06 Sodium And Potassium Balance Flashcards
(15 cards)
How does high dietary sodium increase BP
Increase sodium intake increases plasma osmolarity which in turn increases ECF volume and result in increase in blood volume and BP
What factors have an effect on sodium reabsorption
- Renal plasma flow
- Gradient of pressure between afferent and efferent
- Reabsorption of sodium from PCT
These are affected by increased sympathetic activity to retain salt. Sympathetic activity also causes the formation of Ang II by stimulating juxtaglomerular cells.
Ang II also stimulates PCT reabsorption and aldosterone release
Aldosterone increases the reabsorption of sodium from DCT
What are the effects of ANP
Increase pressure gradient between afferent and efferent
Increase RPF
Decrease uptake of sodium from PCT and DCT
Inhibitor of juxtaglomerular apparatus
What are the stimuli of the release of aldosterone
Ang II
Decreased volume via baroreceptor
Decreased osmolarity of ultrafiltrate
What are the effects of aldosterone
Increase sodium intake (by increasing the expression of apical sodium channel on principle cells and sodium potassium pump)
Increase secretion of potassium and H+
What are the symptoms of hypoaldosteronism. What are the processes involved to correct this
Dizziness Low BP Salt craving Palpitations Due to the reduction of blood volume, Ang II, ADH and renin are increased
What are the symptoms of hyperaldosteronism. How does the body react to it
Increased BP Muscle weakness Polyuria Thirst Increased ANP and BNP and reduce renin, Ang II and ADH
What is Liddel’s syndrome
Inherited disease of high BP due to mutation in aldosterone activated sodium channel and make it open constantly
Name the 5 baroreceptors
Atria Right ventricle Pulmonary vascularture Carotid sinus Aortic sinus Juxtaglomerular apparatus
Name the different diuretic drugs
Osmotic diuretic Carbonic anhydride inhibitor Thiazide diuretic Loop diuretic ACE inhibitor (captopril) Aldosterone receptor inhibitor (spirinolactone) Amigo ride (sodium channel inhibitor) The latter two are K+ sparring diuretics
What increases potassium ion uptake from plasma
Insulin
Adrenaline
Aldosterone
What stimulates potassium secretion and how does the biochemistry of principle cells aid with the secretion
High plasma K+
Aldosterone
High tubular flow rate
High pH
Potassium channel, membrane potential and Na/K ATPase
Why does high flow rate triggers potassium secretion
There is PDK1 on DCT cilia which become activated at high tubular flow rate. This then increases intracellular calcium to activate potassium secretion
What can cause hypokalaemia
Diuretics
Vomiting
Diarrhoea
Genetics
What can cause hyperkalaemia
K+ sparring diuretics
ACE inhibitors
Elderly
