How we breathe

Question 1

Intercostal muscles

Answer 1

• The muscle that runs across the ribs
• Moves the ribs up and outwards when contract, causing the thoracic cavity to expand

Question 2

Diaphragm

Answer 2

• The muscle below the lungs
• Moves inferiorly when contract, causing the thoracic cavity to expand

Question 3

Inspiration (inhalation)

Answer 3

• the diaphragm contracts and flattens out, intercostal muscles contract and pull the ribs upwards and outwards.
  -the thoracic cavity to expand and enlarge, which decreases the pressure in lungs to belong atmospheric pressure (760 mmHg)
  -Air rushes in the lungs through nose and mouth because of diffusion
• Inspiration ends when the pressure is equal inside and out

Question 4

Expiration (exhalation)

Answer 4

• Diaphragm and intercostal muscles relax, causing the ribs to move down and in, and diaphragm raises
• Causes the thoracic cavity to decrease in size
• Causes the pressure in lungs to be higher than pressure outside
• Air rushes out through nose and mouth as the result