The Adrenal Glands Flashcards
What are the hormones of the adrenal glands?
In the Zona glomerulosa there are mineralocorticoids, e.g. aldosterone. In the Zona fasiculatathere are glucocorticoids 3.g. cortisol. In the Zona reticularis there are androgens, e.g. androstenedione.
What are steroid hormones.
Lipid soluble hormones synthesised from cholesterol in adrenal glands and gonads. They bind to receptors of the nuclear receptor family to modulate gene transcription.
How do corticosteroids exert their actions?
They readily diffuse across plasma membrane and bind to glucocorticoid receptors causing dissociation of chaperone proteins. Receptor ligand complex translocates to nucleus, receptors bind to GREs or other transcription factors.
What is aldosterone?
A staid hormone which plays a central role in regulation of plasma Na+, K+ and arterial BP. The aldosterone receptor is intracellular and exerts its actions by regulating gene transcription.
Describe primary and secondary hyperaldosteronsim.
Primary is a defect in the adrenal cortex, it has low renin levels, secondary is due to over activity of the RAAS and has high renin levels.
What are the signs for hyperaldosteronism?
High BP, LV hypertrophy, stroke, hypernatraemia and hypokalaemia.
What’s the treatment for hyperaldosteronism?
Aldosterone-producing adenomas removed by surgery, spironolactone (mineralocorticoid receptor antagonist).
Describe role of cortisol.
Released by ZF in response to ACTH, negative feedback to hypothalamus inhibits CRH and ACTH release.
What are the actions of cortisol?
Increase protein breakdown in muscle, increase lipolysis in fat and increased gluconeogenesis in liver. Resistance to stress, anti-inflammatory effects and depression of immune response.
What are the net effects of glucocorticoid actions on metabolism?
Increase glucose production, breakdown of proteins and redistribution of fat.
What are some causes of Cushing’s syndrome?
External causes: prescribed glucocorticoids. Endogenous causes: excess cortisol produced by adrenal tumour, benign pituitary adenoma secreting ACTH.
Signs and symptoms of Cushing’s syndrome.
Moon-shaped face, ‘buffalo hump’, abdominal obesity, purple striae, hyperglycaemia and hypertension
What are steroid drugs used to treat?
Used to treat inflammatory disorders, e.g. asthma, inflammatory bowel disease, rheumatoid arthritis. Examples of drugs are prednisolone and dexamethasone.
How should steroid dosage be reduced?
It should be reduced gradually and not stopped suddenly.
What is Addison’s disease + signs & symptoms?
It is chronic adrenal insufficiency. Signs and symptoms: postural hypertension, lethargy, weight loss, increased skin pigmentation, hypoglycaemia.
Cause of hyperpigmentation in Addison’s.
Decreased cortisol -> negative feedback on anterior pituitary reduced -> more POMC require to synthesise ACTH -> ACTH + MSH.
What is Addisonian crisis and what causes it?
A life threatening emergency due to adrenal insufficiency. Caused by severe stress, salt deprivation, infection, trauma.
Symptoms and treatment of Addisonian crisis.
Symptoms: nausea, vomiting, pyrexia, hypotension. Treatment: fluid replacement, cortisol.
What are androgens?
Steroid hormone partially regulated by ACTH and CRH, they promote axillary and pubic hair growth in both sexes.
Effect of adrenaline in heart, lungs and blood vessels.
Heart: increases HR and contractility (β1), Lungs: Bronchodilation (β2), Blood vessels: Vasoconstriction (α1), Vasodilation (β2).
