Respiratory system

Question 1

What is the primary reason for breathing?

Answer 1

1. To supply O2 to blood.

2. To remove CO2 from blood.

Question 2

What is the significance for the cartilage in the upper airways?

Answer 2

Keeps the airway open and prevents it from collapsing.

Question 3

Describe the structures of the conducting zone

Answer 3

The conducting zone is made up of:
>Nose
>Pharynx
>Larynx
>Trachea
>Bronchi
>Bronchioles
>Terminal bronchioles

Question 4

Describe the function of the conducting zone

Answer 4

The structures of the conducting zone filters, warms, moistens and conducts air into the respiratory zone.

Question 5

Describe the structures of the respiratory zone

Answer 5

The respiratory zone consists of:
>Respiratory bronchioles
>Alveoli

Question 6

Describe the function of the respiratory zone

Answer 6

Gas exchange occurs here.

Question 7

Is VD (dead space) in the conducting zone or the respiratory zone?

Answer 7

The conducting zone.

Question 8

What is the usual approximate volume of VD (dead space).

Answer 8

2.2mL/Kg of body weight.

VD is usually 150mL.

Question 9

What is VD (dead space)?

Answer 9

The amount of air inhaled which does not participate in gas exchange.

Question 10

Describe the function of the alveoli.

Answer 10

Type 1 alveoli are where 90% of the gas exchange in our body occurs.

Type 2 alveoli produce a surfactant which helps to create surface tension, preventing the alveoli from collapsing.

Question 11

Which structures comprise the respiratory membrane?

Answer 11

The respiratory membrane is composed of:

1. A layer of type 1 and type 2 alveolar cells.
2. An epithelial membrane underlying the alveolar wall.
3. A capillary membrane that is often fused with the epithelial membrane.
4. The capillary endothelium (capillary wall).

Question 12

Why is the surfactant produced by type 2 alveolar cells needed in the liquid film that coats alveolar walls?

Answer 12

The surfactant facilitates lung inflation by lowering the surface tension on gas-exposed alveolar surfaces.

Question 13

What is the significance of the amount of smooth muscle in the smaller airways in terms of airflow?

Answer 13

The smooth muscle enables control of the diameter of the airways in relation to the rate of gas exchange required.

For example, airways are slightly wider (brochodilation) during exercise and slightly narrower (bronchoconstriction) during tidal breathing.

Question 14

Describe the function of the pleurae in the mechanics of breathing

Answer 14

The pleurae reduce friction during breathing.

They also help the create negative pressure when we breathe in and positive pressure when we breathe out.

Question 15

How is O2 transported in the blood?

Answer 15

97% of O2 is carried when attached to haemoglobin (forming oxyhaemoglobin) because it is not very soluble.

The other 3% of O2 is dissolved in plasma.

Question 16

What is the normal range for PaO2?

Answer 16

80-100mmHg

Question 17

What is the normal range for SaO2?

Answer 17

95-99%

Question 18

What is cyanosis?

Answer 18

Bluish discolouration of the skin and mucous membranes caused by increased amounts of desaturated haemoglobin or reduced haemoglobin.

Question 19

What are the predominant factors that influence rate of breathing?

Answer 19

Changes in O2 demand and/or CO2 levels in the blood.

The most powerful stimulation to breathe is the accumulation of CO2 in the blood. Chemoreceptors in the brainstem, carotid arteries and aortic arch detect elevated levels of CO2 and stimulate the respiratory centre in the medulla oblongata.

Question 20

What are some activities or medical conditions that might increase ventilation rate?

Answer 20

Exercise

Stress

All cases of metabolic acidosis where ventilation rate increases to reduce levels of CO2 in the blood.

Emphysema (hypoxia)

Anxiety

Question 21

How does maximal breathing affect CO2 levels?

Answer 21

CO2 levels should decrease in response to maximal breathing.

Question 22

Why does hyperventilation allow for prolonged breath holding?

Answer 22

hyperventilation reduces blood CO2 so the stimulus to breathe is absent for longer.

Question 23

What can affect respiratory drive?

Answer 23

The drive to breathe is affected by:
>Level of CO2 in the blood
>Narcotics
>Brain damage
>Elevated ICP (inter-cranial pressure)
>Decrease in metabolic rate.

Question 24

What are some activities or medical conditions that might decrease respiratory rate?

Answer 24

Rest

Meditation

Narcotics