SEHS Topic 2.1

Question 1

What is the principal structures of the ventilatory system?

Answer 1

Nose, Mouth, Pharynx, Larynx, Trachea, Bronchi, Bronchioles, Lungs, Alveoli

Question 2

What are the functions of the conducting airway?

Answer 2

1. Low resistance pathway for airflow
2. Defence against chemicals and other harmful substances that are inhaled
3. Warming and moistening the air

Question 3

What is the function of the Nose? (Conducting Airways)

Answer 3

Humidifies the air and filters particles

Question 4

What is the function of Pharynx? (Conducting Airways)

Answer 4

Offers a low resistance pathway for airflow

Question 5

What is the function of Larynx? (Conducting Airways)

Answer 5

Functions as the ‘voice box’ and protects the trachea from invasion of foods and fluids

Question 6

Define Pulmonary Ventilation.

Answer 6

Movement of air in and out of the lungs (breathing)

Question 7

Define Total Lung Capacity (TLC).

Answer 7

The amount of air in the lungs after a maximal inspiration

Question 8

Define Vital Capacity (VC).

Answer 8

The amount of air an individual can inhale or exhale during normal quiet breathing (7-8% of total lung capacity)

Question 9

Define Expiratory Reserve Volume (ERV).

Answer 9

The amount of air that an individual can inhale above a tidal inspiration (20% of the total lung capacity)

Question 10

Define Inspiratory Reserve Volume (IRV).

Answer 10

The amount of air that an individual can inhale above a tidal inspiration (60% of total lung capacity)

Question 11

Define Residual Volume (RV).

Answer 11

The amount of air remaining in the lungs after a maximal exhalation (makes up 20% of the total capacity)

Question 12

What happens during inhalation? (Mechanics of Ventilation)

Answer 12

1. Diaphragm contracts and lowers
2. External intercostal muscles contract
3. This causes the rib cage to move upwards and outwards
4. The volume of the chest cavity increases
5. The pressure inside the lungs drops below atmospheric pressure
6. Air rushes into the lungs

Question 13

What happens during Exhalation? (Mechanics of Ventilation)

Answer 13

1. The diaphragm relaxes and turn to a dome shape
2. Internal intercostal muscles contract
3. This causes the ribcage to move downwards and inwards
4. The volume of the chest cavity decreases
5. The pressure inside the lungs increases above atmospheric pressure
6. Air is forced out of the lungs and into the atmosphere

Question 14

Describe how Ventilation differs during exercise. (Nervous & Chemical Control)

Answer 14

Ventilation increases as a direct result of increases in blood acidity levels due to increase in CO2 content in the blood, which is detected by the respiratory centre.

This results in an increase in the rate and depth of ventilation.

Question 15

What receptors does the respiratory centre (Neural control) go through in order to send messages to the ventilatory muscles? (Nervous & Chemical Control)

Answer 15

Neural control of ventilation includes lung stretch receptors, muscle proprioceptors and chemoreceptors.

Question 16

What is the role of hemoglobin in oxygen transportation?

Answer 16

98.5% of oxygen in the blood is transported by hemoglobin as oxyhemoglobin within red blood cells

Question 17

What is Gaseous Exchange at the alveoli?

Answer 17

The delivery of oxygen from the lungs to the bloodstream, and the elimination of carbon dioxide from the bloodstream to the lungs. It occurs in the lungs between the alveoli and the capillaries which are located around the walls of the alveoli.

Question 18

How do oxygen and carbon dioxide take place in the alveoli during gas exchange?

Answer 18

1. Oxygen from the inhaled air diffuses through the walls of the alveoli and into the capillaries
2. The red blood cells carry the oxygen to the body (oxygenated)
3. Carbon dioxide which is produced by the body return to the lungs in the red blood cells (deoxygenated)
4. The carbon dioxide then diffuses across the capillary and the alveolar walls into the air so that it can be removed from the body via expiration

Question 19

What are the adaptations of Alveoli?
(These adaptations make the gaseous exchange more efficient)

Answer 19

• Walls of the alveoli are one cell thick
• They are folded, providing a larger surface area
• They are each surrounded by capillary which allows the good blood supply