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2.4 BRS Endocrinology > Adrenal Gland > Flashcards

Adrenal Gland Flashcards

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1
Q

Where are the adrenal glands located?

A

Sit on the top of the kidneys

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2
Q

How does blood circulate the adrenal glands?

A

Right:
Abdominal aorta —> right adrenal arteries (3 groups - middle, inferior) —> gland —> IVC (inferior vena cava)

Left:
Abdominal aorta —> left adrenal arteries (3 groups)
—> gland —> left adrenal vein —> IVC

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3
Q

What are the layers of the adrenal glands?

A

Cortex —> secrete corticosteroids
- Zona glomerulosa —> aldosterone
Zona fusciculata —> cortisol (+ sex hormones)
Zona reticularis —> cortisol (+ sex hormones)

Medula —> secrete catecholamines
- neuroendocrine cells (chromaffin)

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4
Q

Which 7 hormones are secreted from the adrenal glands and their functions?

A

Corticosteroids:
1. Aldosterone (mineralcorticoid)
2. Cortisol (glucocorticoid)
3. Androgens (sex steroids)
4. Oestrogens (sex steroids)

Catecholamines:
5. Adrenaline - 80%
6. Noradrenaline - 20%
7. Dopamine

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5
Q

What is the histology of an adrenal gland? (5)

A
  1. Capsule —> short layer, long cells
  2. Zona glomerulosa —> bundles, clear cells
  3. Zona fasiculata —> long layer, strips, clear cells
  4. Zona reticularis —> bundles, spaces, compact cells
  5. Medulla —> bundles, chromaffin cells
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6
Q

What is the path of blood through the adrenal glands?

A
  1. Abdominal aorta
  2. Suprarenal arteries
  3. Capsular plexus - arterioles
    Medullary arteriole branches —> medulla
  4. Subcapsular plexus (Z. glomerulosa) - arterioles
  5. Cortical capillaries (Z. fasciculata)
  6. Deep plexus (Z. reticularis)
  7. Medullary capillaries
  8. Central vein (medulla)
    Left —> left adrenal vein
  9. Inferior Vena Cava
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7
Q

What are the 5 steps of aldosterone synthesis from cholesterol? (draw out functional groups)

A
  1. Colesterol
    • side chain cleavage
  2. Pregnenolone
    • 3β-Hydroxysteroid dehydrogenase
  3. Progesterone
    • 21-Hydroxylase
  4. 11-Deoxycorticosterone
    • 11-Hydroxylase
  5. Corticosterone
    • 18-Hydroxylase
  6. Aldosterone
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8
Q

What are the 5 steps of cortisol synthesis from cholesterol?

A
  1. Colesterol
    • side chain cleavage
  2. Pregnenolone
    • 3β-Hydroxysteroid dehydrogenase
  3. Progesterone
    • 17-Hydroxylase
  4. 17-Hydroxyprogesterone
    • 21-Hydroxylase
  5. 11-Deoxycortisol
    • 11-Hydroxylase
  6. Cortisol
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9
Q

What are the 3 steps of cortisol synthesis from cholesterol?

A
  1. Colesterol
    • side chain cleavage
  2. Pregnenolone
  3. Sex steroids —> androgens
    —> oestrogen
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10
Q

How does aldosterone regulate blood pressure, Na+ and K+?

A
  1. Released by kidney
  2. Absorbed by kidney distal convoluted tubule and
    cortical collecting duct from peritubular capillaries
    (+ sweat glands, gastric glands, colon)
  3. Binds to nuclear receptors in cells —> changes in
    gene expression
    • Inc Na+ reabsorption - inc Na+ channel proteins
      - inc Na+K+ATPase
    • Inc K+ secretion
    • Inc H+ secretion
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11
Q

How are aldosterone levels regulated?

A

Inc:
1. Low Na+ —> dec renal perfusion pressure
—> inc renal sympathetic activity
—> dec Na+ to macula densa cells (top of
loop of Henle)
+ ACTH acts on adrenal glands
2. Stimulates renin release from adjacent
juxtaglomerular apparatus
3. Renin —> Angiotensinogen release from liver
4. Angiotensinogen —> angiotensin I
5. Angiotensin I —> angiotensin II via ACE in lungs
6. Angiotensin II —> vasoconstriction —> inc BP
—> activates side chain cleavage, 3β-
hydroxysteroid dehydrogenase,
21, 11 and 18 hydroxylase in Z.g
7. BP dec
Serum Na+ inc
Serum K+ dec

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12
Q

What are the 4 main functions of cortisol?

