L27 - Endocrine Disorders

Question 1

Describe the Hypothalamic Pituitary Thyroid axis?

Answer 1

hypothalamus releases TRH (thyrotropin releasing hormone). This then signals to the pituitary gland to release TSH (thyroid stimulating hormone)

TSH acts on the thyroid gland to release T3 and T4.

T3 and T4 act on the hypothalamus and pituitary gland and cause inhibition of TRH and TSH. This is a negative feedback mechanism

Question 2

Where in the adrenal glands is each of the adrenal steroids produced?

Answer 2

mineralocorticoids are produced in the zona glomerolusa of the cortex.

glucocorticoids are produced in the zona fasiculata of thr cortex

adrenal androgens are produced in the zona reticularis of cortex

catecholemines are produced in the medulla

Question 3

What is the condition called whereby cortisol levels are high?

Answer 3

excess cortisol = Cushing’s syndrome

Question 4

What ais the condition whereby aldosterone levels are high?

Answer 4

excess aldosterone = Conn’s syndrome

Question 5

What is Hypocortisolism?

Answer 5

insufficient levels of cortisol

Question 6

What is the condition whereby aldosterone ad cortisol levels are both low?

Answer 6

Addison’s

Question 7

Describe the control of aldosterone secretion

Answer 7

Aldosterone secretion is increased by RAAS and increased plasma K+.

Question 8

Describe how the RAAS is activated?

Answer 8

Macula densa cells in the distal tubule of the kidney detect a decrease in salt and perfusion pressure, as well as sympathetic activity via b1 adrenergic receptors.

They communicate with the juxtaglomerular cells which secrete renin. Renin converts angiotensinogen into angiotensin 1. ACE enzymes then convert angiotensin 1 into angiotnsin 2. This increases thirst and also causes release of aldosterone as well as vasoconstriction.

Question 9

What is primary hyperaldosteronism?

Answer 9

Excess secertion of aldosterone due to problem with adrenal glands

Question 10

What is secondary hyperaldosteroinism?

Answer 10

excss secretion of aldosterone but due to a secondary factor not the adrenal glands

Question 11

What are the main functions of cortisol?

Answer 11

• increases blood pressure
• promotes glycolysis
• promotes gluonogenesis

Question 12

What is Cushing’s Syndrome?

Answer 12

Excess cortisol for any reason
the most common cause for Cushing’s syndrome iatrogenic

• exogenous gluccocorticoids activate cortisol receptor
• at high doses it will shut down HPA
• could also be due to ectopic ACTH

Question 13

What are the signs and symptoms of Addison’s Disease?

Answer 13

• anorexia
• weakness, fatigue
• GI symptoms
• low blood pressure
• salt cravings
• muscle/joint pain
• postural dizziness