CHAPTER 1: RESPIRATION

1.1 Human Breathing Mechanism

Learning outcomes

The human respiratory system consist of:1.Respiratory organs (nasal cavity, trachea,

bronchi, lung)2.Rib cage3.Diaphagram4.Intercostal muscles

The route taken by the air from the nose till the alveolus can be as follows:

Nose Trachea

Bronchus

Bronchiole Alveolus

5. Process of inhalation and exhalation. Inhalation Exhalation

1. The ribcage moves UPWARDS and outwards.

1. The ribcage moves DOWNWARDS and inwards.

2. The diaphragm contracts, BECOME FLATTEN.

2. The diaphragm BECOME DOOM SHAPE

3. The thoracic cavity becomes BIGGER. 3. The thoracic cavity becomes SMALLER.

4. This causes the air pressure to DECREASE. 4. This causes the air pressure to INCREASE.

5. The HIGHER air pressure outside the lung forces air to enter the lungs.6. INTERCOSTAL MUSCLES CONTRACT.

5. The HIGHER air pressure in the lungs pushes the air out.6. 6. INTERCOSTAL MUSCLES RELAX.

• http://www.youtube.com/watch?v=Mf8xTqfspp4

1.2 TRANSPORTATION OF OXYGEN IN HUMAN BODY.

The diagram shows the transport of oxygen from the lungs to the body cells.

1.The air that is inhaled into the lungs has a HIGHER concentration of oxygen than the blood in the blood capillaries.2.This causes the oxygen to DIFFUSE from the lungs into the bloodstream.

3. Then, the oxygen combines with haemoglobin to form OXYHAEMOGLOBIN and transported to all parts of the body.

4. Normally the body cells have a LOWER concentration of oxygen.

5. This makes the oxyhaemoglobin to BREAKDOWN to haemoglobin and oxygen.

6. Then the oxygen diffuses from the blood capillaries into the cell tissue.

The characteristics of alveolus that make it as an efficient tissues for gas exchange.1.Large surface area.2.Moist surface3.Thin alveolar walls ( only a single layer thick)4.Alveolar walls covered by network of blood capillaries.