Understanding the Circulatory System: Heartbeat and Blood Pressure
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blood circulation: closed: blood always circulates through the blood vessels and never leaves them. double: blood must flow through the heart twice to complete a circuit. oxygenated and deoxygenated blood never mix. they circulate through different circuits. systematic and pulmonary circuits: VI>CU>AD> VD> PUL>AI
systematic/major/ general circulation pulmonary/minor circulation
/ 2 movements: systole: contraction, diastole: relaxation
cardiac circle: heartbeat: the cardiac circle is the join of phases which heart pass through in each beat
phases: atrium systole atrium contraction: atria full of blood, contract, mitral and tricuspid valves open (because atrium pressure is bigger than ventricle pressure), blood passes to ventricle, mitral and tricuspid valves close (atrium p is smaller than ventricle p)
ventricle systole ventricle contraction: ventricle full of blood contract, sigmoid valves open (ventricle p is bigger than artery p) blood passes to arteries, sigmoid valves close (ventricle p is smaller than artery p)
general diastole: heart relaxation: atria and ventricle, empty of blood relax, blood pass to atria from the veins by suction
cardiac parameters: heart rate: number of times heart beat by unit of time, usually 70 beats per minute but depends on age, sex, size. changes to adapt to physiologic demands. rises during exercise or exciting situations and falls during rest or sleep
cardiac output: volume of blood which heart can pump in a minute. usually it about 5.5 l per min. could be larger in sport people because their in each beat.
stroke volume: volume of blood which heart can pump in each beat.
blood pressure: blood pressure is the pressure exerted by blood on the walls of the blood vessels. this pressure is stronger during systole, when it's provoked by heart, and lower when it is provoked by expanded arteries during systole:
two readings: systolic blood pressure (top): this is maximum blood pressure in the cardiovascular system. coincident with ventricular systole.
diastolic blood pressure (bottom): this is the minimum blood pressure in the arteries. coincident with ventricular diastole.
normal adult blood is less than 140 systolic and less than 80 diastolic although these values are relative