mass transport

• haemoglobin:

  protein:

  quaternary structure

  • 4 polypeptide chains
  • haem group in each chain which consist of iron
  • binds to oxygen
• loading/association with O2

  binding of O2 with haemoglobin
• affinity of haemoglobin

  ability of haemoglobin to bind with oxygen
• saturation of haemoglobin

  when haemoglobin holds max amount of oxygen
• what happens when there's high partial pressure of oxygen

  high partial pressure: (occurs in alveoli,etc)

  • affinity of oxygen increases
  • loading occurs
  • haemoglobin becomes saturated
• what happens when there's low partial pressure of oxygen

  low partial pressure (respiring tissues)

  • lower affinity of oxygen
  • unloading of o2
• cooperative binding:

  at low partial pressure 

  • difficult to bind oxygen to the haem group
  • once the first O2 binds - becomes easier to bind O2 as the shape of the protein changes 
• bohr effect:

  at high partial pressure of CO2 (respiring tissues)

  • blood becomes acidic - carbonic acid

  -  changes the shape of haemoglobin

       -  affinity for oxygen decreases - unloads more oxygen
• where does the curve shift when there's high concs of carbon dioxide 

  curve shifts to the right
• why does different animals have different affinities for oxygen

  has a different type of haemoglobin to adapt to their environment

  eg: foetus
• how does deoxygenated flow through the heart

  vena cava (from the body) → right atrium → right ventricle → pulmonary artery
• how does oxygenated blood flow through the heart

  pulmonary vein (from the lungs) → left atrium → left ventricle → aorta
• why does the right ventricle have thinner walls than the left ventricle

  the right ventricle pumps blood to the lungs and if its done at a high pressure, capillaries will be damaged so when its done at a lower pressure, there is time for gas exchange to occur

  left ventricle also sends blood towards the body so it requires a high pressure
• what valves are in the heart

  semi-lunar valves

  atrioventricular valves
• where are the atrioventricular valves

  between the atria and ventricles

  bicuspid valve: left atrium and left ventricle

  tricuspid valve: right atrium and right ventricle
• where are the semi-lunar valves

  in the aorta and pulmonary artery
• how do valves work

  valves open when the pressure is high

  valves close when the pressure is low

  prevents backflow and keeps blood flow in one direction
• what is the function of the septum

  separates deoxygenated and oxygenated blood

  • maintains high conc. of oxygen in oxygenated blood for maintaining conc gradient for diffusion of respiring cells
• role of coronary arteries:

  in the aorta

  • supply cardiac muscle with oxygenated blood
• compare arteries and veins:

  arteries:

  carries blood away from the heart

  narrow lumen (high pressure)

  thick muscular walls and elastic tissue

  veins:

  carries blood to the heart

  wider lumen (low pressure)

  thin muscular walls and elastic tissue

  • contains valves
• what are arterioles

  arteries that branch to narrower blood vessels supplying blood to capillaries

  • able to partially stop blood flow to organs that are less in demand
• capillaries:

  • thin walls - short diffusion distance

     - 1 cell thick: made from endothelial cells

  -small lumen 
• what does the elastic layer do

  maintains the blood pressure and it stretches and recoils
• cardiac cycle (diastole)

  all chambers are relaxed:

  • blood enters the atria (via vena cava and pulmonary vein)

    -   increasing the pressure in atrium - causing atrioventricular valves to open

  • pressure in ventricles = lower so semilunar valves remain closed
• cardiac cycle (atrial systole)

  • atria walls contract : forces remaining blood to travel to ventricles
• cardiac cycle (ventricular systole)

  • ventricular walls contract - increasing pressure
  • atrioventricular valves close
  • semilunar valves opening so blood leaves via aorta and pulmonary artery
• how to calculate cardiac output

  cardiac output = heart rate x stroke volume
• how is tissue fluid formed

  • contraction of the ventricles causes high hydrostatic pressure of blood flow
  • small molecules and water to be forced out the gaps of capillaries - ultrafiltration
• how is water from tissue fluid returned to the circulatory system

  • large molecules (plasma proteins) remain
  • reduces water potential of blood
  • water re-enters blood via osmosis
  • and also can return to blood via the lymphatic system