Transport of respiratory gases

Nature of science:

Scientists have a role in informing the public—scientific research has led to a change in public perception of smoking. (5.1)

• Oxygen dissociation curves show the affinity of hemoglobin for oxygen.
• Carbon dioxide is carried in solution and bound to hemoglobin in the blood.
• Carbon dioxide is transformed in red blood cells into hydrogencarbonate ions.
• The Bohr shift explains the increased release of oxygen by hemoglobin in respiring tissues.
• Chemoreceptors are sensitive to changes in blood pH.
• The rate of ventilation is controlled by the respiratory control centre in the medulla oblongata.
• During exercise the rate of ventilation changes in response to the amount of CO2 in the blood.
• Fetal hemoglobin is different from adult hemoglobin allowing the transfer of oxygen in the placenta onto the fetal hemoglobin.

Applications and skills:

• Application: Consequences of high altitude for gas exchange.
• Application: pH of blood is regulated to stay within the narrow range of 7.35 to 7.45.
• Application: Causes and treatments of emphysema.
• Skill: Analysis of dissociation curves for hemoglobin and myoglobin.
• Skill: Identification of pneumocytes, capillary endothelium cells and blood cells in light micrographs and electron micrographs of lung tissue.

• Training camps for athletes are frequently located at high altitude to increase the hemoglobin content of the blood. This puts the athlete at an advantage when they return to lower ground for competition.

• Syllabus and cross-curricular links:
• Biology
• Topic 6.4 Gas exchange
• Physics
• Topic 3.2 Modelling a gas

Aims:

• Aim 8: Some sports, such as high-altitude mountain climbing or scuba diving, may push the limits of the human body beyond endurance and cause damage. Should they be controlled or banned?