Regulation of Metabolism (Tissue-Specific and Hormonal) Flashcards

1
Q

Which metabolic pathways produce CO2?

A
  • Oxidative decarboxylation
  • TCA cycle
  • Oxidative phosphorylation
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2
Q

________ play a significant role in the integration of mammalian metabolism

A

Hormones

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3
Q

Give examples of types of hormones.

A
  • Peptide
  • Catecholamine
  • Eicosanoid
  • Steroid
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4
Q

What are the two major endocrine glands?

A
  • Pituitary

- Hypothalamus

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5
Q

Which glands produce steroid hormones?

A

Ovaries and testes

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6
Q

Which gland releases insulin and glucagon?

A

Pancreas

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7
Q

Which gland releases leptin?

A

Adipose tissue

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8
Q

What is the negative feedback regulation of hormones?

A
  • A signal from the central nervous system leads to the production of hormones in an endocrine gland
  • The end-product (hormone) inhibits its own production by blocking the hypothalamus
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9
Q

Which structure is responsible for:
o Transports ions to maintain membrane potential
o Integrates inputs from the body and surroundings
o Send signals to other organs

A

Brain

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10
Q

Which structure is responsible for:

o Uses ATP generated aerobically to pump blood

A

Cardiac muscle

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11
Q

Which structure is responsible for:
o Synthesizes, stores, and mobilizes triacylglycerol
o Brown adipose tissue carries out thermogenesis

A

Adipose tissue

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12
Q

Which structure is responsible for:

o Uses ATP generated aerobically or anaerobically to do mechanical work

A

Skeletal muscle

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13
Q

Which structure is responsible for:
o Process fats, carbohydrates, proteins from the diet
o Synthesizes and distributes lipids, ketone bodies, and glucose for other tissues
o Converts excess nitrogen to urea

A

Liver

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14
Q

Which nutrients do hepatocytes metabolize?

A

Carbohydrates, amino acids, and lipids

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15
Q

What varies the nutrient supply?

A

Diet and feeding

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16
Q

What varies the precursor requirement?

A

Level of activity and health

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17
Q

Why is the liver capable of maintaining balance between nutrient supply and precursor demand?

A

Remarkable flexibility in “enzymatic machinery”

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18
Q

What are hepatocyte enzymes sensitive to?

A

Various hormones (insulin, glucagon, epinephrine, leptin)

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19
Q

Which glucose transporter is not inhibited by glucose-6-phosphate? What is the consequence?

A
  • Hexokinase IV

- The liver may easily supply glucose to other tissues, as it does not use glucose

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20
Q

Where is Glucose-6-Phosphate diverted to?

A
  • Pentose phosphate pathway
  • Glycolysis
  • Production of liver glycogen
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21
Q

Where does the pyruvate from glycolysis enter in the liver? Which is more common?

A
  • Fatty acid and cholesterol synthesis (more common)

- Enters the TCA cycle

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22
Q

When do hepatocytes use glucose as energy?

A

If there is an excess of glucose

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23
Q

What does amino acid metabolism in the liver produce?

A
  • Produces proteins for the liver and other tissues

- Produces hormones and nucleotides

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24
Q

What are the TCA intermediates used for in the liver?

A
  • Gluconeogenesis: glucose enters circulation or is stored as glycogen
  • Converts Pyruvate to Acetyl-CoA for liver cell energy
  • Fatty acid synthesis
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25
Q

What does the liver store to produce hormones?

A
  • Iron

- Vitamin A

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26
Q

What are the two sources of fatty acids?

A
  • Diet

- Adipose tissue

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27
Q

Where are fatty acids sent to in the liver?

A
  • Used for B-oxidation
  • Released into the plasma as lipoproteins to adipose tissue
  • Released in the form of free fatty acids in the blood (bound to albumin) –> fuel for muscles
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28
Q

What is Acetyl-CoA used for in lipid metabolism in the liver?

A
  • Used to form ketone bodies in the blood (fuels heart and brain)
  • Enters cholesterol synthesis (bile salts and steroid hormones)
  • Enters the TCA cycle
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29
Q

Where is white adipose tissue found? Where is brown adipose tissue found?

