T1 L6 Adrenal cortex - hormones and physiology Flashcards

1
Q

What male sex hormones are produced by the outer adrenal cortex?

A

Dehydroepiandrosterone
Androstenedione
Testosterone
Oestradiol

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2
Q

What enzyme is contained in the outer zona glomerulosa?

A

18-hydroxylase enzyme

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3
Q

What hormone is synthesised by outer zona glomerulosa?

A

Aldosterone

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4
Q

What hormone is synthesised by middle zona fasciculata?

A

Cortisol

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5
Q

What hormone is synthesised by inner zona reticularis?

A

Androgens

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6
Q

What are steroids synthesised from?

A

Cholesterol from the diet or synthesised within the adrenal gland

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7
Q

Give an example of a glucocorticoid

A

Cortisol

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8
Q

Give an example of a mineralocorticoid

A

Aldosterone

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9
Q

When is ACTH secretion at its highest?

A

Early in the morning

Increased secretion during times of prolonged stress

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10
Q

When is ACTH secretion the lowest?

A

In the middle of the night

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11
Q

What percentage of cortisol is bound to plasma proteins?

A

90%

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12
Q

Describe the plasma proteins that cortisol is bound to

A

Corticosteroid binding globulin (CBG) - 75%

Albumin - 15%

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13
Q

Why is pregnancy associated with an increase in CBG?

A

It is a compensatory increase in circulating plasma cortisol concentration so the levels remain stable

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14
Q

What converts cortisol to inactive cortisol?

A

11-B-hydroxysteroid dehydrogenase contained in aldosterone sensitive tissue

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15
Q

How does cortisol elevate blood glucose?

A

Antagonises effects of insulin. on cellular uptake of glucose
Stimulates glycogenolysis
Stimulates hepatic gluconeogenesis

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16
Q

What actions does cortisol have on metabolism?

A

Elevates blood glucose
Stimulates lipolysis and mobilisation of fatty acids
Stimulates amino acid uptake in the liver
Inhibits amino acid uptake and protein synthesis in the periphery

17
Q

What happens if there is excess cortisol?

A

Fat synthesis and deposition in novel anatomical sites such as the face, trunk and intrascapular region of the shoulders

18
Q

What is the effect of glucocorticoids on the immune response?

A

Suppress lymphoid tissue
Reduce antibody production
Inhibit cellular immune system
Stabilise leucocyte membranes and reduce release of proteolytic enzymes
Inhibit phospholipase A2 and reduce synthesis of inflammatory mediators

19
Q

What happens during an injury?

A
Pain alerts sufferer to damage
Oedema
Infiltration by leucocytes
Antibodies inactivate foreign proteins
Tissue repair enhanced by prostaglandins
20
Q

How does adrenocortical stress response decrease the inflammatory response?

A

Removes pain
Decreases immobilisation induced by oedema
Steroid-induced sedation leading to lack of awareness of severity of the situation
Individual can continue to perform despite presence of injury or infection

21
Q

What is the main role of mineralocorticoids?

A

Control sodium and potassium

22
Q

What controls the secretion of aldosterone?

A

Renin-angiotensin system

23
Q

What can directly stimulate release of aldosterone?

A

Trauma
Anxiety
Hyperkalaemia
Hyponatraemia

24
Q

What inhibits the secretion of aldosterone?

A

Atrial natriuretic peptide (ANP)

25
Q

Where does aldosterone have an effect?

A
Distal tubule of kidney
Collecting duct
Proximal tubule
Ascending loop of Henle
Colon
Sweat
Salivary glands
26
Q

What are some pharmacological uses of glucocorticoids?

A
Replacement therapy
Immunosuppressive
Anti-inflammatory effects
Arthritis, asthma or allergies
Treatment of proliferative conditions e.g. leukaemia
27
Q

What are some adverse effects of glucocorticoids?

A

Steroid usage may suppress wound healing
Exacerbate infections due to their immunosuppressive effects
Long term use in children can inhibit growth
Long term use in adults can cause osteoporosis
Development of DM and other symptoms of Cushing’s syndrome
Suppression of HPA
Menstrual disturbances

28
Q

What can happen if steroids are stopped abruptly?

A

Adrenal cortex is unable to secrete endogenous hormones leading to Addisonian crisis which can be fatal

29
Q

What pharmacological uses does hydrocortisone have?

A

Hormone replacement therapy
Anti-inflammatory agents
Immunosuppressants

30
Q

What adverse effects does hydrocortisone have?

A

Hyperglycaemia
Osteoporosis
Cushing’s syndrome