Transport in animals

• What is it meant by the term open circulatory system?

  • Pumped straight from the heart into the body cavity of animal
  • Not enclosed in vessels but circulates in body spaces
• Whats it meant by the term close circulatory system?

  • Blood is enclosed in vessels and isn't directly into contact with the cells of the body
• What are the advantages of a double circulatory system?

  -Simultaneous high pressure delivery of oxygenated blood to all regions of the body

  Oxygenated blood reaches respiring cells undiluted by deoxygenated blood
• Whats happens in a single circulatory system?

  • The blood passes through two sets of capillaries before it returns to the heart
  • The deoxygenated and oxygenated blood mixes
• What are the stages of the cardiac cycle?

  • Arital Systole > Ventricular systole > Diastole
• What happens in the arital systole stage?

  • Atria contracts
  • Volume of atria decreases
  • Pressure in atria increases higher than pressure in ventricle
  • The AV valves open and the blood flows from atria to ventricle
• What happens in the ventricular systole stage?

  • Ventricular walls contract
  • Volume of ventricular decreases
  • Pressure of ventricular increases higher than artery pressyre
  • The SL valves open
  • AV valves close
  • Blood flows from ventricles to arteries
• What happens in the diastole stage?

  • Atria and Ventricle walls relax
  • Volume of atria and ventricle increases (at max)
  • Pressure is low
  • SL valves close
  • Blood flows into atria passively (70%)
  • AV valves start to open
• What is the cardiac muscle?

  Its myogenic meaning it contracts on its own
• What happens at the SAN (Sino-atrial node)?

  • Sends excitation waves over atrial walls
  • Causes atrial contraction
• What happens at the AVN (atrio-ventricular node)

  • Sends an impulse from SAN (excitation wave down bundle of His)
  • When it reaches apex of the heart it spreads up through the ventricle
  • Ventricle muscle contracts from the apex
• What do the collagen fibres do?

  Prevents wave of excitation from passing from atria to ventricle walls (non-conductive)
• Function of ateries:

  • Smooth muscle located in middle layer- function is to regulate blood flow by contracting and relaxing
  • Elastic fibres to withstand force of the blood pumped out of the heart and stretch to take larger blood volume
  • Collagen provides structural protein in walls of arteries-prevents arteries from failing at high pressure
• Function of veins:

  • Smooth muscle in veins in called 'vascular smooth muscle'-regulate blood flow and pressure
  • Elastic fibres provides a degree of flexibility and expansion to accommodate blood flow
  • One way valves at intervals
  • Collagen maintains the structure of the blood vessels
• Function of capillaries:

  • Collagen fibres of capillary walls which are barrier that controls the exchange of substances between tissues and blood stream
  • Collagen affects leakiness of capillaries
• Whats the lub sound?

  • Produced when tricuspid valve close
  • Beginning of ventricular systole
• Whats the dub sound?

  • Pulmonary valves close
  • End of ventricular systole
• Whats bloods composition?

  • Plasma (55%)
  • Buffy Coat - leukocytes and platelets
  • Erythrocytes (45%)
• Whats the definition of hydrostatic pressure?

  Pressure of fluid against the side of its container- blood against vessel walls
• Whats osmotic pressure?

  Pressure generated by a difference in water potential
• The movement of tissue fluid:


  • Blood flows through the capillaries and the HP is higher as the OP pressure increases due the effect on plasma proteins -reducing water potential of blood
  • Tissue fluid is formed HP>OP
  • Tissue fluid then returns HP<OP
  • Tissue fluid is drained into lymphatic vessel however not all tissue fluid will return to capillary and any excess will be drained into lymphatic system
• Oxygen transport:

  • Referred to as PO2 or oxygen tension-measured in KPa
  • In lungs the partial pressure of oxygen is high and it moves from high to low into the blood
  • In respiring tissue the PO2 is low-when its low oxygen dissosiates from hemoglobin and can move to respiring cell
• What is affintity?

  The binding of oxygen to Hb
• Whats meant by high affinity?

  Hb can assosiate with oxygen easily but doesnt give up oxygen easily
• Whats it meant by low affintiy?

  Hb doesnt associate with oxygen as easily but gives it up easily
• How is oxygen transported in the blood?

  • RBC containing hemoglobin containing 4 haem groups
  • In the capillaries in the lungs oxygen binds to the haem groups foming oxyhaemoglobin
  • oxyhaemoglobin can be transported via blood
  • at the body cells the oxygen dissociates from haemoglobin
• What happens at high pO2?

  • Haemoglobin has a high infinity for oxygen and binds with it (in the lungs)
• What happens at a low pO2?

  • Haemoglobin has a low affinity and releases it (in body cells)
• How does oxygen co-operate with haemoglobin?

  • When haemoglobin binds with oxygen it changes shape so that it becomes easier to bind with another oxygen
  • When haemoglobin is saturated with oxygen it becomes harder for more oxygen to bind to it
• Why does fetal haemoglobin differ from adult haemoglobin?

  • As the fetus needs to obtain oxygen from the mothers blood
  • This allows oxygen to dissociate from the mothers haemoglobin and bind with their own
  • Ensures the fetus gets enough oxygen to survive
• What is the Bohr Effect?

  Oxygen dissociation shifts to the right

  
• How does pCO2 effect haemoglobin saturation?

  • Higher PCO2 at respiring tissue causes haemoglobin to release oxygen
  • This is due to the Bohr Effect decreased affinity for oxygen in haemoglobin when CO2 is present
  • Oxygen saturation of haemoglobin is lower for given pO2 when PCO2 is higher
• Why does the Bohr Effect shift the dissociation curve to the right?

  As the active tissues that produce CO2 require a lot of oxygen from the blood
• What are the stages of transport of CO2 as hydrogen carbonate ions?

  • CO2 reacts with H2O to from H2CO3 catalysed by the enzyme carbonic anhydrase
  • H2CO3 dissociates to H+ to HCO3
  • H+ binds to haemoglobin forming forming haemoglobinic acid causing haemoglobin to release oxygen
  • this prevents the blood from becoming too acidic
  • it also causes the Bohr effect at high pCO2 haemoglobin releases oxygen so it can diffuse into respiring cells
  • HCO3- ions leave RBC and are transported by plasma while chlorine ions enter (chloride shift)
  • this maintains the charge