Respiratory Physiology - Control of ventilation - chemoreceptors

Question 1

What type of muscle control breathing?

Answer 1

Voluntary skeletal muscles

Question 2

Wha nerve innervates the diaphragm for breathing?

Answer 2

Phrenic nerve

Question 3

What nerve inner ages the external intercostal muscles during inspiration?

Answer 3

Intercostal nerves

Question 4

What are the brain stem respiratory centres?

Answer 4

Resides within the defined centres located in the pons and medulla

Question 5

What happens if you sever the phrenic nerve above C3?

Answer 5

Breathing ceases

Question 6

What do the respiratory centres set?

Answer 6

Intrinsic control of breathing

Basal rhythm

Question 7

What modulates the rhythm of the respiratory system?

Answer 7

1. Emotion (via lambic system)
2. Voluntary override (via higher centres in brain)
3. Mechanic-sensory input from the thorax (e.g. stretch reflex/ threshold reached)
4. Chemical compost of the blood (PCO2, PO2 and pH detected by chemoreceptors)

Question 8

What is the limbic system?

Answer 8

the part of the brain involved in our behavioural and emotional responses,

Question 9

Answer 9

Question 10

What are the 2 major groups of neurones in the respiratory system?

Answer 10

DRG (dorado respiratory group)
VRG (ventral respiratory group)

Question 11

What does the VAR INNERVATE?

Answer 11

Tongue
Pharynx
Larynx
Expiratory muscles

Question 12

What does the DGR innervate?

Answer 12

Inspiration muscles

Question 13

How does the DRG innervate muscles?

Answer 13

Via phrenic and intercostal nerves

Question 14

What input most significantly affects the VRG and DRG?

Answer 14

Chemoreceptors

Question 15

What are the 2 types of chemoreceptors?

Answer 15

Central
Peripheral

Question 16

Where are the central chemoreceptors?

Answer 16

Medulla

Question 17

Where are the peripheral chemoreceptors?

Answer 17

Carotid and aortic bodies

Question 18

What allows for a smooth, low and controlled expiration?

Answer 18

Basal tone in expiratory muscles

VGR

Question 19

What do the central chemoreceptors respond to?

Answer 19

Hydrogen ions

Question 20

What do the H+ that the central chemoreceptors come from?

Answer 20

CO2

Reflect PCO2 level

Question 21

Are we sensitive to the change in H+ in cerebral spinal fluid?

Answer 21

Yes

Question 22

What do the H+ ions reflect ?

Answer 22

The PCO2 in systemic arterial blood

Question 23

What do the peripheral chemoreceptors directly respond to?

Answer 23

PO2 and plasma [H+]

Less so to PCO2

Question 24

What chemoreceptor is the primary ventilators drive?

Answer 24

Central

Question 25

What is the chemoreceptor is the secondary ventilators drive?

Answer 25

Peripheral

Question 26

Where are the H+ found which are detected by central chemoreceptors?

Answer 26

CSF Cerebral spinal fluid which surround the brain

Question 27

How is the car regulated?

Answer 27

Blood brain Barrier

Question 28

How do the central chemoreceptors responds to changes in [H+]?

Answer 28

Increase rate and depth of breathing

Question 29

What happens when there is an increase in [H+]?

Answer 29

Reflex stimulation

Question 30

What drives the increase in [H+]?

Answer 30

Increase in PCO2 of systemic arterial blood supplying the brain

Question 31

What is it called when there is an increase in PCO2 in the systemic blood?

Answer 31

Hypercapnea

Question 32

What is hypercapnea?

Answer 32

Increase in PCO2in systemic arterial blood

Question 33

What does CO2 and H2O (plasma) form?

Answer 33

Carbonic acid H2CO3

Question 34

What does carbonic acid dissociate to?

Answer 34

H+ and HCO3-

Question 35

Can central chemoreceptors respond to H+ in plasma?

Answer 35

No Only car

Question 36

What causes reflex inhibition?

Answer 36

A decrease in arterial PCO2 (reduces CSF ([H+]) (hyperventilation) Long deep breaths

Question 37

How does the brain maintain a stability composition of the CSF?

Answer 37

Not allow ions to cross

Question 38

What can and cannot travel from the arteries into the CSF?

Answer 38

CO2 can move in H+ cannot

Question 39

What happens when CO2 crosses the blood brain barrier?

Answer 39

Dissociation and H+ formed as byproduct

Question 40

Once the CO2 dissociates and forms h+ in the CSF, what detects it?

Answer 40

Central chemoreceptors

Question 41

What is the effect of H+ stimulating central chemoreceptors?

Answer 41

Stimulate respiratory control centre and increase ventilation Reduces the pco2 of CO2 Need more oxygen, H+ reflects higher PCO2

Question 42

Why do we want to regulate the levels of CO2 in the blood?

Answer 42

CO can be produced and that is toxic High affinity for haemoglobn and reduce the amount of O2 that can bind

Question 43

Are we sensitive to small changes in co2?

Answer 43

Yes Small changes in CO2 mean large changes in ventilation to help get rid of the CO2 and reduce toxic CO