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50 Cards in this Set
- Front
- Back
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Describe how the positions of the left and right adrenal glands differ (2) |
- right adrenal gland is partly overlapped by the liver and inferior vena cava - left adrenal gland is behind the stomach with the lower tip overlapped by the pancreas |
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Which arteries supply the adrenal glands? What mechanism allows blood to reach each of the tissue layers? |
- superior, middle and inferior suprarenal artery - centrepedal blood flow |
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Describe the venous supply to the adrenal glands |
- flows to the central meduallary vein - medullary veins drain into the suprarenal veins - suprarenal vein drains into the IVC on the right, and left renal vein on the left |
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Describe the nerve supply to the adrenal glands |
coeliac plexus and thoracic splanchnic nerves |
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What are the 2 main regions of the adrenal glands? |
cortex and medulla |
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What is the embryological origin of the adrenal cortex? What is the embryological origin of the adrenal medulla? What type of molecule are streroid hormones derived from? |
- intermediate mesoderm - neural crest cells (ectoderm) - cholesterol |
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What are the 3 functional classes of adrenal steroids, and what is each classes's general function |
- mineralcorticoids: electrolyte and fluid metabolism - glucocorticoid: wide range of effects on carbohydrates, protein and lipid metabolism - androgens: supplement gonadal secretion |
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What are the 2 main secretions of the adrenal medulla? What part of the nervous system regulates the adrenal medulla? |
catecholmaines: adrenaline and noradrenaline sympathetic nervous system |
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From superficial to deep, what are the 5 layers of the adrenal gland? |
capsule zona glomerulosa (cortex) zona fasciculata (cortex) zona reticularis (cortex) renal medulla |
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List 4 histologica features of the zona glomerulosa |
- ovoid cells - round nuclei with small cytoplasm - high amounts of endoplasmic reticulum and mitochondria - small amount of lipid |
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What is the main product of the zona glomerulosa What are the 2 triggers for its secretion? |
(-mineralocorticoids) aldosterone - aldosterone and extracellular potassium |
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List 4 histological features of the zona fasciculata |
- thickest of the three zones - consists of columns of cells seperated by strands of collagen - large amount of lipid droplets - contains mitochondria and smooth endoplasmic reticulum |
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What is the main product(s) of the zona fasciculata |
- (glucocorticoid) cortisol - small amounts of androgenic sex hormones |
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List 4 histological features about zona reticularis |
- irregular network of glandular cells - seperated by wide-diameter capillaries - small cells with small nuclei - few lipid droplets |
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What are the main hormones produced by the zona reticularis (3) What regulates it? |
- androgens and a small amount of glucocorticoids - notable examples: dehydroepiandrosterone (DHEA) and androstenedione (testosterone preceursor) - ACTH |
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What are the main products of the adrenal medulla what regulates it (3)? |
- adrenaline and noradrenaline - SNS |
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List 3 histological features of the adrenal medulla |
- clusters of chromaffin cells with basophilic cytoplasm - numerous capillaries - cytoplasm contains dense granules |
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Draw a diagram illustrating how cortisol is produced? How is regulated (2)? |
- regulated by the hypothalamic-pituitary -adrenal axis and 17-hydroxylase (among other enzymes) |
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Describe how cortisol exerts if effect on target cells (3) |
- transverses cell membranes (lipid-soluble) - binds to intracellular receptors - receptor/ligand complex binds to DNA to change transcription |
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What are the 5 main regions in the body where cortisol exerts an effect |
- circulatory/renal - CNS - bone and connective tissue - metabolic - immunological |
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What effect does cortisol have on circulation/renal function (3) |
- increases CO - increases BP - increases renal blood flow and GFR |
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What effect does cortisol have on CNS (3)? |
- mood changes - euphoria/psychosis - decreased libido |
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What effect does cortisol have on bone/connective tissue (4) |
- accelerates osteoporosis - decreases serum calcium - decreases collagen synthesis - decreases wound healing |
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Whta effect does cortisol have on metabolism (3)? |
- increases blood glucose - increases lipolysis - increases proteolysis |
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What effect does cortisol have on the immune system (4)? |
- decreases capillary dilation/permeability - decreases leukocyte migration - decreased macrophage activity - decreased production of inflammatory cytokines |
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Draw a diagram illustrating the production of aldosterone? How is regulated? |
- regulated by Angiotensin II (Ang II), potassium (K+) and adrenocorticotropin (ACTH) - regulated ultimately by the RAA system |
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How does aldosterone exert its effect on target cells? |
- acts via mineralcorticoid receptors - transolates to the nucleus to induce translocation |
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Cortisol and aldosterone bind mineralocorticoid receptors with equal affinity, and the concentration of cortisol is ~2000-fold higher than aldosterone. Considering this, how is aldosterone still able to exert its specific effect on target cells? |
- Target cells for aldosterone express the enzyme 11-beta-hydroxysteroid dehydrogenase, which has no effect on aldosterone, but converts cortisol to cortisone, which has only a very weak affinity for the mineralocorticoid receptor. - allows aldosterone to act appropriately without interference |
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What are the main tissues which aldosterone acts on (4)? |
- kidneys - salivary glands - gut - sweat glands |
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Describe the effect of aldosterone in the kidney (essay answer) |
