Transport in animals

• Circulatory system


  The main transport system in animals, made up of blood vessels such as arteries, veins and capillaries, in which blood travels around the body, carrying nutrients and waste products
• Fish circulatory system


  • Single circulatory system, heart has two chambers, blood passes through it only once, oxygen absorbed at gills, no lungs
• Mammalian circulatory system


  • Double circulatory system, blood passes through the heart twice each circuit, heart has four chambers to keep oxygenated and deoxygenated blood separate, more efficient at supplying oxygen and maintaining high blood pressure
• Heart function


  1. Deoxygenated blood enters right atrium

  2. Right atrium contracts, blood moves through tricuspid valve to right ventricle

  3. Ventricle contracts, blood exits through semilunar valve to lungs via pulmonary artery

  4. Blood becomes oxygenated in lungs, returns to left atrium via pulmonary vein

  5. Left atrium contracts, blood moves through bicuspid valve to left ventricle

  6. Left ventricle contracts, oxygenated blood exits through semilunar valve to aorta and around body
• Blood flow


  1. Deoxygenated blood travels in veins to the heart

  2. Oxygenated blood travels in arteries away from the heart

  3. Pulmonary artery carries deoxygenated blood from the heart to the lungs

  4. Pulmonary vein carries oxygenated blood from the lungs to the heart
• Heart structure


  • Left ventricle wall much thicker than right, to pump blood at high pressure around body
  • Ventricle walls thicker than atria walls
  • Left and right sides separated by septum to keep oxygenated and deoxygenated blood separate
• Electrocardiogram (ECG)


  Records the electrical signals in the heart that cause contractions of the atria and ventricles
• Valves


  • Present in heart and veins to prevent backflow of blood
  • Bicuspid and tricuspid valves are atrioventricular valves, prevent backflow between ventricles and atria
  • Not present in arteries as pressure is high enough that backflow does not occur
• Coronary bypass


  More invasive method, where an artery from the patient's leg or arm is grafted onto the damaged artery to divert the blood flow around the damaged section
• Pulse rate


  Can be monitored to listen to the heart rate and valve activity
• Arteries


  • Carry oxygenated blood at high pressure to the tissues
  • Have a thick elastic layer and wall to maintain high pressure without bursting
  • Have a thick muscle layer to control the volume of blood by dilating and constricting the artery
  • Branch into arterioles, which enter the tissues and become capillaries
• Physical activity


  Increases short-term heart rate changes
• Lymph


  Fluid that enters the lymph vessels and travels through them, draining into the blood system in the chest cavity
• Veins


  • Have a thin elastic and muscle layer as the blood travels at low pressure back to the heart
  • Adapted to prevent backflow of blood by containing valves
  • Venules are small veins which are formed by groups of capillary vessels
  • Venules eventually become veins
• Aerobic respiration


  Requires oxygen, thus the heart rate speeds up to pump blood around the body more quickly
• Capillaries


  • Thin blood vessels used to exchange substances with tissues, such as oxygen, carbon dioxide and other nutrients
  • Have a large surface area and are branched
  • Have a narrow diameter and lumen to decrease diffusion distance
  • Have a slow rate of blood flow to allow time for exchange
• Exercising regularly and eating healthily

  Result in a lower resting heart rate
• Lymph nodes


  • Located in the neck, armpits and groin
  • Function is to filter the lymph fluid, removing bacteria and foreign particles from it
  • Help protect the body from infection
• Shunt vessels


  • Connect arteries to veins without the blood travelling through capillaries
  • Can dilate and constrict like arteries to control blood flow
  • Dilate in cold conditions to limit blood flow to extremities to reduce heat loss
• Diets high in salt and caffeine

  Raise heart rate
• Red blood cells


  Contain haemoglobin (protein) which binds to oxygen, allowing it to be transported around the body to cells
• Coronary heart disease


  Caused by a buildup of cholesterol in the coronary artery which narrows the artery thus limiting blood flow to the heart
• Lymphatic system


  Made up of lymph vessels and lymph nodes
• White blood cells


  • Play a major role in fighting off infection
  • A lymphocyte is a type of white blood cell which produces antibodies
• Eating a healthy diet

  Can reduce the risk of coronary heart disease
• Tissue fluid production


  1. Capillaries exchange substances with cells by producing tissue fluid

  2. Tissue fluid forms at the arteriole end of the capillary when nutrients are forced out of capillaries due to the high pressure in the narrower blood vessel

  3. Tissue fluid bathes the cells and allows nutrients to diffuse into cells, and waste substances to diffuse out into the tissue fluid

  4. Most of the tissue fluid is reabsorbed into the capillary at the venous end

  5. Larger molecules, such as lipids and large proteins, cannot re-enter the capillary, thus must be carried away by the lymph
• Antigens


  • Proteins found on the cell-membrane of pathogens
  • Each antibody is specific to one type of antigen, and they bind to these antigens, causing the foreign cells to clump together, making them harmless
• Regular exercise


  Can decrease the risk of coronary heart disease by lowering blood pressure
• Other risk factors for coronary heart disease

  • Stress
  • Smoking
  • Genetic predisposition
  • Age
  • Gender
• Phagocytosis


  • 1. Phagocyte recognizes and attaches to foreign pathogen
  • 2. The membrane of the phagocyte envelopes the pathogen and folds inwards, trapping it inside the phagocyte
  • 3. The phagocyte releases enzymes which break down the pathogen, killing it
• Platelets


  Involved in blood clotting
• Aspirin


  Can be used to reduce the risk of heart disease by thinning the blood and making platelets less likely to clump together to block the artery, and also helps to reduce high blood pressure
• Plasma


  The liquid in blood vessels in which contains blood cells, ions, soluble nutrients, hormones and carbon dioxide
• Stent


  A small tube that can be inserted into the artery to keep it open, allowing blood to flow
• Blood clotting


  1. Platelets stick to the broken vessel wall and clump together, blocking the cut

  2. Fibrinogen is then converted to a protein called fibrin, which forms a mesh of fibrin fibers across the wound

  3. More platelets stick to this mesh, forming a scab and preventing bleeding by blocking the cut

  4. This prevents blood loss and allows the vessel to heal, as well as preventing pathogens from entering the blood vessel
• Angioplasty


  Helps widen the artery by inserting a deflated balloon into the artery, before inflating it, causing the artery to widen. The balloon is then removed, and the artery remains widened. A stent can also be inserted at the same time to remain after the balloon has gone.