Adrenal gland

Question 1

what are the 3 zones of the adrenal cortex?

Answer 1

glomerulosa
fasciculata
reticularis

Question 2

what hormone(s) does the medulla of the adrenal gland secrete?

Answer 2

catecholamines i.e. norepinephrine, epinpehrine (mainly) , dopamine

Question 3

what hormone (s) does the cortex of the adrenal gland secrete?

Answer 3

glomerulosa - minerocorticoids i.e. aldosterone
fasciculata - glucocorticoids i.e. cortisol
reticularis - asex steroids i.e. testosterone, orstrogen

Question 4

what is the function of the minerocorticoids?

Answer 4

regulation of Na and K
when plasma vol is decreased, it increases Na retension and K loss
if the plasma vol is increased vice versa

Question 5

what is the medulla of the adrenal gland derived from?

Answer 5

neural crest tissue

its a modified sympathetic ganglion

Question 6

a deficiency in what enzyme causes congenital adrenal hyperplasia?

Answer 6

21 hydroxylase

Question 7

how does a deficiency in 21 hydroxylase cause adrenal gland hyperplasia?

Answer 7

a deficiency in 21 hydroxylase results in a deficiency of cortisol and aldosterone
with a decrease in those hormones there is no negative feedback on the CRH and ACTH to stop releasing hormones which act on the adrenal gland
increased ACTH is responsible for enlargement of adrenal glands

Question 8

what is the difference is the busts of release of ACTH and cortisol and why?

Answer 8

bursts of cortisol persists longer than ACTH because it is a steroid hormone therefore has a longer half life whereas ACTH is a peptide hormone which has a short half life

Question 9

what hormone released from the adrenal glands is repsonsible for glucose metabolism?

Answer 9

cortisol

Question 10

how does cortisol affect glucose metabolism?

Answer 10

enhances gluconeogenesis and glucose production
proteolysis - breaks down protein to provide gluconeogenic substances to the liver
lipolysis - for alternative food supply for BG (FFA) and another substrate for gluconeogenesis (glycerol)
decreases insulin sensitivity of muscle and adipose tissue (insulin dependant tissues)

Question 11

what effect does cortisol have on Ca balance?

Answer 11

net effect decreases Ca plasma levels
it increases Ca excretion from kidneys and decreases absorption from the gut
also increases Ca resorption of bone but net effect is a decrease

Question 12

how does excess cortisol cause hypertension?

Answer 12

cortisol has permissive effects of norepinephrine on vascular smooth muscle = vasoconstriction
= hypertension

Question 13

what effect does cortisol have on the immune system?

Answer 13

cortisol suppressess the immune system by reducing lymphocyte count
also reduces antibody formation and inhibits inflammatory responses

Question 14

how can glucocorticoids be used to treat inflammatory conditions?

Answer 14

cortisol has anti inflammatory properties as it acts on the nucleus switching off the expression of inflammatory markers

Question 15

what are the side effects of glucocorticoid therapy?

Answer 15

increased severity / frequency of infection (suppress immune system)
loss of percutaneous fat stores = thinning of skin = fragile (because it cause increase in lipolysis)
muscle wasting (causes protein catabolism)
osteoporosis (increases bone resorption of Ca)

Question 16

what is the secretion of minerocorticoid controlled by?

Answer 16

renin angiotensin aldosterone production

Question 17

does an increase in aldosterone cause an increase or decrease in BP?

Answer 17

aldosterone causes Na retension and K depletion therefore causing an increase in blood vol and BP

Question 18

name a conditon caused by hyperexcretion of cortisol and hyposecretion of cortisol.

Answer 18

hyper = cushings
hypo = addisons

Question 19

what can be the cause of cushings?

Answer 19

a tumour in the adrenal cortex (primary)

a tumour in the pituitary gland (secondary)

Question 20

what is the most common cause of cushings?

Answer 20

pituitary tumour causing an excess of ACTH production and therefore cortisol

Question 21

what is the presentation of someone with cushings?

Answer 21

wasting of the limb muscles
distribution of fat in the trunk and face (giving moon face appearance)
hump at the top of the back as fat collects there

Question 22

what effect does alcohol have on the production of CRH and ACTH?

Answer 22

alcohol depresses the neurones involved in the negative feedback on ACTH and CRH release
therefore causes increased production levels

Question 23

how doess stress, alcohol and lack of sleep result in a depressed immune system?

Answer 23

stress & lack of sleep promotes the release of CRH and ACTH.
alcohol inhibits the negative feedback on ACTH and CRH
therefore this further enhances the release of CRH, ACTH and therefore cortisol
cortisol diminishes the immune system by reducing lymphocytes and inhibiting antibody formation

Question 24

what is characteristic about the presentation of phaeochromocytomas?

Answer 24

presents with ‘episodes’ of symptoms

Question 25

what effects does phaeochromocytoma have?

Answer 25

they cause excess cetacholamine release resulting in increased HR, CO and BP
diabetogenic due to adrenergic effect on glucose metabolism

Question 26

why would glucocortiocoid therapy result in adrenal atrophy?

Answer 26

with exogenous cortisol, there will be a greater negative feedback signal on the CRH and ACTH therefore reducing their signals
with a decrease in signals coming form CRH and ACTH, there is less stimulation of the adrenal gland = atrophy as it can sustain cortisol levels from the exogenous cortisol

Question 27

why do you have to take care when withdrawing from glucocorticoid therapy?

Answer 27

excess exogenous cortisol = atrophy of the adrenal gland as the excess cortisol caused increased negative feedback
this reduces CRH and ACTH signals
if you suddenly withdraw , then the atrophied adrenal gland wont be able to produce sufficient cortisol
therefore slow withdraw is required in order to build up the adrenal gland
- risk of adrenal insufficiency

Question 28

what does the L and R adrenal veins drain into?

Answer 28

L drains into the L renal vein

R drains into IVC

Question 29

what are the non-glucocorticoid actions of cortisol?

Answer 29

negative effect on Ca balance causing decreased Ca levels
impiarement of mood and cognition
permissive effects on norepinephrine, particularly vascular = hypertension
suppresses the immune system
anti inflammatory properties

Question 30

what is congenital adrenal hyperplasia ?

Answer 30

21 hydroxylase deficiency which results in a decrease in cortisol and aldosterone production and an increase in testosterone & oestrogen