Respiratory system maintains blood O2 and CO2 concentration and blood qpH.
1. Chemoreceptors
a. Peripheral chemoreceptor
b. Central chemoreceptor
2. Effect of pH
3. Effect of CO2
4. Effect of O2
5. Inflation reflex
6. Other influencers
1. Blood Pressure
2. Temperature
3. Pain
4. Stretching the Anal sphincter muscle
5. Irritation of airways
1. Chemoreceptor
Chemoteceptor are specialized neurons involves with regulation of respiration respond to change in hydrogen ion concentration or changes in PO2 (or both).
a. Central chemoreceptors
Located in medulla oblongata and connected to respiratory center.
They response to changes in H+ concentration or PCO2 or both in cerebrospinal fluid (CSF)
b. Peripheral chemoreceptor
Located in carotid and Aortic body.
Respiratory center is connected to the carotid body chemoreceptory through -
Glossopharyngeal nerves and to the aortic body chemoreceptors by Vegus nerve.
Respond to changes in blood concentration, oxygen (O2) and help maintain cardio-respiratory homeostasis.
2. Effect of pH
Maintaining body pH is necessary for proper functioning of cells.
Because changes in CO2 levels change in pH
Respiratory system plays an important role in acid - base balance.
Examples,
If pH decreases
Respiratory center stimulated, resulting elimination of CO2 and increase in pH back to normal.
If pH Increases
Respiratory rate decreases and CO2 level increases
pH fall back to normal level
1. Chemical control of Respiration
Stimulus distrust homeostasis by causing
Increase H+ ion concentration, increase in arterial blood CO2 or decrease in pH or PO2.
Receptors
Central chemoreceptors in medulla oblongata and peripheral chemoreceptors in aortic and carotid bodies.
3. Effect of CO2
Greater than normal amount of CO2 in blood is hypercapnia
Lowe than normal amount of O2 in blood is hypocapnia
Small increase in CO2 in circulatory system cause increase in the rate and depth of Respiration.
4. Effect of O2
Decrease in oxygen level below normal value of hypoxia.
A drop in PO2 from normal can cause an increase in breathing.
But if PO2 falls below 50mmHg
Hypoxia depressed activity of central chemoreceptors and respiratory center, do not respond to any inputs.
As respiration rate decreases, PO2 falls lower and lower.
5. Inflation Reflex/ Hering breuer reflex
It is reflex triggered to prevent over-inflation of the lung.
Pulmonary stretch receptor present in visceral pleural, wall of bronchi and bronchioles and alveolar of the airway respond to excessive stretching of Lung during large inspiration.
Inflation reflex
Over inflation of Lung
Stretching of pulmonary stretch receptors
Initiation of impulses to respiratory center in medulla oblongata and Apneustic area.
Inspiratory area inhibited and Apneustic area is inhibited from activating the respiratory area
Thus respiratory area causes inspiration to stop
Expiration
Air leaves lung during expiration
Lung deflate
Stretch receptors are no longer stimulated
Nerve impulses cease
No inhibition of inspiratory and Apneustic area
Respiratory center "call for" an inspiration
Flowchart - inflation reflex
5. Propriocepters/ sensors and reflexes
Excercise result in increased breathing
Due to increase of CO2 and sensors located in joints and muscles spindle (stretch receptosreceptor)
Propriocepters in joints are stimulated
Send impulses to cerebral cortex
Transfer impulses to the medullary breathing area
Deep breathing
Regulation of Respiration
6. Other influencer
1. Blood pressure
Baroreceptors (pressure receptors) that detect changes in blood pressure.
2. Temperature
Increase in body temperature during fever, excercise (muscular) increases rate of Respiration.
Decrease in body temperature decreases respiratory rate.
3. Pain
A sudden, severe pain bring increases respiratory center.
4. Stretching the Anal sphincter muscle
Increase respiratory rate
5. Irritation of Airways
Mechanical and chemical irritation of pharynx and larynx affect rate of Respiration.
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