Human respiratory and circulatory system*Sci*

• The circulatory system transports substances around the body
• Organ systems work together to carry out all the tasks required in a living thing
• Two major and important organ systems

  • The respiratory system
  • The circulatory system
• Respiration


  The chemical reaction that releases energy from glucose, involving oxygen
• Respiration


  1. Glucose + oxygen

  2. Carbon dioxide + water + energy
• Aerobic respiration


  Respiration that involves oxygen
• Anaerobic respiration


  Respiration that takes place without oxygen
• During respiration


  Cells use up oxygen and produce carbon dioxide and water
• Breathing is a way of getting oxygen into the body and getting rid of carbon dioxide
• Lungs


  • Two elastic pouches lying inside the ribs
  • Connected to the air outside by the windpipe or trachea
  • Trachea divides into bronchi, bronchioles, and alveoli
• Alveoli


  • Tiny, thin-walled air sacs
  • Large surface area
  • Walls are very thin
  • Lining is moist
• Breathing in


  Rib muscles contract, diaphragm contracts, air pressure in lungs decreases, air moves in
• Breathing out


  Rib and diaphragm muscles relax, air pressure in lungs increases, air moves out
• Lung capacity


  Fully inflated lungs hold about 5 litres of air
• Breathing rate


  At rest, 16 times per minute, rises to 20-30 times per minute during exercise
• Respiration


  The process of releasing energy from glucose, occurring in cells
• Breathing


  The exchange of gases between the lungs and the surrounding air
• Aerobic respiration releases more energy than anaerobic respiration
• Anaerobic respiration


  1. Glucose

  2. Lactic acid + small amount of energy
• Aerobic exercise


  • Walking
• Anaerobic exercise


  • Running fast
• Open circulatory system


  Blood is not contained in blood vessels, pumped by heart into body cavity
• Closed circulatory system


  Blood is contained in blood vessels (arteries, veins, capillaries), pumped by heart
• Human heart


  • Muscular pump about the size of a fist
  • Located between the lungs
  • Divided into 4 chambers (atria and ventricles)
  • Valves prevent blood flowing the wrong way
• Pumping cycle of the heart

  1. Blood enters right atrium from vena cava

  2. Blood enters left atrium from pulmonary vein

  3. Atria contract, pushing blood into ventricles

  4. Left ventricle pumps blood to body via aorta

  5. Right ventricle pumps blood to lungs via pulmonary artery

  6. Ventricles contract together
• Valve


  Stops blood going back into the left atrium
• Right ventricle


  • Has thick walls
  • Pumps blood to the lungs
• Left ventricle


  • Has very thick walls
  • Pumps blood to the whole body except the lungs
• The human heart pumps approximately 7500 litres of blood around the body every day
• The pumping cycle


  1. Blood from the body enters the right atrium

  2. Blood from the lungs enters the left atrium

  3. Atria contract pushing blood into the ventricles

  4. Left ventricle pumps blood to the body

  5. Right ventricle pumps blood to the lungs

  6. Ventricles contract at the same time
• The heart beats about 70 times a minute when resting but this can increase to well over 100 times a minute during physical activity or excitement
• You can measure your heartbeat by taking your pulse
• It takes about 30 seconds for blood to go once around the body
• Some athletes have a heartbeat of more than 200 beats per minute
• You can hear a double beat when listening to someone's heartbeat - a faint one followed by a louder one
• Blood


  A mixture of a liquid called plasma with red blood cells, white blood cells, and platelets floating in it
• Plasma


  A straw-coloured liquid that is mainly water with things dissolved in it
• Red blood cells


  • Made in the marrow of large bones
  • Rounded with biconcave surfaces
  • Contain haemoglobin
  • Carry oxygen from the lungs to all the cells in the body
  • Have no nucleus
• White blood cells


  • Have a big nucleus and can change their shape
  • Protect the body against disease
  • Some eat microbes that cause disease
  • Others make antibodies or antitoxins
• Antibodies


  Chemicals that destroy microorganisms by dissolving them