Circulatory System

• What are the three different types of blood vessels?

  Arteries, capillaries, and veins
• What is the primary function of arteries?

  To carry blood away from the heart
• What role do capillaries play in the circulatory system?

  They are involved in the exchange of materials at the tissues
• What is the function of veins?

  To carry blood to the heart
• Why do arteries carry blood under pressure?

  Because the heart pumps the blood out at high pressure
• What is the lumen in blood vessels?

  The hole down the middle of the blood vessel
• Why do arteries have thick walls?

  To make them strong and withstand high pressure
• What do elastic fibers in arteries allow them to do?

  Stretch and spring back
• How small are capillaries?

  They are really tiny—too small to see
• What is the significance of capillaries being close to every cell?

  To exchange substances with them
• What do the permeable walls of capillaries allow?

  Substances to diffuse in and out
• What do capillaries supply and remove?

  They supply food and oxygen and remove waste like CO2
• How thick are the walls of capillaries?

  Usually only one cell thick
• Why does the thinness of capillary walls increase the rate of diffusion?

  By decreasing the distance over which it occurs
• What happens to capillaries as they join up?

  They form veins
• Why do veins have thinner walls than arteries?

  Because the blood is at lower pressure in the veins
• What is the lumen size comparison between veins and arteries?

  Veins have a bigger lumen than arteries
• What do valves in veins do?

  Help keep the blood flowing in the right direction
• How do you calculate the rate of blood flow?

  Rate of blood flow = volume of blood ÷ number of minutes
• What does the circulatory system carry to every cell in the body?

  Food and oxygen
• What are the two circuits of the double circulatory system in humans?

  The right ventricle pumps deoxygenated blood to the lungs, and the left ventricle pumps oxygenated blood to the body
• What happens to blood after it returns from the lungs?

  It returns to the heart
• What is the role of the heart in the circulatory system?

  To pump blood around the body
• What prevents backflow of blood in the heart?

  Valves
• How does blood flow through the heart?

  Blood flows into the atria, then to the ventricles, and out through the pulmonary artery and aorta
• What is the function of coronary arteries?

  To supply the heart with oxygenated blood
• What controls your resting heart rate?

  A group of cells in the right atrium wall that act as a pacemaker
• What do pacemaker cells produce?

  A small electric impulse
• What is an artificial pacemaker used for?

  To control heartbeat if natural pacemaker cells don’t work properly
• What is the primary function of red blood cells?

  To carry oxygen from the lungs to all the cells in the body
• What shape do red blood cells have and why?

  A biconcave disc shape for a large surface area to absorb oxygen
• Why do red blood cells not have a nucleus?

  To allow more room to carry oxygen
• What pigment do red blood cells contain?

  Haemoglobin
• What occurs to oxyhaemoglobin in body tissue?

  It splits into haemoglobin and oxygen
• What is the primary function of white blood cells?

  To defend against infection
• What is phagocytosis?

  A process where some white blood cells change shape to gobble up microorganisms
• What do some white blood cells produce to fight microorganisms?

  Antibodies and antitoxins
• Do white blood cells have a nucleus?

  Yes, they do
• What are platelets?

  Small fragments of cells that help blood to clot
• What is the role of platelets in the body?

  To help the blood clot at a wound