Control of Breathing in Human Physiology

Chemoreceptor Triggering

• A change in blood pH, specifically an increase in acidity (lower pH) triggers chemoreceptors.
• This increase in acidity can be caused by an elevated concentration of carbon dioxide (CO2CO_2CO2​) in the blood.
• These chemoreceptors are located in the carotid and aortic bodies.

Blood pH Range

• The normal stable range for blood pH is 7.35 to 7.45.
• This range is crucial for maintaining proper function of the body's enzymes and proteins.

Hemoglobin Saturation and Baroreceptors

• Baroreceptors, which are pressure-sensitive receptors, are not triggered by hemoglobin saturation.
• Baroreceptors respond to changes in blood pressure.

H2CO3H_2CO_3H2​CO3​ Formation and Breakdown

• If the rate of formation of H2CO3H_2CO_3H2​CO3​ (carbonic acid) exceeds its breakdown in the alveoli, it leads to a decrease in blood pH (acidosis).
• This can happen during conditions like respiratory failure, which impairs the ability to exhale carbon dioxide.

Baroreceptor Response to Blood Pressure Changes

• Baroreceptors detect changes in blood pressure and send this information to the brain's medulla oblongata.
• This triggers an appropriate response - an increase in blood pressure leads to decreased heart rate and vasodilation, whereas a decrease in blood pressure leads to increased heart rate and vasoconstriction.

Rapid Chest Volume Changes and Breathing Rate

• The rapid changes in chest volume that affect breathing rate are due to two factors:
  • The elastic property of the lungs, which allows them to expand and contract.
  • The action of the respiratory muscles (diaphragm and intercostals), which contribute to the pressure changes within the thorax.

Carbonic Acid-Bicarbonate Buffer System

• The carbonic acid-bicarbonate buffer system stabilizes blood pH by converting excess hydrogen ions (H+H^+H+) into carbonic acid (H2CO3H_2CO_3H2​CO3​).
• This process helps to counteract changes in blood pH caused by metabolic or respiratory disturbances.

Hypotension and Baroreceptor Response

• When hypotension (low blood pressure) occurs, baroreceptors detect this decrease and send signals to the brain.
• This leads to an increase in heart rate, vasoconstriction, and increased release of hormones like epinephrine and norepinephrine, in an attempt to restore normal blood pressure.

This quiz focuses on the control mechanisms of breathing within the human body, specifically how the medulla oblongata and various receptors regulate respiratory functions. Explore the processes involving blood pH, oxygen saturation, and the interactions between the diaphragm and rib cage muscles. Test your knowledge on the intricate system that maintains homeostasis in gas exchange.