Ventilation & Compliance 1-2

Question 1

What is the definition of tidal volume & what is the figure ?

Answer 1

Tidal volume: How much air is breathed in & out of the lungs each breath (500ml)

Question 2

Define Expiratory Reserve Volume

Answer 2

The maximum volume of air which can be expelled from the lungs at the end of a normal expiration (1100ml)

Question 3

Define Inspiratory Reserve Volume

Answer 3

The maximum volume of air which can be drawn into the lungs at the end of a normal inspiration

Question 4

Define Residual Volume

Answer 4

The amount of gas left in the lungs/alveoli at the end of a maximum expiration (cannot expel this from the lungs its always present) (1200ml)

Question 5

Define Vital Capacity

Answer 5

Tidal volume + inspiratory reserve volume + expiratory reserve volume (total lung capacity -residual volume)

Question 6

Define Total Lung Capacity

Answer 6

The total volume of air that the lungs can hold upon maximum inspiration and maximum expiration.

Question 7

Define inspiratory Capacity

Answer 7

Tidal volume + inspiratory reserve volume

Question 8

Define Functional Residual Capacity

Answer 8

Expiratory reserve volume + residual volume

Question 9

What is pulmonary ventilation ?

Answer 9

Total air movement in & out of the lungs (Anatomical dead space isn’t counted)

Question 10

What is alveolar ventilation ?

Answer 10

Fresh air getting into the alveoli and therefore available for gas exchange (includes 150ml of dead space in the conduction airway)

Question 11

What is Dalton’s law ?

Answer 11

The total pressure of a gas is the sum of all the individual gasses

Question 12

What role does sufactant play in respiration ?

Answer 12

It reduces the surface tension of the Alveoli meaning they do not collapse and are more easily filled up.

Question 13

What is the law of Laplace ?

Answer 13

P=2T/r (where P= pressure, T=Surface tension & r= radius of alveoli) surfactant works best within alveoli with a small radius

Question 14

Define the term compliance

Answer 14

Compliance: The change in volume is relative to the change in pressure.

Question 15

What does high compliance and low compliance mean ?

Answer 15

High compliance: Large increase in lung volume for small decrease in Pip (normal)
Low compliance: Small increase in lung volume for small decrease in Pip (fibrotic lungs)

Question 16

What causes loss of lung compliance ?

Answer 16

lung stiffness and incomplete lung expansion

Question 17

What is the normal FEV1/FVC ratio ?

Answer 17

80%

Question 18

What are the two forms of spirometry & what do they measure ?

Answer 18

static: Volume exhaled
Dynamic: Time taken to exhale a certain volume (most common form)

Question 19

Name the two main respiratory groups found within the medulla

Answer 19

The Dorsal respiratory group & the ventral respiratory group.

Question 20

What are the receptors in the medulla called ?

Answer 20

The central chemo receptors

Question 21

What are the DRG and VRG responsible for >

Answer 21

DRG: Inspiration muscles via phrenic & intercostal nerves.
VRG: Responsible for expiatory muscles & stops tongue from blocking airway

Question 22

Explain how the central chemo receptors serve to regulate arterial PCO2

Answer 22

1: PCO2 increases in the bloodstream
2: This increases the amount of H ions in the CSF
3: This is picked up by the central chemo receptors
4: Brain then tells brain to increase ventilation until normal levels are reached

Question 23

What is the condition caused by too many H ions ?

Answer 23

Acidosis

Question 24

What is the condition caused by a decrease in H ions ?

Answer 24

Alkalosis

Question 25

Where are the peripheral receptors found ?

Answer 25

In the carotid & aortic bodies

Question 26

How do the peripheral receptors assist in regulating oxygenation ?

Answer 26

They respond to H ions but not necessarily PaCO2 levels. They also provide reflex stimulation of ventilation following a significant fall in PO2