Animal Transport

• Open Circulatory System = blood doesn’t move around in blood vessels, it bathed the tissue directly while held in a cavity called haemocoel
• Open Circulatory System

  • Contains blood
  • Doesn’t contain blood vessels
  • Slow
  • Low pressure
  • e.g insect
• Closed Circulatory System = blood moves in blood vessels and has two types: single and double circulation
• Closed circulation:

  • contains blood
  • contains blood vessels
  • fast
  • high pressure
  • e.g mammals, fish
• Single circulation = blood moves through the heart once in its passage around the body
• double circulation = blood passes through the heart twice in its passage around the body
• Double circulatory:

  • pulmonary circulation - serves the lung
  • systematic circulation - serves the body tissue
• Double circulation of a mammal is more efficient than single circulation of a fish as more oxygenated blood can be pumped around the body at higher temperature
• Single circulation:

  • 4 chambers
  • slow
  • low pressure
• Double circulation:

  • 4 chambers
  • fast
  • High pressure
• myogenic = intrinsic contraction of cardiac muscle initiated from within the heart itself, not by nervous/hormonal stimulation
• • Superior/inferior vena cava
  • right atrium
  • flow through right atrio-ventricular valve (tricuspid)
  • right ventricle
  • flow through semi-lunar valve
  • Left pulmonary artery
  • to the lungs
• • left Pulmonary vein
  • Left atrium
  • flow through left atrio-ventricular valve (bicuspid)
  • left ventricle
  • flow through semi-lunar valve
  • aorta
  • to the body
• Valve will open when the pressure behind is greater than infront
• Valves function is to prevent back flow of blood and to maintain pressure
• 3 types of blood vessels:

  • arteries
  • veins
  • capillaries
• Structure of arteries & veins:

  • inner most layer is endothelium

  one cell thick, surrounded by tunica media

  • middle layer is tunica media

  contains elastic fibres, smooth muscle, thicker in arteries than in vein, in arteries elastic fibres allow stretching to accommodate changes in blood flow/pressure, elastic fibres recoil -> pushing blood on through the artery -> felt as a pulse and maintains blood pressure, contraction of smooth muscle regulates blood flow and maintains pressure

  • outer layer is tunica externa

  contains collagen fibre -> resist overstretching
• Arteries = carries blood away from the heart

  • thick muscular walls -> withstand high blood pressure, derived from the heart
  • branch into smaller vessels, called arterioles, -> further subdivide into capillaries
  • elastic tissue -> maintains pressure
• Veins = carries blood towards the heart, by gravity for veins above the heart

  • move through other veins by the pressure from surrounding muscle
  • thinner walls, less muscle -> blood pressure and flow rate are lower
  • larger diameter lumen than arteries
  • have semi-lunar valves along their length -> ensures the flow in one direction / prevent backflow
  • faulty valves -> heart failure
• Capillaries:

  • Form a vast network that penetrates all the tissues and organs of the body
  • Blood from capillaries collects into venules, takes blood into veins, which returns it to the heart
  • Have thin walls, consisting of one layer of endothelium on a basement membrane
  • Pores between the cells make capillary walls permeable to water and solutes
• Exchange of materials between the blood and tissue takes place in capillaries, where blood flows slowly to allow for this exchange
• The small diameter of capillaries causes the rate of blood flow to slow down
• Many capillaries in a capillary bed reduce the rate of blood flow and give plenty of time for the exchange of materials with the surrounding tissue fluid
• Artery:

  • pulsates
  • high blood pressure -> rise and fall due to contraction of left ventricle
  • No valves
  • oxygenated blood
• Arteriole:

  • like artery but smaller diameter and has more muscle in tunica media
  • pulsates
  • high blood pressure
  • rise and fall due to contraction of left ventricle
  • no valves
  • oxygenated blood
• Capillary:

  • does’t pulsate
  • blood pressure decreases -> blood spread between many capillaries
  • no valves
  • at the start blood is oxygenated
  • at the end blood is deoxygenated as gas exchange has occurred
• Venule:

  • like vein but has a smaller diameter
  • doesn’t pulsate
  • low blood pressure
  • has valves -> prevent backflow or low pressured blood flow
  • deoxygenated blood
• Vein:

  • doesn’t pulsate
  • low blood pressure
  • has valves-> prevents back flow of low pressured blood
  • oxygenated blood
• What is in blood:

  plasma :

  • fluid containing 90% water containing solutes such as food molecules (Minerals), waste products (urea), hormones/plasma proteins (antibodies)
  • cells such as white blood cells, red blood cells, platelets