Central Control of Respiration Flashcards
What is respiration mainly controlled by?
Nerve cells or neurones in the medulla oblongata of the brain
What neurons set the basic rhythm of respiration and can it be influenced?
Medullary, and yes from peripheral sensory receptors
What part of the brain is associated with the respiratory centre?
Medulla oblongata
What are the 2 regions of the respiratory centre?
Inspiratory centre
expiratory centre
What does the inspiratory centre consist of?
2 dorsal regions of the medulla
What rhythm does neurones show for inspiratory?
Spontaneous with a cyclic form of activity
Where are action potentials arised from for the muscles of inspiration?
pass along intercostal nerves and phrenic nerves to inspiration muscle
Where are the neurones for expiratory situated in the medulla?
More ventrally either side
What are the neurones like in the expiratory centre?
Mostly inactive but during heavy breathing send AP to expiration muscles
What are the other brain centres associated with respiration?
Apneustic centre
Pneumotaxic centre
What does the apneustic centre consist of?
Scattered neurones in the pons which send AP to inspiratory centre
What does the pneumotaxic centre consist of?
group of neurones in the superior of the pons - have an inhibitory effect on inspiratory and apneustic
What does the apneustic and pneumotaxic centre function as?
to regulate the inspiratory centres to insure rhythmical breathing
What is the hering bruer reflex? what receptors are associated?
Control mechanism associated with stretch receptors in the walls of the bronchi
When are stretch receptors activated and what nerve is associated?
during inspiration and send AP to vagus nerve to medulla
What does the AP do during inspiration?
inhibit inspiratory centre and allow expiration
When are stretch receptors inactive?
during expiration, to allow activation of inspiration
What is chemical control of respiration activated by? what receptors?
Chemoreceptors, central and peripheral
Where are central chemoreceptors located and what does it influence?
in the medulla in chemosensitive area where they influence respiratory centres
Where are peripheral chemoreceptors located and what does it influence?
Located in carotid and aortic bodies connect to respiratory centres by glossopharyngeal and vagus nerve respectively
What does the chemoreceptors respond to changes in?
concentrations of hydrogen ions (PH) and oxygen
What is hypercapnia and hypocapnia?
Hypercapnia = excessive PCO2 in the blood Hyopcapnia = lower than average PCO2 in the blood
How are carbon dioxide concentrations detected in the blood?
Not directly but chemoreceptors detect changes in blood PH
What is PH detected by?
Chemoreceptive area in medulla by peripheral chemoreceptors
What detects PH in the blood indirectly?
chemoreceptive area in medulla
What detects blood PH directly?
chemoreceptors in the Carotid and Aortic bodies
What does decrease in PH do?
increases in respiratory rate
What does increase in PH do?
decrease in respiratory rate
What % of total response in PH changes is medulla responsible for?
80 whilst peripheral receptors are 20%
What are 02 conc in the blood detected by?
Chemoreceptors in the carotid and aortic bodies
If PCO2 in constant what does PO2 change to for blood conc to have large sim effec on respiration?
drop 50% of normal value
What is haemoglobin saturated with?
O2 at PO2 of 80mm
Where does PO2 levels drop to for low O2 conc to trigger increase in respiratory rate?
Carotid and Aortic arteries
