Normal function and disease Flashcards
What does the SNS and adrenaline do in response to stress? What role does cortisol have in this?
increase cardiac output and ventilation
diversion of blood flow to muscles and heart
mobilisation of glycogen and fat stores
fight or flight
cortisol has a permissive act
what does cortisol do in a stress-activated immune response? Why?
expand glycogen stores and plasma glucose availability
aa available for tissue repair
to protect body against damage from potential over-activation of immune defense mechanisms
What are some effects of chronic cortisol?
muscle wasting
hyperglycaemia
GI ulcers
impaired immune response
What hormones regulate cortisol?
ACTH/CRH
What is Cushing’s syndrome, Conn’s syndrome, Addison’s disease and CAH?
Glucocorticoid excess - Cushing’s syndrome
Mineralocorticoid excess - Conn’s syndrome
Adrendal insufficiency - Addison’s disease
Congenital adrenal hyperplasia (CAH)
What blood hormone levels are found in primary vs secondary Cushing’s syndrome? What’s the most common cause of Cushing’s syndrome?
primary cause - low ACTH, high cortisol
secondary - high ACTH, high cortisol
main cause is pituitary ACTH-secreting tumour Cushing’s disease (secondary cause)
What’s an ectopic ACTH-Secreting tumour?
ACTH levels greatly elevated
the cells lack feedback control
what are the ‘beauty’ symptoms of Cushing’s syndrome down to?
altered fat distribution
what do you also get with excess ACTH?
excess adrenal androgens protein breakdown, muscle wasting, collagen loss immunosuppression altered bone met excess mineralcorticoid activity hyperglycaemia mental changes
What are 3 big symptoms of Cushing’s syndrome? Why?
osteoporosis
hypertension
diabetes
What’s a key distinguishing feature of Cushing’s from normal cortisol secretion in terms of diurnal rhythm?
there’s a loss of diurnal rhythm of cortisol in Cushing’s
what is the DEX test and what would be expected for normal, and pathological?
suppression test (DEX is a synthetic glucocorticoid)
lack of supression - hyper/autonomous secretion
What can be suppressed by high dose dexamethasone?
will suppress pituitary ACTH
will not affect tumour or ectopic ACTH source
In a CRH test, what would you expect to see in a pituitary-dependent Cushing’s disease, and for an ectopic CRH syndrome?
this test is used to distinguish
normally there should be a rise in ACTH and cortisol
in Cushing’s - response is exaggerated and in ectopic there is no response
What are the treatment options?
Localise tumour
surgery/radiotherapy
drugs to inhibit steroidogenesis (rarely for long-term therapy)
