression of the mammary gland.

39
Q

What hormone is given to cows to increase milk yield? How does it work?

A

Bovine growth hormone. Inhibits apoptosis of mammary glands and regression.

40
Q

How does uncontrolled proliferation occur? What can protect against this?

A

Mutation to DNA, apoptosis.

41
Q

What is Hayflick’s number?

A

The number of times an animal cell can replicate.

42
Q

What does uncontrolled cell proliferation trigger?

A

Apoptosis.

43
Q

What is senescence?

A

Once a cell reaches Hayflick number it stops proliferating.

44
Q

How does the body control cancer cells that loose control of proliferation??

A

Apoptosis and senescence.

AHS 1 (15 decks)

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