Reg Of Respiration Flashcards
What is the higher brain area to regulate Rhythmic breathing
Cerebral cortex
Which parts of the brain are the respiratory centre in
Pons and medulla
Which types of receptors go to the medulla/ pons (6)
Receptors Eg for pain to hypothalamus
Irritant receptors
Stretch receptors in lungs
Peripheral and central chemoreceptors
Proprioreceptors
How do signals get from medulla to inspristory muscles or expiratory muscles
AFFERENT Motor neurones
Which types of muscles are involved in inspiration which are attached to motor neurones from medulla
External intercostal
Diaphragm
Which types of muscles allow expiration forced
Abdominal muscles
Internal intercostal muscles
What system makes up the pons
Pontine respiratory group (PRG)
What 3 things makes up the pons PRG
2 pneumotaxic centres
1 apreustic centre
What are the 2 medullary neurones
DRG (dorsal)
VRG (ventral)
Which medullary neurone is responsible for inspiration
DRG
How does the DRG/VRG get inputs to change insp/exp
From craniofacial nerves IX (glossy pharyngeal) and X (vagus)
Which send impulses eg from chemoreceptors
How does the DRG for inspiration send impulses to the diaphragm to contract
Down phrenic nerves
Which nerves contact the intercostal muscles eg expiratory to contract in inspiration
Thoracic
Which complex in the VRG links it to the DRG for rhythmic breathing
Pre botzinger complex
What does VRG signalling do
Allow expiration mostly
And affects the pharynx, larynx
What happens when DRG neural activity inhibits
Expiration can occur as inspiration muscles like diaphragm relax
What do the apreustic centre in the pons do
Promotes inspiration via the DRG and also stimulating the inspiratory neurones eg phrenic
The pneumotaxic centres inhibit apreustic stimulation of the DRG , which neurones does it inhibit to stop inspiration
T5 to the external intercostal
Phrenic to the diaphragm
Which chemoreceptors are most sensitive to 02 levels
Peripheral chemoreceptors
When would peripheral chemoreceptors start to increase ventilation
When levels of o2 are below 60 (usually 100)
Where are peripheral chemoreceptors
Aortic arch
Carotid arteries (both internal and external)
How do aortic arch chemoreceptors transmit info to the medulla
Via craniofacial nerve IX (glossopharyngeal)
How does the carotid artery send impulses to the medulla
Via vagus X nerve
What would happen when peripheral (aortic and carotid) chemoreceptors detected o2 low levels below 60
Impulses down the IX and X
Medulla DRG and VRG would be stimulated
Hyperventilation would occur to increase Po2 and decrease Pco2
Which cells in the carotid chemoreceptors detect low Po2
Glomus cells
What happens in glomus cells to cause impulse for low o2 down to the medulla
Low po2 closes the K channels in glomus cells
This causes depolarisation
Ca channels can open in depolarisation
DA vesicles fuse and released
DA binds to receptors on neurones
AP sent down vagus to the medulla for hyperventilation
Which receptors are better at detecting high pco2
Central chemoreceptors
Where are central chemoreceptors found
At the csf / blood brain barrier
How can pco2 be detected from the capillaries to the csf but H can’t
Pco2 can diffuse through blood brain barrier
How is co2 levels detected in the csf indirectly via central chemoreceptors
They detect HCO3 and H levels from the splitting of carbonic acid when co2 reacts with h20
What happens when high co2 senses indirectly via HCO or directly via co2
Impulses sent to medulla from the central chemoreceptors
Causes hyperventilation via DRG and VRG
How are central chemoreceptors adaptive
After many days of high co2 levels these become normal and hyperventilation stops
What happens when low co2 levels are sensed via chemoreceptors
Hypoventilation
What causes respiratory alkalosis
Increased ph due to hyperventilation removing co2
This means less co2 present to produce Hco3 and H
This increases ph (alkalosis)
What causes respiratory acidosis
Hypoventilation
Increased co2 levels
More co2 into HCO and H
H reduces ph
Causes respiratory acidosis
What is metabolic acidosis
The increase of acids / decrease in ph due to exercise lactic acid rather than co2 levels
Which chemoreceptors deal with metabolic acidosis (high co2)
Peripheral chemoreceptors
Why aren’t central chemoreceptors affected by ph
They can’t sense ph as H can’t pass the blood brain barrier to the csf
What happens when peripheral chemoreceptors sense metabolic acidosis via exercise
They send impulses down the vagus or IX to medulla
Cause hyperventilation
Reduces pco2 which counteracts the low ph
Can peripheral sense co2 as much as central chemoreceptors?
No, weak stimuli sent from aortic or carotid
What are stretch receptor connected to the DRG and VRG for
when inflation of lungs is too high during inspiration
They cause inactivation of the DRG and activation of expiration via VRG
What are irritant receptors connected to the medulla for
Detect stimuli like allergens or cold air to cause a cough
Which nerve has impulses sent from irritant receptors
Vagus X
Explain how a cough is produced from irritant receptors
When triggered via cold air etc
Impulse sent down vagus to DRG
DRG sends impulses down phrenic and thoracic to intercostal and diaphragm for inspiration
This reduces pleural cavity pressure
Air enters
The larynx and glottis close after
Abdomen muscles and expiratory muscles contract via VRG to cause expiration
Glottis and larynx open
Air is forced out fast and down narrow bronchi and trachea as they are collapsed
What are proprioreceptors for
They increase Po2 and decrease pco2 before exercise has begun to meet demands
Via induction of the DRG and VRG = hyperventilation
