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P&R > Metabolism > Flashcards

Metabolism Flashcards

1
Q

delta G of catabolic pathways

A

negative, exergonic - break down of large to small

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2
Q

delta G of anabolic pathways

A

positive, endergonic, synthesis of large from small

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3
Q

where are ATP and GTP derived from (2) which are used in catabolism

A
  1. Directly (ie, through glycolysis)

2. Through reducing equivalents (NADH and FADH2)

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4
Q

where does ATP come from which is used in anabolism?

A
  1. Directly (through gluconeogenesis)

2. Through reducing equivalents (NADPH in fatty acid synthesis)

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5
Q

how are metabolic pathways segregated (2)? give an example

A
  1. physical segregation (fatty acid synthesis in cytoplasm, oxidation in the mito)
  2. intrinsic limitations on substrate access (insulin-stimulated display of glucose transporeters on surface of muscle and fat cells)
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6
Q

what are examples of competing pathways which are segregated? (4)

A
  1. Glycolysis and gluconeogenesis
  2. Glycogen breakdown and synthesis
  3. Triglyceride synthesis and breakdown
  4. Fatty acid oxidation and synthesis
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7
Q

why does bioenergetics require complex regulation? (4)

A
  1. Only a narrow range of blood glucose which can be tolerated by humans before coma/death
  2. We eat a ton of sugar and excess glucose needs to rapidly be cleared
  3. Fasting/starvation leads to huge drops in energy intake and we need to be able to mobilize energy stores
  4. Exercise can create large energy demands and these can’t deplete blood glucose
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8
Q

Role in division of bioenergetic labor: pancreas

A

Pancreatic islets (5% of organ) sense glucose and release insulin/glucagon

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9
Q

Role in division of bioenergetic labor: liver

A

Glucose buffer. Removes excess blood glucose and either storing or exporting it, and also generating glucose via gluconeogenesis, using fat + amino acids

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10
Q

Role in division of bioenergetic labor: muscle

A

removes glucose from blood in response to insulin only, converts to glycogen

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11
Q

Role in division of bioenergetic labor: adipose

A

removes glucose from blood in response to insulin only, converts to fat, releases fat to liver

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12
Q

Role in division of bioenergetic labor: brain

A

glucose sink, requires a relatively constant blood glucose concentration

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13
Q

Role in division of bioenergetic labor: red blood cells

A

utilize glucose by glycolysis only (no mitos)

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14
Q

what pancreatic cells produce insulin?

A

beta cells

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15
Q

what pancreatic cells produce glucagon?

A

alpha cells

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16
Q

what pancreatic cells produce digestive zymogens

A

acinar cells

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17
Q

what pancreatic cells produce somatostatin?

A

delta cells

18
Q

type 1 diabetes is characterized by the loss of which cell type?

A

beta cells

19
Q

type 2 diabetes is the result of what?

A

insulin resistance and loss of beta cell function

20
Q

what type of protein is the insulin receptor

A

tyrosine kinase

21
Q

insulin is secreted in response to what?

A

increasing glucose concentration

22
Q

when is glucagon secreted?

A

during glucose deprivation

23
Q

what type of protein is the glucagon receptor?

A

GPCR

24
Q

what are some important tissues that insulin acts on in the fed state?

A
  1. liver, promotes fatty acid and glycogen deposition
  2. muscle, glucose uptake via GLUT4
  3. adipose, glucose uptake via GLUT4
25
Q

what are some important tissues that insulin acts on in the fasted state, and what do they do?

A
  1. Liver, promotes gluconeogenesis and glycogen breakdown

2. Muscle, activates NO

26
Q

Liver is conveniently located next to? Why does this matter?

A

Close proximity to gut, transport of nutrients via portal vein. Liver receives fat and cholesterol from the gut in the form of chylomicrons and repackages them into VLDL particles

27
Q

what do bile salts do?

A

emulsify dietary fats in the small intestine, forming mixed micelles

28
Q

what do intestinal lipases do?

A

degrade triacylglycerols in the small intestine

29
Q

how do fatty acids get from small intestine to capillary?

A

taken up by the intestinal mucosa and converted to triacylglycerols, which are then incorporated into chylomicrons, which move through lymphatic and bloodstream to tissues

30
Q

function of lipoprotein lipase?

A

releases fatty acids and glycerol from chylomicrons, allowing them to enter cells

31
Q

foam cells

A

macrophages that have phagocytized large amounts of oxidized LDL

32
Q

LDL vs HDL

A

LDL (bad cholesterol) delivers cholesterol to target tissues, while HDL (good) delivers cholesterol from these tissues to the liver.

33
Q

T/F. Muscle stored glycogen can only be utilized within muscle tissue

A

True, although it does lend amino acids to liver for gluconeogenesis

34
Q

What is the largest insulin sensitive tissue?

A

Muscle

35
Q

T/F. Both too much and too little fat leads to insulin resistance

A

True

36
Q

what happens to pancreas/insulin/glucagon/etc during a fast?

A
  1. Blood glucose drops, pancreas stops production of insulin and begins secreting glucagon.
  2. Change in insulin/glucagon tells liver to breakdown glycogen to buffer blood glucose
  3. Gluconeogenesis begins in liver
  4. Adipose tissue hydrolyzes triglycerides to provide liver with glycerol and fatty acids, muscle provides protein
  5. Liver makes ketone bodies from FAs for use by brain and muscle primarily
37
Q

what happens to pancreas/insulin/glucagon/etc during feeding post fast?

A
  1. Blood glucose rises, pancreas starts making insulin and stops secreting glucagon
  2. Change in insulin/glucagon tells liver to store glycogen and stop gluconeogenesis
  3. Insulin inhibits lipolysis in adipose and amino acid breakdown in muscle
  4. Decreased lipolysis and increased FA production in liver, stops ketone body production
38
Q

what does cortisol do?

A

stimulates gluconeogenesis, promotes breakdown of muscle proteins, and stimulates ketogenesis in liver

39
Q

what does epinephrine do?

A

stimulates glycogenolysis, and lipolysis from adipose

40
Q

where is cortisol production controlled?

A

hypothalamic/pituitary axis

41
Q

where is epinephrine production controlled?

A

sympathetic nervous system

P&R (15 decks)

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