- acts on the mineralocorticoid receptor in principal cells of the distal tubule and collecting ducts. Causes upregulation of Na/K pumps, increasing K+ - upregulates ENaCs, increasing apical permeability to Na+ - reabsorbs chloride and sodium to maintain electrochemical balance - stimulates Na and water reabsorption from the gut, salivary glands and sweat glands in exchange for K+ - stimulates secretion of H+ in exchange for Na in the itercalated cells of the cortical collecting tubules |
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Describe the various stages which occur in the synthesis of cortisol, including its stimuli and feedback (essay answer) |
- Corticotropic Releasing Hormone is released form the hypothalamus due to stress, different times of day and serum cortisol levels - Corticotropic-Releasing Hormone travels in the blood and binds to receptors on the pituitary gland - binding increases the production of Adrenocorticotropic Hormone (ACTH), which is then released and travels to the adrenal glands - Adrenocorticotropic Hormone then binds to to specific receptors in the adrenal cortex, stimulating the release of cortisol into the blood - when cortisol levels become to high it inhibits the production of Corticotropic-Releasing Hormone and Adrenocorticotropic Hormone from the hypothalamus and the anterior pituitary - respectively |
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Draw a diagram summarising the hypothalamic-pituitary-adrenal axis |
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List the tests used to assess adrenal insufficiency (8) |
- single cortisol measurements - short adrenocorticotropic hormone stimulation test (syncACTHen test) - 09:00 hours plasma ACTH - Electrolytes and urea - blood glucose - adrenal antibodies - X-ray - plasma renin activity |
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What single cortisol measurement is indicative of adrenal insufficiency? |
- <100nmol/L - >550nmol/L makes the diagnosis unlikely |
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Describe how the short ACTH stimulation test is perfomed |
- used to test adrenal reserve - basal cortisol is recorded - 250ug of synacthen is then administered (IV or IM) - cortisol is the measured at 30 and 60 mins - in healty individuals, serum cortiol will rise (170nmol/L at basal to >580nmol/L after synacthen); hypoadrenal patients will not invoke a response |
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What is indicative of primary hyperadrenalism in a 09:00 hours plasma ACTH test? |
>80ng/L with low or normal cortisol |
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What 3 aspects of electrolytes and urea test are supportive of renal insufficiency |
- hyponatraemia - hyperkalaemia - high urea |
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What might you expect someone's blood glucose to be with adrenal insufficency? |
- hypoglycaemia |
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How might you expect someone's plasma renin concentration to change with adrenal insufficency? |
- increased due to low serum aldosterone |
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What is the most common cause of Cushing's syndrome |
- exogenous corticosteroid exposure |
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What is the most common cause of endogenous Cushing's syndrome? |
Adrenocorticotropic hormone-secreting adenomas |
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List 17 clinical features of Cushing's |
- central obesity - moon face - facial plethrora (redness) - buffalo hump - acne - thinning skin - dry skin - telangiectasia (spider veins) - hyperhidrosis (excessive sweat) - stretch marks - proximal muscle weakness - osteoporosis - hirsuitism - amenorrhoea - insomnia - euphoria - psychosis |
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What is the first line investigation for diagnosing Cushing's? Describe how it is done (essay answer). |
- dexamethasone suppresion test - 1mg dexamethasone at 11pm - plamsa cortisol (and dexamethasone) measured following morning - morning cortisol of >50nmol/L is suggestive of Cushing syndrome. Requires a late night salivary cortisol or 24 hour free urinary cortisol measurement for confirmation. |
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Describe how a late night salivary cortisol test is done (2) |
- saliva is collected at 11pm (saturate a cotton swab or collect drool). Multiples samples increases sensitivity. - values range betweeen laboratories but >4nmol/L is suggestive |
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How is 24-hour urinary free cortisol performed? |
- urine collected over 24 hours - postive result: >50ug/24 hours |
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What happens in Addison's disease (1)? How common is Addison's? |
- underproduction of cortisol and aldosterone by the adrenal cortex - 8 in a million |
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List and breifly describe the 8 different causes of Addison's |
- Autoimmune destruction: most common (70%). Antibodies are produced against the adrenal cortex or 21-hydroxylase. Causes destruction of the adrenal cortex and cortisol deficiency. - adrenoleukodystrophy: disorder of fatty acid metabolism which presents in childhood. Causes progressive brain damage, failure of the adrenal glands and death. - malignanacy: adrenal metastasis. - infection: TB is accociated with spread and destruction of the adrenals. Also occurs with opportunistic infections (e.g. cryptococcosis, candidiasis and histoplasmosis) - vascular (Waterhouse-Friderichsen syndrome): causes haemorrhage of the adrenals, often due to meningococcal septicaemia - adrenal dysgenesis (abnormal development): e.g. congenital adrenal hypolasia caused by mutations in DAX-1 - impaired steroid production: mutations in genes which encode enzymes in the cortisol and/or aldosterone pathways can cause Addison's. - haemochromatosis: causes deposition of iron into adrenal tissue (and liver, heart and pancreas). Accumulation of iron becomes toxic causing necrosis. Iatrogenic: could be due to several reasons e.g. adrenal haemorrhage due to anticoagulation therapy, adrenalectomy due to malignancy, fluconazole and ketoconazole (inhibitors of cortisol production) and phenytoin and rifampicin (increase cortisol metabolism in the liver) |
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List 8 common symptoms of Addison's |
- weight loss and anorexia is common (90%) - fatigue and weakness - hyperpigmentation (due to increased POMC) - GI symptoms - postural hypotension due to lack of aldosterone - decreased libido (males) - pinna (external ear) calcification - decrease in axillary and pubic hair |
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List 6 potential causes of secondary adrenocortical insufficiency |
- ACTH suppression by sodium valporate - metastases - carniopharyngioma (brain tumour) - TB - trauma - radiotherapy or surgery |
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List the side effects of corticosteroid use (16) |
- increased BP - pancreatitis - polyuria - nocturia - depression - psychosis - insomnia - weight gain - glycosuria/hyperglycaemia/diabetes - impaired growth - amenorrhoea - osteoporosis and fractures - wasting - thin skin and bruising - cataracts - increased risk of infection |
