Teevo's superb biology questions

[HERculina]

yea they were all plants, but they werent all leaves.
and congrats, your answers for the heart q. were right
so if ventricles act as a pump does that mean that's wat our heartbeat is..the ventricle squeezing blood to the aorta?
then wats teh sound of the valves opening and closing? i thought that was the heartbeat :/

[Russ]

Well the term "heartbeat" is a bit vague. Yes, the sound of the heartbeat is the valves shutting. The first sound is the closure of the atrioventricular valves and the second sound is the closure of the semilunar valves.

But in order to get blood out of the ventricles, they have to contract to force it out, which means they require a large amount of muscle. The LV requires more muscle because it has to pump blood around the body, whilst the RV only has to pump to the lungs (pulmonary circuit). So a way to measure heartbeat is by how many times that happens per minute.

When you look at an ECG, you can see what are called QRS complexes that spike upwards - measuring between those is the time between ventricular contractions or one "heartbeat".

[HERculina]

kkays that made it a lot clearer,
you deserve some karma