Circulatory system

• What does the circulatory system carry to every cell in the body?


  Food and oxygen
• What is the primary function of the circulatory system besides carrying food and oxygen?


  Removing waste products
• What are the main components of the circulatory system?


  • Heart
  • Blood vessels
  • Blood
• What type of circulatory system do humans have?


  A double circulatory system
• Describe the two circuits of the human double circulatory system.


  1. Deoxygenated blood is pumped from the heart to the lungs to take in oxygen and returns to the heart.
  2. Oxygenated blood is pumped from the left ventricle to the rest of the body, delivering oxygen and returning deoxygenated blood to the heart.
• What is the role of the heart in the circulatory system?


  The heart pumps blood around the body
• What are the walls of the heart primarily made of?

  Muscle tissue
• What is the function of the valves in the heart?


  To ensure blood flows in the right direction
• How does blood flow through the heart's chambers?

  1. Blood flows into the atria from the vena cava and pulmonary veins.
  2. Atria contract, pushing blood into the ventricles.
  3. Ventricles contract, forcing blood into the aorta and pulmonary artery.
  4. Blood flows to organs through arteries and returns through veins.
  5. The cycle repeats as atria fill again.
• What is the purpose of coronary arteries?


  To supply the heart with oxygenated blood
• Where is the pacemaker located in the heart?


  In the right atrium wall
• What do the pacemaker cells produce?


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


  To control heartbeat if natural pacemaker cells fail
• What are the three types of blood vessels?

  • Arteries
  • Capillaries
  • Veins
• What is the primary function of arteries?


  To carry blood away from the heart
• Why are artery walls strong and elastic?


  To withstand high pressure from the heart
• What is the lumen in blood vessels?


  The hole down the middle of the vessel
• What is the thickness of capillary walls?


  One cell thick
• What are the functions of capillaries?


  • Carry blood close to body cells for exchange
  • Have permeable walls for diffusion
  • Supply food and oxygen, and remove waste like CO2
• What do veins do?


  Carry blood back to the heart
• Why do veins have a larger lumen than arteries?


  To help blood flow despite lower pressure
• What is the purpose of valves in veins?


  To keep 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 is the rate of blood flow if 1464 ml of blood passes through an artery in 4.5 minutes?


  $325 \text{ ml/min}$
• If 2.175 litres of blood passed through a vein in 8.7 minutes, what is the rate of blood flow in ml/min?


  $250 \text{ ml/min}$
• What are the four main components of blood?

  • Red blood cells
  • White blood cells
  • Platelets
  • Plasma
• What is the primary function of red blood cells?


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


  They are biconcave discs for a large surface area
• Why do red blood cells not have a nucleus?


  To allow more room to carry oxygen
• What pigment do red blood cells contain and what is its function?


  Haemoglobin, which binds to oxygen
• What happens to oxyhaemoglobin in body tissues?


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


  To defend against infection
• What is phagocytosis?


  A process where some white blood cells engulf microorganisms
• What do some white blood cells produce to fight microorganisms?


  Antibodies and antitoxins
• What are platelets?


  Small fragments of cells with no nucleus
• What is the function of platelets in blood?


  To help blood clot at a wound
• What can a lack of platelets cause?


  Excessive bleeding and bruising
• What does plasma carry in the blood?


  • Red and white blood cells and platelets
  • Nutrients like glucose and amino acids
  • Carbon dioxide from organs to lungs
  • Urea from liver to kidneys
  • Hormones
  • Proteins
  • Antibodies and antitoxins
• Why can blood tests diagnose various disorders?


  Because blood transports many chemicals produced by different organs