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• What is the structure of haemoglobin?

  Quaternary structure with four polypeptide chains
• What is associated with each polypeptide in haemoglobin?

  A haem group containing Fe$^{2+}$ ion
• Where does haemoglobin load and unload oxygen?

  Loads in lungs, unloads in respiring tissue
• What must haemoglobin do to efficiently transport oxygen?

  Associate at gas exchange, dissociate at tissues
• How does haemoglobin's affinity for oxygen change?

  It changes depending on its environment
• What happens at low partial pressure of oxygen?

  Little oxygen binds to haemoglobin
• What effect does the first oxygen binding have on haemoglobin?

  It changes haemoglobin's shape for easier binding
• What is positive cooperativity in haemoglobin?

  Smaller increase in pressure needed for second binding
• Why is the fourth oxygen molecule harder to bind?

  Fewer binding sites are available on haemoglobin
• How do oxygen dissociation curves vary among animals?

  They differ based on environment and metabolic rate
• What happens to carbon dioxide at the gas exchange surface?

  It is constantly being removed
• How does pH change at the gas exchange surface?

  pH is raised due to lack of carbon dioxide
• What effect does higher pH have on haemoglobin?

  Increases haemoglobin's affinity for oxygen
• What happens in tissues regarding carbon dioxide?

  Carbon dioxide is produced by respiring cells
• How does pH change in tissues?

  pH is lowered due to increased carbon dioxide
• What effect does lower pH have on haemoglobin?

  Decreases haemoglobin's affinity for oxygen
• What is the normal saturation of haemoglobin at atmospheric pressure?

  97%
• What is the saturation of blood returning to the lungs during exercise?

  Usually at 75% saturation
• What are the features of a transport system?

  • Suitable medium to carry materials
  • Form of mass transport
  • Closed system of tubular vessels
• What type of circulatory system do mammals have?

  Closed, double circulatory system
• What is the function of the atrium in the heart?

  Collects blood, thin-walled and elastic
• What is the function of the ventricle in the heart?

  Pumps blood to the lungs or body
• What does the aorta do?

  Carries oxygenated blood to the body
• What are the names of the valves between the atrium and ventricles?

  Left bicuspid and right tricuspid valves
• What does the pulmonary artery do?

  Carries deoxygenated blood to the lungs
• What does the vena cava do?

  Brings deoxygenated blood back to the heart
• What does the pulmonary vein do?

  Brings oxygenated blood back from the lungs
• What do coronary arteries supply?

  Supply the heart with oxygen
• What happens if coronary arteries are blocked?

  Leads to a myocardial infarction
• What are the risk factors associated with cardiovascular disease?

  • Smoking
  • High blood pressure
  • Genetic inheritance
  • Lifestyle (prolonged stress)
  • Blood cholesterol (HDLs and LDLs)
  • Diet (high salt and saturated fat)
  • Antioxidants (lower risk)
• What is diastole in the cardiac cycle?

  Relaxation of the heart
• What happens during atrial systole?

  Atria contract, forcing blood into ventricles
• What occurs during ventricular systole?

  Ventricles contract, forcing blood into arteries
• How do valves control blood flow?

  Open when pressure difference favors blood movement
• What is cardiac output?

  Volume of blood pumped by one ventricle per minute
• How is cardiac output calculated?

  Cardiac output = heart rate X stroke volume
• What happens to aortic pressure during ventricular contraction?

  Aortic pressure rises and gradually falls
• What is the pressure in the aorta never below?

  Never below 12 kPa
• How does ventricular pressure change during filling?

  Increases as ventricles fill with blood
• What is the structure of blood vessels?

  Tough fibrous outer layer, muscle layer, elastic layer, endothelium