Transport in Animals

• What are the two types of circulatory systems?

  Open and closed circulatory systems
• How does a closed circulatory system differ from an open one?

  Blood is confined to vessels in closed systems
• What is the structure of a single closed circulatory system?

  Heart with two chambers
• How does a double closed circulatory system function?

  Blood passes through the heart twice per circuit
• What are the main functions and adaptations of arteries?

  • Carry blood away from the heart
  • Thick walls withstand high pressure
  • Elastic tissue allows stretching and recoiling
  • Smooth muscle varies blood flow
  • Lined with smooth endothelium to reduce friction
• What is the role of arterioles in the circulatory system?

  Feed blood into capillaries
• What are the characteristics of capillaries?

  • Smallest blood vessels
  • Site of metabolic exchange
  • One cell thick for fast exchange
• How do veins differ from arteries in structure?

  Veins have a wide lumen and thin walls
• What is the function of valves in veins?

  Prevent backflow of blood
• What is tissue fluid and its role?

  Supplies tissues with nutrients and oxygen
• What creates hydrostatic pressure in the circulatory system?

  Blood pumped through arteries and capillaries
• What determines which substances can escape from capillaries?

  Size of the substances relative to capillary gaps
• How does osmotic pressure affect tissue fluid movement?

  Pushes some fluid back into capillaries
• Why does water move from tissue fluid to blood?

  Tissue fluid has a less negative water potential
• What system carries remaining tissue fluid back to the heart?

  Lymphatic system
• What is the composition and function of lymph fluid?

  • Similar to tissue fluid
  • Contains less oxygen and nutrients
  • Main purpose is to carry waste products
  • Contains lymph nodes for filtering bacteria
• What is the term for the heart's ability to initiate its own contraction?

  Myogenic
• What is the role of the sinoatrial node?

  Initiates electrical stimulation for heart contraction
• What happens to the ventricles during atrial contraction?

  Ventricles do not contract until atria finish
• What is the function of the atrioventricular node?

  Passes excitation to the ventricles
• What are the three stages of the cardiac cycle?

  1. Atrial systole: Atria contract, valves open
  2. Ventricular systole: Ventricles contract, valves close
  3. Cardiac diastole: Heart relaxes, blood fills chambers
• What occurs during atrial systole?

  Atria contract and fill ventricles with blood
• What happens during ventricular systole?

  Ventricles contract and blood is ejected
• What is the purpose of cardiac diastole?

  Allows heart chambers to relax and fill
• What is haemoglobin and its structure?

  • Water soluble globular protein
  • Composed of two alpha and two beta chains
  • Each chain contains a haem group
• How does haemoglobin carry oxygen?

  Oxygen binds to the haem (Fe2+) group
• How many oxygen molecules can one haemoglobin carry?

  Four oxygen molecules
• What happens to haemoglobin's affinity for oxygen as partial pressure increases?

  Affinity for oxygen increases with partial pressure
• What is the process called when oxygen binds to haemoglobin in the lungs?

  Loading
• What occurs during the unloading process of oxygen from haemoglobin?

  Oxygen is released in respiring tissues
• What do dissociation curves illustrate regarding haemoglobin?

  Change in haemoglobin saturation with partial pressure
• How does saturation affect haemoglobin's affinity for oxygen?

  Increases affinity after binding first oxygen
• Why does fetal haemoglobin have a higher affinity for oxygen?

  To absorb oxygen at low partial pressure
• How does carbon dioxide affect haemoglobin's affinity for oxygen?

  Decreases affinity, causing oxygen release
• What is the Bohr effect?

  • Decreased affinity of haemoglobin for oxygen
  • Occurs in presence of carbon dioxide
  • Causes oxygen to be released in respiring tissues
• What is the circulatory system composed of?

  A system of blood vessels, pump, and valves

  
• What is the function of valves in the circulatory system?

  To ensure one-way flow of blood

  
• How many chambers does a fish heart have?

  Two chambers

  
• What does single circulation mean in fish?

  Blood passes through the heart once per circuit

  
• How many chambers does a mammal heart have?

  Four chambers