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Biochemistry 2 > Tissue Specific Metabolism > Flashcards

Tissue Specific Metabolism Flashcards

(94 cards)

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1
Q

What is neuronal signaling? How far do the neurotransmitters travel to their target cells?

A

Nerve impulses from the cell body of a neuron travel to the axon tip. Here neurotransmitters are released and travel to the target cell a fraction of a micrometer away.

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2
Q

What is endocrine signaling? How far do the neurotransmitters travel to their target cells?

A

Hormones are secreted into the bloodstream, which carries them through the body to target tissues that may be a meter or more away!

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3
Q

What are hormones produced by?

A

Endocrine glands

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4
Q

What are the 8 major endocrine glands?

A

Hypothalamus, pituitary, thyroid, adipose tissue, adrenals, pancreas, ovaries, testes

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5
Q

Which two endocrine glands make the regulatory hormones that regulate all other endocrine glands?

A

Hypothalamus and pituitary glands

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6
Q

Which two endocrine glands are connected through special blood vessels and neurons?

A

Pituitary and hypothalamus

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7
Q

Where are the adrenal glands located?

A

Above kidneys

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8
Q

What does the pancreas release?

A

Insulin and glucagon

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9
Q

What do the adipose tissues release?

A

Leptin, adiponectin, etc.

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10
Q

What do the pituitary glands produce as a response to hypothalamic hormones carried in the blood?

A

Tropic hormones that activate the other endocrine glands

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11
Q

Once the central nervous system releases a hormonal signal to the hypothalamus, what is special about the final product of the signalling cascade?

A

The end product negatively regulates (inhibits) its own production.

Makes sense: once it is produced enough and has done its job, not needed anymore.

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12
Q

What 3 nutrients do hepatocytes metabolize?

A

COH, AA, lipids

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13
Q

What is the function of hepatocytes?

A

Transform dietary nutrients into precursors required by other tissues and exports them via the blood.

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14
Q

What does the liver maintain the balance between?

A

Nutrient supply and precursor demand.

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15
Q

What does nutrient supply vary with? what does precursor requirement vary with? (In the liver)

A

Nutrient supply: diet and feeding

Precursor requirement: level of activity and health

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16
Q

Which hormones are liver enzymes sensitive to?

A

Insulin, glucagon, epinephrin, leptin

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17
Q

What does this statement mean: the liver has remarkable flexibility in “enzymatic machinery”?

A

That the liver synthesizes enzymes based off of the nutrients present in the body that need to be metabolized.

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18
Q

Transport of glucose in and out of the liver via the blood stream is done by what transporter? What type of transport is this?

A

GLUT2. Passive transport

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19
Q

What is hexokinase 4’s affinity for glucose?

A

Very low (high Km)

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20
Q

Is hexokinase inhibited by G6P?

A

No

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21
Q

When G6P undergoes glycolysis and is converted to pyruvate then acetyl CoA, what path does it mainly take afterwards?

A

Mainly gets turned into FA/cholesterol. It is more rare for Acetyl-CoA to go through TCA cycle

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22
Q

AA metabolism in the liver yields proteins for what?

A

For the liver and other tissues

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23
Q

What are some of the AAs in the liver precursors of?

A

Nucleotides & hormones

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24
Q

The AAs in the liver not needed as biosynthetic precursors are turned into what?

