Chemical Control Of Breathing

Question 1

What is a rise in pCO2 called?

Answer 1

Hypercapnia

Question 2

What is a fall in pCO2 called?

Answer 2

Hypocapnia

Question 3

What is a fall in pO2 called?

Answer 3

Hypoxia

Question 4

What is a hyperventiliation?

Answer 4

Ventiliatiln increase without a change in metabolism

Question 5

What is hypoventilation?

Answer 5

A ventiliation decrease without a change in metabolism

Question 6

What are some of the effects of pH distubances?

Answer 6

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

Question 7

What can hypercapnia cause?

Answer 7

Respiratory acidosis

Question 8

What can hypocapnia cause?

Answer 8

Repsiratory alkalosis

Question 9

How can changes in plama pH be compensated?

Answer 9

Respiratort acidosis is compenstated by the kidneys increasing HCO3- whereas respiratory alkalosis is compensated by the kidneys decreasing HCO3-

Question 10

How can metabolic acid be produced?

Answer 10

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

Question 11

How can metabolic alkalosis occur?

Answer 11

Of the plasma HCO3- rises (after vomiting) the plasma pH rises and then metbolic alkalosis which can be compensated by decreasing ventiliaiton

Question 12

What are the different sensors invovled in the respiratory control pathways?

Answer 12

Central chemoreceptors, the peripheral chemoreceptors, pulmonary receptors and joint and muscle receptors

Question 13

What will large falls in pO2 detected by the carotis amd teh arotic bodies stimulate?

Answer 13

Increased breathing, changes in heart rate, changes in blood flow disrtubution

Question 14

What is the role of the central chemoreceptors?

Answer 14

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

Question 15

What is the physiology of the central chemoreceptors?

Answer 15

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

Question 16

What determines the pH of the CSF?

Answer 16

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

Question 17

How do the central chemoreceptors determine the normal pCO2?

Answer 17

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

Question 18

What happens in persisitng hypoxia?

Answer 18

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

Question 19

What happens during persisting hypercapnia?

Answer 19

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