Most Sought After Biology Notes

Most Sought After Biology Notes

monthly poster

Friday, 10 January 2014

Why Total Surface Area/ Volume Matters?

What is actually the Total Surface Area over Volume (TSA/V) thing that we learnt the first thing in Chapter 1 (Transport) in the Form 5? Here we shall discover more about the confusing concept:

First, see the diagram of cells below:




As you can see, the large animals have LESS CELLS EXPOSED FOR DIFFUSION of substances compared to its volume or size.

Diagram: 14 cells exposed compared to overall 27 cells --> 14/27 = 0.52

The small animal, it has MORE CELLS EXPOSED FOR DIFFUSION of substances compared to its volume or size.

Diagram: 5 cells exposed compared to overall 6 cells --> 5/6 = 0.83 (HIGHER TSA/V)

That explains why large animals such as whales have a VERY LOW HEARTBEAT RATE. This is because the heart doesn't need to pump much because the large size can retain more heat & substances in the body (heat is difficult to diffuse out because of less cells for diffusion).

My heart beats 6 times per minute...

Compared to small animals such as mouse. it has a VERY HIGH HEARTBEAT RATE. This is because the body cells constantly need to replace lost heat/substances thanks to the high diffusion rate.

My heart beats more than 600 times per minute!!!

Now you know :-) See you in the next post!

One more thing, I want you to ponder this...

Q: Why big/obese individuals have HIGHER HEARTBEAT RATE than normal ones?????

Is it violating the TSA/V rule? Google now & let me know.

RESPECTO

1 comment:

  1. Obese people have fats deposited in their blood vessel hence making it hard for transportation of oxygen. This is detected by the receptors which then send nerve impulses to the cerebellum which controls this involuntary act. The cerebellum sends nerve impulses to the heart to pump more to overcome hurdle of clogged blood vessel thus increasing its heart beat… I think :)

    ReplyDelete