Dynamics of Ultrafiltratio physiology 1404 lect 1

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Questions and Answers

What is the formula to estimate the Glomerular Filtration Rate (GFR)?

GFR = PCr / (UCr × V)
GFR = PCr × V / UCr
GFR = UCr × V / PCr (correct)
GFR = UCr / (Pcr × V)

What is the characteristic of a substance that can be used to measure GFR?

It must be secreted by the nephron.
It must be reabsorbed by the nephron.
It must be produced by the kidney.
It must meet specific criteria, including being freely filtered across the glomerulus. (correct)

What is the unit of measurement for urine flow (V)?

milliliters per minute (mL/min) (correct)
millimoles per second (mmol/s)
liters per hour (L/h)
microliters per minute (μL/min)

What is the purpose of measuring the clearance of creatinine?

To measure the Glomerular Filtration Rate (GFR). (D) Signup and view all the answers

What is the advantage of using inulin as a marker for GFR measurement?

It meets the criteria for a GFR marker. (B) Signup and view all the answers

What is the relationship between the equation for estimating GFR and the equation for clearance?

The equations are identical in form. (C) Signup and view all the answers

What is the primary reason for complete emptying of the bladder at the beginning and end of the clearance period?

To reduce possible errors introduced by urine remaining in the bladder (C) Signup and view all the answers

What is a limitation of using creatinine clearance as a marker for GFR?

It is affected by certain drugs that inhibit tubular secretion of creatinine (D) Signup and view all the answers

What is an advantage of using creatinine clearance over inulin clearance?

It can be measured over a longer period of time (B) Signup and view all the answers

Why is creatinine a suitable marker for GFR?

It is always present in the blood and its concentration remains fairly constant over a 24 hour period (A) Signup and view all the answers

What is the benefit of using creatinine clearance in patients with compromised renal function?

It overcomes some of the practical problems of inulin clearance (D) Signup and view all the answers

How many blood samples are needed for creatinine clearance?

Only one blood sample is needed (B) Signup and view all the answers

What is the formula for GFR in terms of Net Filtration Pressure (NFP) and ultrafiltration coefficient (Kf)?

GFR = Kf x NFP (C) Signup and view all the answers

What is the primary reason why the rate of glomerular filtration is higher in glomerular capillaries than in systemic capillaries?

Higher ultrafiltration coefficient (Kf) in glomerular capillaries (A) Signup and view all the answers

What is the effect of chronic uncontrolled hypertension and diabetes mellitus on the glomerular capillary membrane?

Decreases the intrinsic permeability of the membrane (A) Signup and view all the answers

What is the unit of measurement for the ultrafiltration coefficient (Kf)?

mL/mmHg (C) Signup and view all the answers

What is the effect of reducing the number of functional glomerular capillaries on the ultrafiltration coefficient (Kf)?

Decreases Kf (B) Signup and view all the answers

What is the net effect of πBS on GFR?

Has no effect on GFR (A) Signup and view all the answers

What is the unit of clearance?

ml/min (B) Signup and view all the answers

What is the concentration of Na+ in the plasma?

145 mmol/L (A) Signup and view all the answers

What is the volume of urine collected in 1 hour?

450 ml (B) Signup and view all the answers

What is the unit of inulin concentration?

mg/ml (A) Signup and view all the answers

What is the clearance of glucose in a normal individual?

0 ml/min (D) Signup and view all the answers

What happens to a substance that is filtered but partially reabsorbed?

Its clearance is between zero and ~600 ml/min (B) Signup and view all the answers

What is the formula for GFR?

GFR = Kf x Net Filtration Pressure (NFP) (A) Signup and view all the answers

Which of the following changes would increase GFR?

Dilation of afferent arteriole (C) Signup and view all the answers

What is the effect of sympathetic stimulation on GFR?

Decreases GFR (A) Signup and view all the answers

How does AgII affect efferent and afferent arterioles?

Constricts efferent arteriole more than afferent arteriole (C) Signup and view all the answers

What is the effect of haemorrhage on GFR?

Decreases GFR (D) Signup and view all the answers

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