29 Questions
What is the formula to estimate the Glomerular Filtration Rate (GFR)?
GFR = UCr × V / PCr
What is the characteristic of a substance that can be used to measure GFR?
It must meet specific criteria, including being freely filtered across the glomerulus.
What is the unit of measurement for urine flow (V)?
milliliters per minute (mL/min)
What is the purpose of measuring the clearance of creatinine?
To measure the Glomerular Filtration Rate (GFR).
What is the advantage of using inulin as a marker for GFR measurement?
It meets the criteria for a GFR marker.
What is the relationship between the equation for estimating GFR and the equation for clearance?
The equations are identical in form.
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
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
What is an advantage of using creatinine clearance over inulin clearance?
It can be measured over a longer period of time
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
What is the benefit of using creatinine clearance in patients with compromised renal function?
It overcomes some of the practical problems of inulin clearance
How many blood samples are needed for creatinine clearance?
Only one blood sample is needed
What is the formula for GFR in terms of Net Filtration Pressure (NFP) and ultrafiltration coefficient (Kf)?
GFR = Kf x NFP
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
What is the effect of chronic uncontrolled hypertension and diabetes mellitus on the glomerular capillary membrane?
Decreases the intrinsic permeability of the membrane
What is the unit of measurement for the ultrafiltration coefficient (Kf)?
mL/mmHg
What is the effect of reducing the number of functional glomerular capillaries on the ultrafiltration coefficient (Kf)?
Decreases Kf
What is the net effect of πBS on GFR?
Has no effect on GFR
What is the unit of clearance?
ml/min
What is the concentration of Na+ in the plasma?
145 mmol/L
What is the volume of urine collected in 1 hour?
450 ml
What is the unit of inulin concentration?
mg/ml
What is the clearance of glucose in a normal individual?
0 ml/min
What happens to a substance that is filtered but partially reabsorbed?
Its clearance is between zero and ~600 ml/min
What is the formula for GFR?
GFR = Kf x Net Filtration Pressure (NFP)
Which of the following changes would increase GFR?
Dilation of afferent arteriole
What is the effect of sympathetic stimulation on GFR?
Decreases GFR
How does AgII affect efferent and afferent arterioles?
Constricts efferent arteriole more than afferent arteriole
What is the effect of haemorrhage on GFR?
Decreases GFR
Learn about the dynamics of ultrafiltration and how the glomerular filtration rate (GFR) is calculated. Understand the role of Starling forces, ultrafiltration coefficient, and net filtration pressure in GFR. Test your knowledge of this important concept in nephrology.
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