Respiration and Breathing System in Humans

RESPIRATION AND BREATHING  SYSTEM IN HUMANS

A  Aerobic respiration

• Respiration is the release of energy by the breakdown of food substances in all living cells.
• There are two ways in which respiration can occur: aerobically, the presence of oxygen, and anaerobically, without oxygen.
• Aerobic respiration is the release of energy by the breakdown of food substances in the presence of oxygen.
• Sugar releases energy when it is combined with oxygen during oxidation.
• The apparatus used to show that foods release stored energy when they are OXIDISED is shown in the Figure below.

                              [pic 1]

• The sequence of steps in this investigation is as follows:

      • the temperature of the water in the test tube is recorded

      • a peanut is then heated and, when it starts to burn, is held under the test tube of    

        water

      • the temperature of the water is recorded again as soon as the peanut has stopped  

        burning.

• An increase in the water temperature shows that the peanut releases energy when it is oxidised by burning.
• Heat from the burner provides the energy to start the sugar reacting with oxygen.
• Once started, the sugar-oxygen reaction continues, with a lot of heat given off by the sugar.
• This form of oxidation outside living cells is called combustion.

The respiration equation

• This word equation summarises aerobic respiration:

• sugar + oxygen                carbon dioxide + water + energy [pic 2]
• The sugar that is normally used is glucose
• The balanced symbol equation for respiration shows how many molecules of each substance are involved in the reaction:
• [pic 3]
• The carbon dioxide and water are by-products. The reaction produces energy for the cell.

Uses of energy in the body

• Living organisms use energy released by respiration to carry out
• many different processes.
• For example:

      • to move around, in order to look for food and hide from enemies

      • to obtain food and digest it

      • to make your heart beat, in order to circulate blood in your body

      • to speak, in order to communicate with people

      • to reproduce, in order to have offspring to maintain the human population

      • to keep your body warm

      • to send nervous impulses from one part of your body to another part in order to    

        coordinate your body

      • to grow

      • to remove waste substances.

All the energy to do these things comes from the food you eat.