transport in animal

• what type of circulatory systems are there?

  • open
  • closed
  • double
  • single
• what do circulatory systems do?

  • they transport gases and nutrients around an organism in a transport liquid e.g. blood
  • this liquid is transported around in vessels and there is a pump to move the liquid e.g. heart
• features of open circulatory system?

  • invertebrates and insects have them
  • transport medium is pumped directly to open body cavity + very few transport vessels
  • medium is pumped at low pressure + transport food and waste but not gases (they are transported via tracheal system)
  • once exchange has happened transport medium returns to the heart
• features of closed circulatory system?

  • all vertebrates (fish and mammals) some invertebrates (annelid worm)
  • transport through blood and remains inside blood vessels
  • gases and small molecules can leave and enter through diffusion or high hydrostatic pressure
  • transports oxygen, CO2, oxygen transported by haemoglobin
• features of a single closed system?

  • blood only passes through the heart once per cycle
  • fish have single closed system
  • blood passes through two sets of capillaries immediately after being pumped out of the heart
  • the blood flows through the capillaries in the gills to become oxygenated
  • blood them flows through capillaries = deliver to body then back to the heart
  • would not be efficient gas exchange in mammals
• Why does single closed circulatory system work in fish?

  due to counter current system
• features of a double closed circulatory system?

  • blood pass through heart twice per cycle
  • birds and most mammals have it
  • one circuit of blood vessels carries blood from the heart to the lungs for gas exchange
  • second circuit of blood vessels carries blood from heart to rest of the body to deliver oxygen, nutrients
  • collects waste as well
• Arteries properties

  • thicker smooth muscle = constriction and dilation to control the volume of blood
  • thicker elastic layer to maintain blood pressure
  • collagen outer layer to provide structural support
  • thicker walls to maintain blood pressure
• Arterioles properties

  • thicker than arteries to restrict blood flow into the capillaries
  • thinner elastic layer than arteries as the pressure is lower
  • thinner layer of collagen than arteries
  • thinner wall thickness than arteries due to pressure being slightly lower
• Capillaries properties

  • no smooth muscular wall
  • no elastic layer
  • no collagen
  • one cell thick to allow a short diffusion distance
• Venules properties

  • a thin layer of smooth muscle
  • no elastic layer
  • no collagen layer
  • very thin wall (several venules join to make a vein)
• Veins properties

  • relatively thin smooth muscle layer so it can not control blood flow
  • relatively thin elastic layer as the pressure is much lower
  • contains lots of collagen
  • thin wall thickness as the pressure is a lot lower so there is a risk of them bursting
  • thinness helps the flow of blood up to the heart
• functions of capillaries

  • form capillary beds (branched capillaries) at exchange surfaces
  • have narrow diameter to slow blood flow
  • red blood cells can only just fit through and are squashed against the walls
• what is hydrostatic pressure?

  the pressure exerted by liquid
• what is oncotic pressure?


  is the tendency of water to move into the blood via osmosis
• Tissue Fluid Formation

  • blood enters through capillaries from the arterioles the smaller diameter results in high hydrostatic pressure
  • the pressure forces water, glucose, amino acid, ions and oxygen out of the capillaries at the end arterial end
  • this solution that has been forced out is called tissue fluid
• the hydrostatic pressure is higher than the oncotic pressure at the arterial end of the capillaries so the net movement of liquid is out of the blood in the capillaries
• Tissue fluid reabsorption

  once equilibrium reached nothing moves in or out of capillaries

  large molecules no absorbed in to TF

  liquid left in TF is absorbed into the lymphatic system drain back into the blood stream

  this liquid is now known as lymph
• mammalian heart

  • cardiac muscle is myogenic (moves automatically)
  • coronary arteries supply the cardiac muscle with oxygenated blood for aerobic respiration
  • pericardial membranes = stops the heart from filling and swelling with blood
• left ventricle features

  • thicker muscular wall
  • higher pressure
• right ventricle feature

  • pumps blood to the lungs
  • muscular walls are thinner as blood does not need to be pumped at a high pressure
• Atria

  • both have very thin muscular walls
  • minimal pressure
• what are the 3 main stages of the cardiac cycle?

  • diastole
  • atrial systole
  • ventricular systole
• Diastole

  • atria and ventricular muscles are relaxed
  • blood enters atria through vena cava and pulmonary vein
  • blood following into atria increases pressure in atria
• atrial systole

  • atria contracts and pressure increases
  • atrioventricular valves open and blood flows into ventricle
  • ventricular muscular walls relax (ventricular diastole)
• ventricular systole

  • ventricle contracts increasing pressure
  • atrioventricular valves close and semi linear valves open
  • blood is pushed out the ventricles into the arteries (pulmonary + aorta)
• cardiac output 


  cardiac output = heart rate X stroke volume

  heart rate = beats of the heart per minute

  stroke volume of blood that leaves the heart each beat
• where is the sinoatrial node (SAN)?

  located in the right atrium and is known as the pacemaker
• what is the atrioventricular node (AVN)?

  located near the border of the right and left ventricle within the atria still
• where is the bundle of His?

  runs through the septum
• where is the Purkyne fibres?

  in the walls of the ventricles
• what does the SAN do?

  SAN releases a wave of depolarisation across the atria, causing it to contract.
• what does the AVN do?

  • AVN releases another wave of depolarisation when the first reaches it.
  • Non-conductive layer between the atria & ventricles prevents the wave of depolarisation travelling down to the ventricles
• what does the Bundle of His do?

  • the wave of depolarisation down the septum & Purknye fibres
  • the apex and then walls of the ventricles contract
  • a short delay happens
  • AVN transmits second wave of depolarisation
  • this allows atria to pump blood to ventricle and repolarise and cardiac muscle relaxes
• what is tachycardia?


  whe the heart is beating over 100 bpm = normal during exercise
• what is bradycardia?


  heart is beating less than 60bpm many athletes have this as the muscle beats harder therefore less beats are needed
• what is fibrillation?


  this is when there is an irregular rhythm of the heart
• what is ectopic heartbeat?


  additional heartbeats that are not on rhythm

  • common once a day if it happen not good if it happens many times
• what is haemoglobin?

  • haemoglobins are groups of globular proteins found in different organisms
  • protein with a quaternary structure
  • haemoglobin and red blood cells transport of oxygen
• what is the oxyhaemoglobin dissociation curve?

  • oxygen loaded with a high partial pressure of oxygen (e.g. alveoli) and is unloaded
  • regions of low partial pressure of oxygen (e.g. respiring tissue) shown on the oxyhaemoglobin dissociation curve