Nervous Ventilation Flashcards
Name the different structures found in the pons
. Ventral and dorsal respiratory groups (VRGs and DRGs)
. Pneumotaxic centres
. Apneustic centre
Which brainstem structures are found above and below the pons?
. Midbrain is above pons
. Medulla is below pons
. Spinal cord is below medulla
What does the DRG do?
. DRG fibres innervate diaphragm and external IC muscles
. Activity enhanced for inspiration
What does the VRG do?
. VRG fibres innervate abdominal muscles and internal intercostal muscles
. Activity enhanced for forced expiration
What do the pneumotaxic centres do?
Limit inspiration to 2 seconds to prevent overinflation
What does the apneustic centre do?
Prolong inspiratory gasp (opposite of pneumotaxic centre)
What are analeptics used for?
Reverse respiratory depression (when ventilation is insufficient)
What role does the vagus nerve play in ventilation?
Vagus nerve sends afferent signals to lungs to switch off inspiration to prevent over-inflation, similar to pneumotaxic centres)
What is apneusis? How is this affected when the vagus nerve is cut?
. Deep gasping inspiration (past 2 secs normal inspiration)
. Cut vagus nerve increases apneusis
Describe the role of the cerebral cortex in ventilation
. Stimulates inspiratory muscles (diaphragm and external IC muscles)
. Bypasses medullary centres when holding breath or changing depth of breath (limited ability to hold breath, will be overridden if oxygen levels too low)
Name two higher brain centres
Cerebral cortex and hypothalamus
Describe the role of the hypothalamus in ventilation
. Strong emotions, pain, or decrease in temperature can cause apnoea (breathing suspended)
. Excitation or increase in temperature can cause tachypnoea (rapid breathing)
Where are respiratory stretch receptors located? What do they do?
. Located in smooth muscle of trachea and bronchi
. Prevent over-inflation of lungs
Where are juxtapulmonary receptors (a.k.a. J-fibres or C-fibres) found? What are they activated by and what effects does their activation have?
. Found in alveolar walls between epithelium and endothelium
. Activated by oedema, congestion, histamine
. Activation results in tachypnoea, mucus secretion, and bronchoconstriction
Where are irritant receptors found? What are they stimulated by and what effects does their activation have?
. Found between epithelial cells of alveoli
. Activated by irritant gases, dust, smoke
. Activation results in tachypnoea, mucus secretion, bronchoconstriction, gasping
