Osmolality And Hyper/Hyponatraemia Flashcards
What effects does angiotensin II have in the RAAS pathway?
Directly constricts the efferent arterioles within the glomerulus,
Stimulates the zona glomerulosa of the adrenal glands to release aldosterone.
What effects does aldosterone have?
Up regulates ENAC channels to increase sodium reabsorption,
Stimulates release of ADH,
Stimulates thirst.
What effects does ANP have?
Inhibits sodium potassium ATPase and closes ENAC channels in collecting ducts and distal convoluted tubule,
Vasodilator afferent arteriole,
Inhibits release of aldosterone and ADH,
Decreases release of renin.
What are pressure natriuresis and pressure diuresis?
Increased sodium and water excretion governed by an increase in pressure at the proximal tubule. Occur together.
What are the renal responses to increased blood pressure?
Release of ANP,
pressure natriuresis,
Pressure diuresis,
What are the renal responses to a decrease in blood pressure?
Prostaglandin release,
Activation of RAAS.
What role do the kidneys play in congestive heart failure?
Hypoperfusion leads to activation of the RAAS pathway and sodium and water retention, causing oedema.
What management options are there for reducing fluid load in congestive heart failure?
Furosemide,
Ace inhibitors,
Nitrates or other vasodilators.
What are common causes of hypervolaemia?
Kidney retention of sodium and water,
Hyperaldosteronism,
Excessive sodium or fluid intake.
What are common signs of hypovolaemia?
Dizziness, Fatigue, Confusion, Syncope, Thirst.
What mechanisms does the body employ to attempt to maintain blood pressure in hypovolaemic shock?
Raise heart rate (tachycardia),
Peripheral vasoconstriction,
Increased myocardial contractility.
What pathological changes are seen in hypertensive renal disease?
Arteriosclerosis of major renal arteries,
Hyalinization of small vessels with intima thickening.
How is serum osmolality regulated?
Osmoreceptors in the OVLT of the hypothalamus detect plasma osmolarity and stimulate release of ADH from pituitary or stimulate thirst as needed.
Where is ADH synthesised?
Where is it secreted?
Synthesised in supraoptic nucleus of the hypothalamus,
Released by the posterior pituitary gland.
What is diabetes insipidus?
What are common symptoms?
Inability to reabsorb water from the distal nephron due to failure of secretion or action of ADH.
Common symptoms include poluria, polydipsia and dilute urine.
