Human Respiration

Larynx

  • Voice box

Trachea > Bronchi > Bronchioles

  1. Passageway for air to enter and leave the lungs

  2. Trachea and bronchi contain gland cells that secrete mucus to trap dust particles and bacteria

  3. Trachea and bronchi contains cilia that sweeps up dust particles and bacteria into pharynx and swallowed into oesophagus

Alveoli

  • Site for gaseous exchange

Adaptation of alveoli for gaseous exchange

  1. Presence of numerous alveoli: provides a large surface area to volume ratio for faster gaseous exchange

  2. Alveolar walls are only one cell thick: faster diffusion of gases

  3. The alveoli are supplied with a lot of capillaries: ensures continuous blood flow to maintain diffusion gradient for oxygen and carbon dioxide between alveolus and blood

  4. Surface of alveoli has a thin film of moisture: allows oxygen to dissolve before diffusing into blood capillaries

Major toxic components of TOBACCO SMOKE

Tobacco smoke consists nicotine, tar and carbon monoxide

Nicotine

  • Addictive drug, dulling brain and senses

  • Causes blood clot easily, increasing risk of blood clots in blood vessels

Tar

  • Contains cancer-causing (carcinogenic) chemicals

  • Paralyses cilia

    • Blocking air sacs and reduction in gaseous exchange efficiency

    • Dust particles trapped in mucus inside the airways cannot be removed > persistent coughing > may cause chronic bronchitis or emphysema

Carbon monoxide

  • Combines irreversibly with haemoglobin to form carboxyhaemoglobin. Less oxygen is carried by red blood cells.

  • Increases fatty deposits on artery walls increasing risk of atherosclerosis and blood clotting in arteries.

Aerobic respiration

Definition: Is the breakdown of glucose, in the presence of oxygen to release a large amount of energy.

Word equation: Glucose + oxygen > carbon dioxide + water + large amount of energy released (cell growth to make proteins)

Anaerobic respiration

  • During vigorous exercise, anaerobic respiration occurs together with aerobic respiration.

    • Anaerobic respiration occurs due to insufficient oxygen

Definition: Is the breakdown of glucose in the absence of oxygen to release a small amount of energy

Word equation: Glucose > lactic acid

  • Lactic acid causes muscle fatigue


Explain why cells respire anaerobically during vigorous exercise resulting in oxygen debt that is removed by rapid, deep breathing after exercise.

During vigorous exercise

  1. Muscular contractions increase

  2. Muscle cells respire more to release more energy

  3. However, insufficient oxygen is supplied to muscle cells to meet oxygen demand

  4. Thus, muscle cells carry out anaerobic respiration to release extra energy and produces lactic acid

  5. When this occurs, the muscle cells is said to occur an oxygen debt

During resting after vigorous exercise

  1. During resting, oxygen uptake remains high to repay oxygen debt incurred during the vigorous exercise

  2. There is rapid, deep breathing to remove lactic acid produced by bringing oxygen to the liver

  3. There is also an increased in heart rate to transport lactic acid to liver via blood for removal and to transport oxygen to liver

  4. Oxygen is used to convert lactic acid back to glucose