1.2 The Respiratory System

Question 1

What is the passage of air?

Answer 1

1. Nose
2. Pharynx
3. Larynx
4. Trachea
5. Bronchi
6. Bronchioles
7. Alveoli

Question 2

What muscles are used for inspiration at rest?

Answer 2

Diaphragm
External intercostals

Question 3

What muscles are used for inspiration during exercise?

Answer 3

Diaphragm
External intercostals
Sternocleidomastoid
Scalene
Pectoralis minor

Question 4

What muscles are used for expiration at rest?

Answer 4

Diaphragm
External intercostal
(relax)

Question 5

What muscles are used for expiration during exercise?

Answer 5

Internal intercostals
Abdominals

Question 6

Definition of gaseous exchange

Answer 6

The movement of oxygen from the air into the blood, and carbon dioxide from the blood into the air.

Question 7

Features of alveoli to assist gaseous exchange

Answer 7

• Large SA –> more rapid diffusion
• Thin/moist walls –> short distance for diffusion
• Lots of capillaries –> large blood supply

Question 8

Definition of diffusion

Answer 8

The movement of gas molecules from high to low concentration/partial pressure.

Question 9

Definition of tidal volume

Answer 9

Volume of air breathed in or out per breath. Increases during exercise.

Question 10

Definition of inspiratory/expiratory reserve volume

Answer 10

Inspiratory is the volume of air that can be forcibly inspired after a normal breath.

Expiratory is the volume of air that can be forcibly expired after a normal breath.

Question 11

Definition of residual volume

Answer 11

The volume of air remaining in the lungs after maximum expiration.

Question 12

Definition and calculation of minute ventilation

Answer 12

Volume of air breathed in or out per minute.

Minute ventilation = tidal vol x number of breaths/min

Question 13

What does a spirometer measure?

Answer 13

Volume of air inspired and expired by the lungs.

Question 14

What happens to CO₂ and O2 during gaseous exchange?

Answer 14

CO₂ diffuses from the blood capillary into the alveolus along the concentration gradient.
O2 diffuses from the high concentration in the alveolus to the low concentration in the blood capillary.

Question 15

What happens to pressure during inspiration?

Answer 15

When the diaphragm and external intercostals contract, it causes the ribcage to move upwards/outwards which DECREASES pressure in the chest cavity as there is more space.

Question 16

What happens to pressure during expiration?

Answer 16

When the diaphragm relaxes, it rises into a dome-shaped position which INCREASES pressure in the chest cavity.

Question 17

What is the function of the respiratory system?

Answer 17

To get oxygen to the working muscles and get rid of CO2.

Question 18

Gas exchange at the alveoli

Answer 18

O2 diffuses from alveoli into blood, CO2 diffuses from blood into alveoli.

Partial pressure of oxygen is higher in the alveoli than in the blood capillary.
This is because oxygen has been removed by the working muscles so the concentration/partial pressure in the blood is lower.
Oxygen will diffuse from the alveoli into the blood until the pressure is equal in both.

Question 19

Gas exchange at the muscles

Answer 19

O2 enters the muscles from the blood, and CO2 enters the blood from the muscles.

Question 20

How does smoking affect the respiratory system?

Answer 20

• Causes irritation in the trachea and bronchi.
• Reduces lung function.
• Increases breathlessness (swelling/narrowing of airways).
• Cigarette smoke damages cell lining.
• Smokers cough.
• COPD, emphysema, lung disease.
• Inhalation of smoke causes paralysis of the cilia.

Question 21

What happens when blood acidity is high?

Answer 21

The brain sends impulses through the nervous system to increase breathing.

Question 22

How is pulmonary ventilation controlled?

Answer 22

By the nervous system, which has two systems: sympathetic and parasympathetic.

Question 23

What does the sympathetic nervous system do?

Answer 23

Prepares the body for exercise and increases breathing rate.

Question 24

What does the parasympathetic nervous system do?

Answer 24

Lowers breathing rate.

Question 25

Where is the respiratory centre located and what does it do?

Answer 25

Located in the medulla oblongata and controls the rate/depth of breathing using neural and chemical control

Question 26

The Respiratory Centre (4 steps)

Answer 26

1. Responds to changes in blood chemistry.
2. These changes are detected by chemoreceptors.
3. They send impulses to the inspiratory centre to increase ventilation until blood acidity returns to normal.
4. Respiratory centre sends impulses down the phrenic nerve to stimulate more inspiratory muscles to increase breathing.

Question 27

Order of neural/chemical control for inspiration

Answer 27

Receptors
Medulla oblongata
Phrenic nerve
Diaphragm, external intercostals, sternocleidomastoid, scalene, pectoralis minor

Question 28

Order of neural/chemical control for expiration

Answer 28

Receptors
Medulla oblongata
Intercostal nerve
Abdominals, internal intercostals

Question 29

Factors affecting neural control of breathing

Answer 29

• Mechanical factors: provide feedback to respiratory centre to increase breathing during exercise.
• Baroreceptors: a decrease in blood pressure in the aorta and carotid arteries = increased breathing.
• Stretch receptors: prevent over inflation of the lungs

Question 30

What is adrenaline?

Answer 30

A natural stimulant which is the body’s activator and is released in response to exercise.

Question 31

Where is adrenaline made?

Answer 31

Adrenal gland in the kidney

Question 32

How does adrenaline work?

Answer 32

Just before exercise, the brain sends impulses to the renal glands which then pumps adrenaline into the blood, in anticipation of the increased need for O2 and CO2 exchange.