Respiratory Physiology 3

Question 1

Define ANATOMICAL DEAD SPACE

Answer 1

The volume of gas occupied by the conducting airways and this gas is not available for exchange.

Question 2

What are the 2 ways to describe VENTILATION?

Answer 2

Pulmonary (Minute) ventilation
Alveolar ventilation

Question 3

Define PULMONARY (minute) VENTILATION

Answer 3

total air movement into/out of lungs (relatively insignificant in functional terms)

Question 4

Define ALVEOLAR VENTILATION

Answer 4

fresh air getting to alveoli and therefore available for gas exchange (functionally much more significant!) (Value of 4200)

Question 5

Under normal conditions what is the relationship between RESTING P02 and PCO2?

Answer 5

remain fairly constant

Question 6

What happens during HYPER-VENTILATION (increased alveolar ventilation) ?

Answer 6

PO2 rises to about 120 mm Hg and PCO2 falls to about 20 mmHg.

Question 7

What happens during HYPO-VENTILATION (decreased alveolar ventilation)

Answer 7

PO2 falls to 30 mmHg and PCO2 rises to 100 mmHg.

Question 8

What is the normal alveolar partial pressure of O2?

Answer 8

100mmHg (13.3kPa)

Question 9

What is the normal alveolar partial pressure of CO2?

Answer 9

40mmHg (5.3kPa)

Question 10

What is the blood supply to the lungs?

Answer 10

Pulmonary artery carries deoxygenated blood AWAY from the heart to the lungs.

Pulmonary vein carries oxygenated blood TOWARDS the heart from the lungs.

Question 11

What is pulmonary circulation opposite in function to?

Answer 11

Systemic circulation
It delivers CO2 to the lungs and picks up O2.

Question 12

How is BRONCHIAL CIRCULATION (nutritive) supplied?

Answer 12

via the bronchial arteries arising from systemic circulation to supply oxygenated blood to lung tissues

Question 13

What does the PULMONARY CIRCULATION (gas exchange) consist of?

Answer 13

L&R pulmonary arteries originating from the right ventricle.
Entire cardiac output from RV

Question 14

What does the PULMONARY CIRCULATION supply?

Answer 14

The dense capillary network surrounding the alveoli and returns oxygenated blood to the left atrium via the pulmonary vein.

Question 15

What is PaO2

Answer 15

partial pressure of oxygen in arterial blood

Question 16

What is PACO2

Answer 16

Partial pressure of carbon dioxide in alveolar air

Question 17

What is the rate of diffusion across the membrane directly proportional to?

Answer 17

• the partial pressure gradient
• gas solubility
• the available surface area

Question 18

What is the rate of diffusion across the membrane inversely proportional to?

Answer 18

the thickness of the membrane

Question 19

What is EMPHYSEMA?

Answer 19

Destruction of alveoli reduces surface area for gas exchange and loss of elasticity

Question 20

What is Fibrotic lung disease?

Answer 20

Thickened alveolar membrane slows gas exchange.
Loss of lung compliance may decrease alveolar ventilation

Question 21

What is PULMONARY OEDEMA?

Why may Arterial PCO2 be normal?

Answer 21

Fluid in interstitial space increases diffusion distance.

due to higher CO2 solubility in water

Question 22

What is ASTHMA?

Answer 22

Over reactive constriction of bronchial smooth muscle
Increased airway resistance decreases airway ventilation

Question 23

What is an obstructive lung disorder?

Answer 23

Obstruction of air flow, especially on expiration

Increases the work of expiration

Question 24

What is a RESTRICTIVE lung disorder?

Answer 24

Restriction of lung expansion

Increases the work of inspiration
— Loss of lung compliance

Question 25

Give examples of RESTRICTIVE lung disorders

Answer 25

• Fibrosis: formation of excess fibrous connective tissue creates a “stiff” lung.
  ~ Idiopathic (cause unknown)
  ~ Asbestosis (and other occupational origins e.g. coal dust)
• Infant Respiratory Distress Syndrome: (insufficient surfactant production)
• Oedema
• Pneumothorax

Question 26

What is SPIROMETRY?

Answer 26

Technique commonly used to measure lung function

Measurements can be classed as static (where the only consideration made is the volume exhaled) or dynamic (where the time taken to exhale a certain volume is what is being measured)