Control of respiration Flashcards
What is the innervation to skeletal muscles of inspiration?
alpha motor neurones
What innervates diaphragm?
Phrenic nerve C3 -C5
What innervates intercostal muscles?
Intercostal nerves
What controls respiration?
voluntary and subconscious control, entirely depending on the signalling from brain
Where are the respiratory control centres located?
In pons and medulla oblongata
Is it posible to beat without functioning intercostal muscles?
Yes
Is it possible to breath without functioning diaphragm?
No
What are the two respiratory groups in medulla?
dorsal and ventral respiratory group
What is controlled by the dorsal respiratory group?
inspiratory muscles
What is controlled by ventral group?
Some inspiratory, but mainly expiratory muscles, larynges and tongue
How is automatic rhythm of breathing set?
By firing of smooth and repetitive action potentials from dorsal respiratory group, there is some tone of signalling even during expiration to allow smooth expiration
What is the role of ventral respiratory group?
Sends signals to keep the airway open
What affects the pattern of respiration?
Emotions (via limbic system), voluntary override via higher centres and machine-sensory inputs
What includes mechano-sensory input?
Stretch reflex to prevent overinflation of lungs and chemical composition of blood e.i. pH, PO2 and PCO2
What has the most effect on the respiratory pattern?
The PCO2
What are the two types of chemoreceptors?
central and peripheral chemoreceptors
Describe central chemoreceptors
They are located int he medulla and respond to the H+ion concentration change in cerebrospinal fluid which is mostly caused by CO2, therefore they detect CO2 levels indirectly, it is primary ventilation drive
What is primary ventilation drive ?
The PCO2 detected by central chemoreceptors
Where are peripheral chemoreceptors located?
In carotid artery (most sensitive) and aortic bodies
What do peripheral receptors detect?
They detect the plasma PO2, PCO2 (less sensitive than central) and pH
What causes secondary ventilation drive ?
Peripheral chemoreceptors
What causes increased PCO2?
It stimulates the respiratory centres to increase the respiratory frequency and depth of breathing
What is hypercapnia?
Increased levels of CO2 in blood
Is blood brain barrier permeable to H+ ions and CO2?
Blood brain barrier is impermeable to H+ ions, but it is permeable to gases such as CO2
