Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

RS > Session 4: Chemical Control of Breathing > Flashcards

Session 4: Chemical Control of Breathing Flashcards

1
Q

Define hypoxaemia.

A

A fall in arterial pO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why can the body tolerate small changes in pO2 without significant tissue hypoxia?

A

Because due to the oxy-haemoglobin dissociation curve the pO2 can vary over quite a range around the normal value of 13.3 kPa without alteration of O2 sat.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define hypercapnia.

A

Rise in arterial pCO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define hypocapnia.

A

Fall in arterial pCO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What will happen to CO2 and O2 in hypoventilation?

A

pO2 will fall and pCO2 will rise. Removal of CO2 from lungs is less rapid than its production in this case.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Explain respiratory acidosis.

A

Due to hypoventilation increasing pCO2. This leads to increased levels of dissolved CO2. In the short term this alters the ratio between CO2 and HCO3- making the ratio smaller. This leads to a lower pH of the blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

If respiratory acidosis persists, how will the kidneys react?

A

Reducing the excretion of HCO3- to restore the ratio.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the kidney’s response to respiratory acidosis called?

A

Compensated respiratory acidosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What will happen to CO2 and O2 in hyperventilation?

A

pO2 will rise and pCO2 will fall. Removal of CO2 from lungs is more rapid than its production.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Explain respiratory alkalosis.

A

Due to hyperventilation decreasing arterial pCO2. Leads to decreased levels of dissolved CO2. In short term this alters the ratio between CO2 and HCO3 making the ratio larger. This leads to an increased pH of the blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the kidney’s response to respiratory alkalosis?

A

Increased excretion of HCO3- to restore the ratio.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the kidney’s response to respiratory alkalosis called?

A

Compensated respiratory alkalosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain what happens to the blood in excess metabolic production of acid.

A

The HCO3- is used up to buffer the acid and this causes HCO3- to drop. This leads to a decrease in pH. This is called metabolic acidosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Body’s response to metabolic acidosis.

A

The ratio is restored to near normal by increased ventilation (hyperventilation). However the depletion of the buffer base remains until it is corrected by the kidneys.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the response to metabolic acidosis called?

A

Compensated metabolic acidosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explain what happens to the blood in excess production of HCO3-.

A

Excess HCO3- leads to altered ratio. Leads to metabolic alkalosis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Body’s response to metabolic alkalosis.

A

Can be corrected by elevating pCO2. Corrected by the kidneys as well.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How are disturbances of pH arising from persisting alterations of pCO2 corrected by?

A

Slowly corrected by the kidneys.

19
Q

How else are disturbances of pH, pO2 and pCO2 regulated?

A

By chemoreceptors.

20
Q

There are two types of chemoreceptors. Which?

A

Peripheral chemoreceptors Central chemoreceptors

21
Q

Where can peripheral chemoreceptors be found?

A

Carotid bodies and aortic bodies.

22
Q

Explain how the peripheral chemoreceptors work.

A

Respond to a change in pO2, pCO2 and pH. The bodies send impulses via their respective nerves to the brain stem respiratory centre which will then modulate the rate and depth of ventilation.

23
Q

What nerve carries impulses from aortic bodies?

A

Vagus nerve

24
Q

What nerve carries impulses from carotid bodies?

A

Glossopharyngeal nerves

25
Q

Explain the peripheral chemoreceptors response to oxygen.

A

Stimulated by a decrease in O2. They do not respond to a slight change in pO2 but only to a large change. Leads to increase in tidal volume and rate of respiration. They also cause changes in circulation directing more blood to brain and kidneys. They do not adapt to chronic hypoxia which means that the respiratory response will be active for as long as pO2 is low.

26
Q

Explain the peripheral chemoreceptor response to CO2.

A

They are not particularly sensitive to pCO2. A large increase or decrease in pCO2 to stimulate them. Respond quickly to large changes in pCO2.

27
Q

Explain the peripheral chemoreceptor response to pH.

A

Carotid bodies can sense and respond to changes in blood pH.

28
Q

What are the carotid bodies response to a low pH?

A

Increased RR and tidal volume

29
Q

State the main response of the peripheral chemoreceptors.

A

A stimulatory response in a large fall of pO2.

30
Q

Where can central chemoreceptors be found?

A

On the ventral surface of the medulla.

31
Q

What are central chemoreceptors exposed to?

A

CSF

32
Q

What do central chemoreceptor respond to?

A

A drop in CSF pH caused by a rise in arterial pCO2

33
Q

How do central and peripheral chemoreceptors differ in regards of sensitivity to pCO2?

A

Peripheral chemoreceptors will detect a rise in pCO2 but they are relatively insensitive. Central chemoreceptors are much more sensitive to pCO2.

34
Q

Explain the blood brain barrier’s role in the regulation of pH in the CSF.

A

The BBB allows free passage of CO2 but not HCO3-. The CSF has its own HCO3-/Dissolved CO2 buffer system. It contains no haemoglobin and has to regulate the pH by other means.

35
Q

What is dissolved CO2 in the CSF determined by?

A

Plasma pCO2 since passive diffusion is possible across the BBB for CO2.

36
Q

What is HCO3- concentrations in the CSF determined by?

A

Activity of choroid plexus cells. They pump out HCO3- into the CSF, and they can also take up HCO3-. This concentration is independent of plasma HCO3- conc.

37
Q

Explain quick response of the central chemoreceptors to an increase in arterial pCO2.

A

CSF pCO2 will increase as well. This leads to changes in the CSF pH and is then sensed by central chemoreceptors. Chemoreceptors are stimulated and send impulses to the brain stem respiratory centres to increase ventilation. This is done to lower arterial pCO2 and then also pCO2 of the CSF.

38
Q

Explain the CSFs response to persisting hypoxia or lung disease.

A

Persisting changes in CSF pH stimulate the choroid plexus cells to pump more or less HCO3- into the CSF. This is to restore the ratio of HCO3- to Dissolved CO2 in the CSF.

39
Q

What is the consequence of the choroid plexus cells response to persisting changes of pCO2?

A

The CSF will restore its pH back to normal. This leads to the central chemoreceptors shutting off. The changes in ventilation caused by the central chemoreceptors turn off even though the arterial pCO2 to HCO3- ratio could still be off. The CSF ‘resets’ to around a different pCO2.

40
Q

Which is corrected faster; CSF pH or blood pH? Why?

A

CSF pH because of its small volume.

41
Q
A
42
Q
A
43
Q
A

RS (28 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions