Physiology 1 Flashcards
How much filtrate does the kidney produce each day?
180L
how much blood can be redirected from the kidney if its needed in other organs?
up to 800ml, it will cause damage if it is for a long time.
How much fluid is excreted as urine per day?
1-2L - there’s 180L filtered so a massive amount must be reabsorbed.
What is the GFR maintenance zone?
60mmHg - 130mmHg below 60 GFR will fall below 50 GFR will not be present
how much blood does the kidney receive per minute?
1200mls
How does the kidney maintain GFR?
it controls the diameter of the afferent and efferent arterioles. Increase in blood pressure - constriction of afferent arteriole. Constriction of an arteriole causes increased pressure upstream and decreased pressure downstream from the constriction.
What is the hydrostatic, osmotic and fluid pressures?
Hydrostatic pressure inside the glomerular capillaries = 55mmHg oncotic pressure 30mmHg fluid pressure - 15mmHg Hydrostatic pressure is bigger which is why you only ever get filtration at the glomerulus.
How much plasma goes to the kidneys each minute?
660mls
After filtration, what is the state of the efferent arterioles?
They have less plasma but the same amount of proteins - so they have an increased oncotic pressure and a decreased hydrostatic pressure.
How does extrinsic factors maintain GFR?
sympathetic NS - vasoconstriction of afferent arteriole catecholamines - vasoconstriction of afferent arterioles aldosterone - vasoconstriction of just efferent arterioles (at low conc.), vasoconstriction of afferent arteriole too (at higher conc.)
How much filtrate does the kidney produce in 1 min?
125mls
Maintaining the GFR is controlled by?
intrinsically - the kidneys can do this on their own. extrinsically - sympathetic nervous system, catecholamines (adrenaline), aldosterone.
how much of the plasma delivered to the kidney is filtered every minute?
125mls of 660mls (20%)
What are the glomerular filtrate layers?
endothelial layer - stops blood cells being filtered basal lamina (glomerular basement membrane) - stop large protein molecules from being filtered slit processes - made from the foot processes (pedicles) of the podocytes - stops medium sized proteins from being filtered.
How much of the blood is made of plasma?
55%