Chemical Control Of Breathing Flashcards
What is a rise in pCO2 called?
Hypercapnia
What is a fall in pCO2 called?
Hypocapnia
What is a fall in pO2 called?
Hypoxia
What is a hyperventiliation?
Ventiliatiln increase without a change in metabolism
What is hypoventilation?
A ventiliation decrease without a change in metabolism
What are some of the effects of pH distubances?
Plasma pH is controlled between 7.38-7.46 and if it falls below this enzymes become denature,pd and above this the free calcium concentration drops which leads to tetany
What can hypercapnia cause?
Respiratory acidosis
What can hypocapnia cause?
Repsiratory alkalosis
How can changes in plama pH be compensated?
Respiratort acidosis is compenstated by the kidneys increasing HCO3- whereas respiratory alkalosis is compensated by the kidneys decreasing HCO3-
How can metabolic acid be produced?
Of the tissues produce acid this reacts with HCO3_ and the fall in this leads to a fall in pH thereby causing a metabolic acidosis which can be compensated by changing ventiliation
How can metabolic alkalosis occur?
Of the plasma HCO3- rises (after vomiting) the plasma pH rises and then metbolic alkalosis which can be compensated by decreasing ventiliaiton
What are the different sensors invovled in the respiratory control pathways?
Central chemoreceptors, the peripheral chemoreceptors, pulmonary receptors and joint and muscle receptors
What will large falls in pO2 detected by the carotis amd teh arotic bodies stimulate?
Increased breathing, changes in heart rate, changes in blood flow disrtubution
What is the role of the central chemoreceptors?
Detect changes in arterial pCO2, and therefore the small rises in PCO2 increase the ventilation whereas small falls decrease the ventiliation and is the basis of negative feedback control of breathing
What is the physiology of the central chemoreceptors?
Respond to changes in the pH of the cerebro spinal fluid, and this CSF is seperated from blood by the blood brian barrier, and CSF (hco3-) is controleed by the choroid plexus cells, and therefore the CSf pCO2 is determined by the aterial pCO2
What determines the pH of the CSF?
Determined by the ratori of HCO3- to pCO2, HCO3- id fixed in the short term, as the BBB is i per,eable to HCO3-, so falls in Pco2 lead to rises in CSF pH by persisting changes are challenged by the chorioid plexus cells
How do the central chemoreceptors determine the normal pCO2?
CSF hco3- determines which pCO2 is associated with the CSF pH and therefore the HCO3- therefore sets the control system to a paticular Co2 and can be reset by changing the HCO3- in the CSF
What happens in persisitng hypoxia?
Hypoxia is detected by teh periohapela chemorecewptors p, which increase the ventiliation by pCO2 will fall futher and therefore decrease the ventiliation. So CSF will ater for this by increase HCO3- or H+ to maintian a nromal pH
What happens during persisting hypercapnia?
There is respiratory acidosis and therefore a decrease pH of the CSF and the periphral and central chemoreceptors stimulate breathing, but the acidic pH is undesirable for neutrons and therefore the chorid plexus is needed to adjust the pH of the CSF
