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LCRS - Endo and Neuro > Lecture 10 - The Adrenals and their Hormones > Flashcards

Lecture 10 - The Adrenals and their Hormones Flashcards

1
Q

Where are the adrenal glands found?

A

On the superior pole of each of the 2 kidneys

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2
Q

What are the sections of the adrenal gland - from outside to inside?

A

Capsule Cortex: 1) Zona Glomerulosa 2) Zona Fasciculata 3) Zona Reticularis

Adrenal Medulla

Tributary of central vein

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3
Q

How is the Zona Fasciculata arranged?

A

Cells line up as strings

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4
Q

How does the blood flow into adrenal cortex and to the zones?

A

To adrenal cortex via arteries that feed the outside of the gland 2 ways for the zones: Most passes through the cells and there are some vessels which go through the cortex to get to adrenal medulla

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5
Q

What is the medulla made up of?

A

Chromaffin cells - post-ganglionic nerve fibres in a specialised form

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6
Q

What type of hormones does the medulla secrete?

A

CATECHOLAMINES from Chromaffin cells

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7
Q

What type of hormones does the cortex secrete?

A

Corticosteroids

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8
Q

What specific hormones are released by the medulla?

A

Adrenaline - 80% Noradrenaline - 20% Dopamine - very small amounts

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9
Q

What specific hormones are released by the cortex?

A

Mineralocorticoids - aldosterone Glucocorticoids - cortisol Sex steroids - Androgens and Oestrogens

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10
Q

In which zone is aldosterone produced?

A

Zona Glomerulosa

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11
Q

In which zone are cortisol/androgens/oestrogens produced?

A

Zona Fasciculata and Reticularis

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12
Q

What is the nucleus of cholesterol?

A

Cyclopentanoperhydrophenanthrene

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13
Q

Which steroids are produced in the adrenals?

A

Mineralocorticoids Glucocorticoids

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14
Q

Which steroids produced in the gonads?

A

Progestogens Androgens Oestrogens

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15
Q

Where androgens produced and then moved to become stronger?

A

Produced in the adrenals (weak) and become stronger in the gonads (testes)

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16
Q

What is androstenedione useful for?

A

Its a less weak androgen and can be converted into testosterone and DHT

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17
Q

What is the precursor for aldosterone?

A

Progesterone

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18
Q

What is the precursor for Oestrogen?

A

Androgens

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19
Q

How is cortisol transported around the blood?

A

75% bound to corticosteroid binding globulin (Transcortin) 15% bound to albumin 10% free - BIOACTIVE

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20
Q

How is Aldosterone transported around the blood?

A

60% bound to corticosteroid binding globulin 40% free - BIOACTIVE

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21
Q

What happens to cortisol levels?

A

Levels change during day Released in pulses In morning higher than evening MORE cortisol than aldosterone

22
Q

What happens to aldosterone levels?

A

They remain the same during the day Controlled by position - involved in control of fluid and balance

23
Q

What are the main actions of aldosterone?

A

Stimulate Na+ reabsorption and K+ and H+ secretion in DISTAL CONVOLUTED TUBULE and cortical collecting duct

24
Q

When does the adrenal gland form during pregnancy?

A

Week 6 when the adrenal glands form but only one zone- fetal zone One week after birth is when the 3 zones develop

25
Q

What is the main target tissue for aldosterone?

A

Kidneys

26
Q

What is the mechanism of action of aldosterone?

A

Aldosterone enters cell and binds to receptors in cytoplasm HR complex enter the nucleus and attach to genes Causes increase in ion channel and enzyme production Na/K channel causes Na to move in and K to move out Na is also pumped out into the blood as Na reabsorption is increased

27
Q

What are the key features of the juxtaglomerular apparatus (JGA)?

A

Efferent and afferent arterioles Glomerulus Macula densa Distal tubule Juxtaglomerular cells

28
Q

What does the macula densa react to?

A

To Na concentration in tubule fluid

29
Q

What are stressors?

A

Variety of things perceived by an organism as a threat e.g. Hypoglycaemia, trauma (NOT chronic)

30
Q

What are the causes of renin release?

A

Decreased renal perfusion pressure Increased renal sympathetic activity Decreased Na load to top of loop of Henle - macula densa

31
Q

Describe the renin-angiotensin-aldosterone system

A
32
Q

Where is Renin produced?

A

In the juxta-glomerular cells

33
Q

Where is ACE produced?

A

Lungs and kidneys

34
Q

What are the metabolic actions of cortisol?

A

Peripheral protein catabolism Hepatic gluconeogenesis ^ BGL Fat metabolism - lipolysis in adipose cells Enhanced effects of glucagon and catecholamines

35
Q

What are the other effects of cortisol?

A

Some mineralocorticoid effects Cardiovascular and renal effects - excretion of water load, ^ vascular permeability Other effects - on bone (^ breakdown), growth, CNS (^ = associated with depression)

36
Q

What are the effects of large pharmacological amounts of cortisol?

A

Anti-inflammatory action Immunosuppressive action Anti-allergic action Associated with decrease production of prosteoglandins, histamine and interleukins and movement and function of leukocytes

37
Q

What does cortisol bind to?

A

Glucocorticoid receptors Turns into Cortisone (inactive) via T2 Aldosterone receptors (also aldosterone)

38
Q

What is the full name for enzyme T2?

A

11beta-hydroxysteroid dehydrogenase

39
Q

What are the problems that are caused by binding to aldosterone receptors?

A

It inhibits greatly as there is 1000x higher concentration of cortisol c.f. aldosterone

40
Q

What is the mechanism of action of cortisol?

A

Cortisol enters and forms a hormone-receptor complex which acts as a transcription factor

New proteins - Annexin: controls prostaglandin synthesis - synthesis AUTOCRINE - acts on Annexin receptor

Release of Arachidonic acid which inhibits prostglandin synthesis

41
Q

What does POMC turn into?

A

POMC > Pro-ACTH and beta-LPH > Pro-gamma-MSH, ACTH, gamma-LPH, b-endorphin

42
Q

What is hypothalamic enzymes are secreted to release ACTH?

A

CRH and VP

43
Q

How is ACTH released?

A

In a cicadian rhythm - BIOLOGICAL CLOCK otherwise it inhibits CRH

44
Q

Where does ACTH act on in adrenal?

A

Adrenal cortex - zona fasciculata and reticularis

45
Q

What does the adrenal cortex do when stimulated by ACTH?

A

Releases CORTISOL and small amounts of androgens

46
Q

What does DHEA stand for?

A

Dehydroepiandrosterone

47
Q

What is DHEA?

A

Precursor for androgens and oestrogens Converted to active form when in target cells

48
Q

When is the peak serum level for DHEA?

A

20-30 years with a particularly important effect

49
Q

What does DHEA do?

A

Important in postmenopausal women as precursor for oestrogen synthesis by target tissues in absence of ovarian steroids

50
Q

How is cortisol production regulated?

A

LCRS - Endo and Neuro (22 decks)

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