REB 13. Effects of Adrenal Hormones Flashcards

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1
Q

Each adrenal is composed of 2 endocrine organs which are…

A

[1] Adrenal Cortex (80%)

[2] Adrenal Medulla (20%)

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2
Q

What percentage is the adrenal cortex?

A

80%

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3
Q

What percentage is the adrenal medulla?

A

20%

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4
Q

What are the 3 layers of the adrenal cortex?

A

[1] Zona Glomerulosa
[2] Zona Fasciculata
[3] Zona Reticularis

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5
Q

What are the hormones that are produced in the adrenal glands? First general term, then the 3 branches

A

Adrenocortical Hormones:
[1] Mineralocorticoids (aldosterone)
[2] Glucocorticoids (cortisol)
[3] Sex Hormones (dehydroepiandrosterone)

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6
Q

Where in the cortex is Aldosterone synthesized?

A

Zona Glomerulosa

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7
Q

Where in the cortex is Cortisol synthesized?

A
Zona Fasciculata (primary source)
\+ Zona Reticularis
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8
Q

Where in the cortex is the Adrenal Sex Hormones synthesized?

A

Zona Fasciculata + Zona Reticularis

- produced in greater abundance in the gonads

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9
Q

Where is the adrenal sex hormones synthesized in the greatest abundance?

A

the gonads

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10
Q

Why are there only small amounts of aldosteroe, cortisol and DHEA found in the adrenocortical cells at any given time?

A

This is because the hormones are not stored in there, they are rather secreted on demand

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11
Q

Describe the characteristics of adrenocortical hormones? (are the lipophobic, lipophilic…) How do these hormones move through the blood?

A

they are lipophilic - so they can diffuse into the blood after synthesis

  • they are extensively bound to plasma proteins (such as CBG and albumin)
  • binding prevents hormone entering a cell + being excreted
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12
Q

What is the average daily production of cortisol in the adrenal cortex?

A

20 mg/day

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13
Q

What is the average daily production of aldosterone in the adrenal cortex?

A

0.1 mg/day

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14
Q

What is the average daily production of DHEA in the adrenal cortex?

A

30 mg/day

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15
Q

What are the 2 main functions of aldosterone?

A

[1] Acts as Distal + Collecting Tubes of Kidney

  • Na+ retention and K+ elimination during urine formation
  • promotion of Na+ retention secondarily induces osmotic retention of water, expanding ECF volume

[2] Essential for Life
- without aldosterone, death results from circulatory shock due to fall in plasma volume caused by excessive loss of H2O-holding Na+

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16
Q

What increases the secretion of the aldosterone?

A

Increased By…
[1] activation of the renin-angiotensin-aldosterone system (RAAS) by factors related to the reduction in Na+ fall in blood pressure

[2] direct stimulation of adrenal cortex by a rise in plasma K+

17
Q

What are the 5 main categories of functions of cortisol?

A

[1] Metabolic
- increases glucose concentration in blood at expense of protein + fat in response to fasting

[2] Permissive Actions
- cortisol enhances the capacity of glucagon and catecholamines

[3] Stress Adaptation

[4] Anti-Inflammatory + Immunosuppressive Effects

  • if stress is accompanied by tissue injury, inflammation and immune responses accompany the stress response
  • cortisol holds these responses in check as exaggerated response could cause harm

[5] Glucocorticoid Therapy

  • rheumatoid arthritis + in preventing organ transplant rejection
  • use only when warranted
18
Q

What stimulates the secretion of cortisol from the adrenal cortex?

A

the anterior pituitary gland secretes Adrenocorticotropic Hormone (ACTH) which stimulates the adrenal cortex to secrete cortisol

19
Q

What is the Adrenocorticotropic Hormone (ACTH) secretion regulated by?

A

it is regulated by Corticotropin-Releasing Hormone (CRH)

- CRH is secreted by the hypothalamus

20
Q

What is the feedback control loop? What does cortisol inhibit (negatively feedback loop)?

A
Cortisol inhibits:
[1] Anterior Pituitary Gland 
(inhibits Adrenocorticotropic Hormone) 
[2] Hypothalamus 
(inhibits Corticotropin-Releasing Hormone)
21
Q

What are 3 factors that cortisol secretion is dependent on?

A

[1] Diurnal Rhythm

  • plasma concentration of cortisol displays a characteristic diurnal rhythm
  • highest in morning, lowest at night

[2] Stress
- increase occurs in response to all kinds of stressful situations

22
Q

What sex hormones does the adrenal gland produce and what effects do they have?

A
  • it produces androgens and estrogens

- it normally does NOT have an abundant/powerful effect

23
Q

What is Dehydroepiandrosterone?

A

It is DHEA

- only adrenal hormone with biological significance

24
Q

What is the function of DHEA in males?

A
  • overpowered by testosterone
25
Q

What is the function of DHEA in females?

A
  • governs androgen-dependent processes
26
Q

What hormone controls the secretion of adrenal sex hormone secretion?

A

ACTH - adrenocorticotropin hormone

27
Q

Which hormone does DHEA inhibit?

A

gonadotropin-releasing hormone

28
Q

How does the adrenal sex hormones change during puberty?

A
  • surge in secretion of adrenal androgen
  • peaks at 25 to 30 years
  • slowly tapers (60 years plasma DHEA concentration <15% peak value)
29
Q

Are disorders of the adrenal cortex common?

A

No, they are uncommon

30
Q

What are the 2 possible causes of hypersecretion of Aldosterone?

A

[1] Hypersecreting Adrenal Tumour of the Aldosterone-Secreting Cells
- primary hyperaldosteronism/Conn’s syndrome

[2] Inappropriately High Activity of RAAS
- secondary hyperaldosteronism

31
Q

What are the symptoms of aldosterone hypersecretion?

A
  • increased whole body sodium, fluid + circulating blood volume
  • excessive K+ depletion - hypokalemia
  • high blood pressure (hypertension)