11.1.3 The Circulatory System and the Heart

• What type of circulatory system do fish have?

  Single circulatory system
• How does blood flow in a fish's circulatory system?

  Blood flows in one direction
• How many chambers does a fish heart have?

  Two chambers (one atrium and one ventricle)
• How many times does blood pass through the heart during one circuit in fish?

  Once
• What type of circulatory system do mammals have?

  Double circulatory system
• How many chambers does the human heart have?

  Four chambers (two atria and two ventricles)
• What are the two circuits in the human circulatory system?

  Pulmonary circuit and systemic circuit
• How many times does blood travel through the heart in one cycle for mammals?

  Twice
• What are the advantages of a double circulatory system?

  • Blood can be pumped at a higher pressure
  • Blood travels faster around the body
  • Respiring cells receive oxygen and glucose for aerobic respiration

  
• What are the valves between the atria and ventricles called?

  Atrioventricular valves
• What is the name of the right atrioventricular valve?

  Tricuspid valve
• What is the name of the left atrioventricular valve?

  Mitral valve
• What do the semilunar valves separate?

  The ventricles from the arteries
• What is the function of the heart valves?

  To ensure blood flows in one direction and does not flow back
• When do the atrioventricular valves open and close?

  They open when pressure in the atria is higher than in the ventricles
• When do the semilunar valves open and close?

  They open when pressure in the ventricles is higher than in the arteries
• What does the septum do in the heart?

  It separates the two sides of the heart
• What type of blood does the right side of the heart pump?

  Deoxygenated blood
• What type of blood does the left side of the heart pump?

  Oxygenated blood
• What is the cardiac cycle?

  • Involves periods of contraction (systole) and relaxation (diastole)
  • Blood leaves the heart via the pulmonary artery (to the lungs) and the aorta (to the body)

  
• What happens to blood pressure as the heart muscles contract?

  Blood is forced away from the heart at a high pressure
• Where is the pressure greatest in the circulatory system?

  In the arteries
• What causes the regular rise and fall in arterial pressure?

  The action of the heart
• What is systolic pressure?

  The pressure in the arteries when the heart is contracting
• What is diastolic pressure?

  The pressure in the arteries when the heart's chambers are refilling with blood
• What do you not need to know about pressure terms at IGCSE?

  • You do not need to know the terms systolic pressure and diastolic pressure at IGCSE.