C2 - Functions of the respiratory system

Question 1

What are the mechanisms of breathing?

Answer 1

• breathing or ‘pulmonary ventilation’ is the process of air being transported into and out of the lungs

Question 2

What are the two phases of the respiratory system?

Answer 2

• inspiration (active)
• expiration (passive)

Question 3

Inhalation is …

Answer 3

• external intercostal muscles contract, lifting the ribs upwards and outwards
• partial pressure drop inside the lungs to below atmospheric pressure
• air particles move from an area of high concentration to an area of low concentration
• diaphragm contracts an is forced downwards

Question 4

Exhalation is …

Answer 4

• internal intercostal muscles contract, drawing the ribs downwards and inwards
• partial pressure increases inside the lungs to above atmospheric pressure
• air particles move from an area of high concentration to an area of low concentration
• diaphragm relaxes and moves upwards

Question 5

Gaseous exchange is …

Answer 5

• occurs at the alveoli and working muscles
• through the process of diffusion (high to low)
• alveoli and capillary walls create a respiratory membrane which has gas on one side and blood on the other
• oxygen is transferred through simple diffusion from high within the alveoli to low in the red blood cells
• oxygen diffuses through the alveolar walls, the capillary wall through the red blood cell membrane and attaches to the haemoglobin in the red blood cell

Question 6

The alveoli are perfectly designed for their job by …

Answer 6

• having a very high surface area
• having a million of alveoli in each lung
• having a very good blood supply