Chapter 10: Respiration

• Respiration: is a chemical reaction in cells which release energy from nutrient molecules.

• It has two types Aerobic and Anaerobic.

• Aerobic Respiration: is the breakdown of food substances in the presence of oxygen.

  • glucose is broken down into carbon dioxide and water.

  • this occurs in mitochondria.

  • equation:

    

  • Uses of energy in Body:

    • synthesis of protein.

    • building up of protoplasm for growth.

    • cell division.

    • heartbeat + muscle contraction.

    • absorption of food.

    • transmission of nerve impulses.

• Anaerobic Respiration: is the breakdown of food substances in the absence of oxygen.

  • It does not occur in mitochondria.

  • Use of energy:

    • It occurs in some microorganisms such as yeast (yeast respires in both way depending on the condition) - yeast release ethanol and carbon dioxide as waste products.

Anaerobic Respiration in Muscles:

• During vigorous muscle contractions (such as exercise), the muscle cells first use oxygen and respire aerobically; then when in oxygen debt they start to respire anaerobically.

• When muscle respire they produce lactic acid.

• If there is high lactic acid concentration, it may start to cause soreness and fatigue to the body.

• During period of rest lactic acid is removed from the muscles and transported to the liver. Some of the lactic acid is oxidised to produce energy. This energy is used to convert the remaining lactic acid to glucose. Glucose is then transported back to the muscle.

Gaseous Exchange in Animals:

• Taking air in is inspiration or inhalation.

• Giving air out is expiration or exhalation.

• Human air passages - nasal passages, pharynx, larynx, trachea, bronchi and bronchioles.

• Muscles involved - thoracic cavity, ribs, diaphragm.

• Advantages of breathing through the nose:

  • Dust, foreign particles are trapped by the hair of nostrils.

  • As air passes it is warmed and moistened before it enters lungs.

Composition of Air