Physiology 1

Question 1

How much filtrate does the kidney produce each day?

Answer 1

180L

Question 2

how much blood can be redirected from the kidney if its needed in other organs?

Answer 2

up to 800ml, it will cause damage if it is for a long time.

Question 3

How much fluid is excreted as urine per day?

Answer 3

1-2L - there’s 180L filtered so a massive amount must be reabsorbed.

Question 4

What is the GFR maintenance zone?

Answer 4

60mmHg - 130mmHg below 60 GFR will fall below 50 GFR will not be present

Question 5

how much blood does the kidney receive per minute?

Answer 5

1200mls

Question 6

How does the kidney maintain GFR?

Answer 6

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.

Question 7

What is the hydrostatic, osmotic and fluid pressures?

Answer 7

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.

Question 8

How much plasma goes to the kidneys each minute?

Answer 8

660mls

Question 9

After filtration, what is the state of the efferent arterioles?

Answer 9

They have less plasma but the same amount of proteins - so they have an increased oncotic pressure and a decreased hydrostatic pressure.

Question 10

How does extrinsic factors maintain GFR?

Answer 10

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.)

Question 11

How much filtrate does the kidney produce in 1 min?

Answer 11

125mls

Question 12

Maintaining the GFR is controlled by?

Answer 12

intrinsically - the kidneys can do this on their own. extrinsically - sympathetic nervous system, catecholamines (adrenaline), aldosterone.

Question 13

how much of the plasma delivered to the kidney is filtered every minute?

Answer 13

125mls of 660mls (20%)

Question 14

What are the glomerular filtrate layers?

Answer 14

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.

Question 15

How much of the blood is made of plasma?

Answer 15

55%

Question 16

What is filtered at the glomerulus?

Answer 16

Anything <1 nanometre in radius - things larger are only partly filtered (like inulin).