Nervous control of ventilation

Question 1

What is the role of neural regulation in ventilation

Answer 1

• Sets the rhythm and pattern of ventilation

- Controls the respiratory muscles

Question 2

What is the role of chemical regulation in ventilation

Answer 2

Detects central and peripheral arterial PCO2 and pH and peripheral PO2

Question 3

Why does neural regulation have a faster response than chemical regulation

Answer 3

Fast acting impulses to and from the central nervous system

Question 4

What does chemical control detect

Answer 4

Changes in partial pressure of CO2 / O2

Question 5

What is respiratory depression

Answer 5

Rate and/or depth of respiration is insufficient to maintain adequate gas exchange in the lungs

Question 6

What does respiratory depression occur as a result of

Answer 6

Effects on the medullary an pons respiratory centre

Question 7

What can cause respiratory depression

Answer 7

Drugs e.g. opioids and benzodiazepines

Question 8

What can respiratory depression be reversed by

Answer 8

Analeptics e.g. xoxo-ram hydrochloride

Question 9

What does the medulla contain

Answer 9

Dorsal respiratory group (DRG)

Ventral respiratory group (VRG)

Question 10

What do fibre from the dorsal respiratory group innervate

Answer 10

Diaphragm and external intercostal muscles

Question 11

What does diaphragm contraction and thoracic cavity expansion cause

Answer 11

Inspiration

Question 12

How long do dorsal respiratory group neurons switch on and off for

Answer 12

On for 2s
Off for 3s

Causes a rhythmic pattern

Question 13

What do fibres from the ventral respiratory group innervate

Answer 13

Abdominal muscles and internal intercostal muscles

Question 14

When is the activity of ventral respiratory group enhanced

Answer 14

forced expiration

Question 15

What does the pneumotaxic center do

Answer 15

Transmit signals to the DRG (dorsal respiratory group)

Question 16

What is the role of pneumotaxic center

Answer 16

• Limit inspiration

- Fine-tunes breathing; sends inhibitory impulses to the DRG

Question 17

What does the pneumotaxic center limit the period of inspiration to

Answer 17

2s

Question 18

What does the pneumotaxic center prevent

Answer 18

Over-inflation of lungs

Question 19

Two parts of the ‘Pons’

Answer 19

Pneumotaxic center

Apneustic center

Question 20

What is the apneustic center responsible for

Answer 20

Prolonged inspiratory gasps

-(prolongs DRG stimulation)

Question 21

What does the vagus nerve do

Answer 21

Sends afferent information from the lungs to the DRG

Question 22

What is the role of the vagus nerve

Answer 22

Prevent over inflation of the lungs by switching off inspiration

Question 23

What does the cerebral cortex do

Answer 23

Stimulates motor neurons of the inspiratory muscles

Question 24

When consciously controlling breathing, what does the cerebral cortex do

Answer 24

Bypass the medullary centers

Question 25

When O2 concentrations in blood reach critical levels when holding breath, what happens

Answer 25

Respirator centers automatically reinitiate breathing

Question 26

What can apnoea (suspension of breathing) be induced by

Answer 26

Anger, pain, or decrease in temperature

Question 27

What can tachypnoea (rapid breathing) be induced by

Answer 27

Excitation, or increase in temperature

Question 28

Where are stretch receptors located

Answer 28

Smooth muscle of trachea and bronchi

Question 29

What are stretch receptors sensitive to

Answer 29

Lung expansion

Question 30

What happens when lung expands (in relation to stretch receptors)

Answer 30

Lung expands—>respiratory center—-> inspiration is shorter and shallower—> prevents overinflation of the lungs

Question 31

Where do juxtapulmonary receptors lie

Answer 31

In alveolar wall between epithelium and endothelium (close to pulmonary capillaries)

Question 32

What are juxtapulmonary fibres stimulated by

Answer 32

Congestion, edema, histamine

Question 33

What does the activation of juxtapulmonary fibres lead to

Answer 33

Apnoea or rapid shallow breathing, bronchoconstriction and mucus secretion