A

Transaminated or deaminated into pyruvate and TCA intermediates

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25
For what two reasons is pyruvate sometimes converted to acetyl-CoA in the liver?
1. liver cell energy | 2. conversion to lipids
26
Once AAs have been converted into pyruvate in the liver, what are the 2 fates it can take?
Gluconeogenesis Acetyl-CoA
27
Why can the liver be referred to as an endocrine gland?
Because it stimulates insulin-like-growth-factors (IGF(IDF?)-1 and IGF(IDF?)-2)
28
What is the main fate of lipids in the liver?
They undergo Beta-oxidation which yeilds NADH and acetyl-CoA for TCA cycle --> to make energy for hepatocytes
29
What 2 paths might the excess acetyl-CoA that does not enter the TCA cycle in the liver? c
1. It is converted to ketone bodies that are sent to heart and brain. 2. biosynthesis of cholesterol (required for membrane synthesis)
30
What is cholesterol a precursor of?
Bile salts and all steroid hormones
31
What are the main lipo-proteins released from the liver?
VLDL
32
What are non-esterified free fatty acids that leave the liver bound to? Where do they go?
Albumin --> heart and skeletal muscle
33
What nutrients does the liver store?
Iron and Vitamin A
34
Where are white adipose tissues located?
Under skin, around major blood vessels and abdomen
35
How many lipid droplets do the adipocyte cells contain in white adipose tissues?
1 lipid droplet
36
What is the energy source of white adipose tissue?
glucose
37
What are white adipose tissues sensitive to? They are capable of synthesis of what from glucose?
Insulin sensitive. Capable of FA synthesis from glucose
38
What is the major storage of white adipose tissues?
TAG
39
What do white adipose tissues do when the demand for fuel rises? (between meals, for example). What is this greatly accelerated by?
lipases and adipocytes hydrolyze stored TAGs to release (non-esterified) free fatty acids, which can travel in the blood stream to muscle and heart. Greatly accelerated by epinephrine
40
Where is Brown Adipose Tissue located?
Under skin (chest and back)
41
In what age range in Brown Adipose Tissue found?
Only in infants
42
What is high in concentration in Brown Adipose Tissue?
Mitochondria, blood supply
43
How are TAGs stored in Brown Adipose Tissue compared to White Adipose Tissue?
Many small lipid droplets per cell
44
How do fatty acids undergo complete conversion to CO2 in Brown Adipose Tissue?
FAs stored in lipid droplets are released, enter mitochondria, and go through Beta-oxidation and the TCA cycle
45
What gene is strongly expressed in Brown Adipose Tissue? What does this gene encode for? What inhibits/activates this gene?
UCP-1. Codes from thermogenin which is the protein that allows H+ to bypass ATPase in the mitochondria to produce heat. Inhibits: Purines Activates: non-esterified FAs
46
How are Brown Adipose Tissue formed in humans during chronic cold exposure?
Preadipocytes differentiate into Brown Adipose Tissue
47
What 3 things can skeletal muscles use for energy?
FA, ketone bodies, glucose
48
What is used as fuel for ATP synthesis in skeletal muscles in resting humans?
- FAs from adipose | - Ketone bodies from liver
49
What is used as fuel for ATP synthesis in skeletal muscles during moderate exercise?
Blood glucose, FA, Ketone bodies
50
During moderate exercise, does the blood glucose undergo aerobic or anaerobic glycolysis?
Aerobic
51
What is used as fuel for ATP synthesis in skeletal muscles humans undergoing vigorous exercise? Why?
Stored glycogen because of increased energy demand and reduced incoming oxygen
52
What does the phosphocreatine buffering system provide? When does this conversion occur?
Phosphate group to make ATP --> during vigorous exercise.
53
What happens in the phosphocreatine buffering system during recovery?
Phosphate group gets stored as phosphocreatine for future use.
54
In muscle metabolism, each glucose from glycogen yeilds how many ATP? Why is this as the net normal yield is 2?
3 The end product of gluconeogenesis is G-1-P which is converted to G6P via phosphoglucomutase which doesn't require ATP (simply transfers a phosphate)
55
What does epinephrine help in muscle metabolism?
It helps using glucose from blood and glycogen
56
What is a biproduct of vigorous exercise? What is the role of lactic acid?
