Control of Ventilation Flashcards
what is the role of the respiratory chemosensors?
they monitor CO2, O2 gas levels in the system and they send a signal up to the central controller- which then tells our respiratory muscles to increase or decrease activity - the respiratory control system is based on a negative feedback system
what is the main region of the brain in control of respiration?
the Medulla of the brain stem - contains a cluster of neurons which control respiration-
- medullary respiratory center
- pons respiratory center
what are the two main clusters of neurons in the medullar respiratory center?
the dorsal respiratory group and the ventral respiratory group.
when inspiratory neuron fibers fire- what occurs?
it induces muscle contraction and therefore inspiration - but their inhibition then induces exhalation
*so you can think of them as controlling both inspiration and exhalation - where exhalation is passive*
during what action are inspiratory and expiratory ventral respiratory group neurons inactive?
they are both inactive during quiet breathing
- they are utilized when damad for ventilation is increased beyond normal (active expiration)
which respiratory group is most often quiet?
the ventral respiratory group
describe the generation of respiratory rhythm?
the neurons in the pre-botzinger complex- constantly fire and activate inspiratory neurons in the dorsal group which then activate muscles
so this pre-botzinger complex sets the pace of breathing
the role of the pons respiratory center is what?
composed of two clusters of neurons ( the pneumotaxic center and the apneustic center) - it fine tunes our breathing
what is the pneumotaxic center’s role?
•Pneumotaxic centre sends signals to the DRG that help silence/inhibit the inspiratory neurons.- prevents overinspiration
What is the role of the apneustic center?
•Apneustic centre conversely prevents the inspiratory neurons from being switched off.
what occurs if the pneumotaxic center is damaged?
you get really long isnpiration and really short exhalation
what other regions of the brain can affect respiration?
cortex = can exert voluntary control of our breathing-
limbic system and hypothalamus = emotional states - ‘sobbing’
main effectors of the inspiration/exhalation
•1. Diaphragm- phrenic nerve
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•2. Intercostal muscles- intercostal nerves
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•3. Abdominal Muscles-
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•4. Accessory muscles- neck muscles - activated in patients extremely short of breath
what are the different sensors of the respiratory control system?
chemoreceptors
lung receptors
other receptors
what are the two main types of chemoreceptors?
central and peripheral chemoreceptors
what is a chemoreceptor?
•Specialised tissue that respond to changes in the chemical composition of the blood or other fluid.
where are the central chemoreceptors found?
in the central nervous system
what is the most important regulator of ventilation?
the central chemoreceptors - they respond to a chnage in pH of the cerebrospinal fluid or the blood
does cerebrospinal fluid have a greater or lesser buffereing copacity than plasma?
cerebrospinal fluid has a lesser buffereing ability than plasma - so a small change in pH is detected very quickly
someone who hyperventilates often - what prevents them from having consisently lowered pH of the cerebrospinal fluid?
the ependymal cells - which act as a ‘kidney’ for the cerebrospinal fluid - therefore even if your plasma pH has dropped quite substantially, this regulates your pH around the brain so there is no lasting damage
were are peripheral chemorectors found?
carotid bodies
and aortic bodies
where are the carotid bodies found?
where the carotid divides into external and internal -
how do the aortic bodies communicate with the brian?
through the vagus nerve
what type of cells make up the carotid body receptor?
gloma cells