A
  1. Stress response
  2. Metabolism - hepatic gluconeogenesis
    - inc blood glucose levels
    - inc peripheral protein catabolism
    - inc fat metabolism + adipose lipolysis
    - enhance glucagon + catecholamines
  3. Mineralocorticoid effects (weak)
  4. Renal + CV effects - inc water excretion
    - inc vascular permeability
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13
Q

How are cortisol levels regulated?

A

Inc:
ACTH - from anterior pituitary
—> activates side chain cleavage,
3βhydroxysteroid dehydrogenase, 21, 11
and 18 hydroxylase in Z.f + r —> inc cortisol

Dec:
Cortisol negative feedback to hypothalamus and pituitary gland —> dec CRH and ACTH —> dec cortisol

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14
Q

What are the 2 rhythms cortisol levels follow?

A
  1. Dirunal —> day/night based on light
    - lowest —> 12am (midnight)
    inc steeper —> 5am
    peak —> 8:32am
    fall slower —> 2pm
    fall faster —> 7pm
  2. Circadium —> internal clock
    - ACTH and cortisol
    - lower between 8am and 8pm
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15
Q

What is Addison’s disease?

A

Primary adrenal failure —> Low cortisol
- Cause: autoimmune —> destroys adrenal cortex
TB of adrenal glands (commonest worldwide)
- Effects: Low aldosterone
Low cortisol
High ACTH
High MSH

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16
Q

What are the 5 main symptoms of Addison’s disease?

A
  1. Tanned - low cortisol —> more ACTH secreted —>
    more POMC (pro-opio-melanocortin)
    cleaved to form ACTH, MSH (melanin
    stimulating), endorphins —> inc melanin
    Vitiligo
  2. Low blood pressure
  3. Weight loss
  4. GI issues
  5. Adrenal crisis - fever
    - syncope
    - convulsions
    - hypoglycaemia
    - hyponatremia (low Na)
    - severe diarrhoea and vomiting
17
Q

What is an adrenal crisis?

A

Low cortisol
- fever
- syncope
- convulsions
- hypoglycaemia
- hyponatremia (low Na)
- severe diarrhoea and vomiting

18
Q

How is Addison’s disease treated?

A

Addisonian crisis —> urgent treatment:
1. Saline —> rehydrate
2. Dextrose —> prevent hypoglycaemia (low
glucocorticoid)
3. Glucocorticoid (hydrocortisone)

19
Q

What is Cushing’s syndrome?

A

High cortisol

20
Q

What are the 4 causes of Cushing’s syndrome?

A
  1. Adrenal tumour (adenoma/carcinoma)
  2. Pituitary tumour (adenoma)
  3. Lung cancer —> ectopic ACTH
  4. Oral steroids
21
Q

What are the 7 symptoms of Cushing’s syndrome?

A
  1. Centripetal obesity (lemon on stick)
  2. Diabetes, hypertension and osteoperosis
  3. Thin skin
  4. Immunosuppression
  5. Moon face
  6. Striae (stretch marks)
22
Q

What type of cells make up the medulla and why?

A

Neuroendocrine cells (chromaffin)
- derived from ectodermal neural crest

23
Q

What are the 4 steps of noradrenaline synthesis?

A
  1. Tyosine
    Oxidised —> another hydroxyl group
  2. Dopa
    Demethylated —> CO2 out
  3. Dopamine
    Oxidised —> another hydroxyl group
  4. Noradrenaline
24
Q

What are the 5 steps of adrenaline synthesis?

A
  1. Tyosine
    Oxidised —> another hydroxyl group
  2. Dopa
    Demethylated —> CO2 out
  3. Dopamine
    Oxidised —> another hydroxyl group
  4. Noradrenaline
    Methylated (N)
  5. Adrenaline
25
Q

How are the catecholamine levels regulated?

A

Inc:
ACh - from preganglionic sympathetic neurones
—> release stores in cytoplasmic granules

Dec:
Degraded in liver by - MOA (monoamine oxidase)
- COMP (catechol-O-methyl
transferase)

26
Q

What is the main function of the catecholamines?

A

Fight or Flight response
- tachycardia
- sweating
- inc blood glucose
- more alert
- vasoconstriction

27
Q

How do the catecholamines travel round the body?

A

In blood - bound to albumin

2.4 BRS Endocrinology (9 decks)

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