LOCAL METABOLIC PRODUCTS

• Key Metabolic Products: that affects your heart rate and blood vessels (vasoconstriction and vasodilation)

  • Partial pressure of oxygen (PO2)
  • Partial pressure of carbon dioxide (PCO2)
  • Hydrogen ion concentration (pH)
  • Temperature

  these can be detected by chemoreceptors
• Chemoreceptors are located in the carotid bodies (near the bifurcation of the common carotid arteries) and along the aortic arch. They are sensitive to chemical changes in the blood rather than stretch or movement.
• Mechanisms:

  • Decreased Oxygen:When oxygen levels decrease, carbon dioxide levels tend to rise.
• CO2 combines with water to form carbonic acid, which dissociates to produce hydrogen ions (H+) (acidic)
• This results in a decrease in pH, making the body more acidic. This is detected by chemoreceptors.
• Chemoreceptor Types:

  1. Peripheral Chemoreceptors (Located in the carotid and aortic bodies):

  • Sensitive to changes in oxygen levels.
• PERIPHERAL CHEMORECEPTORS

  Response to decreased oxygen:

  • The chemoreceptors send signals to the brain (via the same pathway as baroreceptors), triggering the Nucleus Tractus Solitarius (NTS) to promote a sympathetic response.
• PERIPHERAL CHEMORECEPTORS

  The result is an increase in heart rate to improve oxygen delivery.
• Central Chemoreceptors (Located in the brainstem):

  • Sensitive to changes in carbon dioxide (CO2) and hydrogen ion (H+) concentrations.
• Response to increased CO2 or H+:

  • This leads to a decrease in pH, which is detected by the central chemoreceptors
• The chemoreceptors stimulate the NTS, promoting cardiovascular changes such as:

  • Increased heart rate
  • Peripheral vasoconstriction (to increase blood pressure and improve oxygen delivery).
• Decreased Oxygen (Peripheral Chemoreceptors):

  • Increases heart rate via sympathetic stimulation.
• Increased CO2 or H+ (Central Chemoreceptors):

  • Decreases pH, leading to an increase in heart rate and vasoconstriction, both aimed at restoring homeostasis and improving oxygen delivery.