Topic 1- complete Flashcards
why do small organisms not need a mass transport system?
their surface area to volume ratio is high enough for diffusion to be effective enough on its own
why is mass transport needed?
because cells need a constant supply of reactants (oxygen and glucose) for metabolism
why do larger organisms need a mass transport system?
low surface area to volume ratio, large diffusion distance, high energy requirement due to high metabolic rate (so more reactants needed)
what is included in a mass transport system?
a network to move through (vessels),
a medium for movement (blood),
controlled movement (pressure from heart and controlled by valves),
maintenance of speed (contraction of heart and elastic recoil of arteries maintain blood pressure and therefore speed)
define mass transport
the bulk movement of gases or liquids in one direction usually by a system of vessels and tubes
what are the benefits of a mass transport system?
moves substances quickly, maintains diffusion gradients, ensures effective cell activity by supplying reactants and removing waste products
define cohesive
the attraction between molecules of the same type (water)
what are the 5 properties of water?
solvent- disolves polar
transport medium
metabolite- made and used in metabolic reactions
high heat capacity- reliable habitat
high heat of vaporisation- sweating is affective without losing lots of water
what are the stages of the cardiac cycle?
atrial systole, ventricular systole, cardiac diastole
describe atrial systole
atria contract, atrial pressure increases and volume decreases, blood enters ventricles, slight increase in ventricular pressure
describe ventricular systole
atria relax, ventricles contract, ventricular pressure increases and volume decreases, pressure in ventricles higher than in atria and atrioventricular valves close, pressure continues to increase (now higher than pulmonary artery) semi lunar valves open, blood forced out
describe cardiac diastole
ventricles and aria relax, pressure in ventricles drop and semilunar valves close, pressure in vena cava and pulmonary vein higher than in the atria, blood enters atria, atria contracts, atrial pressure increases and volume decreases, atrioventricular valves open
what are the 4 main blood vessels of the heart?
pulmonary vein, pulmonary artery, vena cava, aorta
what is the function of the septum?
prevents oxygenated and deoxygenated blood mixing
why does the left ventricle have thicker walls than the right ventricle?
the left needs to pump blood all around the body so needs a more powerful contraction
why does the right ventricle have thinner walls than the left ventricles?
the right only needs to pump blood to the lungs which are nearby
why do the ventricles have thicker walls than the atria?
the atria only have to pump blood to the ventricles but the ventricles have to pump blood out of the heart
how are the atria adapted to their function?
thin, elastic walls to allow for stretching when filled with blood
what supplies the cardiac muscle with blood?
coronary arteries
why do the veins have valves?
lower pressure than arteries so valves stop back flow of blood
describe how the features of the arteries show they are adapted to their function
thick-walled (provides strength), muscular, elastic tissue (expands and contracts) to cope with high pressure (away from heart), endothelium is folded to allow artery to expand, narrow lumen, outer walls contain collagen for protection
describe features of the veins
wide lumen, thin muscle tissue, valves, low pressure (back towards heart), blood flow helped by contraction of body muscles surrounding them
describe how features of the capillaries show they are adapted to their function
smallest, endothelium 1 cell thick to lower diffusion distance, capillary beds increase surface area, where metabolic exchange occurs, narrow lumen means red blood cells flow single file which reduces speed so more time for diffusion, cells in walls have pores which allow white blood cells or plasma to leak out
what are the ethical issues with using invertebrates in research?
cannot give consent, cannot express pain