Page 90 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

What is the difference between Why does your
heat and temperature? heart pump

eat (measured in joules) is the amount the average kinetic energy in the molecules
H of thermal energy (molecular of an object. twice for
movement) something has and it can vary Temperature is not dependent on the mass
depending on the mass of the object; if the of an object, so objects of different sizes every beat?
object has a large mass, its thermal energy could have the same temperature, but they’d
will also be large as it has a lot of molecules, have different heats. For instance, a mug of he human heart has four chambers;
while a smaller object will have less thermal tea may have the same temperature as a Ttwo atria at the top of the heart,
energy as it has fewer molecules. bath of hot water, but as the bath has more which collect blood returning from the
Temperature, however, is a measure of the water, it takes more energy to get its body and lungs, and two larger
relative thermal energy of something; it’s the molecules to that temperature, and therefore ventricles at the bottom, which pump
degree of hotness or coldness, measuring it has more heat. blood back out again.
The heart has its own biological
pacemaker, which triggers a rhythmic
electrical wave that spreads across the
muscle. It starts at the top and travels
down the walls of the two atria, making
them squeeze and transferring the blood
into the ventricles. Valves then snap
shut to prevent the blood moving back,
making the ‘lub’ sound of the heartbeat.
The electrical impulse moves down to
the bottom of the heart through
specialist cells in the middle, and then
comes up in a wave, making the
ventricles contract and forcing blood
towards the body and the lungs. Then a
second set of valves snap close, making
the ‘dub’ sound of the heartbeat.

Why do we

need protein?
Why does coffee make me roteins form the molecular machinery
dehydrated but tea doesn’t? P that makes the human body work, from

the structure of our muscles, skin and bones,
to the digestive enzymes that break down our
affeine in general – whether it’s in tea, food. They are made from long chains, folded
C coffee, or soda – is definitely dehydrating. into three-dimensional structures, and are
However, when you consume these beverages constructed using around 20 different
you’re also consuming water, which seems to building blocks known as amino acids.
ultimately counteract any dehydrating effect. All living things use the same 20 or so
Studies have given us conflicting information, amino acids, so we are able to use the
though there appears to be a limit. According proteins from plants and animals as a source
to the Mayo Clinic, if you consume more than for the building blocks we need to construct
500 milligrams of caffeine per day on a our own bodies. However, unlike fat and
regular basis, you could be at risk of carbohydrate, the human body cannot store
dehydration. As long as you drink a variety of excess protein, so we need to eat it every day
beverages and drink whenever you’re thirsty, in order ensure a steady supply of the amino
you shouldn’t have a problem. Although it acids we need for growth and repair. The liver
might seem that you have to urinate more is able to convert some amino acids into
frequently when you drink coffee, you’d others, but around eight of them are known
probably have to go just as often if you were as ‘essential’ and can only be obtained from
drinking an equivalent amount of plain water. our diets.

90 How It Works