Mass Transport in Humans

• Pathway of blood through heart

  Vena Cava

  Right Atrium

  Right atrioventricular valve

  Right Ventricle

  Right Semilunar valve

  Pulmonary Artery

  Lungs

  Pulmonary Vein

  Left Atrium

  Left Atrioventricular Valve

  Left Ventricle

  Left semilunar valve

  Aorta

  Body
• What is stroke volume

  volume of blood pumped by each ventricle sually left per beat / ml/beat
• Cardiac Output equation

  CO = SV x HR
• Blood vessel trends

  1 pressure trends - the further the vessel from the heart, the lower the blood pressure

  2 lumen diameter trend - wider lumen = higher vol of blood flow

  3 ''organ'' - arteries/arterioles/veins are organs due to multiple tissues

  4 structures of vessels

  5 structure to function
• Arteries / Arterioles structure to function

  Muscle contracts / vasoconstriction so that - blood flow is reduced / maintains blood pressure and narrows lumen and reduced blood flow to capillaries (arterioles only)

  Elastic tissue stretches and recoils so that pressure is evened out / ensure smooth blood flow

  Epithelium / Endothelium is smooth so that friction is reduced / to maintain blood flow

  Thick walls of arteries / arterioles so that they can withstand high pressure
• Capillaries Structure to Function

  Smooth endothelium so that friction is reduced to maintain bloodflow

  Narrow so that -they have a short pathway -have a large SA -are fast at exhange -have more time for exchange

  Thin walls - so that they have a short diffusion pathway - gaps and pores for tissue fluid formation
• Explain how heart muscles and valves maintain a one way flow of blood from LA to Aorta (5)

  1- Atrium has higher pressure than ventricle due to filling

  2- Atrioventricular valve opens

  3- ventricle has higher pressure than atrium due to filling

  4- atrioventricula valve closes

  5- ventricle has higher pressure than aorta

  6- semilunar valve opens

  7- higher pressure in aorta than ventricle

  8- semilunar valve closes

  9- muscle contraction causes increase in pressure in atria
• Explain the role of the heart in formation of tissue fluid (2)

  1- contraction of the ventricles produce high hydrostaic pressure

  2- this forces water and dissolved substances out of blood capillaries
• Describe how tissue fluid is formed and how it is retured to the circulatory system (6)

  Formation

  1- high hydrostatic pressure

  2- froces water out of capillaries

  3- large plasma proteins remain in capillary Return

  4- lower water potential in capillary / blood

  5- due to plasma proteins

  6- water enters capillary / blood

  7- by osmosis

  8- correct reference to lymph - e.g excess fluid drained into lymph vessels and lymphatic system