Gas Exchange In Humans

Question 1

Gas Exchange System

Answer 1

• breathe in air enters trachea
• trachea splits into 2 bronchi - 1 bronchus leading to each lung
• each bronchus branches into smaller tubes called bronchioles
• bronchioles end in smaller air sacs called alveoli where gases exchange happens
• ribcage, intercostal muscles and diaphragm all work together to move air in and out

Question 2

intercostal muscles

Answer 2

• found between ribs

- internal and external intercostal muscles

Question 3

insparation

Answer 3

• external intercostal and diaphragm muscles contract
• rib cage moves upwards and outwards and diaphragm flattens increasing volume of thoracic cavity
• thoracic cavity increases, lung pressure decreases to below atmospheric pressure
• high pressure to low pressure so down pressure gradient allowing air to flow down trachea and into lungs

Question 4

Expiration

Answer 4

• external intercostal muscles and diaphragm relax
• ribcage moves downwards and inwards
• diaphragm curves upwards again so becomes dome shaped
• volume of thoracic cavity decreases, causing air pressure to increase above atmospheric pressure
• air forced down pressure gradient and out of lungs
• passive process - doesn’t require energy

Question 5

Forced Ventilation

Answer 5

• external intercostal muscles relax and internal intercostal muscles contract
• pulling rib cage further down and in
• during this time the movement of 2 sets of intercostal muscles is said to be antagonistic