Heart Beat Flashcards
what are heart muscles cells specialized to do?
heart muscles cells are specialized to contract and relax rhythmically on their own without nerve activity = myogenic contraction
the pacemaker
the sinoatrial node (SAN) is located in the wall of the right atrium and is called the pacemaker since it sets the pace of the heart beat and causes the atria to contract
the node that delays the singals from the SA node?
The antrioventricular node (AVN) is located between atria and the ventricles and delays signals from the SA node and allows atria to completely empty before ventricles contract.
Electrical stimulation
the sinoatrial node (SAN) produces a wave of electrical stimulation which causes the atria to contract
electricity passes
The SAN passes the electricity to the AVN
delay
the AVN delays the signal and then conducts the signal down the specialized fibers called the bundle of HIS
bundle of HIS
the bundle of His transmits the electrical signal to the base of the heart (apex) and through the** purkinje fibers** and branches up around each ventricle.
what do the purkinje fibers cause the ventricles to do?
The electricity signal along the purkinje fibers causes the ventricles to contract and push the blood out of the ventricles and into the aorta (left side) and pulmonary artery (right side)
ECG
- An electrocardio (gram/graph) (ECG) is used to record the electrical events (voltage changes) generated by a beating heart using electrodes on the skin of the chest.
- it can detect a hearts frequency, strength, and duration by analyzing the “waves” of electrical activity that relate to the heart beat.
wave
P wave- represents atria contractions
QRS wave- represents ventricles filling and contracting
T wave- represents the ventricles relaxing
what is used to listen to the heart beat?
A stethoscope is used to listen to the heartbeat - “lub-dub”
“lub-dub”
Lub = the closing of the AV valves during the contractions of the ventricles (ventricles are emptying)
dub= closing of the SL valves during relaxtion of the ventricles (ventricles are filling)
what delays the signals from the SA node?
