Microurition

Question 1

What is GFR?

Answer 1

Total GFR = sum of all filtration by functioning nephrons so progression of disease would be indicated by the reduction in GFR.

Question 2

What is the equation of plasma clearance?

Answer 2

Plasma clearance of X,  CX= [UX] V/[PX]                                     
 units are mls/min
UX = Urine concentration of X, 
V = urine flow rate, 
PX = plasma concentration of X

Question 3

What are some factors that affect using creatinine to measure renal function?

Answer 3

Muscle mass: athletes vs malnutrition
Dietary intake: creatine supplements vs vegetarians
Drugs: Some lead to spurious increases as does ketoacidosis.

Question 4

What should the clearance of glucose be?

Answer 4

0 as it should all be reabsorbed by the kidneys

Question 5

What is the clearance rate of urea?

Answer 5

50ml/min

Question 6

What is the motor innervation of microurition?

Answer 6

Motor innervation:
Rich parasympathetic supply (pelvic nerves)  activity  contraction of detrusor muscle 
Pressure within the bladder, S2-S4
Sparse sympathetic supply (hypogastric nerves), inhibit bladder contraction and closes the internal urethral “sphincter”. (Sympathetic supply is not very important to bladder function but cutting the hypogastric nerve  frequency of micturition).
Main function is to prevent reflux of semen into the bladder during ejaculation L1-L3.
Somatic motoneurones (pudendal nerves), innervate the skeletal muscle that forms the external urethral sphincter, keeps the sphincter closed, even against strong bladder contractions S2-S4.