Respiratory 3

Question 1

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

carbon dioxide in blood.

“The changes that occur at the alveolar and peripheral tissue interfaces” here are probably referring to X

Answer 1

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

“The changes that occur at the alveolar and peripheral tissue interfaces” here are probably referring to the Bohr and Haldane effects

deranged 2020 march, Q1

Question 2

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

CO2 is transported by three major mechanisms:

Answer 2

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

As bicarbonate (HCO3- ), 70-90% of total blood CO2 content
As carbamates, the conjugate bases of carbamino acid (about 10-20%)
As dissolved CO2 gas, about 10%
Carbonic acid

deranged 2020 march, Q1

Question 3

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

CO2 is transported by three major mechanisms:

As bicarbonate

Answer 3

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

As bicarbonate (HCO3- ), 70-90% of total blood CO2 content
.
Combined with water, CO2 forms carbonic acid, which in turn forms bicarbonate:
CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+
This mainly happens in RBCS
The rise in intracellular HCO3- leads to the exchange of bicarbonate and chloride, the chloride shift. Chloride is taken up by RBCSs, and bicarbonate is liberated.
Thus chloride concentration is lower in systemic venous blood than in systemic arterial blood
.
deranged 2020 march, Q1

note; I used to not get this, so the bicarb is in the red blood cell and negatively charged so to get it into the serum chloride goes into rbc so serum chloride goes down

Question 4

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

CO2 is transported by three major mechanisms:

As carbamates,

Answer 4

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march
.
As carbamates, the conjugate bases of carbamino acid (about 10-20%)
Dissociated conjugate bases of carbamino acids, which form in the spontaneous reaction of R-NH2 and CO2.
Intracellular (RBC) carbamino stores are the greatest: haemoglobin, particularly deoxygenated haemoglobin, has a high affinity for CO2, whereas most other proteins do not
.
deranged 2020 march, Q1

Question 5

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march
.
CO2 is transported by three major mechanisms:
.
dissolved CO2 gas,

Answer 5

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march
/
As dissolved CO2 gas, about 10%
Henry’s law states that the amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid
Thus, for every 1 mmHg of pCO2 the blood concentration increases by about 0.03 mmol/L
Thus, CO2 is 10-20 times more soluble than oxygen
/
deranged 2020 march, Q1

/
note; notice CO2 is 0.03 and O2 is 0.003

note; this is a super important point and units too

Question 6

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

CO2 is transported by three major mechanisms:

Carbonic acid:

Answer 6

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

A miniscule proportion of total carbon dioxide exists in this form, i.e. it is not a major contributr to CO2 transport

deranged 2020 march, Q1

Question 7

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

There is a difference between arterial and venous CO2 content:

Answer 7

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

There is a difference between arterial and venous CO2 content:

-Mixed venous blood has a total CO2 content of about 22.5 mmol/L
(or 520 mL/L)
-Arterial blood has a total CO2 content of about 20.5 mmol/L
(or 480ml/L)
-Much of this difference is due to the increase in bicarbonate concentration (85%)

-Some of this difference is also due to the Haldane effect:
Deoxyhaemoglobin has about 3.5 times the affinity for CO2 when compared to oxyhaemoglobin
This increases the CO2 binding capacity of venous blood
Deoxyhaemoglobin is also a better buffer than oxyhaemoglobin, which increases the capacity of RBCs to carry HCO3-

deranged 2020 march, Q1

Question 8

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

examiner comments

Answer 8

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

2020 march
1 Describe the carriage of carbon dioxide in blood

A detailed understanding of the carriage of carbon dioxide (CO2) in the blood is essential to the
practice of intensive care medicine. Comprehensive answers classified and quantified the
mechanisms of CO2 carriage in the blood and highlighted the differences between the arterial and
venous systems. An explanation of the physiological principles surrounding these differences and
the factors which may affect them was expected. The changes that occur at the alveolar and
peripheral tissue interfaces with a similar explanation of process was also required. Candidate
answers were often at the depth of knowledge required for an ‘outline question’ and a more
detailed explanation was required to score well

2018 aug 5
5 Describe the carriage of carbon dioxide (CO2) in the blood.

