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2) Biochemistry II > Regulation of Metabolism (Tissue-Specific and Hormonal) > Flashcards

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
What does the liver store to produce hormones?
- Iron | - Vitamin A
26
What are the two sources of fatty acids?
- Diet | - Adipose tissue
27
Where are fatty acids sent to in the liver?
- 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
28
What is Acetyl-CoA used for in lipid metabolism in the liver?
- Used to form ketone bodies in the blood (fuels heart and brain) - Enters cholesterol synthesis (bile salts and steroid hormones) - Enters the TCA cycle
29
Where is white adipose tissue found? Where is brown adipose tissue found?
- WAT: under skin, around major blood vessels (aorta) and abdomen - BAT: under skin (chest and back)
30
How many lipid droplets are in WAT and BAT?
- WAT: one lipid droplet | - BAT: many lipid droplets
31
What provides the brown color in BAT? Who has BAT?
- Many mitochondria and high blood supply | - Children only
32
In which situation may an adult contain BAT?
Pre-adipocytes can differentiate into brown adipose tissue in adults during chronic cold exposure
33
What are the energy sources in WAT? BAT?
- WAT: glucose from glycolysis | - BAT: fatty acids from B-oxidation
34
Is WAT or BAT capable of fatty acid synthesis from excess glucose? Why?
- WAT | - Since it is insulin-sensitive
35
Is WAT or BAT a major store of TG?
WAT
36
WAT is epinephrine sensitive. What is the consequence?
Hydrolysis of TG to FAs
37
What is non-shivering thermogenesis due to?
- Thermogenin (UCP1) --> uncoupling protein | - Found in BAT
38
What inhibits UCP1? What activates UCP1?
- Purines inhibit UCP1 | - Non-esterified fatty acids activate UCP1
39
What can skeletal muscle use for energy?
- Fatty acids - Ketone bodies - Glucose
40
What does skeletal muscle use for energy at a resting state?
- Fatty acids from adipose tissue | - Ketone bodies from the liver
41
What does skeletal muscle use for energy during moderate exercise?
- Blood glucose* (undergoes aerobic glycolysis) - Fatty acids from adipose tissue - Ketone bodies from the liver
42
What does skeletal muscle use for energy during vigorous exercise?
Stored glycogen gives glucose
43
What buffers ATP?
Phosphocreatine
44
Each glycogen-originated glucose provides how many ATPs during glycolysis? Why?
- 3 ATPs, instead of 2 | - In glycogenolysis, phosphoglucomutase (does NOT require ATP) is used instead of hexokinase (requires ATP)
45
What helps continue anaerobic glycolysis?
Lactic acid, synthesized from pyruvate
46
What helps in using glucose from the blood and glycogen?
Epinephrine
47
What is the Cori Cycle?
- 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
What synthesizes ATP during vigorous activity?
Phosphocreatine --> creatine provides a phosphate group to ADP, which synthesizes ATP
49
How is phosphate stored during recovery?
Creatine --> Phosphocreatine uses ATP to store phosphate groups in phosphocreatine
50
What kind of metabolism occurs in cardiac muscle? What is the main energy source?
- Aerobic metabolism (abundant mitochondria) | - Mainly fatty acids, but also use ketone bodies and glucose
51
Which structure contains less stored glycogen?
- Cardiac muscle (less) | - Brain (none)
52
Which structure is sensitive to O2 deprivation?
Cardiac muscle
53
What can neurons use in addition to glucose?
B-hydroxybutyrate (ketone body)
54
What is ATP used for in metabolism in the brain?
To maintain membrane potential
55
What energy source can astrocytes use?
Fatty acids
56
Neurons utilize glucose through which metabolic pathway?
Aerobic glycolytic metabolism
57
What does the brain use during fasting/starvation?
- Ketone bodies from fatty acids | - Glucose from muscle proteins
58
What happens to glucose after it is digested? (3)
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
Where do amino acids enter after digestion? What are their functions? (3)
- Liver - Protein synthesis (primarily) - a-Keto acids can be converted to other amino acids - Excreted in the form of ammonia
60
What is the role of Acetyl-CoA after it is synthesized?
- Used in the synthesis of TG and VLDL (lipoproteins) | - VLDLs are used for adipose tissue storage
61
How does an increase in glucose uptake (muscle, adipose) affect GLUT4?
Increases
62
How does an increase in glucose uptake (liver) affect glucokinase?
Increases
63
What does an increase in glycogen synthesis and a decrease in glycogen breakdown affect? (2)
- Increases glycogen synthase | - Decreases glycogen phosphorylase
64
How does an increase in glycolysis and acetyl-CoA production affect PFK-1 and PDC?
- Increases PFK-1 (by an increase in PFK-2) | - Increases PDC
65
How does an increase in fatty acid synthesis (liver) affect acetyl-CoA carboxylase?
Increases
66
How does an increase in TG synthesis affect lipoprotein lipase?
Increases
67
What does an decrease in glycogen synthesis and a increase in glycogen breakdown affect? (2)
- Decreases glycogen synthase | - Increases glycogen phosphorylase
68
How does a decrease in glycolysis affect PFK-1?
Decrease
69
How does an increase in gluconeogenesis (liver) affect FBPase-2, pyruvate kinase, and PEP carboxykinase?
- Increases FBPase-2 - Decreases Pyruvate kinase - Increases PEP carboxykinase
70
How does an increase in fatty acid mobilization affect hormone-sensitive lipase and PKA?
- Increase in HSL | - Increase in PKA
71
How does an increase in ketogenesis affect acetyl-CoA carboxylase?
Decreases
72
What synthesizes glucose-6-phosphate during the fasting state?
Glycogenolysis and gluconeogenesis
73
What are ketone bodies synthesized from in the fasting state? Where are they transported to?
- Fatty acids in hepatocytes and amino acids | - Brain
74
What is released by adipose tissue during the fasting state? What does it enter?
- Glycerol | - Enters gluconeogenesis
75
What is converted to pyruvate during gluconeogenesis? What does it enter?
- Amino acids | - Gluconeogenesis
76
Why do running records always happen in Berlin?
- Lack of drastic elevations, which require a lot of energy | - Time (temperature) of the marathon (September)
77
Which muscle fibers are used in marathons?
Slow twitch red
78
Which muscle fibers are used in sprinting?
Fast twitch white
79
What are the energy sources in the initial 80 meters of a marathon?
- Free ATP | - Phosphocreatine
80
How long do the heart and lungs take to reach their maximum capacity? What metabolic pathways occur during this time?
- 2 minutes (oxygen is not great during 2 minutes) | - Anaerobic glycolysis
81
What is the energy source after 2 minutes in a marathon?
Aerobic glycolysis
82
Whenever the road is uphill in a marathon, the muscle requires additional energy. What energy source is utilized?
Anaerobic glycolysis
83
What does a runner exhibit after 45 minutes?
Endorphin peak
84
What is the glycogen storage limit? It is sufficient for how many kilometers?
- 500 grams | - 30 km
85
What is the Runner's wall?
- No more glycolysis (no glucose or glycogen); requires motivation to continue - Energy is solely from fatty acid oxidation
86
What energy source is used during the initial 40-60 meters in a sprint?
- Free ATP and phosphocreatine | - Creatine: dietary or de novo (glycine, arginine, methionine)
87
What metabolic pathway is used during the last 40 meters of a sprint?
Anaerobic glycolysis

2) Biochemistry II (23 decks)

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