Q 01/05

How many chambers does the human heart have?

A) Two

B) Three

C) Four

D) Six

Answer · why

C) Four

The upper two are the atria and the lower two the ventricles; fish get by with two and most reptiles with three.

Q 02/05

What are the two upper chambers of the heart called?

A) Ventricles

B) Atria

C) Septa

D) Valves

Answer · why

B) Atria

The word is Latin for an entrance hall, which is roughly what they are: blood arrives there before being passed down to the pumping chambers below.

Q 03/05

Roughly how much does an adult human heart weigh?

A) 50-100 grams

B) 250-350 grams

C) 700-900 grams

D) 1.5-2 kilograms

Answer · why

B) 250-350 grams

That is about the weight of a large orange, and it is famously about the size of the owner's clenched fist.

Q 04/05

What is the normal range for an adult's resting heart rate?

A) 30 to 50 bpm

B) 60 to 100 bpm

C) 110 to 140 bpm

D) 150 to 180 bpm

Answer · why

B) 60 to 100 bpm

Fitness pushes the number down: an ultra-trained endurance athlete can tick over at 37 or 38 beats a minute.

Q 05/05

Which structure acts as the heart's own natural pacemaker, setting the normal sinus rhythm?

A) The bundle of His

B) The mitral valve

C) The sinoatrial node

D) The pericardium

Answer · why

C) The sinoatrial node

It sits in the wall of the right atrium and would fire about 100 times a minute if the nervous system did not rein it in to a resting 70 or so.