Ventilation Control Flashcards
What stimulation does ventilation control need for inspiration
stimulation of skeletal muscle
What two nerves stimulate skeletal muscle
Phrenic
Intercostal
What does the phrenic nerve supply
the diaphragm
What are the two respiratory centres in the brain
Pons and medulla
What is ventilation control dependent on
signals from the brain
What would happen if the spinal chord was severed above c3 - c5
breathing would cease
As supply the diaphragm
What does dorsal respiratory group control
muscles of inspiration contractions
What does the ventral respiratory group control
Muscles of expiration and some inspiratory to pharynx, larynx and tonuge
What does the ventral respiratory do to the pharynx, larynx and tongue
maintain the tone of the muscle to ensure patency
What is the function of the respiratory centres
set automatic rhythm of breathing
adjust the rhythm in response to a stimuli
What is the automatic rhythm of breathing co-ordinated by
firing of smooth muscle
Action potential in then dorsal respiratory group
What four factors can modulate the rhythm of breathing
Emotion
Voluntary override
Mechano sensory input from the thorax
Chemical composition of the blood
Where does emotion come from
Via the limbic system in the brain
When does the mechno sensory input from the thorax
as a safety mechanism performs a stretch reflex to prevent over inflamation from the lungs
What makes up the chemical composition in the blood
CO2, pH, and O2
What detects chemical composition
chemoreceptors
What is the most significant input in altering the rhythm of breathing
chemical composition
Where is the central chemoreceptors located
In the medula
Where is the peripheral chemoreceptors located
carotid (neck) and aortic bodies
What out out of the two receptors is the primary ventilation drive
Central
What does central chemoreceptors respond directly to?
CO2 increasing [H+] in the CSF around the brain
What triggers the raised [H+] levels in the CSF
raised PCO2 levels crossing across the blood brain barrier increasing the CSF [H+] levels
Why cant CO2 directly cross the blood brain barrier
its impermeable
How much does a 10% increase in PCO2 levels increase minute ventilation, and why is this
100%
The body is extremely sensitive to CO2
Linear relationship
When arterial PCO2 drops what happens to the CSF [H+]
decreases - HYPERVENTILATION
What do the peripheral chemoreceptors respond to
the H+ in the plasma and PO2
When will peripheral chemoreceptors be stimulated
When PO2 levels fall below 60mmHg - hypoxic drive
When is peripheral chemoreceptors more commonly stimulated
In people with a hypoxic drive
How does H+ increase, increase ventilation
as H+ increase is accompanied by an increase in PCO2 (equation swings left)
Can you override involuntary stimuli such as arterial PCO2?
No
What are examples of ways you can control your breathing in voluntary override
Breath holding
hyperventilation
Breathing in high levels of CO2
What is the result of breathing in high levels of CO2
increase PCO2, Partial pressure of CO2 has a small gradient therefore the overall partial pressure gradient is imparied
What neural pathway allows a control over breathing
cerbral cortex to respiratoty motor neurons
When in breathing inhibited
when swallowing to avoid aspiration of food
Why do you expire after you swallow
to dislodge any food particles
What is the affect of Barbiturates and opiods, gaseous anaesthetics have on the respiratory system (e.g. NO2)
depress peripheral chemoreceptors breath shallower (decrease tidal volume) and faster (increase respiratory rate)
When would nitrous oxide cause you problems
if you are having an hypoxic drive -already low on oxygen
When does the central pathway no longer become you primary drive
when you experience type 2 reparatory failure
Why wouldnt you give pure oxygen to someone on hypoxic drive
as Oxygen needs have been satisfied and you stop breathing, retaining CO2 then ya die
