4.5 Breathing And Gas Exchange

Question 1

Describe how air is moved in and out of the lungs.

Answer 1

by the contraction and relaxation of the intercostal muscles and the diaphragm, changing pressure inside the chest cavity

Question 2

What is meant by the term “gaseous exchange”?

Answer 2

The exchange of oxygen and carbon dioxide between the air in the lungs and the bloodstream.

Question 3

Why is ventilation important for your body?

Answer 3

supplies oxygen to the body and removes waste carbon dioxide from the blood.

Question 4

What is the difference in the composition of gases when you breathe in compared to when you breathe out?

Answer 4

80% nitrogen, 16% oxygen, and 4% carbon dioxide

Question 5

Why is there less oxygen in exhaled air compared to inhaled air?

Answer 5

Oxygen is absorbed by the bloodstream from the lungs during gas exchange, leaving less oxygen in the exhaled air

Question 6

Describe the adaptations of the alveoli and explain how they make gas exchange efficient.

Answer 6

• The alveoli provide a large surface area
• Have thin walls (only one cell thick)
• surrounded by capillaries with rich blood supply
• these adaptations create a steep concentration gradient and allow rapid diffusion of gases

Question 7

Describe the passage of air to the lungs

Answer 7

Nose —> trachea —> bronchi —> bronchioles —> alveoli —> blood

Question 8

How does the diaphragm contribute to ventilation?

Answer 8

The diaphragm contracts and flattens to increase the volume of the chest cavity during inhalation and relaxes to decrease the volume during exhalation, causing air to flow in and out of the lungs

Question 9

What happens to the pressure inside the chest cavity when you inhale?

Answer 9

The pressure decreases as the chest cavity expands, allowing air to flow into the lungs

Question 10

How does oxygen move from the alveoli into the blood?

Answer 10

Oxygen diffuses across the thin walls of the alveoli into the blood, where it binds to the haemoglobin in red blood cells

Question 11

How is carbon dioxide removed from the bloodstream?

Answer 11

Carbon dioxide diffuses from the blood into the alveoli and is expelled from the lungs during exhalation

Question 12

What role do the intercostal muscles play in ventilation?

Answer 12

The intercostal muscles contract to raise the ribs and expand the chest cavity during inhalation and relax to lower the rubs during exhalation

Question 13

What is the purpose of maintaining a steep concentration gradient in the lungs?

Answer 13

A steep concentration gradient ensures efficient diffusion of oxygen into the blood and carbon dioxide out of the blood

Question 14

What gases are exchanged in the alveoli during breathing?

Answer 14

Oxygen is absorbed into the blood, and carbon dioxide is released from the blood into the air from the lungs

Question 15

What happens in our body when we inhale

Answer 15

1. external intercostal muscles contract
2. internal intercostal muscles relax
3. ribs move upwards and out
4. diaphragm flattens
5. volume of the chest increases
6. pressure inside the chest decreases
7. air is drawn into the lungs