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WEEK 17:
Nervous control of ventilation:
| Question | Answer |
|---|---|
| what is found in the medulla (2) | dorsal and ventral respiratory group |
| what is found in the pons (2) | pneumotaxic center and apenustic center |
| function of neural regulation | sets rhythm and pattern of ventilation, and controls respiratory muscles |
| compare neural and chemical control | neural is fast acting using impulses to and from CNS but chemical needs to wait for changes in partial pressure |
| respiratory depression | when rate/ depth of respiration is insufficient to maintain adequate gas exchange in lungs |
| when does respiratory depression occur | as a result of effects on medullary and pons respiratory centres eg some drug side effect (benzodiazepines, opioid) |
| how can you reverse respiratory depression | analeptics eg doxapram hydrochloride |
| dorsal respiratory group function | fibres innervate diaphragm and external intercostal muscles which cause diaphragm to contract and thoracic cavity to expand for 2s during inhalation and switch off for 3s making the rhythmic pattern of breathing |
| ventral respiratory group function | fibres innervate abdominal muscles and internal intercostal muscles and is said to be enhanced during forced expiration and might play some role in inspiration |
| what does the DRG fibres innervate (2) | diaphragm and external intercostal muscles |
| what does the VRG fibres innervate (2) | abdominal muscles and internal intercostal muscles |
| penumotaxic center function | transmit inhibitory signals to DRG to limit inspiration to 2s to prevent over inflation of lungs (switch off inspiration) |
| apneustic center function | responsible for prolonged inspiratory gasps (apneusis) to prolong DRG stimulation |
| when can apneusis be observed | in severe brain injury |
| vagus nerve | sends afferent information from lungs to DRG to prevent overinflation of lungs by switching off inspiration |
| cerebral cortex function | stimulates inspiratory muscles motor neurons and bypasses medullary centres when consciously controlling breathing eg when holding breath/ change depth |
| higher brain centres (2) | cerebral cortex and hypothalamus |
| limitation of cerebral cortex function | respiratory centers automatically start breathing when O2 concentration in blood reaches critical levels |
| hypothalamus function | when emotions, pain and changes in temperature alter respiration rate and rhythm |
| apnoea | suspension of breathing |
| tachypnoea | rapid breathing |
| where are stretch receptors found | smooth muscle of trachea and bronchi |
| function of stretch receptors | prevent over expansion of lungs |
| juxtapulmonary (J/ C fibre) receptors location | lie in alveolar wall between epithelium and endothelium close to pulmonary capillaries |
| what are juxtapulmonary (J/ C fibre) receptors stimulated by | congestion, oedema, and histamine |
| activation of juxtapulmonary (J/ C fibre) receptors results in what (4) | apnoea, rapid shallow breathing, bronchoconstriction and mucus secretion |
| types of respiratory reflexes (3) | stretch receptors, juxtapulmonary (J/ C fibre) receptors, and irritant receptors |
| irritant receptors location | between epithelium cells |
| what are irritant receptors sensitive to (3) | irritant gases, smoke and dust |
| activation of irritant receptors lead to what (5) | rapid shallow breathing, cough, bronchoconstriction, mucus secretion, and augmented breaths (gasps) |
| function of irritant receptors | send signals to respiratory centres via afferent fibres of vagus nerve which stimulate receptors |
| stimulation of receptors due to irritant receptors in trachea and bronchi lead to what | airway constriction (asthma) |
| stimulation of receptors due to irritant receptors in bronchioles | coughing |
| stimulation of receptors due to irritant receptors in nasal cavity | sneezing |
Created by:
kablooey
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