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Endocrine System > Lecture 12 The Adrenal Gland > Flashcards

Lecture 12 The Adrenal Gland Flashcards

1
Q

Where is the adrenal gland situated

A

Superior pole of the kidney in the retroperitoneal space and weighs 4g in adults

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2
Q

What are the 2 separate endocrine glands that make up the adrenal glands

A 
Adrenal medulla (25%)
Adrenal cortex (75%)
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3
Q

Describe the function of the adrenal medulla

A

Modified sympathetic ganglion derived from the neural crest tissue.
Secretes catecholamines: epinephrine (adrenaline) also norepinephrine and dopamine

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4
Q

Describe the function of the adrenal cortex

A

True endocrine gland
Derived from mesoderm
secretes 3 classes of steroid hormones
 Mineralocorticoids (salt)- aldosterone: involved in the regulation of Na+ and K+
 Glucocorticoids (sweet)- cortisol: involved in maintaining plasma glucose
 Androgens (sex)- testosterone

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5
Q

What hormone does Zone glomerulus release

A

Mineralocorticoids- Aldosterone

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6
Q

What hormone does Zone Fasciculata release

A

Glucocorticoid- Cortisol

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7
Q

What hormone does Zone Reticularis release

A

Sex hormones- Androgens

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8
Q

What hormone is needed to make cortisol and aldosterone from cholesterol

A

21-hydroxylase

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9
Q

All steroid hormones ae defined from__

A

Cholesterol

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10
Q

Defects in 21-hydroxylase cause what and why?

A

Congenital adrenal hyperplasia

  1. Lack of 21-hydroxylase inhibits synthesis of cortisol.
  2. This removes the negative feedback on ACTH and CRH release
  3. Increased ACTH secretion is responsible for enlargement of adrenal glands- Androgen biosynthesis is unaffected so accumulating steroid precursors are channelled into excessive adrenal androgen production
  4. Negative feedback of ACTH on CRH synthesis remains.
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11
Q

95% of plasma cortisol is___

A

Protein bound

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12
Q

All nucleated cells have what type of receptor

A

Glucocorticoid receptor

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13
Q

Describe the characteristic pattern of release of cortisol

A
  • Marked circadian rhythm, precede by a similar pattern of release of ACTH
  • Cortisol burst persist longer than ACTH burst because the half-life is much longer
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14
Q

Why would removal of adrenal gland lead to death?

A

Unable to deal with stress (maintaining glucose levels)
Cortisol helps protect brain from hypoglycaemia
Incapable of maintaining ECF volume

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15
Q

Cortisol has a permissive action on what hormone

A

Glucagon

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16
Q

Name the actions of Cortisol on glucose metabolism

A

Gluconeogenesis
Proteolysis
Lipolysis
Decreases insulin sensitivity in muscle and adipose tissue

17
Q

What are the non-glucocorticoid actions of cortisol

A

Reduce calcium plasma levels
Impair mood and cognition
Permissive effect on norepinephrine
Suppression of the immune system

18
Q

What are the side effects of glucocorticoid therapy

A

Muscle wastage
Increases severity and frequency of infection
Loss of percutaneous fat- thinning of skin, more fragile

19
Q

What organ does aldosterone act on

A

Distal tube of kidney

20
Q

What is the action of increased aldosterone

A

Increases Na+ (H20) retention and excretes K+

Results in high blood volume and raised blood pressure

21
Q

Secretion of the adrenal cortex is controlled by a complex pathway called

A

Renin-angiotensin-aldosterone system (RAAS)

22
Q

What is the action of decreased aldosterone

A

Decreased absorption of Na+ (H20) and increase in K+ which results in low blood volume and pressure

23
Q

Hypersecretion of cortisol leads to

A

Cushing’s disease/syndrome

24
Q

What conditions can lead to hyper secretion of cortisol

A

Tumour in adrenal cortex (primary hypercortisolism) or pituitary gland (secondary hypercortisolism)- most common. Excess ACTH

25
Q

Name a condition that is caused by hypo secretion of cortisol

A

Addisons Disease

Due to autoimmune destruction of adrenal cortex

26
Q

How do neurohormones travel from CNS to blood

A

Preganglionic fibres terminate on specialised postgranglionic cells in the adrenal medulla. The postganglionic fibres do not have axons and the neurohormones are released directltinto the blood

27
Q

What is Pheochromocytoma

A

Rare neuroendocrine tumour
in adrenal medulla
Excess catecholamines, increased HR, CO, BP
Diabetogenic due to adrenergic effect on glucose metabolism. Can be resolved with surgery

Endocrine System (26 decks)

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