9. Transport in animals

• Circulatory system: a system of blood vessels with a pump and valves to ensure one way flow of blood
• Single circulation:

  • hearts are two chambered (single atrium and ventricle) -> low oxygen delivery rate -> lowers rate of metabolism
  • atrium collects de-oxygenated blood -> ventricle pumps blood to gills for gas exchange and blood is re-oxygenated

  Double circulation:

  • 4 heart chamber (right/ left atrium/ventricle)
  • allow separation of blood
  • maintain high blood pressure required for essential processes
  • enables pure blood to reach different tissues and organs
• Advantages of double circulatory system:

  • deliver greater blood flow rate to tissue
  • cells can be provided with oxygen and glucose they need for respiration
  • support high metabolic demands
  • reduce mixing of oxygenated and deoxygenated blood
  • thermoregulation
• Heart structure:

  • muscular wall
  • septum - ensure separation of oxygenated and de-oxygenated blood
  • left/ right atrium/ventricle
  • one way vavlevs
  • coronary arteries
  • artery: pump blood away from the heart
  • vein: pump blood into the heart
• Thickness of atrium/ ventricle:

  • left ventricle is thicker due to the fact that they have to pump blood around the whole body
  • atrium thickness < ventricle thickness
• Pathway of blood in heart:

  1. red blood cell return to heart through vena cava
  2. then get pumped into the right atrium
  3. pass through atrioventricular valve (between atrium & ventricle) into the right ventricle
  4. pumped through semilunar valve (between ventricle & pulmonary) into the pulmonary artery in lungs for gas exchange
  5. return through pulmonary vein into left atrium
  6. through another atrioventricular valve in left ventricle
  7. pump to the body through aorta
• Monitoring heart rate:

  • electrocardiogram (ECG)
  • measuring pulse rate for 15s and multiply by 4
  • stethoscope
  • listening to the sound of valve closing
• Effect of exercising on the heart:

  • increase heart rate
  • breath becomes deeper
  • increase pulse rate
• Coronary heart disease:

  • blockage of coronary arteries interrupting blood supply to the heart muscle
  • risk factor: bad diet, lack of exercise, stress, smoking, genetic predisposition, age, sex (male)

  Prevent:

  • exercise to reduce fat build up
  • diet: reduce eating high amount of saturated fats
• C.H.D treatment:

  • drugs (aspirin): can reduce inflammation and prevent blood clot from forming
  • stents: small tubes put in arteries to keep them open
  • angioplasty: small balloon put in to increase blood flow & break up blockage
  • by-pass: take blood vessel from somewhere else & putting it in the heart to divert blood away from artery
• Arteries - transport high pressure blood away from heart

  • elastic tissue walls stretch & relax as blood is forced out - cause a pulse
  • thick wall to withstand high pressure
  • small lumen maintains high blood pressure

  
• Veins - transport low pressure blood to the heart

  • valves prevent backflow of blood
  • blood is at low pressure, nearby muscles squeeze veins and help push blood to the heart
  • large & wide lumen to reduce resistance to the flow of blood

  
• Capillaries - allow substances to diffuse into cells

  • one cell thick for easy diffusion
  • highly branched - large surface area
  • capillary beds constantly supplied with fresh blood, so diffusion occurs

  
• Main blood vessels:

  • heart: vena cava, aorta, pulmonary arteries & vein
  • lungs: pulmonary arteries & vein
  • kidney: renal arteries & vein
• Function:

  • arterioles: connect arteries to capillaries
  • venules: connect capillaries to veins
  • shunt vessels: control blood flow by constriction & dilation
• Lymphatic system:

  • lymphatic vessels: collect lymph (fluid that is essential for the immune system) from around the body & return it to the blood --> blockage: swelling
  • lymph node: filters lymph to remove harmful microbes that have infected the body
• Blood:

  • red blood cell: biconcave shape, haemoglobin - transporting oxygen
  • white blood cell: phagocytes - phagocytosis (engulf); lymphocyte - antibody production
  • platelets - blood clot through the conversion of fibrinogen into fibrin forming a mesh to trap in red blood cell/ prevent entry of pathogens
  • plasma - transport blood cells, ions, nutrients, urea, hormones, CO2..

  
• Exchange of materials:

  • capillaries: allow exchange of substances with body tissues through the thin walls
  • as blood travel at high pressure from arteries - pressure filtration occurs = plasma passing through capillary walls into tissue fluid around the cell
  • tissue fluid: provide cells with useful substances such as glucose & O2, waste product are passed out of the cells into tissue fluid to be removed