Lecture 4 - The Role of Fat Flashcards

1
Q

what dominated a adipocyte

A

lipid droplet

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2
Q

where are triglycerides stored within adipocytes

A

triglycerides are stored in lipid droplets within the cytoplasm of adipocytes

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3
Q

what are the other functions of adipocytes

A
  • maintains many other cellular functions
  • produce hormones
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4
Q

how is fat normally stored

A

triacylglycerol (3 fatty acids and a glycerol)

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5
Q

what can not cross the cell membrane, but fatty acids can

A

triacylglycerol can not cross cell membranes where as fatty acids can

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6
Q

what breaks down TAG (triacylglycerol)

A

lipoprotein lipase (LPL) enzyme

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7
Q

what is TAG (triacylglycerol) broken down into

A

free fatty acids, glycerol is disconnected

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8
Q

how are fatty acids carried in the blood

A

bound to albumin

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9
Q

what are tissues that lipoprotein lipase is found in

A
  • liver
  • adipocytes
  • muscle
  • lactating mammary glands
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10
Q

what are the two forms of lipoprotein lipase

A

hormone sensitive and hormone insensitive lipoprotein lipase

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11
Q

how are hormones that affect LPL are mediated through what

A

mediated through signalling pathways typically involving second messengers

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12
Q

what does hormone insenstive lipoprotein lipase provide and what does this mean in adipocytes

A

a base level of activity in the absence of hormones

  • adipocytes will continue to release a small amount of fatty acids in the absence of hormones
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13
Q

what will glucagon do to hormone sensitive lipase and what will this do

A

glucagon will stimulate hormone sensitive lipase

  • this will start breaking down TAG and release free fatty acids into the circulation
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14
Q

if insulin is present what will be inhibited in terms of fatty acids

A

inhibit the conversion of triacylglycerol to fatty acids

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15
Q

how is growth hormone different and what will it stimulate

A

growth hormone is a longer acting hormone (days to months)

  • it will stimulate the release fatty acids, providing fuels for metabolic activity
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16
Q

how is noradrenaline and adrenaline different to growth hormone and what does it do

A

much shorter acting, fight or flight

  • these will override the other settings, adipocytes will release fuel
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17
Q

Diacyl and monoacyl-glycerol have different what

A

different properties

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18
Q

TAG is broken down in several steps involving …

A

different enzymes

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19
Q

what are the two things that triacylglycerol is converted to before glycerol

A

diacylglycerol and monoacylglycerol

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20
Q

during fasting how many days does the body take to produce ketone bodies

A

1-2 days

21
Q

what are the two major forms of ketone bodies

A
  • acetoacetate
  • hydroxybutyrate
22
Q

during fasting what does the brain use to replace some glucose as a fuel

A

ketone bodies

23
Q

during long term fasting, ketone bodies will provide the body with how much of the energy that would normally come from glucose

A

about half

24
Q

what gives rise to the acetone smell on breath when someone is producing ketone bodies

A

acetone produced from acetoacetate

25
Q

what are the precursors of fatty acid synthesis

A

glucose through glycolysis

amino acids to Oxoacids and Acetyl-CoA

fats are already fats

26
Q

where is Acetyl CoA produced (fatty acid synthesis)

A

produced in the mitochondria

27
Q

where does fatty acid synthesis occur

A

in the cytosol

28
Q

what mechanism moves Acetyl CoA into the cytosol for fatty acid synthesis

A

the citrate shuttle

29
Q

enzymes associated with synthesising fat are found where

A

in the cytosol

30
Q

enzymes associated with breaking down fat are found where

A

in the mitochondria

31
Q

what kind of process is fatty acid synthesis

A

cyclic process

32
Q

what happens during fatty acid synthesis

A

2 C are added to the growing chai (starting with Acetyl CoA)

33
Q

in fatty acid synthesis what is Acetyl CoA converted to

A

malonyl-CoA (addition of CO2)

34
Q

what reducing equivalent is involved in fatty acid synthesis

A

NADHP

35
Q

what are surplus fatty acids mostly used in

A

primarily involved in TAG sinthesis

36
Q

what are surplus fatty acids also used for

A
  • other fatty acyl-CoA
  • phospholipids (important for cell membranes)
  • specialised lipids
  • modifications to proteins
37
Q

what fuel is short term fasting primarily associated with differences

A

primarily associated with carbohydrate differences, although most tissues use fatty acids for fuel

38
Q

what parts of the body really need glucose

A

red blood cells and the brain

39
Q

when does long term fasting come into play

A

when fasting extends out over a number of days

40
Q

during long term fasting, what occurs to liver glycogen and what are the implications of this

A

liver does not have any glycogen left, so will break down amino acids from proteins

41
Q

when liver glycogen is depleted, the body will break down proteins, where and in what form will these be transported (then what will happen to them)

A

broken down proteins most likely in the form of alanine or aspartate will be transported to the liver, and will be used to make glucose which will be used by the brain

42
Q

in long term fasting what will happen to some fatty acids and what does this mean for fuel use

A

some fatty acids will be converted to ketone bodies, these can be used by the brain

43
Q

what are the effects of insulin in muscle

A
  • increased glucose uptake
  • increased glycogen synthesis
44
Q

what are the effects of insulin in adipose tissue

A
  • increased glucose uptake
  • increased lipogenesis
  • decreased lipolysis
45
Q

what are the effects of insulin in the liver

A
  • increased glycogen synthesis
  • increased lipogenesis
  • decreased gluconeogenesis
46
Q

what are the effects of glucagon in adipose tissue

A
  • increased lipolysis
47
Q

what are the effects of glucagon in liver

A
  • decreased glycogen synthesis
  • increased glycogenolysis
48
Q

what are the effects of epinephrine in the liver

A
  • decreased glycogen synthesis
  • increased glycogenolysis
  • increased gluconeogenesis