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Adrenal gland Flashcards

1
Q

Where is the adrenal gland

A

Located above the kidney at the back of the abdomen and is protected by ribs

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2
Q

Blood supply to the adrenal glands

A

57 arteries by only one vein which supplies the adrenal gland

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3
Q

Left adrenal gland blood supply

A

Left adrenal vein drains into renal vein . Many arteries

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4
Q

Right adrenal gland

A

Right adrenal vein drains into IVC. Many arteries but only one vein

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5
Q

3 parts of the adrenal cortex

A

Zona glomerulosa
Zona Fasiculata
Zona reticularis

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6
Q

What does the adrenal cortex secrete

A

Corticosteroids ( cortisol)

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7
Q

What does the adrenal medulla secrete

A

Catecholamines ( adrenaline )

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8
Q

Catecholamines

A

Adrenaline / epinephrine ( 80%)
Noradrenaline / norepinephrine (20%)
[Dopamine]

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9
Q

Corticosteroids

A 
Mineralocorticoids ( aldosterone) 
Glucocorticoids ( Cortisol)
Sex steroids ( Androgen, Oestrogens)
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10
Q

Where do set steroids come from

A

Most come from ovaries and testes but a bit comes from the adrenal gland ( e.g. in children before puberty)

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11
Q

Where is aldosterone released

A

Zona glomerulosa

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12
Q

What does aldosterone do

A

Controls sodium and potassium ion channels ( controls blood pressure )

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13
Q

Where is cortisol and a bit of the sex steroids ( androgens and oestrogen) produced

A

Zona fasciculata and zona reticularis

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14
Q

Which is produced in the adrenal gland / is present in the blood stream more , aldosterone or cortisol

A

Aldosterone - measured in picomol

Cortisol - measured in nanomol

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15
Q

What is a steroid

A

A hormone that is based on a cholesterol molecule - so the adrenal cortex secretions precursor is cholesterol

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16
Q

What is an enzyme

A

Proteins that catalyse a specific reaction
Various enzymes are present in cells
Specific enzymes catalyse the synthesis of particular alterations to the molecule

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17
Q

How is aldosterone ( a mineralocorticoid ) produced in the zona glomerulosa

A

Cholesterol - pregnenolone ( side chain cleavage ) - progesterone( 3 beta Hydroxylase steroid dehydrogenase) - 11 deoxycorticosterone ( catalysed by 21 Hydroxylase) - Corticosterone ( catalysed by 11 Hydroxylase) - aldosterone ( catalysed by 18 Hydroxylase )

18
Q

How is glucocorticoid/ cortisol made in zona fasicularis

A

Cholesterol (side chain cleavage)- pregnenolone - progesterone ( 3 beta Hydroxy steroid dehydrogenase ) - 17 Hydroxy progesterone ( catalysed by 17 Hydroxylase) - 11 deoxy-cortisol ( catalysed by 21 Hydroxylase) - cortisol ( catalysed by 11 deoxyhydroxylase)

19
Q

What does aldosterone do

A

Stimulates Na+ reabsorrption in distal convoluted tubule and cortical collecting duct in kidney ( and in sweat glands, gastric glands , colon)

Stimulates K+ and H+ secretion, also in distal convoluted tubule and the cortical collecting duct

Increased sodium reabsorption water reabsorption , raises blood volume

SO WORKS ON K+/Na+ ION CHANNEL TO KEEP BLOOD PRESSURE

20
Q

How is aldosterone regulated

A

When blood pressure falls, Renin is released,

Decreased renal perfusion pressure is normally associated with decreased arterial BP .

Increased renal sympathetic activity ( direct to Juxtaglomerular apparatus)

Decreased Na+ load to top of the loop of Henle ( macula dense cells)

21
Q

Renin and aldosterone release

A

Cells of macula densa sense the sodium load delivered to the distal tubule and regulate levels of circulating renin according to the body’s sodium requirements

If the sodium concentration in the tubular fluid is low, the juxtoglomerular cells increase secretions of renin

Renin acts on protein angiotensin ( secreted by liver) to convert it to angiotensin 1

ACE catalyses conversion of angiotensin 1 to angiotensin 2

Angiotensin 2 regulates aldosterone release and so now increased sodium reabsorption by distal tubule

