Science Form 3: Chapter 1: Respiration
Respiration is the process of inhaling oxygen and exhaling carbon dioxide and the oxidation of food ( glucose) to release energy.
Nostril > Nasal Cavity > Trachea > Bronchus > Bronchiole > Alveolus
Gaseous exchange takes place in alveolus.
Oxygen diffuses from the alveoli into the blood capillaries.
Oxygen form with haemoglobin to form oxyhaemoglobin.
Blood containing oxygen ( oxyhaemoglobin ) is transported by the red blood cells.
Oxyhaemoglobin breaks up and releases oxygen when it reaches blood tissues which have low oxygen concentration.
Oxygen diffuses from the blood cappilaries into the cells.
PT3 Practice:
1. Explain the characteristic of alveoli which allow the exchange of gases effectively. ( 3 marks)
- has large surface area when compared to its volume
- is surrounded by a network of blood capillaries
- has thin and elastic walls
- is most
2. Explain the breathing mechanism. ( 4 marks)
- During inhalation,the external intercostal muscles contract.The rib cage moves upwards and outwards.The diaphtagm contracts and flattens.The volume of the thoracic increases.This causes the air pressure in the thoracic decreases.The higher atmospheric pressure forces air into the lungs.
- During exhalation,the external intercostal muscles relax.The rib cage moves downwards and inwards.The diaphragm relaxes and curve upwards.The volume of the thoracic decreases.This causes the air pressure in the thoracic cavity increases.As a result,air is forced out of the lungs.
3. Why we are not allowed to sit in a car with running engine.State the reason and explain your answer. ( 3 marks)
- This is because car exhaust contains carbon monoxide.Carbon monoxide competes with oxygen to combine with haemoglobin.The amount of oxygen in the blood will be greatly reduced if oxygen is present.
Nostril > Nasal Cavity > Trachea > Bronchus > Bronchiole > Alveolus
Gaseous exchange takes place in alveolus.
Oxygen diffuses from the alveoli into the blood capillaries.
Oxygen form with haemoglobin to form oxyhaemoglobin.
Blood containing oxygen ( oxyhaemoglobin ) is transported by the red blood cells.
Oxyhaemoglobin breaks up and releases oxygen when it reaches blood tissues which have low oxygen concentration.
Oxygen diffuses from the blood cappilaries into the cells.
PT3 Practice:
1. Explain the characteristic of alveoli which allow the exchange of gases effectively. ( 3 marks)
- has large surface area when compared to its volume
- is surrounded by a network of blood capillaries
- has thin and elastic walls
- is most
2. Explain the breathing mechanism. ( 4 marks)
- During inhalation,the external intercostal muscles contract.The rib cage moves upwards and outwards.The diaphtagm contracts and flattens.The volume of the thoracic increases.This causes the air pressure in the thoracic decreases.The higher atmospheric pressure forces air into the lungs.
- During exhalation,the external intercostal muscles relax.The rib cage moves downwards and inwards.The diaphragm relaxes and curve upwards.The volume of the thoracic decreases.This causes the air pressure in the thoracic cavity increases.As a result,air is forced out of the lungs.
3. Why we are not allowed to sit in a car with running engine.State the reason and explain your answer. ( 3 marks)
- This is because car exhaust contains carbon monoxide.Carbon monoxide competes with oxygen to combine with haemoglobin.The amount of oxygen in the blood will be greatly reduced if oxygen is present.