7.2.2 - The mammalian gaseous exchange system (Part 2 - Inhalation and Exhalation)

Question 1

What is ventillation?

Answer 1

Ventilation, or breathing, is the constant movement of air into and out of the lungs. It consists of inspiration (breathing in) and expiration (breathing out).

It allows air to enter and leave the lungs, providing the body with oxygen and removing carbon dioxide.

Question 2

How is air moved in and out of the lungs?

Answer 2

Air is moved in and out of the lungs through pressure changes in the thorax (chest cavity) caused by breathing movements, a process known as ventilation.

Question 3

What role does the rib cage play in ventilation?

Answer 3

The rib cage provides a semi-rigid structure that helps lower the pressure inside the thorax relative to the outside air, allowing air to flow in and out of the lungs.

Question 4

What is the function of the diaphragm in ventilation?

Answer 4

The diaphragm is a broad, domed sheet of muscle that forms the floor of the thorax. Its contraction and relaxation help change the volume of the thorax and thus control airflow into and out of the lungs.

Question 5

Where are the external and internal intercostal muscles located, and what is their role?

Answer 5

The external and internal intercostal muscles are found between the ribs. They help move the rib cage during breathing, aiding in the expansion and contraction of the thorax.

Question 6

What is the role of the pleural membrane in ventilation?

Answer 6

The pleural membrane surrounds the lungs and lines the thorax. It helps protect the lungs and creates a smooth surface for easy sliding as the lungs expand and contract during breathing.

Question 7

What is the pleural cavity, and what does it contain?

Answer 7

The pleural cavity is the space between the pleural membranes that surrounds the lungs. It is usually filled with a thin layer of lubricating fluid, which allows the membranes to slide smoothly over each other as you breathe.

Question 8

What is the passage of air into the lungs?

Answer 8

1. Nose/Mouth
2. Trachea (Windpipe)
3. Bronchi
4. Bronchioles
5. Alveoli

Question 9

What type of process is inspiration (inhalation)?

Answer 9

Inspiration is an energy-using process that requires the expenditure of energy to draw air into the lungs.

Question 10

Describe what happens during Inspiration (taking in air/inhalation)?

Answer 10

1.Dome shaped diaphragm contracts, flattens and lowers.

2. External Intercostal muscles contract
3. Ribcage move up and out.
4. Volume of Thorax increases
5. Pressure inside thorax decreases
6. Air is drawn in.

Question 11

How is air drawn in during inspiration, and what does this do?

Answer 11

Air is drawn through the nasal passages, trachea, bronchi, and bronchioles into the lungs, equalizing the pressures inside and outside the chest.

Question 12

Is normal expiration (breathing out) an active or passive process?

Answer 12

Normal expiration is a passive process that does not require energy.

Question 13

Describe what happens during expiration (breathing out air/exhalation)?

Answer 13

1. muscle of the diaphragm relaxes, so moves into its resting domed shape.
2. External Intercostal muscle relax.
3. Ribcage moves down and in.
4. Elastic fibres in alveoli return to normal length.
5. Volume of Thorax decreases.
6. Pressure inside Thorax increases.
7. Air is forced out.

Question 14

Can expiration be forced? If so, how?

Answer 14

Yes, expiration can be forced by using energy. The internal intercostal muscles contract, pulling the ribs down hard and fast, while the abdominal muscles contract, forcing the diaphragm up to rapidly increase pressure in the lungs.