RESPIRATION IN ORGANISMS

 The process of breakdown of food in the cell with the release of energy is called cellular respiration.



 Cellular respiration takes place in the cells of all organisms.



 In the cell, the food (glucose) is broken down into carbon dioxide and water using oxygen.



 When breakdown of glucose occurs with the use of oxygen it is called aerobic respiration.





 Food can also be broken down, without using oxygen. This is called anaerobic respiration.

 Breakdown of food releases energy.



 there are some organisms such as yeast that can survive in the absence of air. They are called anaerobes.



 They get energy through anaerobic respiration.



 In the absence of oxygen, glucose breaks down into alcohol and carbon dioxide.



 Yeasts are single-celled organisms.



 They respire anaerobically and during this process yield alcohol. They are, therefore, used to make wine and beer.



 Our muscle cells can also respire anaerobically, but only for a short time, when there is a temporary deficiency of oxygen.



 The taking in of air rich in oxygen into the body is called inhalation and giving out of air rich in carbon dioxide is known as exhalation.



 When we inhale air, it passes through our nostrils into the nasal cavity.

 From the nasal cavity, the air reaches our lungs through the windpipe.

 Lungs are present in the chest cavity



 This cavity is surrounded by ribs on the sides.

 A large, muscular sheet called diaphragm forms the floor of the chest cavity.



 Breathing involves the movement of the diaphragm and the rib cage. A cockroach has small openings on the sides of its body. Other insects also have similar openings. These openings are called spiracles.





 Insects have a network of air tubes called tracheae for gas exchange.

 Oxygen rich air rushes through spiracles into the tracheal tubes, diffuses into the body tissue, and reaches every cell of the body.



 Earthworms breathe through their skins.

 The skin of an earthworm feels moist and slimy on touching. Gases can easily pass through them.



 Though frogs have a pair of lungs like human beings, they can also breathe through their skin, which is moist and slippery.



 Gills in fish help them to use oxygen dissolved in water.

 Gills are projections of the skin.

 Gills are well supplied with blood vessels for exchange of gases.