M3 chapter 8:transport in animals Flashcards
why do multicellular organism need a transport system?
they have a low Sa:V ratio
high metabolic rate
very active
cells respire quickly
need constant supply of oxygen
what is a single circulatory system?
blood only passes through heart once on each circuit
what is a double circulatory system?
blood passes through heart twice on each system
what is a closed circulatory system?
where blood is enclosed inside blood vessels
all vertebrates have this
what is a open circulatory system?
blood isn’t enclosed in blood vessels, blood flows freely through body cavity
why can’t humans have an open circulatory system?
we need more oxygen
where do arteries carry blood?
away from the heart towards rest of the body
what is the structure of arteries?
walls are thick and muscular and have elastic tissue to stretch and recoil the arteries to maintain high pressure
inner lining is folded allowing it to expand
what blood do the arteries carry?
all carry oxygenated blood apart from pulmonary arteries
what are arterioles?
when arteries branch into arterioles which are much smaller
they have layers of smooth tissue cells in rings to help them expand and contract to control amount of blood
what are capillaries?
arterioles branch into capillaries, which are the smallest of blood vessels.
allow glucose to be exchanged as they have walls only 1 cell thick
what are venules?
capillaries connect to venules, which have thin walls that can contain some muscle cells, join together to form veins
what are veins?
take blood back to the heart under low pressure
what are the structure of veins?
wider lumen and little elastic tissue, to keep blood at a low pressure.
contain valve to prevent backflow
blood flow helped by muscles contracting from other body muscles
what is tissue fluid?
surrounds cells in tissues. Made from substances that leaves blood plasma such as oxygen,water, nutrients.
how does substances move out of capillaries?
by pressure filtration
what is pressure filtration?
hydrostatic pressure inside capillaries at capillary bed is higher than in tissue fluid therefore fluid moves out of capillaries into spaces around cells. as water leaves conc of plasma proteins increases,decreasing water potential therefore wp is lower inside capilaries so water re-enters by osmosis.
what does lymph vessels do?
excess tissue fluid left over gets returned to blood via lymphatic system made up of lymph vessels
how many muscular pumps does the heart have?
2
what does the right side of the heart do?
pumps deoxygenated blood to the lungs to receive oxygen
what does the left side of the heart do?
pumps oxygenated blood to rest of the body
what do the valves do?
stop blood flowing the wrong way, valves only open 1 way which depends on pressure of heart chambers
what are the atrioventricular valves?
link the atria to the ventricles
what are semi-lunar valves?
link the ventricles to the pulmonary artery or aorta
what is the cardiac cycle?
ongoing contraction and relaxation of the atria and ventricles which changes the volume and therefore pressure which causes valves to open and blood flow through the heart
what is cardiac diastole?
when the entire heart is relaxed so blood can enter at low pressure. as the blood flows into the atria the pressure increases causing the av valves to open
what happnens after cardiac diastole?
atrial systole/ ventricular diastole
what happens in atria systole?
artira contract pushing blood into the ventricles when they are half empty, this causes pressure to increase in the ventricles causing the av valves to shut
what happens after atria systole?
ventricles contract pushing blood out of the heart, this increases pressure is higher than the pressure in the arteries causing the sl valves to open and blood to flow out of the heart
what does systole mean?
contraction
what does diastole mean?
relaxation