Control Of Breathing

Question 1

What is the average gas exchange at rest

Answer 1

250ml of O2/min and -200ml CO2 - breathing is highly stable

Question 2

What is the gas exchange when walking 3mph

Answer 2

800ml O2/min and 750ml/min CO2

Question 3

what is the gas exchange when intense exercise is taking place

Answer 3

5000 ml O2/min and 6000ml/min CO2

Question 4

What two things send the brain neural signals

Answer 4

Chemoreceptors and mechanoreceptors

Question 5

What is the function of chemoreceptors

Answer 5

Provide feedback on blood PO2 and PCO2 and pH

Question 6

What is the role of mechanoreceptors

Answer 6

Provide feedback on the mechanical status of lungs, chest wall and airways

Question 7

What does the brain send neural signals to to control breathing

Answer 7

• respiratory muscles to produce rhythmic breathing movements
• upper airway muscles eg laryngeal, pharyngeal and tongue
• produce reflexes to keep airways patent eg cough sneeze ect

Question 8

What part of the brain controls breathing

Answer 8

The brainstem

Question 9

What do chemoreceptors detect

Answer 9

They detect changes in partial pressure of oxygen and carbon dioxide and also the pH in blood

Question 10

What are peripheral chemoreceptors

Answer 10

Peripheral chemoreceptors are small highly vascularised bodies in region of aortic arch and carotid sinuses, information is sent via the glossopharyngeal and vagus nerves to the nucleus in the brainstem called NTS

Question 11

What are decreases in oxygen referred to as

Answer 11

Hypoxia

Question 12

What are increases in carbon dioxide referred to as

Answer 12

Hypercapnia

Question 13

What do peripheral chemoreceptors respond to

Answer 13

Decreases in partial pressure of oxygen (hypoxia)

Question 14

What partial pressure would oxygen have to drop to to have a significant effect

Answer 14

Below about 60mmHg at which there would be a progressive hyperventilation

Question 15

What are central chemoreceptors

Answer 15

Clusters of neurones in the brainstem that are activated when PCO2 is increased (hypercapnia) or pH decreased

Question 16

What causes central chemoreceptors to become activated

Answer 16

Increase in arterial PCO2

Question 17

Explain the ventilatory response to hypercapnia

Answer 17

Very small changes in PCO2 have large effects on ventilation (unlike O2)

Hypercapnic response originates in central chemoreceptors in the brainstem

Plays a major role in moment to moment control of breathing

Question 18

What are mechanoreceptors

Answer 18

Sensory receptors that detect changes in pressure, movement and touch

In the respiratory system mechanoreceptors detect movement of lung and chest wall

Question 19

What activates mechanoreceptors

Answer 19

Inflation of the lungs

Question 20

What nerve sends neural signals from mechanoreceptors to the brainstem

Answer 20

The vagus nerve

Question 21

What part of the brainstem are signals sent from mechanoreceptors to

Answer 21

Signals are sent from mechanoreceptors to the nucleus tractus solitarius in the brainstem

Question 22

Where are mechanoreceptors found in the respiratory system

Answer 22

They are found in airways smooth muscle and airway epithelium

Question 23

What generates the rhythm of breathing

Answer 23

A cluster of respiratory neurones in the brainstem generate rhythm of breathing

Question 24

What sends information to the NTS

Answer 24

The NTS recieves information from mechanoreceptors and peripheral chemoreceptors

Question 25

What neurons are active during inspiration

Answer 25

Inspiratory neurones

Question 26

What neurons are active during expiration

Answer 26

Expiratory neurones

Question 27

What does the phrenic nerve innervate

Answer 27

Innervates the diaphragm