Adrenal gland Flashcards
What are the roles of the adrenal glands?
Responding to acute and chronic stress.
What type of stress might the adrenal glands respond to?
Infection, intense temperatures, prolonged exercise, sleep deprivation, fright, emotional stress.
What does the medulla secrete?
Epinephrine and noepinephrine (adrenaline and noradrenaline).
What are the three zones of the outer cortex region of the adrenal gland?
Mineralocorticoid, glucocorticoid and androgen precursors.
What is an example of a mineralcorticoid?
Aldosterone.
What is an example of a glucocorticoid?
Cortisol.
What is an example of androgen precursors?
Dehydroepiandosterone.
What effects do catecholamines cause?
Bodily symptoms (adrenaline).
What effects do glucocorticoids cause?
Metabolic effects.
What effects do mineralocorticoids cause?
Sodium effects - blood volume.
What part of the nervous system is the adrenal medulla a part of?
Sympathetic division of the autonomic nervous system.
What type of neurones makes up the adrenal medulla?
Postganglionic neurones.
What is secretion from the adrenal medulla controlled by?
Sympathetic preganglionic nerve fibres.
What is the fight-or-flight response?
Activation of the sympathetic nervous system during stress - release of adrenal medullary hormones.
What is the process in which adrenal catecholamines are released?
The hypothalamus is stimulated by stress, physical activity or low blood glucose which sends action potentials through the sympathetic division of the autonomic nervous system which causes the adrenal medulla to release adrenaline and noradrenaline.
What are mineralocorticoids synthesised from?
Cholesterol.
What is cortisol synthesised from?
17-hydroxy-pregnenolone
What does aldosterone do?
Stimulates the reabsorption of Na+ and the excretion of K+ in the cortical collecting ducts, and decreases the ratio of Na/K in sweat and saliva. It increases the reabsorption of Na in the colon and excretion of K+ in the faeces.
What drug is an aldosterone antagonist?
Spironolactone which is a potassium-sparing diuretic.
What are ACE inhibitors?
Captopril and enalapril.
What is an ATII antagonist?
Losartan, simular to ACE inhibitors
What is ACTH?
Adreno cortico trophic hormone.
What causes fluctuations in cortisol secretion?
Fluctuations in ACTH secretion from the pituitary gland.
What is addison’s disease?
A cortisol deficiency.
What effect does reduced cortisol have on salt balance?
Reduced sodium, increased potassium.
What effect does reduced cortisol have on the cardiovascular system?
Vasodilation, hypotension, reduced blood volume, anaemia and lymphocytosis,
What effect does reduced cortisol have on cellular metabolism?
Hypoglycaemaia and weight loss.
What effect does reduced cortisol have on the inflammatory and immune system?
Tendency towards autoimmune disease.
What effect does reduced cortisol have on the CNS?
Fatigue, anorexia.
What effect does cortisol have on the liver?
Increased glycogen formation and storage, increase gluconeogenesis, increased plasma glucose and increased plasma proteins.
What do corticosteroids do to plasma glucose levels?
They cause them to rise - they are released from the liver and cause increased gluconeogenesis.
What is the result of increased proteolysis due to corticosteroids?
Muscle wasting and skin thinning.
What else do corticosteroids do?
Fat redistribution (Cushing syndrome), moon face and buffalo hump.
What do corticosteroids do to triglycerides?
Increased breakdown leading to a rise in plasma fatty acid levels.
What is corticosterone synthesised from?
Cholesterol.
What are sex steroids synthesised from?
17-hydrozy-pregnenolone.
What is the renin-angiotensin system?
A hormone system that regulates blood pressure and electrolyte and fluid balance.
What is CRH?
Corticotrophin releasing hormone.
What is ACTH?
Adreno cortico trophic hormone.
What causes the hypothalamus to release CRH?
Stress such as acute trauma, major surgery or infection.
What happens when CRH reaches the pituitary?
ACTH is released.
What does ACTH act on?
The adrenal glands.
What does CRH act on?
The pituitary gland.
