Adrenocortical Function and Dysfunction Flashcards
Where are the adrenal glands located?
Sit on top of kidneys
Do the adrenal cortex and medulla have the same embryological origin?
No - 2 different glands
What type of gland is the adrenal medulla?
Modified sympathetic ganglion
What does the adrenal medulla secrete?
Catecholamines
What type of gland is the adrenal cortex?
True endocrine gland
What does the adrenal cortex secrete?
Steroid hormones
What does the zona reticularis secrete?
Sex steroids
What does the zona fasciculata secrete?
Glucocorticoids
What does the zona glomerulosa secrete?
Aldosterone
Are sex hormones also produced by the zona fasciculata?
Yes, a little bit
Are glucocorticoids also produced by the zona reticularis?
Yes, a little bit
What stimulates the synthesis and release of cortisol?
Hypothalamic-pituitary-adrenal axis
What stimulates the synthesis and release of aldosterone?
RAAS
Plasma K
Why do different cells of the adrenal cortex produce different steroids?
Contain different enzymes
Why can you get crossover effects with steroid hormones?
Chemically related
Are steroid hormones stored or made on demand?
Made on demand
What are the major triggers for cortisol release?
Circadian rhythm
Stress
What is the effect of cortisol on the immune system?
Function suppressed
What is the effect of cortisol on the liver?
Gluconeogenesis
What is the effect of cortisol on the muscle?
Protein catabolism
What is the effect of cortisol on adipose tissue?
Lipolysis
What are the other functions of CRH and ACTH?
Some stress-related functions in immune and nervous systems
What is urocortin?
Peptide related to CRH
Brain neuropeptide decreases appetite
What is pro-opiomelanocortin (POMC)?
Large protein
Yields several bioactive peptide by proteolysis
What peptides are produced from POMC by the anterior pituitary?
ACTH
Beta-endorphin
What does beta-endorphin do?
Block pain perception
What peptide is produced from POMC outside the pituitary?
Alpha-MSH
What is alpha-MSH?
Melanocyte stimuating hormone
Decreases food intake
Increases skin melanin
What are melanocortins?
Family name for MSH hormones and ACTH
Is cortisol essential for life?
Yes
What does cortisol do?
Helps body cope with long-term stress
Protects against hypoglycaemia
- Stimulates catabolism of energy stores
Permissive for glucagon and catecholamine actions
When is cortisol released?
Diurnal rhythm
- Peaks morning
- Low night
What is the effect of cortisol on calcium balance?
Negative Ca balance
- Decreased absorption
- Increased excretion
- Increased bone breakdown
What are the therapeutic uses of cortisol?
Bee stings, poison ivy, pollen allergies
Prevents rejection of transplanted organs
What does long-term use of cortisol result in?
Inhibition of ACTH (and its related peptides) secretion
Atrophy of cortisol-secreting cells
What is the half life of cortisol?
60-90 min
What are the target tissues of cortisol?
Most
Where is the target receptor of cortisol located?
Intracellular
What does hyperaldosteronism cause?
Hypernatremia
Hypokalemia
Hypertension
What is primary hyperaldosteronism called?
Conn’s syndrome
What is Cushing’s syndrome?
Excess cortisol
What causes primary hypercortisolism?
Adrenal cortex tumours autonomously secrete cortisol
What is Cushing’s disease?
Secondary cause of hypercortisolism
Pituitary tumour autonomously secretes ACTH
What are the possible causes of Cushing’s syndrome?
Primary
Secondary
Hyperstimulation by CRH/ACTH
Iatrogenic
What is adrenogenital syndrome?
Excess androgen and oestrogen
What causes adrenogenital syndrome?
Lack enzyme in cortisol steroidogenic pathway
What is the clinical presentation of adrenogenital syndrome?
Inappropriate masculinisation in all but adult males
What is the treatment for adrenogenital syndrome?
Glucocorticoids
- Repairs glucocorticoid deficit
- Inhibit ACTH > reduce steroid secretion
What are the symptoms of Cushing’s syndrome?
Excess gluconeogenesis > hyperglycaemia mimicking diabetes
Muscle protein breakdown and lipolysis > wasting
Increased appetite > paradoxical fat deposits in trunk and face
Thin arms and legs
Trunk obesity
Moon face
Stretched skin > reddish striae
Excess cortisol binds to mineralocorticoid receptors
- Salt and water retention
- Moon face
- Weakness
- Hypertension
Osteoporosis
Mood elevation then depression
Difficulty in learning and memory
What is more common: adrenal hypersecretion or hyposecretion?
Hyposecretion
What is Addison’s disease?
Primary adrenal insufficiency
Autoimmune destruction of adrenal cortex
Hyposecretion of all adrenal steroid hormones
What does decreased aldosterone in Addison’s disease cause?
K retention > cardiac arrythmias
Na depletion > hypotension
What does decreased cortisol in Addison’s disease cause?
Decreased stress respone
Hypoglycaemia
What do hereditary adrenal steroid enzyme defects cause?
Lack of cortisol and aldosterone > increased androgens > adrenogenital syndrome
What does a secondary hyposecretion of the adrenal cortex cause?
Decreased ACTH
Deficient cortisol only
Which cells in the adrenal medulla secrete neurohormones?
Chromaffin cells
What are the actions of adrenomedullary hormones?
Flight or fight responses - Increased cardiac rate and contractility - Increased TPR - Increased BP Metabolic effects - Increased glucose and FFAs - Increased basal metabolic rate Central effects - Increased arousal and alertness
Does hyposecretion of the adrenal medulla occur?
No
What causes hypersecretion of the adrenal medulla?
Pheochromocytomas = tumour
What type of response does acute stress result in?
Fight or flight
What type of response does chronic stress result in?
Elevated cortisol levels
