Ventilation and gas exchange

Question 1

Draw and label the graph that show tidal volume

which is the least useful clinically? Why

Answer 1

Expiratory capacity- it fluctuates (in tidal volume area)

Question 2

What is the equation for minute ventilation?

what is the normal breathing frequency

Answer 2

Tidal volume X Breathing frequency

normal breathing frequency is 12 breaths/min

Question 3

What is the equation for alveolar ventilation

Answer 3

(Tidal volume - Dead space ) X breathing frequency

Question 4

What are the factors affecting lungs volumes and capacities?

Answer 4

• Body size- larger height increases lubing volume
• Fitness- more training increases volume and capacity
• sex- males have higher lung volume
• Disease-
• Age- chronological (time) and physical( how well your body looks)

Question 5

What is dead space? What are the areas of dead space in a healthy individual - describe it’s features

Answer 5

Spaces in airway where THERE IS NO VENTILATION (gas exchange)

in healthy individuals it is the conduction zone of the trachea and brochi

CONDUCTING ZONE

• 16 generations
• No gas exchange
• 150 mL in adults at FRC
• THIS IS THE ANATOMICAL DEAD SPACE

Question 6

Describe the features of the respiratory zone of the airway

Answer 6

• 7 generations
• Gas exchange
• typically 350mL in adults
• air reaching here is equivalent to alveolar ventilation

Question 7

What is the physiological dead space in healthy and unhealthy individuals ?

Answer 7

Healthy- physiological dead space is equal to anatomical dead space

unhealthy- physiological dead space = anatomical plus ALVEOLAR SPACE

Question 8

What is alveolar dead space?

Answer 8

Alveoli without blood supply - non perfused parenchyma

No gas exchange

Typically 0mL in healthy adults

Question 9

What are the ways of increasing or decreasing dead space

Answer 9

Increase

• anaesthetic snorkelling

decrease

• tracheostomy or cricothyroidostomy

can you think of any more

Question 10

Describe the relationship between the chest wall and the lungs

Answer 10

Chest wall wants to expand outwards and lung wants to collapse inwards.

at functional residual capacity, they are at equilibrium- Chest recoil= Lung recoil

Question 11

Describe the forces between chest wall and lungs that results to inspiration and expiration

Answer 11

Inspiration

Inspiratory muscle effort + chest recoil is GREATER than lung recoil

Expiration

Chest recoil is LESS than LUNG RECOIL and expiratory muscle effort

Question 12

How is the chest wall connected to the lungs- anatomy

Answer 12

Lung is connected via pleural cavity

visceral pleural is connected to lungs

the parietal pleura is connected to inner surface of thoracic cavity

theres a pleural cavity between the layers containing protein rich fluid- it is also a semi-vacuum and a potential space- a fixed volume

Pleural fluid interacts non-abrasively.

Question 13

What are the different ways in which the pleural cavity integrity can be disturbed, what will this cause the lungs to do?

Answer 13

Haemothorax in which there’s interpleural bleeding- which will cause pressure on the lung

Pneumothroax- when there’s a punctured lung or perforated chest wall; it will cause lungs to collapse

Question 14

What are the different types of breathing in relation to pressure

Answer 14

Negative pressure breathing- when pressure in alveolar is reduced to be lower than atmospheric pressure of (1 atm.). E.G. normal breathing mechanism

positive pressure breathin- when atm pressure is increase to be greater than alveolar pressure.E.g fighter pilots use this, CPR

Question 15

3 compartment model

what leads to expiration and inspiration

Answer 15

• Negative transrespiratory pressure leads to inspiration
• positive trans mural pressure leads to expiration

Question 16

What is the order of FEV1/FVC ratio for restrictive, normal and obstructive disease

calculate the peak respiratory volume fo the graph (L/min)

Answer 16

Order in ascending order: Obstrucitve, normal, restrictive

Find the gradient for the smallest unit of time

Question 17

Describe Henry’s Law

Answer 17

At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with a liquid

Content of dissolved gas = partial pressure of gas X arterial gas

Question 18

What are the key gas laws that describe gas behaviour

Answer 18

• Henry
• Dalton
• Charles
• Boyle’s
• Ficks

Question 19

What are the ways in which inspired gas is modified before it reaches the lungs.

how does Paritel pressure of each gas changes

Answer 19

It is WARMED, HUMIDIFIED, SLOWED, and MIXED as it passes down respirator tree

pO2 decreases; pH2O and pCO2 increases

Question 20

The amount of oxygen dissolving due to Henry’s law isn’t enough (16mLmin^-1) from the body? What is the VO2 of the body and how does it achieve this

Answer 20

VO2 is 250mL/min

This is achieved by Haemoglobin cooperative effect

Question 21

What are the different types of haemoglobin during normal human development

Answer 21

HbA- 2 alpah and 2 beta

HbA₂ - 2 alpha and 2 delta

HbF- 2 alpha and 2 gamma

Question 22

Describe the allosteric behaviour of haemoglobin; what chemical binds to it when it’s saturated and what is it’s significance?

Answer 22

2,3-DPG; This puts the haem in a tensed state enabling unloading of oxygen onto tissue

Question 23

For the oxygen dissipation curve, what causes left shift, i.e. higher affinity of oxygen?

Answer 23

• REDUCED BLOOD temperature
• alkalosis - high O2
• Hypocapnia- low CO2
• low 2,3 DPG

Question 24

In an oxygen dissociation curve what causes right shift, i.e. lower affinity for o2

Answer 24

• HIGHER BLOOD temperature
• Acidosis
• Hypercapnia
• high 2,3, DPG

Question 25

What causes upwards and downwards shift of Oxygen dissociation curve

Answer 25

Upwards * Polycythaemia * Increased oxygen carrying capacity Downwards shift * Anaemia * impaired oxygen carrying capacity

Question 26

Describe what happens in downwards and leftward shift of oxygen dissociation curve?

Answer 26

Decreased capacity and increased affinity this is caused by **increased HbCO**

Question 27

Describe the oxygen dissociation curve for foetal haemoglobin and myoglobin

Answer 27

Foetal- greater affinity to extract blood from mothers blood in placenta myoglobin - much greater affinity is to extract oxygen from circulating blood and store it

Question 28

What is Hb saturation of O2 in venous and arterial blood what else increases during loading

Answer 28

Venous - 75% arterial- 100% PO2 and oxy haemoglobin, saturation of O2 in blood

Question 29

What are the different ways in which C02 can be transported in blood back to the lungs

Answer 29

HbCO₂ HCO₃^- **MAJORITY** dissolved in blood

Question 30

How is carbaaminohaemoglobin made in the red blood cell

Answer 30

* CO2 enters RBC and and binds to water forming H2CO3; CATALYSED by **Carbonic anhydrase** - this is a reversible reaction * H2CO3 breaks down into H+ and HCO3- * the H+ and another CO2 binds to haemoglobin to form carboaminohaemoglobin * the HCO3- is exchanged with Cl- **via AE1 taransporter outside the RBC**

Question 31

Describe the pulmonary transmit time? Overall , then for Oxygen and CO2

Answer 31

0.75s gas exgange time for O2 is 0.25s gas exchange time for CO2 0s 0.125s

Question 32

Describe the following terms?

Answer 32

Question 33

Describe the following terms

Answer 33