A definition of arterial and venous CO2 content (mls and partial pressure) and an outline of the 3 forms of CO2 in the blood and their contribution to the AV difference, followed by a detailed explanation of each form of carriage was required for this question. A good answer included a table of the contribution of each form of carriage to arterial and venous content and the AV difference; explained the concepts of chloride shift when describing carriage as HCO3 - ; detailed the Haldane effect and its contribution to carbamino carriage and referenced Henry’s law when describing dissolved CO2.
West’s Chapter 6 on gas transport details the key information to score well on this question.

2015 march
13 Describe how carbon dioxide (CO2) is carried in the blood?

It was expected answers would describe each of the main categories of how CO2 is carried:
Dissolved (10%), Plasma Bicarbonate (70%) and conjunction with plasma proteins and Hb as
Carbamino Hb (20%). An opening statement quantifying the amount of CO2 dissolved in
arterial (48mL/100mL) and venous blood (52mL/100mL) (4mL/100mL) and how this
compares with Oxygen was expected (20 times more soluble).
For dissolved CO2, the application and description of Henry’s Law was awarded marks.
A description of the consequences of the Haldane effect: difference in CO2 carriage of
oxygenated and deoxygenated blood was expected. A diagram of pCO2 v CO2 content was
helpful

2012 march
6 Describe the carriage of CO2 in blood

For a good answer candidates were expected to mention values for CO2 content in blood as
well as the various ways it is carried (e.g. dissolved, as bicarbonate, combined with
haemoglobin, etc) and a description of these modes. Wherever possible candidates are
encouraged to illustrate their answer, in particular if those illustrations are core knowledge.
Candidates who didn’t, were not penalised if they were still able to provide the required
responses. However, candidates who did appeared to better synthesize a response.
Candidates are reminded to include, and know, what are the appropriate units for any
values they mention.

Question 9

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

Total DO2 =

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Answer 9

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

Total DO2 = Cardiac output (L/min) × Oxygen content (ml/L)

Cardiac output = HR × SV
Where SV is influenced by preload, afterload and contractility.

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Question 10

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

Oxygen content =

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Answer 10

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

Oxygen content = (sO2 × ceHb × BO2 ) + (PaO2 × 0.003), where:

ceHb = the effective haemoglobin concentration
i.e. concentration of haemoglobin species capable of carrying and releasing oxygen appropriately

PaO2 = the partial pressure of oxygen in arterial gas

0.003 = the content, in ml/L/mmHg, of dissolved oxygen in blood
Henry’s law states that the amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid;
Ergo the amount of oxygen dissolved in is proportional to its partial pressure, e.g for a PaO2 of 100 mmHg the oxygen content is 0.003 × 100 = 3ml/L

BO2 = the maximum amount of Hb-bound O2 per unit volume of blood
normally 1.39 of dry Hb, or closer to 1.30 in “real” conditions

sO2 = oxygen saturation:
determined by the sigmoid oxygen-haemoglobin dissociation curve
Sigmoid shape of the curve comes from the positive cooperativityof oxygen binding
Once an oxygen molecule is bound to it, the oxygenated subunit increases the oxygen affinity of the three remaining subunits
This is because of a conformational change produced by each subunit binding oxygen, which mediates the transition from the T (tense, deoxygenated) state to the R (relaxed, oxygenated) state

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

note; CO2 is 0.03 and O2 is 0.003

Question 11

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

ceHb =

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Answer 11

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march
/
ceHb = the effective haemoglobin concentration
i.e. concentration of haemoglobin species capable of carrying and releasing oxygen appropriately
/
2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Question 12

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

PaO2 =

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Answer 12

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

PaO2 = the partial pressure of oxygen in arterial gas
.
2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

got it wrong because I forgot a meant arteriall

Question 13

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

0.003 =

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Answer 13

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

0.003 = the content, in ml/L/mmHg, of dissolved oxygen in blood
Henry’s law states that the amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid;
Ergo the amount of oxygen dissolved in is proportional to its partial pressure, e.g for a PaO2 of 100 mmHg the oxygen content is 0.003 × 100 = 3ml/L

