TBR v. Physio Textbook: Cortisol and Glycogen?

[justadream]

TBR page 45 # 12



“Which of the effects can be attributed to the hormones released by sympathetic nervous system stimulation of the adrenal cortex”?



One of the INCORRECT answers: Storage of glucose in the liver



I thought cortisol stimulation causes the liver to make glycogen (I think I saw that in a TPR problem once).



In addition Silverthorn’s Physio textbook says “Cortisol promotes gluconeogenesis in the liver. Some glucose produced in the liver is released into the blood, and the rest is stored as glycogen. As a result, cortisol increases blood glucose concentrations.”



So is TBR wrong?

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[Cawolf]

For some reason your TBR book is different than mine on that page.

Gluconeogenesis (promoted by cortisol) causes glucose to be formed in the liver and mostly released to the bloodstream.

This is the opposite of storing glucose in the liver.

I think that even though Silverthorn says some glucose is produced and stored, the net effect is the release of glucose from the liver into the bloodstream (at the most basic level).

 

[justadream]

@Cawolf

Sorry, mistyped.

It's #12 on page 43.

I mean okay, I guess the net effect is that glucose is lost but.....it's kinda ambiguous.

 

[Cawolf]

It is slightly ambiguous, but it is generally understood that a stress response increases the BGL - so it isn't promoting glycogenesis directly; which is what I think that question is asking.

Now that I have these books (got them 2 days ago) it is a lot easier to respond in this forum. Haha.

 

[sillyjoe]

Think of cortisol as a glucose "sparing" hormone. Your body is preparing for stress and wants a sufficient supply in the blood for emergencies. It causes a shift in the ratio of fuels towards lipids to spare glucose. It also promotes the breakdown of proteins to amino acids for use in gluconeogenesis. Cortisol also causes most cells of the body to not take up as much glucose by acting in an antagonistic manner to insulin. This is all in line with sparing the use of glucose and making sure there is a sufficient [glucose] in the blood for the stress.

Glycogen synthesis would be counterintuitive in this sense. The body is doing everything it can to mobilize glucose via synthesis or breakdown and is also moderating the usage for the impending/current stress.

 

[Czarcasm]

TBR page 45 # 12



“Which of the effects can be attributed to the hormones released by sympathetic nervous system stimulation of the adrenal cortex”?



One of the INCORRECT answers: Storage of glucose in the liver



I thought cortisol stimulation causes the liver to make glycogen (I think I saw that in a TPR problem once).



In addition Silverthorn’s Physio textbook says “Cortisol promotes gluconeogenesis in the liver. Some glucose produced in the liver is released into the blood, and the rest is stored as glycogen. As a result, cortisol increases blood glucose concentrations.”



So is TBR wrong?

I'm almost certain this is an error because cortisol helps ensure adequate supply of glucose in times of stress. Unfortunately I'm on my phone so can't explain it in detail but I believe they meant the adrenal medulla - this region releases epinephrine which mobilizes blood glucose especially during immediate stress. Adrenal cortex (cortisol) acts as a backup to ensure blood glucose levels stay high by promoting adequate reserves and glycogen synthesis/gluconeogenesis.

 

[Czarcasm]

Also note that the adrenal medulla is innervated by sympathetic nerves (synapses on neuronal chromaffin cells - these cells release neurohormone epinephrine). The cortex is not - atleast not directly. Sympathetic info can be relayed via the hypothalamus which integrates info (whether or not to release CRH and stimulate ACTH release by AP which could then act on the cortex to stimulate cortisol release in times of chronic stress).

The question though is specifically referring to neurohormone epinephrine in the adrenal medulla not cortisol.

 

[The Brown Knight]

cortisol increases blood glucose and will do whatever it needs to make that happen:
1. primarily, it will make the liver release glucose from glycogen
2. but if there is little to no glycogen left, cortisol will promote gluconeogenesis, which is the energy-intensive reverse process of glycolysis so that it takes glucose derivatives (like pyruvate) and push them back up the energy hill to remake them into glucose, which is released into bloodstream - in effect, cortisol is disturbing cells in the middle of busy work and yanking glucose away from them.
3. then it promotes turning other useful nutrients like amino acids into glucose (this is why long-term stress makes you unhealthy)

main goal of cortisol = increase blood glucose at all costs