Q 01/05

An adult human kidney is about the size of which of these?

A) A walnut

B) An egg

C) A fist

D) A melon

Answer · why

C) A fist

A fist: each kidney is only about 12 cm long, yet a person can live a full, healthy life with just one, which is what makes living kidney donation pos...

Q 02/05

Which tube carries urine from each kidney to the bladder?

A) Ureter

B) Renal vein

C) Urethra

D) Collecting duct

Answer · why

A) Ureter

Ureter: each one is a thin tube of muscle that pushes urine down to the bladder with regular contractions, while the similar-sounding urethra is the s...

Q 03/05

Which organ's bulk pushes the right kidney slightly lower than the left?

A) Liver

B) Spleen

C) Stomach

D) Gallbladder

Answer · why

A) Liver

Liver: it sits directly over the right kidney, and the narrow gap between the two is one of the first spots emergency doctors scan for internal bleedi...

Q 04/05

Approximately how many nephrons does each adult human kidney contain?

A) 10,000

B) 100,000

C) 1 million

D) 100 million

Answer · why

C) 1 million

About 1 million in each kidney at 20, but they are not for life: healthy kidneys lose them steadily, and donors studied in their seventies had only ab...

Q 05/05

About what share of the blood pumped by the heart flows through the kidneys?

A) About 1%

B) About 5%

C) About 20%

D) About 60%

Answer · why

C) About 20%

About 20%, and up to a quarter: a vast share for two organs that make up under 1% of body weight, because they need the flow to filter the blood, abou...