cardiovascular system; heartbeat + cardiac cycle Flashcards
control of heartbeat
impulse that triggers the heart beat originates in heart itself
sinoatrial node/ sa node
bundle of specialized tissue, that stimulates muscle fibers to contract and relax rythmically
sa node location
in the wall of right atrium
other node atria contracts
atrioventricular node/ av node
signal of av node
delayed @ av node for 0.01 seconds while atria empties blood into ventricles, then gets activated and enters the bundle of his.
bundle of his function
av bundle that are conducting fibers that distribute the electrical signals to the ventricles
purkinje fibers
specialized conduction fibers that provide the heart’s conduction system to perform synchronized contractions of its ventricles
bundle of his contains purkinje tissue
specialized muscle fibers function (general)
conduct signal to apex of heart + throughout ventricular heart
specialized muscle fibers function cont
triggers ventricles contraction
drives blood from ventricles -> large arteries
hormonal control of heart rate
when you’re relaxed your sa node fires regularly
70 times/minute
heart rate when exercising
increased activity in your muscles produces a faster rate of cellular respiration
-> increase amount of CO2 in blood
-> receptors in blood vessels transmit this info to medulla
oblongata
medulla oblongata -> nervous systems
medulla oblongata sends impulse along nervous system, causes release a chemical called nonadrenaline
nonadrenaline -> sa node
fires more rapidly
when finished exercising
heart rate gradually returns to resting heart rate
-> controlled by medulla oblongata
heart rate that’s fast =
increase in blood pressure, blood being pumped more quickly through vessels
fast heart rate sensed =
receptors in blood vessels sense increase in blood pressure
-> transmit info to medulla oblongata
medulla oblongata -> nervous system path 2
medulla oblongata causes nervous system to release acetylcholine, slows firing of sa node
reason heart beats faster when exercising?
heart needs to transport blood faster as body needs more oxygen
cardiac cycle
sequence of events of a heartbeat (3 stages)
cardiac cycle consists of
systole and diastole
complete cardiac cycle
during a complete cycle, each chamber undergoes a systole and diastole
stage one
atrial systole and ventricular filling
ventricles relax + blood flows into them from atria
70% blood flows passively, during last third of ventricular filling gets contracted by atria
stage two
ventricular systole
atria relaxes, ventricles contract, blood pumped ventricles from aorta
-> pulmonary artery
stage three (has split second of relaxation/ventricular diastole)
semilunar valves close to prevent backflow into the ventricles
cycle begins again.
systole
contractions
diastole
relaxation
ECG - electrocardiogram
electrical impulse transmitted through the heart, generates electrical currents
how to detect ECG
by placing metal electrode on body’s surface
can be recorded on a heart monitor as a trace/ electrocardiogram (ecg)
ECG pattern is produced by
different impulses produced from each phase of cardiac cycle
p wave
spread of impulse from SA node through atria, causing them to contract
qrs complex
corresponds to the spread of the impulse through the ventricles which contract
t wave
represents the recovery of electrical activity of the ventricles which are relaxed.
