L22: Modulation Of Respiratory Control Flashcards
What do chemoreceptors detect
Chemical changes in the blood
What do mechanoreceptors detect
Changes in the irritation and distension of airways and lungs
What are peripheral chemoreceptors
Sensory receptors that are located in the periphery i.e outside the central nervous system
Where are the 2 major location of peripheral chemoreceptors
Carotid bodies
Aortic bodies
What does peripheral chemoreceptors detect and respond to
Po2
Pco2
Ph
Where exactly is the aortic bodies located
Aortic arch
Where exactly is carotid bodies located
Bifurcation of the common carotid artery (in the neck) into external and internal common carotid artery
Does carotid bodies or aortic have the major functional role in ventilators control
Carotid bodies
What is the afferent nerve of the carotid body
Glossopharyngeal nerve
What is the afferent nerve of the aortic body
Vagus nerve
From the carotid and aortic body where does the vagus nerve and glossopharyngeal nerve (sensory nerves) go to
To NTS in the brainstem
What is a sinus
A swelling that contains baroreceptors
What are the sinuses located near the carotid and aortic bodies
Carotid sinus
Aortic sinus
Which cells in the bodies detect the changes in the blood gas
Globular/ type 1 cells
What happens to the firing of the carotid body as pao2 decreases
Increases
What happens to the firing of carotid bodies when there is a high paco2 and ph (metabolic acidosis)
Increases more
What is metabolic acidosis
An increases in H+ that is not related to co2 (breathing)
Overall what are the 3 stimulus that the carotid body increases it firing and responce
Hypoxia
Hypercapnia
Metabolic acidosis
What is the mechanism of sensing hypoxia in the carotid body
1) hypoxia acts on the mitochondria to inhibit oxidative phosphorylation (Electron transport chain)
2) atp production is reduced
3) amp increases
4) this is activated an enzyme called AMPK
5) AMPK inhibits pottassium channels on the type 1 cells in the carotid body
6) this leads to membrane depolarisation
7) voltage gated calcium channels open
8) neurotransmitters are released to synapses to induce an action potential to glossopharyngeal nerve
What can a carotid tumour be a result of
Hypoxia
Apart from peripheral chemoreceptors what are the other types of chemoreceptors found in the body
Central chemoreceptors
Where are the central chemoreceptors located
Brainstem of the CNS
Does central chemoreceptors respond to hypoxia
No
What inhibits central chemoreceptors
Hypoxia
What are central chemoreceptors sensitive to
Carbon dioxide
What can pass through the blood brain barrier from the capillary bed to the chemoreceptors
Carbon dioxide (hypercapnia)
What happens to carbon dioxide when it passes through the blood brain barrier into the medulla
Carbon dioxide reacts with water to give hydrogen and bicarbonate ions
What stimulates the central chemoreceptors
Hydrogen ions from the reaction of carbon dioxide
What happens when the central chemoreceptors are stimulated
It sends activity to the medullary respiratory neurones of DRG etc to adjust ventilation
Does central chemoreceptors respond to metabolic acidosis
No it only responds to hypercapnia
What is acclimatisation
Decrease in H+ in the CSF (brain) by active transport from blood to CSF and vice versa
What membrane is between the CSF and arterial blood
Blood brain barrier
What does blood brain barrier prevent
Ions and large polar molecules from entering the CSF
What is respiratory acid change
Change in ph due to co2
Does respiratory acid affect the ph of CSF
Yes because carbon dioxide can enter the CSF by passing the blood brain barrier
Does metabolic acid affect the CSF ph
Not much because hydrogen ions cannot pass the blood brain barrier
What happens when the CSF ph decreases
Alveolar ventilation increases
Why does alveolar ventilation increase when ph of CSF decreases
To ventilate out carbon dioxide and return the ph back to normal
When does alveolar ventilation increase the highest
Hypoxia and hypercapnia occurring at the same time
Which gas controls pa02
Paco2
What are the 3 types of mechanical receptors in the lung
Rapidly adapting irritant receptors
Slowly adapting stretch receptors
J-type or c-fibre receptors
What do readily adapting irritant receptors respond to
Irritants that are inhaled
What are the afferent nerve of the pulmonary mechanical receptros
Vagus nerve
Where does the vagus nerve feed into in the brainstem after being activated
NTS then DRG
What do mechanical receptors respond to
Foreign bodies
Chemical irritants
Immunologic challenges
Where are rapidly adapting irritant receptors located
Between airway epithelial cells
What does rapidly adapting irritant receptors cause
Cough
Bronchoconstriction
Hyperpnoea (increased ventilation)
All this occurs to stop irritant getting any further into the lung
Where are slowly adapting stretch receptors located
Between smooth muscle cells
What activates slowly adapting stretch receptors
Stretch
What does the slowly adapting stretch receptors cause once activated
Inhibit inspiration and promote expiration
Bronchodilation
Tachycardia
Where does the vagus afferent nerve feed into in the brainstem
NTS
What is the stimulus of j-type/ c fibre receptors
Increase in interstitial fluid
Where are j-type/c-fibre receptors located
Area between alveolus and pulmonary capillary
What does j-type/c-fibre receptors cause once activated
Apnoea Bronchoconstriction Increased mucus secretion Hypotension Bradycardia
What is apnoea
Shallow breathing