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Question 14

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

BO2 =

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Answer 14

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march
.
BO2 = the maximum amount of Hb-bound O2 per unit volume of blood
normally 1.39 of dry Hb, or closer to 1.30 in “real” conditions
.
2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Question 15

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

sO2 =

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Answer 15

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

sO2 = oxygen saturation:
determined by the sigmoid oxygen-haemoglobin dissociation curve
Sigmoid shape of the curve comes from the positive cooperativityof oxygen binding
Once an oxygen molecule is bound to it, the oxygenated subunit increases the oxygen affinity of the three remaining subunits
This is because of a conformational change produced by each subunit binding oxygen, which mediates the transition from the T (tense, deoxygenated) state to the R (relaxed, oxygenated) state

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Question 16

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march
/
That “opening statement” they ask for would probably sound something like this:
/
The arterial blood CO2 content (X ml/L) is lower than the mixed venous CO2 content (X ml/L)
This is substantially higher than the oxygen content of blood
This is because CO2 is not only X times more water-soluble than oxygen, but also because it is carried in a number of different forms
/
2015 march Q13
Describe how carbon dioxide (CO2) is carried in the blood.

Answer 16

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

That “opening statement” they ask for would probably sound something like this:

The arterial blood CO2 content (480ml/L) is lower than the mixed venous CO2 content (520ml/L)
This is substantially higher than the oxygen content of blood
This is because CO2 is not only 20 times more water-soluble than oxygen, but also because it is carried in a number of different forms

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Question 17

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

examiner comment

Answer 17

OXYGEN OR CO2 *repeated 2015 march, 2018 march , 2018 aug, and 2020 march, 2012 sept and 2012 march

2018 march
1 Describe the carriage of oxygen in the blood, including total oxygen delivery per minute

Better answers divided oxygen carriage into that bound to haemoglobin and that carried in the
dissolved form. A reasonable amount of detail on the haemoglobin structure and its binding of
oxygen was expected, including an explanation of co-operative binding and the oxygen carrying
capacity of haemoglobin. Better answers mentioned Henry’s law in the description of dissolved
oxygen, along with an estimation of the amount of oxygen that is normally in the dissolved form.
It was expected that answers include the equation for oxygen delivery, a brief description of the
components of that equation and the normal value, which a large number of candidates omitted.

2015 march
13 Describe how carbon dioxide (CO2) is carried in the blood?

It was expected answers would describe each of the main categories of how CO2 is carried:
Dissolved (10%), Plasma Bicarbonate (70%) and conjunction with plasma proteins and Hb as
Carbamino Hb (20%). An opening statement quantifying the amount of CO2 dissolved in
arterial (48mL/100mL) and venous blood (52mL/100mL) (4mL/100mL) and how this
compares with Oxygen was expected (20 times more soluble).
For dissolved CO2, the application and description of Henry’s Law was awarded marks.
A description of the consequences of the Haldane effect: difference in CO2 carriage of
oxygenated and deoxygenated blood was expected. A diagram of pCO2 v CO2 content was
helpful

2012 aug
1 Compare and contrast the carriage of oxygen and carbon dioxide in blood.

Candidates who scored well for this question not only had a good knowledge of the topic
but also displayed an organised approach to their answer through the use of a tabular
format or some other structured approach. For a good answer, candidates were expected to
provide information on the amount (both arterial and venous blood content, partial
pressure) and form of carriage (binding to, loading and unloading from haemoglobin,
dissolved, as bicarbonate, etc.) of oxygen and carbon dioxide in blood

2012 march
6 Describe the carriage of CO2 in blood

For a good answer candidates were expected to mention values for CO2 content in blood as
well as the various ways it is carried (e.g. dissolved, as bicarbonate, combined with
haemoglobin, etc) and a description of these modes. Wherever possible candidates are
encouraged to illustrate their answer, in particular if those illustrations are core knowledge.
Candidates who didn’t, were not penalised if they were still able to provide the required
responses. However, candidates who did appeared to better synthesize a response.
Candidates are reminded to include, and know, what are the appropriate units for any
values they mention.

