Integrative Physiology (Nutting) Flashcards

1
Q

What are the body’s objectives during absorption and storage?

A
  1. fill glycogen stores
  2. don’t spill too much glu in urine
  3. utilize ingested carbs/fat for energy
  4. package whatever carbs/fats you don’t need as TAG and whatever aa’s as protein
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2
Q

During absorption and storage, what major processes are going on involving carbs?

A

increased glu uptake/utilization

increased glycolysis

decreased gluconeogenesis
decreased glycogenolysis
= increased glycogen stores

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3
Q

During absorption and storage, what major processes are going on involving fats?

A

increased lipogenesis
decreased lipolysis
=increased fat stores

decreased ketogenesis

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4
Q

During absorption and storage, what major processes are going on involving proteins?

A

increased protein synth
decreased protein degradation
=increased protein stores

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5
Q

What are the body’s objectives post-absorption (between meals)?

A
  1. keep glu constant
  2. decrease glu utilization
  3. keep some quick glycogen reserves
  4. burn fats for energy
  5. utilize the protein you can afford to spare
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6
Q

During post-absorption, what major processes are going on involving carbs?

A

decreased glu uptake/utilization

decreased glycolysis

increased gluconeogenesis

slightly increased glycogenolysis
slightly decreased glycogenesis
= only small decreases in glycogen stores

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7
Q

During post-absorption, what major processes are going on involving fats?

A

decreased lipogenesis
increased lipolysis (forming FFA + glycerol)
=decreased fat stores

increased ketogenesis

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8
Q

During post-absorption, what major processes are going on involving proteins?

A

decreased protein synth
increased protein degradation
=decreased protein stores
**esp in muscle, lymphoid tissue

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9
Q

What are the short-acting hormones involved in metabolism?

A

insulin
epi
NE
glucagon

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10
Q

What are the long-acting hormones involved in metabolism?

A

GH
thyroid hormone
GC
sex steroids

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11
Q

What is the onset and duration of short-acting hormones involved in metabolism?

A

rapid onset, with a brief (~mins) duration

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12
Q

What is the onset and duration of long-acting hormones involved in metabolism?

A

delayed (min-hours) onset, with prolonged (hours-days) duration

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13
Q

What is the primary mechanism of short-acting hormones involved in metabolism?

A

increase or decrease enzyme or protein activity

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14
Q

What is the primary mechanism of long-acting hormones involved in metabolism?

A

increase or decrease amount of enzymes or other proteins

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15
Q
How do the following levels change during  prolonged fasting (up to 5 days, not between handfuls of Cheerios)?
Glu:
Insulin:
Glucagon:
Cortisol:
GH:
T3:
A

Glu: maintains steady level
Insulin: decreases (most significantly post-abs)
Glucagon: increases (but then remains steady)
Cortisol: remains constant
GH: increases
T3: steadily decreases (to decrease metabolic rate)

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16
Q

What hormone levels remain constant between the fasting and feeding phases?

A

cortisol
GH
T3

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17
Q

How is glucagon affected by fasting? By feeding?

A

decreases during/after meal

may increase between meals

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18
Q

How are Epi/NE affected by fasting? By feeding?

A

decrease during/after meal

tend to increase between meals

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19
Q

How is insulin affected by fasting? By feeding?

A

increases during/after meal,

decreases between meals

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20
Q

Effects of cortisol during/after meal?

Effects of cortisol between meals?

A

slight decrease in glu uptake and utilization (glycostatic)

  • -Permissive to gluconeogenesis + lipolysis
  • -Mildly decrease glu uptake and utilization
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21
Q

Effects of GH during/after meal?

Effects of GH between meals?

A

increase protein synth (residual effects)

  • -mildly decrease glu utilization (residual effects)
  • -increase lipolysis (residual effects)
  • -slows protein loss
  • -glycostatic
22
Q

Effects of T3 during/after meal?

Effects of T3 between meals?

A
  • -increase protein synth (residual effects)**
  • -increase glycolysis (residual)

Permissive to increased lipolysis**

**synergizes with GH

23
Q

Effects of glucagon during/after meal?

Effects of glucagon between meals?

A

few

  • -increased glycogenolysis, ketogenesis and gluconeogenesis
  • -decreased glycogen synth and glycolysis
24
Q

Effects of Epi/NE during/after meal?

Effects of Epi/NE between meals?

A

few

  • -increased glycogenolysis, glyconeogenesis and lipolysis
  • -decreased insulin secretion
  • -mildly decreased glucose uptake
25
Q

Effects of insulin during/after meal?

