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biochemistry > Chapter 22: Mammalian Fuel Metabolism > Flashcards

Chapter 22: Mammalian Fuel Metabolism Flashcards

1
Q

How do organisms coordinate their metabolic processes?

A

So opposing pathways do not operate simultaneously. And so organism can respond to changing external conditions like nutrient availability.

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2
Q

What is the interconnectedness of various tissues ensured by?

A

Neuronal circuits and hormomes.

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3
Q

Overview of metabolism:

A
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4
Q

What organ carries out all metabolic pathways?

A

Liver

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5
Q

Most to least metabolically active tissues:

A

Liver > Adipose Tissue > Muscle Tissue

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6
Q

How much glucose does the brain require?

A

~ 20% of O2 and ~20% of glucose

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7
Q

What does the brain use O2 and glucose for?

A

Aerobic energy powers the Na+K+ ATPase that maintains membrane potentials to conduct nerve impulse transmission.

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8
Q

The brain does not store _____ well.

A

Glycogen

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9
Q

_____ and ______ function to support nerve cells.

A

Astrocytes, Oligodendrocytes

*Carry out anaerobic metabolism and can supply lactate to nerve cells for further break down.

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10
Q

How much glycogen do muscles store?

A

1-2% of its mass is glycogen.

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11
Q

If fatty acids are a more energy-dense fuel, then why is it not preffered?

A

Glucose is easier to burn and can burn aerobically or anaerobically. Fatty acids can ONLY be burned under aerobic conditions.

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12
Q

In what conditions is muscle contraction anaerobic?

A

High exertion. At rest muscle consumes ~30% O2.

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13
Q

How does muscle respiration rate change?

A

Under strenuous exercise, it will increase by 25% or more and ATP hydrolysis can increase even more.

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14
Q

How can ATP be regenerated for muscles?

A

Phosphocreatine, but only lasts for about 4 seconds. Then the muscle switches to anaerobic metabolism.

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15
Q

The heart cells have how many mitochondria?

A

~40% of cytoplasm is mitochondria in cardiomyocytes (cardiac muscle cells) .

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16
Q

What is the resting hearts fuel of choice?

A

Fatty acids, but will switch to glucose as heart rate increases.

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17
Q

The heart has a ____ supply of glycogen.

A

limited

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18
Q

What are the fuels that the heart uses?

A

Fatty acids

Ketone Bodies

Glucose

Pyruvate

Lactate

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19
Q

What is the function of adipose tissue?

A

To store and release fatty acids as needed for fuel as well as to secrete hormones involved in regulating metabolism.

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20
Q

Where is adipose tissue found?

A

Found under the skin, abdominal cavity, skeletal muscles.

21
Q

How long can fat storage provide fuel for?

A

Average person ~ 3 months

22
Q

Adipocytes require most of their fat through?

A

Circulating lipoproteins.

23
Q

How can adipocytes hydrolyze triacylglycerols?

A

They do so when glucose levels are low and hormones regulating this process are abundant.

24
Q

When are fatty acids released into the bloodstream to be metabolized?

A

When glycerol-3-phosphate levels are low.

25
Q

Where do all the nutrients absorbed by small intenstines go?

A

Directly into the liver by the portal vein (except for fatty acids)

26
Q

What can liver synthesize or degrade?

A

Triacylglycerols

27
Q

The liver acts as a ______

A

blood glucose buffer

28
Q

What does the kidney mainly do?

A

Filters urea and other waste products from the blood while recovering important metabolites like glucose.

29
Q

How does the kidney maintain blood pH?

A

Regenerating depleted blood buffers like HCO3- and excreting excess H+ together with the conjugate bases of excess metabolic acids. Such as ketone bodies acetoacetone and B-hydroxybutarate.

30
Q

How does kidney work in deamination reactions?

A

Excretes excess H+ in the form of NH4+

31
Q

During starvation, how does kidney do its job?

A

Can synthesis glucose through gluconeogenesis, supplying 50% of the body’s glucose needs.

32
Q

Blood transports metabolites in interorgan metabolic pathways (diagram):

A
33
Q

What do hormones do?

A

Enable body to maintain metabolic homeostasis.

34
Q

When is insulin released?

A

Released by pancreas when glucose is consumed.

35
Q

What does insulin do?

A

Promotes fuel storage in muscle and adipose tissue.

Blocks gluconeogenesis and glycogenolysis.

36
Q

What does glucagon do?

A

Stimulates fatty acid mobilization from adipose tissue by activating hormone-sensitive lipase.

37
Q

What doe catecholamines do?

A

Mobilize fatty acids and promote break down of glucose.

Catecholamines - epinephrine, norepinephrine, and dopamine

38
Q

Overview of hormone actions:

A
39
Q

Roles of AMP-dependent protein kinase (4):

A
  1. activates glycolysis in ischemic cardiac muscle
  2. inhibits lipogenesis and gluconeogenesis in liver
  3. promotes fatty acids oxidation and glucose uptake in skeletal muscle
  4. inhibits lipolysis in adipocytes
40
Q

Adiponectin is a hormone that does what?

A

Secreted by adipocytes that helps to regulate metabolism.

Regulates AMPK activity.

41
Q

What is the satiety hormone?

A

Leptin

42
Q

What hormones are the short term regulators of appetite?

A

Ghrelin and PYY 3-36

43
Q

How are calories utilized?

A

Performance of work or release of heat.

44
Q

Type 1 diabetes:

A

Insulin-dependent, juvenile-onset

45
Q

Type 2 diabetes:

A

Non-insulin-dependent, maturity-onset

46
Q

What is insulin-dependent diabetes caused by?

A

Deficiency of pancreatic b cells.

47
Q

Cancer cells have a high rate of?

A

Glucose metabolism through aerobic glycolysis.

48
Q

____, ______, and _____ supports the rapid growth and proliferation of cancer cells.

A

Glucose

Amino acids

Glutamine

49
Q

_____ and _____ metabolism support anabolic processes.

A

Glutamine

Glutamate

biochemistry (12 decks)

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