Lecture 2

Question 1

What are the two parts of the brain that form the central neural control of respiration?

Answer 1

Pons and Medulla

Question 2

Which receptors stimulate breathing during exercise.

Answer 2

Metaboreceptors.

Question 3

Of the pontine group which two centres in the Pon control the speed of inhalation and exhalation?

Answer 3

Pneumotaxic and apneustic centers

Question 4

In the Medulla we have the dorsal and ventral respiratory groups. Which one deals with inspiration?

Answer 4

Dorsal respiratory group.

Question 5

Which two muscles contract during inspiration and expiration respectively?

Answer 5

Inspiration : diaphragm and external intercostal muscles

Expiration : internal intercoastals and abdominal muscles.

Question 6

The ventral respiratory group (expiratory area) is not always active. When is it activated by the inspiratory area?

Answer 6

During forceful breathing

Question 7

Between the apneustic and pneumotaxic centres which one inhibits inhalation and which one prolongs it

Answer 7

Pneumotaxic inhibits (leading to more rapid breathing) and apneustic prolongs it.

Question 8

Describe the inflation reflex

Answer 8

It occurs when the stretch receptors in the walls of the bronchi inhibit inhalation and apneustic(the one that prolongs inhalation), centre to avoid overinflating the lungs with inhalation

Question 9

Which receptors are responsible for detecting tissue damage, distention of capillary walls or oedema that causes shallow and rapid breathing and what results.

Answer 9

Pulmonary J receptors and shortness of breath results.

Question 10

Apnea= when you stop breathing which can be caused by sudden cold. How does change in temperature affect the rhythm of ventilation

Answer 10

When temperatures increase so does the rhythm of ventilation.

Question 11

Sudden severe pain can cause apnea. What is apnea

Answer 11

To stop breathing

Question 12

Which baroreceptors are stimulated by a change in blood pressure

Answer 12

Carotid sinus baroreceptors

Question 13

How will an increase in blood pressure affect ventilation.

Answer 13

An increase in blood pressure will stimulate the carotid sinus baroreceptors to decrease SNS activity which will decrease heart rate and eventually ventilation.

Question 14

Dyspnea occurs when the ventilation need is not met by the physical work of breath in. Define it

Answer 14

It is the shortness of breath.

Question 15

Define hycapnia and describe the relationship between PaCO2 and minute ventilation

Answer 15

When PaCO2 >45mmHg.
Minute ventilation (requirement for ventilation or more oxygen) increases when PaCO2 increases.

Question 16

What is the relationship between minute ventilation and PaO2

Answer 16

As PaO2 decreases minute ventilation increases or vice versa.

Question 17

What would happen if a patient accumulates more and more CO2 or if PaCO2 continues to increase

Answer 17

Minute ventilation will eventually stop increasing resulting in a Coma and eventually death.

Question 18

What are the conditions necessary for a right shift to occur (4) and where does it occur.

Answer 18

1. Increase in PCO2
2. Increase in temperature
3. Decrease in pH
4. Increase in 2.3DPG
   It occurs at the tissues.

Question 19

Define the Bohr and Haldane effects

Answer 19

Bohr effect - shift to the right with response to increased PCO2 and decrease in pH which results in haemoglobin offloading oxygen.

Haldane effect - deoxygenation of the blood increases its ability to carry CO2

Question 20

Put the following in order like you would when answering an APQ question.

•^PCO2 •^O2 unloading•^H+ •low Hb affinity for oxygen•Bohr effect

Answer 20

^PCO2
Increased H+ 
Bohr effect
Decreased Hb affinity for oxygen
Increased oxygen unloading

Question 21

The a-v difference occurs at the tissues and not the lungs. How would the speed of blood flow affect the (a-v) difference

Answer 21

The slower the bloodflow the more time the tissues will have to extract the oxygen and the opposite is true. Therefore the a-v difference will be high when the bloodflow is slow as compared to when it’s flowing fast.