22
Q

What other hormone can regulate aldosterone

A

ACTH but to a lesser extent that angiotensin 2

23
Q

Effects of angiotensin 2 on adrenals

A 
Activation of the following enzymes 
Side chain cleavage 
3 hydroxysteroid dehydrogenase
21 Hydroxylase
11 Hydroxylase
18 hydroxylase
24
Q

Summary of action of aldosterone

A

Controls blood pressure, sodium and lowers potassium

25
Q

How is cortisol secretion regulated

A

ACTH

26
Q

Physiological effects of cortisol

A

Normal stress response
Metabolic effects ; peripheral protein catabolism, hepatic gluconeogenesis, increased blood glucose concentration , fat metabolism ( lipolysis in adipose tissue) , enhanced effects of glucagon and catecholamines

Weak mineralocorticoid effects - may maintain BP and has an effect on heart

Renal and cardiovascular effects ; excretion of water load , increased vascular permeability

27
Q

Effects of ACTH on the adrenal gland

A 
Activation of the following enzymes 
Side chain cleavage 
3 hydroxysteroid dehydrogenase
21 Hydroxylase
11 Hydroxylase 
17 Hydroxylase
28
Q

What rhythm does cortisol have

A

Diurnal - peaks in the morning and then decreases during the night- cortisol is released in pulses

29
Q

Cortisol and circadian rhythm

A

ACTH simulates cortisol and so the ACTH cycle is slightly ahead of the cortisol cycle

30
Q

Addison’s disease

A

Primary adrenal failure
Autoimmune disease where the immune system decides to destroy the adrenal cortex
Tuberculosis of the adrenal glands ( commonest cause worldwide - TB bacteria destroy adrenal gland)

Pituitary starts secreting lots of ACTH and hence MSH and so become tanned

31
Q

Addison’s disease

A

Adrenal glands do not produce sufficient steroid hormone

Adrenal crisis; fever, syncope, convulsion , hypoglycaemia, hyponatremia, severe vomiting and diarrhoea

Hyperpigmentation of skin
Low bp
Weakness
Weight loss
Gastric problems 
Vitiligo
32
Q

Why do patients with Addison’s disease have a good tan

A

POMC is a large precursor protein that is cleaved to form a number of smaller peptides , including ACTH , MSH and endorphins

So people who have pathologically high levels of ACTH may become tanned

33
Q

Summary of Addison’s disease

A 
Cortisol deficiency 
Aldosterone deficiency 
Salt loss
Low bp
Eventual death
34
Q

Urgent treatment of Addisonian crisis

A

Rehydrate with normal saline
Give dextrose to prevent hypoglycaemia which could lead to the glucocorticoid deficiency
Give hydrocortisone or another glucocorticoid or cortisol or give pregnenolone ( analogue of cortisol)

35
Q

What happens if you have too much cortisol

A

Metabolism changes and you put on weight

36
Q

What can cause too much cortisol

A

A tumour of the adrenal - excess cortisol

Tumour of pituitary - excess ACTH

37
Q

Symptoms of Cushing’s syndrome

A 
Mental changes ( depression) 
Red cheeks 
Fat pads 
Moon face 
Easy brusining 
Red stretch marks 
Poor wound healing 
Thin skin 
Impaired glucose tolerance 
High blood pressure 
Proximal myopathy - muscle weakness .
Diabetes , hypertension and osteoporosis 
Immunosuppression
38
Q

Catecholamines

A

Medulla derived from ectoderm album neural crest
Precursor for ADR and NA synthesis = tyrosine
Catecholamines stored in cytoplasmic granules and released in response to ACh from preganglionic sympathetic neurones

39
Q

Role of catecholamines

A

Fight or flight response
Tachycardia, sweating , increased blood glucose , alertness, vasoconstriction
NA and ADR circulate bound to albumin
Degraded by two hepatic enzymes ; monoamine oxidase and catecholamines-O-methyl transferase

40
Q

What controls aldosterone release

A

Angiotensin 2

41
Q

What 4 things can cause an increase in cortisol and so possible Cushings Syndrome

A

prolonged steroid use - can often be be used to treat autoimmune conditions as glucocorticoids can suppress immune system

pituitary adenoma
ectopic ACTH (lung cancer)
adrenal ademona or carcinoma

42
Q

difference between cushings disease and syndrome

A

cushings disease= excess cortisol as a result of a pituitary tumour. cushings syndrome = anyone who has excess cortisol

B (24 decks)

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