B8.1 Gas Exchange

Question 1

How is the respiratory system adapted for efficient gas exchange?

Answer 1

• large surface area
• thin surface
• good blood supply
• good ventilation with air
• The walls of the alveolus and the capillary are one cell thick –> allowing faster gas exchange and diffusion
• The alveoli have a good blood supply–> more carbon dioxide and oxygen can be diffused into the bloodstream allowing better circulation
• There are millions of tiny alveoli instead. of one big alveolus –> to increase surface area for gas exchange
• Breathing helps support gas exchange –> brings in oxygen and takes CO2 out

Question 2

Explain the process of breathing in

Answer 2

• Internal intercostal muscles relax whilst the external intercostal muscles contract
• Ribs rise upwards
• Diaphragm flattens
• Volume increases
• Air enters the lungs

Question 3

Function of the trachea

Answer 3

Allows air to enter the respiratory system

Question 4

Function of the alveoli (air sacs)

Answer 4

• Where gas exchange occurs
• Oxygen moves from the air into the bloodstream and carbon dioxide moves from the bloodstream into the air in the lungs
• Surrounded by capillaries

Question 5

Function of the ribs

Answer 5

Protects the lungs inside the chest cavity

Question 6

Function of the intercostal muscles

Answer 6

Moves the ribcage up and down

Question 7

Function of the diaphragm

Answer 7

Controls the size of the chest cavity during breathing

Question 8

Function of the bronchi

Answer 8

Supplies air to lungs

Question 9

Function of the bronchioles

Answer 9

Supplies air to the alveoli

Question 10

Function of the larynx

Answer 10

Makes sounds

Question 11

Causes of Chronic obstructive pulmonary disease (COPD)

Answer 11

Particles in smoke

Question 12

Consequences of Chronic obstructive pulmonary disease (COPD)

Answer 12

• Cilia gets worn down –> cannot sweep mucus –> mucus builds up –> cough

Question 13

Oxygen and CO2 levels of inspired air

Answer 13

The inspired air always has high oxygen levels and low carbon dioxide levels

Question 14

Oxygen and CO2 levels of blood

Answer 14

• the blood has high carbon dioxide levels and low oxygen levels- so by diffusion, the alveoli loses oxygen and gain carbon dioxide - which is then exhaled

Question 15

What happens to the diaphragm when breathing in?

Answer 15

Contracts and flattens

Question 16

What happens to the diaphragm when breathing out?

Answer 16

Relaxes and creates a dome-shape

Question 17

What would happen to the pH of the blood after exercise?

Answer 17

pH decreases;
increased rate of aerobic respiration;
more carbon dioxide (into blood plasma);
forms (carbonic) acid;
anaerobic respiration occurs (during strenuous exercise);
lactic acid produced;

Question 18

What happens to the rib cage when breathing in?

Answer 18

Rises upwards

Question 19

Test for carbon dioxide

Answer 19

Limewater test

Question 20

How is lung cancer caused?

Answer 20

• Cigarette smoke contains carcinogens (cancer-causing chemicals)
• The cells of the respiratory system grow out of control and form a tumour