Lecture 4-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

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
what are the precursors of fatty acid synthesis
glucose through glycolysis amino acids to Oxoacids and Acetyl-CoA fats are already fats
26
where is Acetyl CoA produced (fatty acid synthesis)
produced in the mitochondria
27
where does fatty acid synthesis occur
in the cytosol
28
what mechanism moves Acetyl CoA into the cytosol for fatty acid synthesis
the citrate shuttle
29
enzymes associated with synthesising fat are found where
in the cytosol
30
enzymes associated with breaking down fat are found where
in the mitochondria
31
what kind of process is fatty acid synthesis
cyclic process
32
what happens during fatty acid synthesis
2 C are added to the growing chai (starting with Acetyl CoA)
33
in fatty acid synthesis what is Acetyl CoA converted to
malonyl-CoA (addition of CO2)
34
what reducing equivalent is involved in fatty acid synthesis
NADHP
35
what are surplus fatty acids mostly used in
primarily involved in TAG sinthesis
36
what are surplus fatty acids also used for
other fatty acyl-CoA phospholipids (important for cell membranes) specialised lipids modifications to proteins
37
what fuel is short term fasting primarily associated with differences
primarily associated with carbohydrate differences, although most tissues use fatty acids for fuel
38
what parts of the body really need glucose
red blood cells and the brain
39
when does long term fasting come into play
when fasting extends out over a number of days
40
during long term fasting, what occurs to liver glycogen and what are the implications of this
liver does not have any glycogen left, so will break down amino acids from proteins
41
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)
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
in long term fasting what will happen to some fatty acids and what does this mean for fuel use
some fatty acids will be converted to ketone bodies, these can be used by the brain
43
what are the effects of insulin in muscle
increased glucose uptake increased glycogen synthesis
44
what are the effects of insulin in adipose tissue
increased glucose uptake increased lipogenesis decreased lipolysis
45
what are the effects of insulin in the liver
increased glycogen synthesis increased lipogenesis decreased gluconeogenesis
46
what are the effects of glucagon in adipose tissue
increased lipolysis
47
what are the effects of glucagon in liver
decreased glycogen synthesis increased glycogenolysis
48
what are the effects of epinephrine in the liver
decreased glycogen synthesis increased glycogenolysis increased gluconeogenesis