A
  • WAT: under skin, around major blood vessels (aorta) and abdomen
  • BAT: under skin (chest and back)
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30
Q

How many lipid droplets are in WAT and BAT?

A
  • WAT: one lipid droplet

- BAT: many lipid droplets

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31
Q

What provides the brown color in BAT? Who has BAT?

A
  • Many mitochondria and high blood supply

- Children only

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32
Q

In which situation may an adult contain BAT?

A

Pre-adipocytes can differentiate into brown adipose tissue in adults during chronic cold exposure

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33
Q

What are the energy sources in WAT? BAT?

A
  • WAT: glucose from glycolysis

- BAT: fatty acids from B-oxidation

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34
Q

Is WAT or BAT capable of fatty acid synthesis from excess glucose? Why?

A
  • WAT

- Since it is insulin-sensitive

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35
Q

Is WAT or BAT a major store of TG?

A

WAT

36
Q

WAT is epinephrine sensitive. What is the consequence?

A

Hydrolysis of TG to FAs

37
Q

What is non-shivering thermogenesis due to?

A
  • Thermogenin (UCP1) –> uncoupling protein

- Found in BAT

38
Q

What inhibits UCP1? What activates UCP1?

A
  • Purines inhibit UCP1

- Non-esterified fatty acids activate UCP1

39
Q

What can skeletal muscle use for energy?

A
  • Fatty acids
  • Ketone bodies
  • Glucose
40
Q

What does skeletal muscle use for energy at a resting state?

A
  • Fatty acids from adipose tissue

- Ketone bodies from the liver

41
Q

What does skeletal muscle use for energy during moderate exercise?

A
  • Blood glucose* (undergoes aerobic glycolysis)
  • Fatty acids from adipose tissue
  • Ketone bodies from the liver
42
Q

What does skeletal muscle use for energy during vigorous exercise?

A

Stored glycogen gives glucose

43
Q

What buffers ATP?

A

Phosphocreatine

44
Q

Each glycogen-originated glucose provides how many ATPs during glycolysis? Why?

A
  • 3 ATPs, instead of 2

- In glycogenolysis, phosphoglucomutase (does NOT require ATP) is used instead of hexokinase (requires ATP)

45
Q

What helps continue anaerobic glycolysis?

A

Lactic acid, synthesized from pyruvate

46
Q

What helps in using glucose from the blood and glycogen?

A

Epinephrine

47
Q

What is the Cori Cycle?

A
  • During recovery
  • Lactate is converted to glucose in the liver
  • Glucose is sent to the blood and synthesized into glycogen, which can be used in vigorous exercise to produce lactate
48
Q

What synthesizes ATP during vigorous activity?

A

Phosphocreatine –> creatine provides a phosphate group to ADP, which synthesizes ATP

49
Q

How is phosphate stored during recovery?

A

Creatine –> Phosphocreatine uses ATP to store phosphate groups in phosphocreatine

50
Q

What kind of metabolism occurs in cardiac muscle? What is the main energy source?

A
  • Aerobic metabolism (abundant mitochondria)

- Mainly fatty acids, but also use ketone bodies and glucose

51
Q

Which structure contains less stored glycogen?

A
  • Cardiac muscle (less)

- Brain (none)

52
Q

Which structure is sensitive to O2 deprivation?

A

Cardiac muscle

53
Q

What can neurons use in addition to glucose?

A

B-hydroxybutyrate (ketone body)

54
Q

What is ATP used for in metabolism in the brain?

A

To maintain membrane potential

55
Q

What energy source can astrocytes use?

A

Fatty acids

56
Q

Neurons utilize glucose through which metabolic pathway?

A

Aerobic glycolytic metabolism

57
Q

What does the brain use during fasting/starvation?

