RENAL FUNCTION

Question 1

Basic structural and functional unit of the kidney

Answer 1

NEPHRON
— 1-1.5 million nephrons per kidney
— consists of glomerulus and renal tubules

Question 2

Order of urine formation

Answer 2

1. Glomerulus
2. PCT
3. Loop of Henle
4. DCT
5. Collecting duct
   ————————————————
6. Calyx
7. Renal pelvis

Question 3

Order of renal blow flow

Answer 3

1. Renal artery (blood in)
2. Afforestation arteriole
3. Glomerulus
4. Efferent arteriole
5. Peritubular capillaries
6. Vasa recta
7. Renal vein (blood out)

Question 4

Renal blood flow

Answer 4

1 200 ml/min

Question 5

Renal plasma flow

Answer 5

600—700 ml/min

Question 6

Resembles a sieve; non-selective filter of plasma substances with a molecular weight of < 70 000 Da

Answer 6

GLOMERULUS
— consists of a coil of approximately 8 capillary lobes (capillary tuft)
— within the Bowman’s capsule

Question 7

1st function to be affected in renal disease

Answer 7

TUBULAR REABSORPTION

Question 8

Renal threshold for glucose

Answer 8

160—180 mg/dl

Question 9

Major site of reapportion of plasma substances

Answer 9

PCT (65%)

Question 10

Regulates water reabsorption in the DCT and CD

Answer 10

ANTI-DIURETIC HORMONE (ADH/VASOPRESSIN)

Question 11

2 major functions of tubular secretion

Answer 11

• Elimination of waste products not filtered by the glomerulus
• Regulation of the acid-base balance in the body thru secretion of hydrogen ions (in the form of NH4+ and H2PO4)

Question 12

Inability to produce an acid urine

Answer 12

RENAL TUBULAR ACIDOSIS

—hydrogen ions are not excreted in the urine

Question 13

This is used to evaluate glomerular filtration

Answer 13

CHEMICAL TESTS

Question 14

Old glomerular filtration test

Answer 14

UREA

Question 15

Most common glomerular filtration test

Answer 15

CREATININE

Question 16

Gold standard glomerular filtration test

Answer 16

INULIN

Question 17

Creatinine clearance formula

Answer 17

Ccr (ml/min) = UV/P x 1.73 m2/A

Ccr = Creatinine Clearance
U    = Urine Creatinine (mg/dl)
P    = Plasma Creatinine 
V    = Urine Volume (ml/min)
A    = Body Surface Area

Question 18

Cockgroft and Gault glomerular filtration formula

Answer 18

(140 - age) (body weight in kg) / 72 x Serum Creatinine (mg/dl)

*** for females: results x 0.85

Question 19

Variables for Cockgroft and Gault formula

Answer 19

• age
• sex
• body weight in kg

Question 20

This is used to evaluate tubular reabsorption

Answer 20

Concentration tests

Question 21

Obsolete tests for tubular reabsorption

Answer 21

1. Fisherberg Test
   — Px is deprived of fluid for 24 hours; Urine SG >/= 1.026
2. Mosenthal Test
   — Compare day & night urine in terms of volume & SG

Question 22

Commonly used tests for tubular reabsorption

Answer 22

1. Specific Gravity
   — influenced by the number & density of particles in a solution
2. Osmolarity
   — influenced by the number of particles in a solution