Respiratory physiology - Chemoreceptors - Lung disease

Question 1

What can happen to PaCO2 levels in chronic lung disease?

Answer 1

Chronically elevated

Question 2

What happens to the sensitivity of central chemoreceptors in chronic lung disease?

Answer 2

Desensitised due to contract chronic levels of CO2

Question 3

What do desensitised chronic lung disease individuals rely on?

Answer 3

Peripheral receptors

Question 4

What do peripheral chemoreceptors detect?

Answer 4

Change in PO2 and H+ conc

Question 5

What is hypoxic drive?

Answer 5

Rather than ring driven by hypercapnea (decreased PO2) but are driven by hypoxia (decreases PO2)

Question 6

Where are the peripheral chemorectrs found?

Answer 6

In the periphery, in the carotid and aortic bodies

Question 7

Where is the [H+] detected in peripheral chemoreceptors?

Answer 7

Systemic Plasma

Question 8

When is a reflex stimulation of ventilation triggered?

Answer 8

When there is a significant fall in PO2 in arterial blood

Question 9

What is a significant fall in PO2?

Answer 9

UNDER 60mmHg (haemoglobin dissociation curve)

Question 10

When the PO2 falls below 60mmHg, what is th effect on the station of haemoglobin by oxygen?

Answer 10

Small changes in the po2 now have a great effect on the percent O2 bound to have haemoglobin

Question 11

What PO2, will the peripheral chemoreceptors kick into action - ventilation?

Answer 11

Below 60mmHg

Around 3000m

Question 12

What needs a greater decrease in partial pressure to increase ventilation, PO2 or PCO2?

Answer 12

O2

Need to be below 60mmHg

Exponential rise in ventilation

Question 13

Are peripheral receptors responding to arterial PO2 or total oxygen content?

Answer 13

Only arterial

Not the po2 bound to haemoglobin

Question 14

What will happen to respiration rate in an anaemic patient with normal lung function, who has a blood oxygen content half the normal value?

Answer 14

It will stay the same

As the peripheral chemoR respond to arterial PO2 and not total.

The plasma PO2 will be normal

Question 15

When does chronic lung disease become important clinically?

Answer 15

administering sedative agents or anaesthetic agents

Question 16

How do gaseous anaesthetic agents effect respiration rate and tidal volume?

Answer 16

increase respiration rate and decrease tidal volume

Question 17

What is the main determinant of alveolar ventilation?

Answer 17

tidal volume

Question 18

Anaesthetic decreases tidal volume, how does this effect alveolar ventilation?

Answer 18

decrease

Question 19

What drugs depress respiratory centres?

Answer 19

barbiturates and opioids

Question 20

Why do overdose on opioids result in death?

Answer 20

as a result of respiratory failure.

decrease sensitivity to pH and therefore response to PCO2.

Also, decrease peripheral chemoreceptors to decrease PO2

Question 21

Do the opioids decrease sensitivity of peripheral chemoreceptors?

Answer 21

yes, decrease response to PCO2

Question 22

What is the effect of nitrous oxide on peripheral chemoreceptors?

Answer 22

blunts the peripheral chemoR to falling PaO2

Question 23

Does nitrous oxide have an effect in the central chemoR?

Answer 23

no, only peripheral

does not monitor PaCO2 in the blood

Question 24

How does nitrous oxide effect individuals with chronic lug disease?

Answer 24

individuals on hypoxic drive

desensitised to CO2

you Knockout the peripheral chemoR response, due to NO

they cant regulate their blood gas composition

Question 25

What are the blood gas compositions in an induvial with chronuic lung disease and taking NO?

Answer 25

PCO2 INCREASES

PO2 decreases

Question 26

Why does administering O2 to an individual with chronic lung disease and taking NO? `

Answer 26

tells the body that O2 levels are fine when they are not.

CO2 levels are not ok and you cannot get rid of CO2

O2 will stop them leaving and further decrease PO2

Question 27

What else do the peripheral chemoR respond to?

Answer 27

increasing plasma [H+]