Transport in animals Flashcards
why do multicellular organisms need a transport system
relatively big
low surface area to volume ratio and a high metabolic rate
what is a single circulatory system
where blood only passes through the heart once per complete circuit of the body
what is a double circulatory system
blood passes through the heart twice per complete circuit of the body
what is a closed circulatory system and what group of organisms have them
when blood is enclosed in blood vessels, vertebrates
what is an open circulatory system and what group of organisms have one
blood is not enclosed in blood vessels and flows freely through body cavity, invertebrates
describe the structure of arteries
walls are thick and muscular, have elastic tissue which allows stretch and recoil to maintain high pressure, inner lining is folded to allow artery to expand, carry oxygenated blood
describe the structure of arterioles
much smaller than arteries, have a smooth muscle layer allowing them to contract to control amount of blood flowing to tissues , less elastic tissue than arteries
describe the structure of capillaries
smallest blood vessel, walls one cell thick,
describe the structure of venules
very thin walls, contain some muscle cells
describe the structure of veins
wider lumen then arteries, very little elastic or muscle tissue, contain valves
what is tissue fluid made up of
oxygen, water and nutrients
describe what happens during pressure filtration
at the start of the capillary bed, near the arteries, hydrostatic pressure inside capillaries is greater than that in the tissue fluid, this forces fluid out of capillaries and into space around cells, as fluid leaves pressure inside capillaries lowers
as water leaves the capillaries the inc, of plasma proteins in the capillaries increases a w.p decreases
this causes oncotic pressure so at venue end there is high oncotic pressure but low w.p
because w.p is lower in capillaries than tissue fluid some water moves back in via osmosis
describe what happens to excess tissue fluid that doesn’t not reenter the capillaries at vein end of capillary bed
gets returned to blood via lymphatic system
excess tissue fluid passes into lymph vessels
once inside is called lymph
valves in lymph vessels prevent lymph going backwards
it moves ro main lymph vessel in thorax and is returned to blood near heart
what does blood contain
red blood cells, white blood cells, platelets, proteins, water and dissolved solutes
what does tissue fluid contain
very few white blood cells(only when infection present), very few proteins, water and dissolved solutes
what does lymph contain
white blood cells, water and dissolved solutes, antibodies
draw an external diagram of the heart
draw an internal diagram of the heart
describe the cardiac cycle
ventricles relax, atria contract, decreasing volume of chambers and increasing pressure, blood passes through atrioventricular valve
ventricles contract, atria relax, pressure becomes higher in ventricles than atria AV valves forced shut, pressure higher than aorta and p artery so SL valves open
ventricles relax and atria relax closing SL valves atria fill again so pressure of atria increases and forces AV valves open passively
what is the equation for cardiac output
heart rate x stroke volume
describe how heartbeat is controlled
starts at Sino-atrial node
this sends waves of electrical activity over atrial walls
band of non conductive collagen tissue presents wave being passed directly to ventricles
instead the waves are transferred to atrioventricular node
AVN passes electrical activity to the bundle of His however there is a slight delay before AVN reacts to allow atria to fully empty
bundle of His transfers electrical activity to Purkyne tissue
purine tissue carries electrical activity to walls of ventricles causing them to contract
heart muscle is
myogenic
label an electrocardiogram
p wave- caused by contraction of atria
QRS complex- caused by contraction o ventricles
T wave- relaxation of ventricles
how do you calculate heart rate
60/ timetaken for one heartbeat
