Nervous control of ventilation Flashcards
What is the role of neural regulation in ventilation
- Sets the rhythm and pattern of ventilation
- Controls the respiratory muscles
What is the role of chemical regulation in ventilation
Detects central and peripheral arterial PCO2 and pH and peripheral PO2
Why does neural regulation have a faster response than chemical regulation
Fast acting impulses to and from the central nervous system
What does chemical control detect
Changes in partial pressure of CO2 / O2
What is respiratory depression
Rate and/or depth of respiration is insufficient to maintain adequate gas exchange in the lungs
What does respiratory depression occur as a result of
Effects on the medullary an pons respiratory centre
What can cause respiratory depression
Drugs e.g. opioids and benzodiazepines
What can respiratory depression be reversed by
Analeptics e.g. xoxo-ram hydrochloride
What does the medulla contain
Dorsal respiratory group (DRG)
Ventral respiratory group (VRG)
What do fibre from the dorsal respiratory group innervate
Diaphragm and external intercostal muscles
What does diaphragm contraction and thoracic cavity expansion cause
Inspiration
How long do dorsal respiratory group neurons switch on and off for
On for 2s
Off for 3s
Causes a rhythmic pattern
What do fibres from the ventral respiratory group innervate
Abdominal muscles and internal intercostal muscles
When is the activity of ventral respiratory group enhanced
forced expiration
What does the pneumotaxic center do
Transmit signals to the DRG (dorsal respiratory group)
What is the role of pneumotaxic center
- Limit inspiration
- Fine-tunes breathing; sends inhibitory impulses to the DRG
What does the pneumotaxic center limit the period of inspiration to
2s
What does the pneumotaxic center prevent
Over-inflation of lungs
Two parts of the ‘Pons’
Pneumotaxic center
Apneustic center
What is the apneustic center responsible for
Prolonged inspiratory gasps
-(prolongs DRG stimulation)
What does the vagus nerve do
Sends afferent information from the lungs to the DRG
What is the role of the vagus nerve
Prevent over inflation of the lungs by switching off inspiration
What does the cerebral cortex do
Stimulates motor neurons of the inspiratory muscles
When consciously controlling breathing, what does the cerebral cortex do
Bypass the medullary centers
When O2 concentrations in blood reach critical levels when holding breath, what happens
Respirator centers automatically reinitiate breathing
What can apnoea (suspension of breathing) be induced by
Anger, pain, or decrease in temperature
What can tachypnoea (rapid breathing) be induced by
Excitation, or increase in temperature
Where are stretch receptors located
Smooth muscle of trachea and bronchi
What are stretch receptors sensitive to
Lung expansion
What happens when lung expands (in relation to stretch receptors)
Lung expands—>respiratory center—-> inspiration is shorter and shallower—> prevents overinflation of the lungs
Where do juxtapulmonary receptors lie
In alveolar wall between epithelium and endothelium (close to pulmonary capillaries)
What are juxtapulmonary fibres stimulated by
Congestion, edema, histamine
What does the activation of juxtapulmonary fibres lead to
Apnoea or rapid shallow breathing, bronchoconstriction and mucus secretion
