Transport in animals

• Describe 2 features of an open circulatory system ?

  transport medium of haemolymph

  few short vessels
• Give an example of an open circulatory system ?

  insects
• Define a closed circulatory system ?

  blood is fully enclosed within blood vessels at all times
• Single circulatory system = blood passes through the heart once for every circuit of the body
• What is a disadvantage of single circulatory system ?

  blood pressure drops on return, oxygen delivery is slow
• Double circulatory system = blood passes through a 4 chambered heart twice for every full circuit of the body
• give an example of single circulatory system ?


  fish
• Example of double circulatory system ?

  Human
• Advantage to double circulatory system ?

  High pressure maintained so delivery is efficient
• How come tissue fluid is able to form ?

  Due to the small gaps in the capillary walls which enable liquid to be forced out when pressure increases
• Hydrostatic pressure = pressure exerted by a liquid
• oncotic pressure =  osmotic pressure generated by plasma proteins in solution
• Name a plasma protein found in capillaries ?

  albumins
• How does tissue fluid form?

  When hydrostatic pressure is higher than oncotic pressure, there is a net movement out of the capillaries.
• Why is there high hydrostatic pressure at the arteriol end of a capillary ?

  The capillary is smaller in diameter than arteriol, due to decrease in volume pressure has increased
• What molecules are moved out of capillary into tissue fluid ?

  glucose, amino acid, fatty acids, ions and oxygen
• Which molecule remains in the capillary at all times ?

  plasma proteins
• Describe how tissue fluid is reabsorbed ?

  At venuole end oncotic pressure is higher than the hydrostatic pressure. Net movement of fluid into the capillary
• What is lymph ?


  Excess tissue fluid that does not get reabosrbed
• Where does lymph go ?

  Joins the lymphatic system where is eventually re-enters the blood stream
• What molecule will not be present in lymph ?

  plasma proteins
• Why do Atria have thinner walls ?

  They only need to exert a small force as they do not need to pump at high pressure
• Which ventricle walls are thicker and why ?

  Let ventricle, contraction with greater force to pump at higher pressure as blood leaving left ventricle must go around entire body
• What type of muscles are cardiac muscle ?

  myogenic
• myogenic = muscle contract is automatic
• Which artery supplies heart with blood ?

  coronary artery
• Name the valve between the ventricles and the arteries ?

  Semi-lunar valves
• Which valve lies between left atrium and ventricle ?

  bicuspid
• Which valve lies between the right atrium and ventricle ?

  tricuspid
• What happens in diastole ?

  atria and ventricles are relaxed

  A.v valves are open

  semi-lunar valves are closed

  blood flows into atria/ventricles
• What happens in Atrial systole ?

  Atria contracts

  Atria volume decreases and blood flows out into the ventricle
• What happens in ventricular systole ?


  ventricles contract

  semi-lunar valves open and A.V valves shut

  blood flows into arteries
• cardiac output = heart rate x stoke volume
• stroke volume = volume of blood pumped out the heart in each beat
• Where is the SAN located ?


  Right atrium
• Where is the AVN located ?

  in the artia near the border of right an left ventricle
• bundle of His = runs through the septum
• Purkyne fibres = branches in the ventricle walls
• Apex of heart = bottom of heart
• What causes atrial systole ?

  SAN releasing a wave of depolarisation across the atria