REB 13. Effects of Adrenal Hormones

Question 1

Each adrenal is composed of 2 endocrine organs which are…

Answer 1

[1] Adrenal Cortex (80%)

[2] Adrenal Medulla (20%)

Question 2

What percentage is the adrenal cortex?

Answer 2

80%

Question 3

What percentage is the adrenal medulla?

Answer 3

20%

Question 4

What are the 3 layers of the adrenal cortex?

Answer 4

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

Question 5

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

Answer 5

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

Question 6

Where in the cortex is Aldosterone synthesized?

Answer 6

Zona Glomerulosa

Question 7

Where in the cortex is Cortisol synthesized?

Answer 7

Zona Fasciculata (primary source)
\+ Zona Reticularis

Question 8

Where in the cortex is the Adrenal Sex Hormones synthesized?

Answer 8

Zona Fasciculata + Zona Reticularis

- produced in greater abundance in the gonads

Question 9

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

Answer 9

the gonads

Question 10

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

Answer 10

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

Question 11

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

Answer 11

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

Question 12

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

Answer 12

20 mg/day

Question 13

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

Answer 13

0.1 mg/day

Question 14

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

Answer 14

30 mg/day

Question 15

What are the 2 main functions of aldosterone?

Answer 15

[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+

Question 16

What increases the secretion of the aldosterone?

Answer 16

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+

Question 17

What are the 5 main categories of functions of cortisol?

Answer 17

[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

Question 18

What stimulates the secretion of cortisol from the adrenal cortex?

Answer 18

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

Question 19

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

Answer 19

it is regulated by Corticotropin-Releasing Hormone (CRH)

- CRH is secreted by the hypothalamus

Question 20

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

Answer 20

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

Question 21

What are 3 factors that cortisol secretion is dependent on?

Answer 21

[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

Question 22

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

Answer 22

• it produces androgens and estrogens

- it normally does NOT have an abundant/powerful effect

Question 23

What is Dehydroepiandrosterone?

Answer 23

It is DHEA

- only adrenal hormone with biological significance

Question 24

What is the function of DHEA in males?

Answer 24

• overpowered by testosterone

Question 25

What is the function of DHEA in females?

Answer 25

• governs androgen-dependent processes

Question 26

What hormone controls the secretion of adrenal sex hormone secretion?

Answer 26

ACTH - adrenocorticotropin hormone

Question 27

Which hormone does DHEA inhibit?

Answer 27

gonadotropin-releasing hormone

Question 28

How does the adrenal sex hormones change during puberty?

Answer 28

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

Question 29

Are disorders of the adrenal cortex common?

Answer 29

No, they are uncommon

Question 30

What are the 2 possible causes of hypersecretion of Aldosterone?

Answer 30

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

[2] Inappropriately High Activity of RAAS
- secondary hyperaldosteronism

Question 31

What are the symptoms of aldosterone hypersecretion?

Answer 31

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