Cortisol

Question 1

The mammalian stress axis is?

Answer 1

hypothalamic-pituitary-adrenocortical Axis

Question 2

the hypothalamus has?

Answer 2

has neuroendocrine function on the ant. pituitary

Question 3

how does blood drain away from ant pit via?

Answer 3

efferent veins and into the peripheral circulatiom

Question 4

what hormones does the anterior pituitary secrete?

Answer 4

gonadotrophin
thyrotrophin
GH
Prolocatin
adrenocorticoptrophin

Question 5

What hormones does the posterior pituitary secrete?

Answer 5

Oxytocin and vasopressin

Question 6

What does stress related stimuli cause the hypothalamus to secrete?

Answer 6

Corticotrophin releasing hormone (CRH) and Arginine vasopressin (AVP) by hypothalamus

Question 7

How many amino acids is CRH?

Answer 7

41aa

Question 8

how many aa is AVP?

Answer 8

9aa

Question 9

What does AVP and CRH do?

Answer 9

stimulates the secretion of adrenocorticotrophic hormone (ACTH) by the ant. pit gland

Question 10

How many amino acids is ACTH?

Answer 10

39aa

Question 11

What is co-secreted with ACTH?

Answer 11

other peptides from the pro-opiomelanocortin (POMC) (ACTH derived from POMC)

Question 12

What is the circadian rhythm of the HPA axis?

Answer 12

circadian rhythm exist in the circulation g level of cortisol

Question 13

How does cortisol circulate?

Answer 13

complexed with corticosteroid binding globulin : TRANSCORTIN

Question 14

why does cortisol circulate as transcortin?

Answer 14

to protect it from metabolism and inactivation in liver

Question 15

what are the major effects of cortisol?

Answer 15

energy for gluconeogenesis, obtained from the breakdown of fats and the release of fatty acids
increases the metabolism of muscle proteins for gluconeogenesis and inhibits protein synthesis

Question 16

What is cushings syndrome?

Answer 16

The over production of cortisol

Question 17

What is the cause of cushings syndrome?

Answer 17

normally caused by a benign tumour at the pituitary
a result of excess CRH production which derives ACTH secretion in turn stimulates excess release of cortisol
Excess ACTH production from an ACTH producing tumour
Adrenal tumour

Question 18

What is cushings syndrome often an extreme side effect of?

Answer 18

steroid medication

Question 19

What are the symptoms of cushings syndrome?

Answer 19

central obesity
thinning of skin
bruising
hypertension
muscle and bone wasting

Question 20

How would you diagnose cortisol overproduction?

Answer 20

• measure cortisol/ACTH levels in urine/plasma
• Normal/very low ACTH concentration – ACTH independent e.g. adrenal tumour or the use of steroid medication
• High ACTH concentration - probably due to an ectopic ACTH-producing tumour.
• Moderately high ACTH levels - tends to be due to a pituitary tumour
• Dexamethasone suppression test

Question 21

Describe the dexamethasone suppression test

Answer 21

low dose will suppress ACTH levels in normal pts, but not in cushings disease.Sample blood from inferior petrosal sinus. Blood from pituitary drains into here and can sample with a catheter – shows source of ACTH

Question 22

Treatment of Cushings syndrome

Answer 22

Reduce steroid medication
surgical removal of the tumour
adrendlectomy - leads to high levels of POMC peptides due to lack of -ve feedback - leads to hyper pigmentation called NELSONS SYNDROME

Question 23

What is underproduction of cortisol known as?

Answer 23

Addisons disease