Gas Exchange

Question 1

2.46: What are the ribs?

Answer 1

Bone structure that protects internal organs including the Lungs

Question 2

2.46: What are the intercostal muscles?

Answer 2

Muscles between the Ribs that move ribcage during inhalation and exhalation

Question 3

2.46: What is the diaphragm?

Answer 3

Sheet of muscle at bottom of Thorax that changes the thoracic volume during inhalation and exhalation

Question 4

2.46: What is the trachea?

Answer 4

Windpipe that connects the Mouth and Nose to the Lungs

Question 5

2.46: What is the bronchi?

Answer 5

Thick tubes that divides into two Bronchi inside Lungs - one Bronchus for each Lung

Question 6

2.46: What are the bronchioles?

Answer 6

Bronchi will split to form thinner tubes called Bronchioles that are connected to Alveoli

Question 7

2.46: What is the alveoli?

Answer 7

Tiny air sacs where gas exchange occurs

Question 8

2.46: What are the pleural membranes?

Answer 8

Thin, moist membrane lining the outside of Lungs for lubrication to reduce friction, and to stick outside of Lungs to chest cavity for Lung to follow chest movement

Question 9

2.47: What is the process of inhalation?

Answer 9

• External intercostal muscles contract, pulling rib cage upwards and outwards
• Internal intercostal muscles relax and are pulled back to their elongated state
• Diaphragm contracts and flattens, pushing abdomen walls outwards
• As a result, thoracic volume increases, causing pressure to decrease
• Decrease in pressure causes air to be drawn into lungs

Question 10

2.47: What is the process of exhalation?

Answer 10

• External intercostal muscles relax and are pulled back to their elongated state
• Internal intercostal muscles contract, pulling rib cage downwards and inwards
• Diaphragm relaxes and forms dome shape
• As a result, thoracic volume decreases, causing pressure to increase
• Increase in pressure causes air to be forced out of lungs

Question 11

2.48: What are the adaptations of alveoli?

Answer 11

• Small - increases surface area to volume ratio of faster exchange.
• Thin wall/ one cell thick - shortens diffusion distance for faster diffusion.
• Surrounded by the dense capillary network
  Moist wall - gases dissolve which facilitates diffusion.
• Ventilation + blood flow maintain conc gradient

Question 12

2.49: What are the ill effects of smoking?

Answer 12

CO
- Binds irreversibly to haemoglobin
- Less oxygen is transported in blood.

Nicotine:
- Constricts arterioles + makes blood more viscous/ sticky.
- Raises blood pressure

Tar
- Carcinogenic
- Paralyses cilia —> mucous buildup -> increases risk of bacterial infection/ pneumonia + inflammation (bronchitis)

Emphysema
- alveoli walls breakdown —> decreases surface area available for gas exchange.

Question 13

2.49: What is coronary heart disease?

Answer 13

• CHD involves the blockage of Coronary Artery by Fat globules (forming plaques), causing insufficient Oxygen transport in blood leading to increased anaerobic respiration (due to lack of Oxygen)
• Increase in anaerobic respiration causes build-up of Lactic acid which creates acidic environment for enzymes to denature, hence causing strokes