L84: Control of Breathing

Question 1

Breathing maintains blood gas homeostasis, what are the factors to this?

Answer 1

O2, CO2 and pH

Question 2

What are the partial pressures of O2 and CO2 at rest?

Answer 2

O2: 100±2, CO2: 40± mmHg

Question 3

What are the exchange rates of O2 and CO2 at rest?

Answer 3

O2: 250, CO2: 200 mL

Question 4

What are the exchange rates of O2 and CO2 at 3mph walking?

Answer 4

O2: 800, CO2: 750 mL

Question 5

What are the exchange rates of O2 and CO2 during severe exercise?

Answer 5

O2: 5000, CO2: 6000 mL

Question 6

What kind of receptors does the brain recieve neural signals from?

Answer 6

Chemoreceptors and mechanoreceptors

Question 7

What changes do chemoreceptors detect?

Answer 7

Chemical changes - PO2, PCO2 and pH in blood

Question 8

Where are peripheral chemoreceptors located?

Answer 8

Aortic arch and carotid sinuses

Question 9

Which cranial nerve do the chemoreceptors in the aortic arch send/ receive information?

Answer 9

CNX - vagus nerve

Question 10

Which cranial nerve do the chemoreceptors in the carotid sinuses send/ receive information?

Answer 10

CNIX - glossopharyngeal nerve

Question 11

A decrease in PO2 (hypoxia) is detected by:

Answer 11

Peripheral chemoreceptors

Question 12

A decrease in PO2 (hypoxia) leads to…

Answer 12

Increased ventilation (to restore PO2)

Question 13

A increase in PCO2 (hypercapnia) is detected by:

Answer 13

Central chemoreceptors

Question 14

A decrease in pH is detected by:

Answer 14

Central chemoreceptors

Question 15

An increase in PCO2 (hypercapnia) leads to…

Answer 15

Increased ventilation (to restore PCO2)

Question 16

At what partial pressure are hypoxic conditions detected to lead to a hyper-ventilatory response?

Answer 16

60mmHg

Question 17

Which gas’ partial pressure plays an important role in moment to moment breathing control?

Answer 17

PCO2 - much more sensitive than PO2.

Question 18

What changes do mechanoreceptors detect?

Answer 18

Pressure, movement and touch - movement of the lungs and chest wall

Question 19

Where are mechanoreceptors located?

Answer 19

Airways smooth muscle and epithelium

Question 20

Which cranial nerve do mechanoreceptors send/ receive information?

Answer 20

CNX - vagus nerve

Question 21

What do mechanoreceptors on smooth muscle of the airway’s respond to?

Answer 21

Inflation and distension of the airways

Question 22

What do mechanoreceptors on smooth muscle of the airway’s lead to?

Answer 22

Termination of breathing

Question 23

What do mechanoreceptors in epithelium of the airway’s respond to?

Answer 23

Rapid lung inflation, deflation or oedema

Question 24

What do mechanoreceptors in epithelium of the airway’s lead to?

Answer 24

Sigh or shortened expiration

Question 25

Where is the respiratory rhythm generated?

Answer 25

The brainstem

Question 26

Which respiratory neurones are active during inspiration?

Answer 26

Inspiratory neurones

Question 27

Which respiratory neurones are active during expiration?

Answer 27

Expiratory neurones

Question 28

Where are rhythmic neural signals sent to?

Answer 28

The spinal cord and then respiratory muscles

Question 29

Where does the phrenic nerve exit the spinal cord?

Answer 29

C3-5

Question 30

What region of the spinal cord innervates intercostal muscles?

Answer 30

Thoracic

Question 31

How is the respiratory centre organised?

Answer 31

• 2 x respiratory neurone groups in the medulla oblongata;

1 x respiratory neurone group in the pons

Question 32

What are the two groups of respiratory neurones in the medulla oblongata?

Answer 32

• Dorsal respiratory group;

- Ventral respiratory group (NTS).

Question 33

Where are rhythmic neural signals sent from?

Answer 33

Ventral respiratory group (NTS) of the brainstem

Question 34

Where do chemoreceptors and mechanoreceptors send neural signals (of detected changes) to?

Answer 34

The nucleus tractus solitarius (NTS), in the brainstem

Question 35

Where is information, detected by chemo- and mechanoreceptors, processed?

Answer 35

Neurones in the brainstem