Lactic acid which helps continue anaerobic glycolysis
57
What is lactate converted to in the liver during recovery from activity?
Glucose
58
What is another source of ATP during vigorous exercise?
Phosphocreatine --> creatine (produces ATP)
59
What is happeing to muscles during shivering thermogenesis?
contracting vigorously, heat produced
60
Does cardiac muscle (heart) undergo aerobic or anaerobic metabolism?
Aerobic!
61
What organelle is present in abundance in cardiac muscle?
Mitochondria
62
What is the main use of energy in cardiac muscles? What else can be used?
Mainly FAs, but ketone bodies and glucose can also be used
63
What is energy production dependent on in cardiac muscles? Why?
Oxygen. Because main source of energy are FAs which undergo Beta-oxidation before becoming Acetyl-CoA & entering TCA cycle
64
What are cardiac muscles sensitive to?
Cardiac deprivation
65
What is cardiac muscle low in compared to liver and skeletal muscles?
Glycogen
66
What are neurons highly dependent on for energy?
glucose
67
The brain's metabolism uses how many grams of glucose per day?
~130 g
68
What can Brain Metabolism also use as a source of energy other than glucose? (during starvation)
Beta-hydroxybutyrate (ketone bodies)
69
Why do neurons require LOTS of energy?
Because the ATP is mainly used to maintain the membrane potential (through Na-K-ATPase)
70
What are astrocytes? What do they use as energy?
Non-neuronal brain cells that use FAs as energy
71
How much stored glycogen can be found in the brain?
none!!!
72
Is metabolism in brain an anaerobic or aerobic process?
Aerobic
73
What are the two sources of energy during fasting/starvation? From which parts of the body?
Ketone bodies (from FA) Glucose (from muscle protein)
74
What enters the liver immediately after a calorie rich meal?
Glucose, fatty acids, & AAs
75
Where is glucose exproted from here? What happens to the excess glucose in the liver?
Brain for energy needs Adipose tissue Muscle tissue Excess glucose: oxidized to acetyl-CoA which is used to synthesize FAs for export as TAGs in VLDLs to adipose and muscle tissue.
76
What happens to AAs that enter the liver?
Excreted as urea or used in protein synthesis for liver proteins.
77
How do dietary fats move throughout the body? As what?
Lymphatic system from the intestine as chylomicrons --> to liver, muscle, & adipose tissues
78
After several hours without a meal, what becomes the main source of glucose for the brain?
The liver via gluconeogenesis
79
During fasting-state, what is used for gluconeogenesis in the liver?
AAs from degradation of proteins in liver, and glycerol from TAG breakdown in adipose tissue
80
What is the liver's main fuel during fasting-state?
FAs
81
What is excess acetyl-CoA converted to in the liver during fasting-state?
Ketone bodies (for brain)
82
While running a marathon, for what distance does your body provide you with free creatine and ATP?
80 meters
83
While running a marathon, how long do your heart and lungs take to reach maximum capacity? Is anaerobic or aerobic glycolysis being used in this initial time period? How many ATPs produced?
2 minutes. Anaerobic glycolysis 2-3 ATP
84
How long after one starts running a marathon do they begin to use aerobic respiration/glycolysis?
2 minutes (30-32 ATP)
85
Is aerobic or anaerobic glycolysis used during uphill running? Why?
Anaerobic because heart and lungs are working as fast as they can
86
After how long is runer's high reached? Why?
45 minutes, endorphins peak
87
How many grams of glycogen runs out after running 30k?
500 g
88
What pathway has completely stopped functioning when runners hit the wall? What is all the energy created in the body being produced by?
Glycolysis FA
89
Why are FA not as efficient a source of ATP as Glucose?
Because FA oxidation is slow in ATP yield, making it harder to run
90
Marathon runners use what type of muscles?
Slow twitch/dark
91
Sprinters use what type of muscles?
Fast twitch/white
92
During the first 40-60m of a 100m dash, where does the ATP come from?
phosphocreatine
93
What AAs are used in the production of creatin from scratch?
Gly. Arg. Met.
94
Is aerobic or anaerobic glycolysis occuring during the last 40 m of a 100 m dash? Is breaking required?
anaerobic. No, some runners take a deep breath then hold it!

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