Kidney - Regualtion Of Fluid And Electrolyte Balace In Health And Disease Flashcards
Where is the bulk of sodium reabsorbed
The proximal consulates tubule
What hormone is responsible for insertion of sodium channels
Aldosterone
What is ANP
Inhibits the hormones ADH and aldosterone which leads to fluid excretion, large volume of dilute urine
What does low blood pressure cause in the distal convulated tubule
A fall in blood pressure will signal for the release of ADH and aldosterone, they will increase fluid reabsorption and help to increase the blood pressure back to homeostatic levels
What will a rise in blood pressure result in
A rise in blood pressure will lower the blood pressure, therefore ANP will be released and fluid excretion will increase from the distal convoluted tubule meaning the blood pressure will be restored to homeostatic conditions
What factors influence the GFR
- glomerular hydrostatic pressure
- capsular hydrostatic pressure
- glomerular osmotic pressure
- systemic blood pressure
- renin-angiotensin-aldosterone system
- disease
How much sodium is absorbed proximal convoluted tubule
65% of sodium is reabsorbed
How much sodium is reabsorbed in the loop of henle
25%
How much sodium is absorbed in the distal convulated tubule
8%
What is the definition of the glomerular filtration rate
The rate at which blood is filtered through the glomerulus into the bowmans capsule
The kidneys measure GFR as a…
Proxy for systemic blood pressure
What is the juxta-glomerular apparatus
- connects the distal convoluted tubule with the glomerulus
- measures and responds to changes in Na+ conc of the filtrate
What is the macula densa
They are a small group of specialised epithelial cells which measure and respond to changes in sodium concentration
What are the juxta golomerular cells
Modified smooth muscle cells, they can adjust the diameter of the afferent arteriole by vasoconstriction and vasodilation the mascula densa cells tell the juxta to constrict or dilate
What are mesangial cells
Supporting cells in the juxta glomerular apparatus
How does blood pressure affect the sodium filtrate concentration
Blood pressure drives the glomerular hydrostatic pressure which in turn determines the sodium filtrate concentration
What does a high blood pressure result in
A high blood pressure would result in a higher glomerular hydrostatic pressure hence a higher GFR and a higher Na+ filtrate concentration
How does the body maintain a stable blood pressure
If blood pressure is within homeostatic conditions in the kidney the large diameter of the arteriole will be maintained
What happens in the case of a high blood pressure(high na) in the kidneys
Because there is a high concentration of sodium, water will follow hence the mascula densa swell, this causes the relaase of adenosine which tells the juxta cells to vasoconstrict, this helps to protect the glomerular capillaries and glomerular hydrostatic pressure returns back to normal
What happens when the blood pressure is low
The macula densa will release prostaglandins, these act on the juxtaglomerular cells and the cells secrete renin this activates the renin angiotensin system and returns the blood pressure to a normal level
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