• Why do you go red when you are hot?
  As different parts of the body burn up energy they make heat. Blood ...

• What is a capillary?
  Blood travels around the body through tubes called arteries and ...

• How often does blood go around the body?
  Blood goes around the body about once a minute or 1,500 times a day.

• What is bile?
  Bile is a yellow-green liquid made by the liver and stored in the ...

• Why is urine yellow?
  Urine contains traces of waste bile and this makes it yellowish. If ...

• What makes you urinate?
  The bladder stretches as it fills. When it has about 1/4 pint (150 ...

• How much urine does the bladder hold?
  An adult's bladder can hold up to about 1/4 pints (600 ml) of urine, ...

• How much liquid do you need to drink?
  You need to drink about 2 3/4 to 3 1/4 pints (1.2 to 1.5 liters) of ...

• How long can you live without water?
  Although some people have lived for several weeks without food, you ...

• Why do you need to drink more in hot weather?
  When it is hot, you sweat more and so lose more water, which you then ...