Question 18

Outline how the respiratory system of a neonate differs from that of an adult.

2020 march Q6

Differences in the neonate vs adult

Airway

Answer 18

neonate
Small mandible
Large tongue
Larger tonsils and adenoids
Superior laryngeal position
Soft, narrow, short trachea
Thus, intubation is more difficult
/
adult
Intubation is easier

Question 19

Outline how the respiratory system of a neonate differs from that of an adult.

2020 march Q6

Airway resistance

Answer 19

neonate
Respiratory resistance is increased at birth: bronchi arre smaller and lung volumes are smaller
/
adult
low airway resistance

Question 20

Outline how the respiratory system of a neonate differs from that of an adult.

2020 march Q6

Lung volumes and spirometry variables

Answer 20

neonate
FRC is similar to adult
VT is similar to adult
Minute volume is increased
Resp rate is increased
ERV is reduced
Closing capacity is increased
Anatomical dead space is increased (3.0 ml/kg)
/
adult
Normal anatomical dead space is 2.2 ml/kg

Question 21

Outline how the respiratory system of a neonate differs from that of an adult.

2020 march Q6

Compliance

Answer 21

neonate
Lung compliance is decreased (less surfactant)
Chest wall compliance is increased (cartilaginous ribs)
.
adult
Good lung compliance
Low chest wall compliance

note; so both have one good and one bad and then they switch

Question 22

Outline how the respiratory system of a neonate differs from that of an adult.

2020 march Q6

Gas exchange

Answer 22

neonate
Increased shunt (10-25%, due to patent ductus arteriosus)
Foetal haemogloin = left shift of the OHDC (poor affinity for 2,3-DPG)
Postatal increase in 2,3-DPG = right shift of the OHDC
Oxygen toxicity includes retinopathy
High oxygen-carrying capacity of blood because of higher Hb and haematocrit
/
adult
Normally shunt should be minimal
Oxygen is relatively nontoxic

Question 23

Outline how the respiratory system of a neonate differs from that of an adult.

2020 march Q6

Control of respiration

Answer 23

neonate
Immature respiratory centre, rhythmogenesis and reflex responses:
Decreased response to hypercapnia
Parradoxuic resposne to hypoxia
Periodic apenoeas and cyclical oscillating respiratory rate
.
adult
Mature reflxes and rhythmogenesis

Question 24

Outline how the respiratory system of a neonate differs from that of an adult.

2020 march Q6

Respiratory enegetics

Answer 24

neonate
The total oxygen consumption of the neonate is increased (6-10ml/kg/min)
Work of breathing is increased
Ideal efficiency is at a resp rate between 30 and 50
Diaphragm is more susceptibel to fatigue (fewer Type 1 fibres)
/
adult
Oxygen consumption is 3ml/kg/min
Max efficiency at resp rate 12-14

Question 25

Outline how the respiratory system of a neonate differs from that of an adult.

2020 march Q6

examiners comments

Answer 25

This question required an outline of the anatomical, mechanical and functional differences. It was expected that factors leading to an increased work of breathing and oxygen cost would be mentioned. The mechanics of expiration were not often included in candidates’ answers. Immaturity of the alveoli and peripheral chemoreceptors were common omissions. Inaccuracies regarding upper airway anatomy and compliance of the chest wall cost some candidates marks. The question did not call for an explanation of the relative difficulty of intubation. Discussion of pathophysiology due to airway obstruction, causes of central apnoea or sensitivity to drugs was not required. Many answers included inaccurate information. Points which were often missed were difference in bronchial angles, number of alveoli, number of type 1 fibres in diaphragm, ciliary function and peripheral chemoreceptors.

note; I need to add this

Points which were often missed were difference in bronchial angles, number of alveoli, number of type 1 fibres in diaphragm, ciliary function and peripheral chemoreceptors.