A

increases many anabolic and anti-catabolic processes

decreased catabolic processes (aside from glycolysis and TCA cycle

26
Q

Effects of insulin between meals?

A

decreases many anabolic and anti-catabolic processes, which allows catabolic processes to dominate (such as proteolysis, glycogenolysis, lipolysis)

27
Q

Where does glucagon act?

A

liver only

28
Q

How does high blood glu affect myocytes and adipocytes?

A

enters myocytes and phosphorylated to glu-6P; in adipocytes, FA are stored as TAG

29
Q

How does low blood glu affect myocytes and adipocytes?

A

TAG in adipocytes is converted to FFA; myocytes then utilize blood FFA (and ketones) to generate energy

30
Q

Epi/NE (increase/decrease) glu levels in the blood.

A

increase (via glu production by liver)

31
Q

GH (increases/decreases) glu levels in the blood.

A

decrease (weakly, due to glu consumption by muscle and adipose)

32
Q

Explain how cortisol, glucagon and epinepherine affect blood glu independently and in combination.

A

Cortisol alone has very little effect on blood glu
Epi alone and glucagon alone each have modest effects on blood sugar

When all 3 combined, hyperglycemic response is far greater than the additive response of all three given singly.

33
Q

Epi/NE stimulate (what enzyme?), in order to generate FFA.

A

hormone-sensitive lipase

aka–epi/NE have lipolytic effects!

34
Q

How does insulin block lipolysis?

A

Insulin antagonizes the lipolytic effects of epi/NE: 1) directly via inhibiting cAMP formation
2) indirectly via increased esterification of FFA

35
Q

How do cortisol, T3 and GH affect lipolysis?

A

All 3 act on epi/NE, encouraging lipolysis via hormone-sensitive lipase (TAG&raquo_space;FFA)

36
Q

In the liver, GC promote gluconeogenesis via what mechanisms?

A
  1. previous induction of KEY gluconeogenic and amino acid metabolizing enzymes
  2. increased hepatic reponsiveness to glucagon (i.e. better aa uptake)
  3. additional GC = further increase in synthesis of gluconeogenic enzymes
37
Q

In muscle, GC promote gluconeogenesis via what mechanisms?

A

provide more substrates for the liver by:

1. increased amino acid release via net protein breakdown (in muscle, esp)

38
Q

In adipose, GC promote gluconeogenesis via what mechanisms?

A

provide more substrates for the liver by:

  1. increased glycerol release (which the liver then turns to glu)
  2. GC + T3 + GH permit spikes in Epi/NE, which increases lipolysis

(**TAG = FA + glycerol)

39
Q

How does glucagon (via cAMP and PKA) affect phosphorylase?

A
increases activity
(=breakdown of glycogen > G6P > glu)
40
Q

How does glucagon (via cAMP and PKA) affect glycogen synthetase?

A
decreases activity
(=breakdown of glycogen > G6P > glu)
41
Q

How does glucagon (via cAMP and PKA) affect F-2,6-BP?

A

decreases formation by decreasing PFK activity and increasing F-1,6-BP activity

42
Q

How does glucagon (via cAMP and PKA) affect PK?

A

decreases activity (which decreases PEP, ultimately decreasing ACoA)

43
Q

How does glucagon (via cAMP and PKA) affect AcetylCoA carboxylase?

A

decreases activity

somehow? this eventually results in inhibition of beta-oxidation?

44
Q

How does glucagon (via cAMP and PKA) affect PEP carboxykinase?

A

increases synthesis

45
Q

How does glucagon (via cAMP and PKA) affect pyruvate carboxylase?

A

slight increase

46
Q

What are the effects of decreased PFK activity?

A

decreased glycolysis (*increased formation of F-2,6-BP)

47
Q

What are the effects of increasing F-1,6-BP activity?

A

increased gluconeogenesis (*decreased formation of F-2,6-BP)

48
Q

With prolonged exercise, the contribution of fuel from ____ increases, while the contribution from _____ decreases.

A

plasma FFA

muscle glycogen

49
Q

During moderate exercise, levels of what hormone(s) decline?

A

insulin

50
Q

During moderate exercise, levels of what hormone(s) increase?

A

epi/NE
glucagon
cortisol
GH

51
Q

As glucose drops from ~100 towards ~45, how does the body counterregulate hypoglycemia?

A
  1. levels of insulin drop
  2. glucagon and epi increase (SNS activation, which promotes gluconeogenesis and glycogenolysis)
  3. GH increases
  4. cortisol increases
  5. hypoglycemic symptoms (~55 mg/dl)
  6. hepatic glucose auto-regulation kicks in
  7. cognition declines (~45 mg/dl)

*actual levels not important, just the sequence