The regulation of respiration

Question 1

what is the neuronal control of breathing ?

3

Answer 1

1- pontine respiratory centre in pons interacts with …

2- medullary respiratory centre which controls insp /exp they have central chemoreceptors around them

3- the medullary respiratory splits into 2 = ventral MRS = rhythm -quicker the AP the quicker the breath rate
dorsal MRS = controllable the diaphragm (inspiration)

Question 2

what can stimulate or opress the MRS and pontine respiratory centre!
(5)

Answer 2

1- Higher stimulation from hypothalamus. limbic centre ,exercise centre in the motor cortex ( this increases breath rate )

2-receptors in muscle joint = increases respiratory rate

3-voluntary control from motor cortex

4-carotid ,aortic , central CHEMORECEPTORS

5- Stretch receptors = Hering -Breler Reflex ( protects from over inflation , suppress the respiratory centre!

Question 3

what is the chemoreceptor control of the breath rate?
(hypoxia and hypercapnia )
(3) +(3)

what happened to central and peripheral receptors …

Answer 3

1- Hypoxia and hypercapnia = LOW O2 and High co2
- REMEMBER IN HEALTH we respond to CO2 levels , the response to the high co2 curve = steeper = high pH = hence the chemoreceptor stimulate respiratory centre to breathe more!

2- ACIDOSIS = when H+ is high due to co2 levels. THE PERIPHERAL CHEMORECPETORS =more response to this! this is because the central chemoreceptors =slower because H+ passes into the brain vvvvvv slowly due to the BRAIN BICARBONATE PUMP ( which prevents pH change in the brain - this limits the central chemoreceptors response to pH!

explanation :
The Hco3 - binds to the H+ –>H2co3
this means the pH is brought back to normal, hence we need our peripheral chemoreceptors to be activated

Question 4

why shouldn’t people who have chronic co2 retention be given 100% o2 ?
-obstructive diseases

Answer 4

1- In chronic co2 retention = hypoventilation the central chemoreceptors go to sleep ( they get used to high co2 = habituated )

2-shift to peripheral chemoreceptors which detects pH and Co2

the pH can be Brought back to normal by the bicarb buffer
HCO3- +H+ –>H2C03
as H+ is reacted , pH increases back to normal ( less acidic )

THIS MEANS THE DIRVE TO BREATHE = OXYGEN dependent ,
if you give them 100% oxygen they don’t feel the need to breathe !

Question 5

what happens at high altitudes?

6

Answer 5

1- pO2 decreases = hypoxic hypoxia

2- peripheral chemoreceptors sense this and increase the ventilation rate

3- HIGH ventilation rate = hypocapnia, alkalosis = this decreases CO2 levels in the body = increasing the ph of the Cerebrospinal fluid

4- this increases ventilation yet again!

5- erythropoietin =hormone secreted by kidney used to increase the number of RBC hence Hb, so more O2 can be transported around the body

6- increased 2,3 DPG MEANS that oxygen dissociates at respiring tissue, but less is taken up in the lungs = increases breath rate! ( DPG reduces infinity for oxygen)