Sodium & Potassium Balance Flashcards
What leads to increased volume
Increased salt or water
What leads to decreased volume
Decreased salt or water
Sodium and blood pressure
Increased dietary sodium Increased body sodium Increased osmolarity (but this can’t happen) Increased water intake and retention Increased ECF volume Increased blood pressure and volume
Best way to retain sodium
Filter less by decreasing pressure gradient from afferent to efferent arterioles
What is aldosterone
Steroid hormone
Aldosterone excess
Hypokalaemic alkalosis
Liddle’s syndrome
Inherited disease of high bp
Mutation in aldosterone activated sodium channel
Channel always on
Results in sodium retention and hypertension
Atrial natriuretic peptide
Small peptide made in atria released in response to atrial stretch
ANP actions
Vasodilation of renal and other systemic blood vessels
Inhibition of sodium reabsorption in PCT and in collecting duct
Inhibits release of renin and aldosterone
Reduces blood pressure
Other diuretics
Osmotic diuretics Carbonic anhydrase inhibitors Loop diuretics Thiazides Potassium sparing diuretics Aquaretics
Osmotic diuretics
Something that doesn’t get reabsorbed in PCT and descending limb to increase osmolarity and thus less water reabsorption
Main intracellular ion
Potassium (150 mmol/L)
Has major effects on excitable membranes of nerves and muscle
Extracellular potassium
What does high potassium do
Depolarises membranes - action potentials, heart arrhythmias
What does low potassium do
Make depolarisation more difficult - heart arrhythmias (asystole)