Question 26

Outline how the respiratory system of a neonate differs from that of an adult.

2020 march Q6

examiners comments

Answer 26

This question required an outline of the anatomical, mechanical and functional differences. It was expected that factors leading to an increased work of breathing and oxygen cost would be mentioned. The mechanics of expiration were not often included in candidates’ answers. Immaturity of the alveoli and peripheral chemoreceptors were common omissions. Inaccuracies regarding upper airway anatomy and compliance of the chest wall cost some candidates marks. The question did not call for an explanation of the relative difficulty of intubation. Discussion of pathophysiology due to airway obstruction, causes of central apnoea or sensitivity to drugs was not required. Many answers included inaccurate information. Points which were often missed were difference in bronchial angles, number of alveoli, number of type 1 fibres in diaphragm, ciliary function and peripheral chemoreceptors.

note; I need to add this

Points which were often missed were difference in bronchial angles, number of alveoli, number of type 1 fibres in diaphragm, ciliary function and peripheral chemoreceptors.

Question 27

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Sensor Organs involved in the Control of Respiratory Function

what are the 4 sensors??

Answer 27

Carotid body glomus
(Type I cells) - sited at the bifurcation of the common carotid

Aortic glomus cells - in the aortic arch, subclavian arteries and pulmonary trunk

Central chemoreceptors

Mechanoreceptors in bronchial and lung tissue

Question 28

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Sensor Organs involved in the Control of Respiratory Function

Carotid body glomus
(Type I cells) - sited at the bifurcation of the common carotid

what is the stimulus and afferent nerve??

Answer 28

Stimulus/
PaO2
PaCO2
pH
Temperature
Glucose (hypoglycaemia)
.
Afferent nerve/
Glossopharyngeal

Question 29

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Sensor Organs involved in the Control of Respiratory Function

Aortic glomus cells - in the aortic arch, subclavian arteries and pulmonary trunk

what is the stimulus and afferent nerve??

Answer 29

Stimulus/
PaO2
Changes in O2 delivery (anaemia, carboxyhaemoglobin, hypotension)
PaCO2
/
Afferent nerve/
Aortic nerve
(branch of the vagus)

Question 30

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Sensor Organs involved in the Control of Respiratory Function

Central chemoreceptors

what is the stimulus and afferent nerve??

Answer 30

Stimulus/
pH

Question 31

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Sensor Organs involved in the Control of Respiratory Function

Mechanoreceptors in bronchial and lung tissue

what is the stimulus and afferent nerve??

Answer 31

Stimulus/
Inflation and deflation (i.e. Hering-Breuer reflex)

Afferent nerve/
Vagus

Question 32

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Respiratory Control Centres

name all 7

Answer 32

Nucleus retroambigualis

Nucleus paraambigualis

Nucleus ambiguous

Pre-Bötzinger complex

Bötzinger complex

Pontine respiratory group

Cerebral cortex

Question 33

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Respiratory Control Centres

Nucleus retroambigualis

Answer 33

Role
Expiratory function

Efferents and effectors
Upper motor neuron axons to contralateral expiratory muscles

Question 34

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Respiratory Control Centres

Nucleus paraambigualis

Answer 34

Role
Inspiratory function

Efferents and effectors
Upper motor neuron axons to contralateral inspiratory muscles

Question 35

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Respiratory Control Centres

Nucleus ambiguous

Answer 35

Role
Airway dilator function

Efferents and effectors/

1 Vagus nerve: to (larynx, pharynx and muscularis uvulae)

2 Glossopharyngeus muscle to stylopharyngeus muscle

Question 36

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Respiratory Control Centres

Pre-Bötzinger complex

Answer 36

Role
Respiratory pacemaker (“central pattern generator”)

Efferents and effectors/

Interneurons connecting to other respiratory control regions

Question 37

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Respiratory Control Centres

Bötzinger complex

Answer 37

Role
Expiratory function

Efferents and effectors/
Inhibitory interneurons to phrenic motor neurons and other respiratory control regions

