What is respiration?

What is respiration?. Respiration is the process by which the body uses food and oxygen to produce energy, carbon dioxide and water vapour. Respiration takes place in body cells.

The by-products of respiration are;

Carbon dioxide

Water vapour


Breathing is the taking in and out of air.

Or it means the constant exchange of gases between an organism and the surroundings. The respiratory organs in man are the lungs.

The respiratory system

  • This deals with the use of oxygen in the body.
  • Lungs are the respiratory organs situated in either sides of the chest cavity.
  • Lungs are covered in a membrane called pleural membrane.
  • Fluid that lubricates the lungs and ribs and so reduce friction.
  • Lungs are protected by the part of the brain called Rib cage.
  • The ribs are held in position by the intercostal muscles.
  • In the lower side of the lungs is a diaphragm that separates the chest cavity from the abdomen;

The structure of the lungs, parts and their functions.

What is respiration?

Types of breathing

  1. Expiration (breathing out) exhalation.
  2. Inspiration (breathing in) inhalation.

Functions of parts of the breathing system

  1. The nose

It contains mucus which /that warms and moistens air before reaching the lungs.

It contains hair like structures called Cilia that trap germs and dirt that may enter the nose.

What happens to the air in the nose?

Air is filtered (cleaned) warmed and moistened.

What happens to the air in the mouth?

No mucus to moisten and warm air.

No cilia to filter air by trapping germs and dirt.

  1. The trachea (wind pipe)

It has an epiglottis that protects the opening of the trachea when swallowing food.

Epiglottis prevents choking.

Air enters into lungs which contains the voice box. Inside voice box are vocal cords which help in producing sound.

Trachea contains rings of cartilage that prevents it from closing and prevents suffocation.

The exchange of gases take place in the air sacs.

  1. The air sacs

This is where the exchange of gases takes place by diffusion.

Adaptations of air sacs to their function

They have walls to all diffusion take place.

They are surrounded by a net work of capillaries which bring carbon dioxide and take oxygen.

They are many in number.

The structure of the villus

Composition of air breathed in and out.

Type of airInspired airExpired air
Oxygen (O2)21%16%
Carbon dioxide (CO2)0.03%4%
Nitrogen (N2)79%79%
Water vapourLessMore

What happens during inspiration (inhalation)

  • The volume of the chest and lungs increases.
  • Diaphragm and intercostals muscles contracts.
  • Ribs move upwards and outwards.
  • The lungs increase in volume

What happens during expiration /exhalation?

  • The volume of the chest and lungs decreases.
  • The diaphragm and intercostals muscles relax.
  • Ribs move downwards and inwards.
  • The lungs decreases in volume.

Diseases that attack the breathing/respiratory system.

Tuberculosis                                        Bronchitis

Influenza                                             Asthma

Diphtheria                                           Pneumonia

Emphysema                                         Whooping Cough

Habits that improve the working of the respiratory system

  • Avoiding smoking
  • Having regular physical exercises.
  • Good feeding/nutrition
  • Eat food with low and fat
  • Keep away from dusty places etc.

Disorders of the respiratory system



Sneezing etc


  • Respiration is the chemical burning of food in the presence of oxygen in order to release ( produce ) energy
  • Water and carbondioxide are released as by products.
  • Respiration takes place in the body cells
What is respiration?

(Starch )

Types  of respiration

Aerobic respiration

Is respiration which uses oxygen.

Anaerobic respiration

It is a type of respiration which takes place in absence of oxygen and in which food substances are only partly broken down. It produces lactic acid in animals and alcohol in parts.

It occurs in muscles during exercise.