Control of breathing Flashcards
What is the dorsal respiratory group primarily responsible for, where is it located and how does it travel to maintain respiratory function input and output)
Breathing pattern generator
Location: Nucleus of the solitary tract
Sensory input: vagus (X) and glossopharyngeal nerve (IX)
Output: increase in firing leads to output through the phrenic nerve to contract diaphragm.
Ventral respiratory group (What, when)
Inactive during quiet breathing
increase respiratory drive
Modulate inspiration/expiration (but not pattern generator)
What is the Pneumotaxic centre and its role in respiration? Where is it located?
It controls the length of respiration by inhibiting the dorsal respiratory group when breathing (reduce firing and this relaxation of the muscles)
Located in nucleus parabrachialis of pons. I suppose just knowing it’s in the pons is sufficient.
Sends inhibitory signals to DRG–>switch off inspiratory–>regulate medullary rhythm
What are the two main system the body uses to control respiration?
Neuronal control - brainstem, lung receptors
Chemical control - response to change in partial pressures, central peripheral chemoreceptors
Lung receptors (what -types)
Stretch receptors Irritant receptors Juxtapulmonary receptors (vagal, myelinated) Proprioceptive afferents Others - pain, trigeminal, arterial
Lung stretch receptors (where, what, how)
In smooth muscle of bronchial walls
Reflex to delay cycle
increase in lung volume increases stretch and firing and stimulates vagal thus the negative feedback loop decreases inspiration
What are lung irritant receptors responsible for and where are they located?
Vagal, unmyelinated
Stimulates cough and bronchoconstriction
Responsible for sighs every 5-20 mins
Reverses slow collapse of lungs in quiet breathing
Located along airways (remember before smoke gets into lungs)
What are lung juxtapulmonary receptors responsible for and where are they located? What are the triggers in firing of this type of receptor?
Vagal, myelinated
Respond to increase in interstitial volume to produce feelings of breathlessness
Located in endings of alveolar walls (at the ends to detect oedema)
Proprioceptive afferents (What, how)
Optimises work of breathing
Stimulated by shortening/increase in load of muscles and copes with it by achieving optimal tidal volume and frequency
What are the two different types of chemoreceptors involved in the control of breathing?
Match ventilation to metabolism
Central Chemoreceptors, peripheral chemoreceptors
Central chemoreceptors (what, where, how)
Determines 80% of ventilatory drive
Located in ventrolateral surface of medullar near exit of CN IX, X
Respond to pH changes in brain CSF (not in plasma), and is influenced only by carbon dioxide
CSF adaptation of lung control (what)
Prolonged hypercapnoea (CO2 retention) and CSF pH resets by pumping in HCO3- and ventilators drive returns to normal
CSF altitude and acclimatisation to low oxygen (how)
Ventilation stimulated by low oxygen leading to hypercapnoea and alkalosis
CSF returns to normal after drive increases
Peripheral chemoreceptors (what, how, where)
Regulates rate of ventilation
Principally to detect variation of the oxygen concentration in the arterial blood, whilst also monitoring arterial carbon dioxide and pH
Stimulated by changes in arterial blood with very fast response in regulating the rate of ventilation
Located in aortic and carotid bodies (major)
What are the chemicals involved in the chemoreceptor control of the central chemoreceptor? (2 types)
Carbon dioxide, and hydrogen ions. Measured as alveolar carbon dioxide production and pH levels