Question 38

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Respiratory Control Centres

Pontine respiratory group

Answer 38

Role
Integrates descending control of respiration from the CNS

Efferents and effectors/
Interneurons connecting to other respiratory control regions

Question 39

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Respiratory Control Centres

Cerebral cortex

Answer 39

Role
Volitional and behavioural respiratory control

Efferents and effectors/
Pontine respiratory group

Question 40

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

Explain the control of breathing., alveolar ventilator and physiological factors effecting RR

Respiratory Control Centres

Cerebral cortex

Answer 40

Role
Volitional and behavioural respiratory control

Efferents and effectors/
Pontine respiratory group

Question 41

marchQ13 2020 , Aug Q13 2015, March Q1 2015, March Q21 2013, March Q6 2010, Aug Q11 2008

examiner comment

Answer 41

marchQ13 2020, - Explain the control of breathing.

Most candidates provided a structured answer based around a sensor / central integration / effector model with appropriate weighting towards the sensor / integration component. Better answers provided an understanding of details of receptor function, roles of the medullary and pontine nuclei and how these are thought to integrate input from sensors. Marks were awarded to PaCO2 ventilation and PaO2 ventilation response when accurate, correctly labelled diagrams or descriptions were provided.
/
Aug Q13 2015, - Describe the control of alveolar ventilation.

The most comprehensive answers were those structured as sensor-controller-effector with an
explanation of each part and how homeostasis was maintained. Insufficient detail was generally
provided as to how central and peripheral chemoreceptors were stimulated. A description of
central control was required, rather than listing nuclei or areas.
Many failed to address all three components of a control question and focused primarily on the
sensors. Many answers were just too brief and did not present enough information to
demonstrate understanding
/
March Q1 2015, - Explain the control of breathing.

This question was generally well done. It was expected answers would include discussion of
the three core elements of sensors, a central controller and effectors. Central control involves
three main groups of neurones in the brainstem with some cortical voluntary control also
possible. More in depth answers included graphs of the ventilatory response to oxygen and
carbon dioxide tensions.
/
March Q21 2013, - How is alveolar ventilation regulated?

This is a core topic (syllabus Level 1) and a high level of understanding was expected. Overall
candidates failed to demonstrate sufficient depth and breadth in their knowledge. A
structured response considering the three basic elements underpinning the control of
alveolar ventilation (the Sensors, Central integration and control and the Effectors) was core
material. A detailed description of each was expected.
/
March Q6 2010,- List the physiological factors that increase respiratory rate. Include an explanation of the mechanism by which each achieves this increase.

Good candidates had a structured approach to this questions. Submitted question
structures took the form of key headings (eg, PaCO2, PaO2, pH, etc) with an
accompanying explanation, which included diagrams, which were often
underutilised. Candidate answers that lacked any structure were more likely to have
omissions and lacked sufficient depth and as a result scored fewer marks. For a
good answers candidates where expected to list and explain (preferably by including
diagrams) physiological factors such as PaCO2, PaO2, pH, Exercise, temperature,
pregnancy and the associated receptors for each mechanism.
Syllabus: B1c 1
Reference: Nunn’s Applied Respiratory Physiology, Lumb, 6th edition 60-68
Principles of Physiology for the Anaesthetist, Power & Kam, 1st edition 92-98
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march Q11 2008- List the physiological factors that increase respiratory rate. Include an explanation of the mechanism by which each achieves this increase.

The main points candidates were expected to cover included:
· A description of the central and peripheral chemoreceptors, their predominant stimuli and effect on ventilation.
· PaCO2 as the main influence on normal ventilation, the near-linear relationship to minute ventilation around the normal range, and how CO2 produces this effect.
· PaO2 and pH and their sites of action.
· Other stimuli to ventilation – exercise, pregnancy, temperature, baroreceptors.
Candidates frequently confused central and peripheral receptor activities and failed to provide any relative significance to the major factor(s). The use of a graph relating the main factors to minute ventilation would have been helpful.
Reference: Nunn 6th edition 60-68
Kam 1st edition 92-98