A
  • Ketone bodies from fatty acids

- Glucose from muscle proteins

58
Q

What happens to glucose after it is digested? (3)

A

o Transported to other tissues (brain)
o Stored in the form of glycogen
o Catabolized to Pyruvate and Acetyl-CoA (synthesis of fatty acids and energy)

59
Q

Where do amino acids enter after digestion? What are their functions? (3)

A
  • Liver
  • Protein synthesis (primarily)
  • a-Keto acids can be converted to other amino acids
  • Excreted in the form of ammonia
60
Q

What is the role of Acetyl-CoA after it is synthesized?

A
  • Used in the synthesis of TG and VLDL (lipoproteins)

- VLDLs are used for adipose tissue storage

61
Q

How does an increase in glucose uptake (muscle, adipose) affect GLUT4?

A

Increases

62
Q

How does an increase in glucose uptake (liver) affect glucokinase?

A

Increases

63
Q

What does an increase in glycogen synthesis and a decrease in glycogen breakdown affect? (2)

A
  • Increases glycogen synthase

- Decreases glycogen phosphorylase

64
Q

How does an increase in glycolysis and acetyl-CoA production affect PFK-1 and PDC?

A
  • Increases PFK-1 (by an increase in PFK-2)

- Increases PDC

65
Q

How does an increase in fatty acid synthesis (liver) affect acetyl-CoA carboxylase?

A

Increases

66
Q

How does an increase in TG synthesis affect lipoprotein lipase?

A

Increases

67
Q

What does an decrease in glycogen synthesis and a increase in glycogen breakdown affect? (2)

A
  • Decreases glycogen synthase

- Increases glycogen phosphorylase

68
Q

How does a decrease in glycolysis affect PFK-1?

A

Decrease

69
Q

How does an increase in gluconeogenesis (liver) affect FBPase-2, pyruvate kinase, and PEP carboxykinase?

A
  • Increases FBPase-2
  • Decreases Pyruvate kinase
  • Increases PEP carboxykinase
70
Q

How does an increase in fatty acid mobilization affect hormone-sensitive lipase and PKA?

A
  • Increase in HSL

- Increase in PKA

71
Q

How does an increase in ketogenesis affect acetyl-CoA carboxylase?

A

Decreases

72
Q

What synthesizes glucose-6-phosphate during the fasting state?

A

Glycogenolysis and gluconeogenesis

73
Q

What are ketone bodies synthesized from in the fasting state? Where are they transported to?

A
  • Fatty acids in hepatocytes and amino acids

- Brain

74
Q

What is released by adipose tissue during the fasting state? What does it enter?

A
  • Glycerol

- Enters gluconeogenesis

75
Q

What is converted to pyruvate during gluconeogenesis? What does it enter?

A
  • Amino acids

- Gluconeogenesis

76
Q

Why do running records always happen in Berlin?

A
  • Lack of drastic elevations, which require a lot of energy

- Time (temperature) of the marathon (September)

77
Q

Which muscle fibers are used in marathons?

A

Slow twitch red

78
Q

Which muscle fibers are used in sprinting?

A

Fast twitch white

79
Q

What are the energy sources in the initial 80 meters of a marathon?

A
  • Free ATP

- Phosphocreatine

80
Q

How long do the heart and lungs take to reach their maximum capacity? What metabolic pathways occur during this time?

A
  • 2 minutes (oxygen is not great during 2 minutes)

- Anaerobic glycolysis

81
Q

What is the energy source after 2 minutes in a marathon?

A

Aerobic glycolysis

82
Q

Whenever the road is uphill in a marathon, the muscle requires additional energy. What energy source is utilized?

A

Anaerobic glycolysis

83
Q

What does a runner exhibit after 45 minutes?

A

Endorphin peak

84
Q

What is the glycogen storage limit? It is sufficient for how many kilometers?

A
  • 500 grams

- 30 km

85
Q

What is the Runner’s wall?

A
  • No more glycolysis (no glucose or glycogen); requires motivation to continue
  • Energy is solely from fatty acid oxidation
86
Q

What energy source is used during the initial 40-60 meters in a sprint?

A
  • Free ATP and phosphocreatine

- Creatine: dietary or de novo (glycine, arginine, methionine)

87
Q

What metabolic pathway is used during the last 40 meters of a sprint?

A

Anaerobic glycolysis