Unit 4- 2.2~ Inspiration and expiration

Question 1

What is the process inspiration (inhalation)?

Answer 1

1. Intercostal muscles contract and diaphragm flattens
2. Ribcage moves up and outwards
3. Air pressure in lungs is less than atmospheric pressure, creating a pressure gradient
4. Air moves through trachea, brochi, bronchioles & across alveoli
5. Oxygen diffuses from alveoli to capillaries binding to haemogloblins
6. Co2 diffuses from capillaries to air sacs
7. Oxygen is carried through capillaires to pulmonary veins delivering to the left side of the heart

Question 2

What are the types of expiration (exhalation)?

Answer 2

Passive or active

Question 3

What is passive expiration?

Answer 3

• Most common, when diaphragm and intercostal muscles relax
• The relaxation reduces the size of chest cavity, increasing pressure
• The pressue forces air out of lungs

Question 4

What is active expiration?

Answer 4

• Happens during vigorous exercise or in conditions like chronic obstructive pulmonary disease
• Involves contraction of the muscle in the abdomen, forcing air out, increasing respiratory rate

Question 5

What is the role of pleural membranes?

Answer 5

The pleural membranes secrete a lubricating fluid which allows them to move freely against each other during ventilation. WIthout this breathing would dbe difficult and painful.

Question 6

What is the role of the diaphragm?

Answer 6

• Inspiration: The diaphragm contracts and flattens causing an increase in the volume of the lungs
• Expiration: The diaphragm relaxes and moves upwards leading to a decrease in the volume of the lungs

Question 7

What is the role of intercostal muscles?

Answer 7

• Inspiration: They contract and move the ribs upwards and outwards, increasing the size of the chest and decrease the air pressure inside which sucks air into the lungs
• Expiration: Muscles relax so the ribs move inwards and downwards, decreasing the size of the chest and increasing air pressure forcing air out the lungs

Question 8

What is the process of expiration?

Answer 8

1. Intercostal muscles relax and diaphragm forms a D-shape
2. Ribcage moves down and inwards
3. Air pressure is higher in lungs than atmospheric pressure, creating a pressure gradient
4. Air moves out of lungs through bronchioles, bronchi and trachea
5. Carbon dioxide moves out the lungs