Pituitary adrenal axis Flashcards
what is the adrenal gland consisted of
cortex and medulla
what are the hormones of the adrenal gland used for
regulators of metabolism and adaptation to stress
what is cortisol and what does it do
glucocorticoid and increases plasma glucose levels
a deficiency in cortisol leads to what
hypoglycaemia
what is aldosterone
mineralocorticoid
what does aldosterone do
promotes salt and water retention by the kidney
what else does the adrenal cortex synthesise and secrete and what are they converted to
androgenic steroids
converted by peripheral tissue to testosterone
what is the primary product of chromaffin in the medulla
adrenaline, also produces adrenaline precursor
noradrenaline
[catecholamines]
name the layers of the adrenal gland, outside -> in
capsule
zona glomerulosa
zona fasciculata
zona reticularis
medulla
what zona is responsible for producing aldosterone
zone glomerulosa
what zona is responsible for producing cortisol
zona fasciculata
what zona is responsible for producing weak androgens
zona reticularis
what do aldosterone, cortisol and weak androgens all have in common
they’re all steroid hormones
(1)MODULATING OUR STRESS RESPONSE
stressful stimuli causes what in the hypothalamus
to activate the adrenal cortex via hormonal signals
(2)MODULATING OUR STRESS RESPONSE
adrenal cortex secrets what and why
mineralocorticoids and glucocorticoids
because the adrenal cortex was sent stimuli (activating it) by the hypothalamus via hormonal signals
what are effects of mineralcorticoids
retention of water ions and water by kidney
increased blood volume and blood pressure
what are effects of glucocorticoids
proteins and fats are broken down and converted t glucose, leading to increased blood glucose
partial suppression of immune system
what are all steroid hormones derived from
cholesterol
what binding globulin transports cortisol
corticosteroid binding globulin
enzymes which produce steroid hormones from cholesterol are located where
mitochondria and SmER
what is the rate limiting step in converting cholesterol to steroid hormones and what protein carries out this step
transport of free cholesterol from the cytoplasm into the mitochondria
StAR -> moves cholesterol from outer membrane to the inner membrane where cholesterol is converted t pregnenolone (precursor)
in the adrenal cortex how many pathways can pregnenolone be converted to
3
mineralocorticoids
glucocorticoids
androgens
adrenal steroidogenesis
what determines which pathway is taken
Each step of the pathway is regulated by a specific enzyme.
Different zones of the adrenal cortex have different relative activities of enzymes, resulting in different chemical reactions taking place.
liver is predominant site of what
steroid inactivation
if the adrenal cortex is not functioning or is removed what must be administered
exogenous glucocorticoids
the actions of glucocorticoids are essential for what
gluconeogenesis, for vascular responsiveness to catecholamines
-> for suppression of inflammatory and immune responses and modulation of CNS function
glucocorticoids are essential for survival during what
fasting
what are metabolic effects of cortisol (stimulation)
Stimulates protein and triglyceride catabolism
Stimulates “gluconeogenesis” in liver
WHAT ARE THE METABOLIC EFFECTS OF CORTISOL (INHIBITORY)
Inhibits bone formation
Inhibition of non-essential functions (reproduction; growth)
Inhibition of glucose uptake by body (insulin antagonism) but not by brain. Elevates blood glucose levels, “diabetogenic effect.” Nervous system becomes primary user of glucose during stress.
when is cortisol prescribed
to suppress inflammation and the immune response
what happens when cortisol levels are high
many of the body’s defence mechanisms against infection are inhibited
what is the activation of glucocorticoid response element (GRE) mediated transcription used for
alterations in water balance, weight gain, hypertension, muscle weakness, diabetes, and osteoporosis. These side effects are mediated through the genomic function of GR
what disease is linked with hypocortisolism and what hypo/hyperglycaemia?
addisons disease
hypoglycaemia
what syndrome is linked with hypercortisolism and hyper/hypoglycaemia
Cushing’s syndrome
hyperglycaemia
what happens if there is a pituitary lesion or no ACTH
fasciculata and reticularis atrophy
-> no cortisol; dependency on exogenous glucocorticoids
what happens if there is excess ACTH
enlarged adrenal glands -> enlarged steroids
if the HPA axis is over stimulated because of stress, and if the body cannot keep up with the demand for cortisol, of if there is any other steroidogenic block what happens
excess ACTH might be shunted int the androgen production pathway
what is Cushing’s syndrome
increased glucocorticoid production (hypercortisolism)
caused by basophilic adenoma
what are the two primary consequences of Cushings syndrome
- moon face (salt/water retention with renal loss of K+)
-> leads to cardiac hypertrophy due to prolonged hypertension
2.catabolism causes
muscle wating, fat accumulation, osteopersis with kyphosis, buffalo hump and fractures, thin skin with ulcers and red stirrer
poor wound healing
Addisons disease main symptom
overproduction of ACTH due to decreased negative feedback by cortisol
what causes addisons disease
adrenal glands do not produce suffiecient steroid hormones (glucocorticoids and mineralocorticoids
decreased by negative feedback
