[OLD] the heart Flashcards
what happens during atrial and ventricular diastole?
atria and ventricles are relaxed
atria and ventricles fill passively
AV valves are open, semilunar valves are closed
what happens during atrial systole
the semilunar valves are closed and the AV valves are open
both atria contract, forcing blood to the ventricles
what happens during ventricular systole?
both ventricles contract simultaneously
the AV valves close
the semilunar valves open and blood enters the pulmonary trunk and aorta.
cardiac cycle
atrium, AV valves are closed
atrium contract, raising pressure and opening valves, ventricles
ventricles contract when full, raising pressure and closing AV valves
ventricles continue to contract, opening semilunar valves, arteries
higher pressure in arteries closes semilunar valves
what do arteries do?
carry blood away from the heart at high pressure
why do arteries have a narrow lumen?
to maintain pressure
what do the arteries walls contain?
collagen
elastic tissue
smooth muscle
folded endothelium
what does collagen do?
provides strength to withstand pressure
what does elastic tissue do?
allows walls to stretch and recoil to maintain pressure
what does smooth muscle do?
contact to constrict lumen to maintain pressure
what does folded epithelium do?
squamous epithelium to provide a smooth surface to reduce friction and folded to allow stretch
what are the two types of artery?
elastic and muscular
examples of elastic arteries
aorta, pulmonary artery
in which of the four chambers does pressure reach the highest value?
the left ventricle
how does the structure of the left ventricle cause a high pressure?
it has a thick muscular wall
how do you find heart rate?
60/(time taken for one cardiac cycle) = heart rate in bpm
how do you calculate cardiac output?
Stoke volume X heart rate
what is Stroke volume?
the different between the highest and the lowest volume of blood in a cardiac cycle
how do elastic fibres help to smooth out blood pressure?
the elastic fibres stretch and absorb the shock waves caused by the hearts forceful pumping action. the fibres recoil to their original length between heartbeats
why is blood leaving the heart through the aorta at a higher pressure than blood leaving through the pulmonary artery?
the walls of the left ventricle are thick than the walls of the right ventricles and so exert more force
risk factors associated sign coronary heart disease
increased age smoking obesity high cholesterol diet genetics
what is the hepatic portal vein?
the vein from the small intestine to the liver
differences between structure of veins and arteries
arteries have thicker walls veins have valves, arteries don't Arteries have more muscle arteries have narrower lumen arteries have more elastic fibres
HOWdoes smooth muscle reduce blood flow to the small intestine
smooth muscle can contract which will reduce the diameter of the lumen, restricting blood flow
how does elastic tissue help to even out the pressure of blood through blood vessels
the elastic fibres absorb. the force of the heart beat by stretching. the fibres recoil to their original length between heartbeats. t his smooths out the changes in pressure
how is plasma different from tissue fluid?
plasma has large proteins in it
what. amuses the. look pressure to decrease along the length of the capillary
fluid is forced out of the capillary
how can low concentrations of plasma cause accumulation of tissue fluid?
for water to be reasoned by osmosis and the venule end of the capillary t he water potential needs to be lower inside the capillary. this will not happen if there is inadequate protein in the plasma. tissue fluid will accumulate and not be reabsorbed
what is meant by a quaternary structure?
a protein with 2 or more polypeptide chains
why is isotonic salt solution used to dilute blood samples?
to examine cells under a microscope a solution is used to prevent the cells from dehydrating. an isotonic solution has the same water potential as the cell cytoplasm, so the cells will not be damaged by osmosis, which would burst them if just water was added.
