Heart Activity Flashcards
What does it mean when cardiac ( heart) muscle is myogenic
This means it can contract or relax without signals from nerves.
what is the sino atrial node and what chamber is it in
It is a pacemaker found in the right atrium
- sets the rhythm of the heart beat by sending out electrical impulses to the atrial walls
- which causes the right and left atria ot contract at the same time
what stops electrical impulses from being passed from the atria to the ventricles?
so where do the electrical impulses from the SAN go?
A band of non- conducting collagen tissue
- the electrical impulses from the the SAN are transferred to the AVN ( Atrioventricular node)
what is the job of the AVN
But why might there be a slight delay for the AVN to carry out its job
to pass on electrical impulses onto the bundle of his
- There might be a slight DELAY before the AVN transfers electrical impulses to the BOH,
to make sure the VENTRICLES CONTRACT after the ATRIA are EMPTY.
What even is the bundle of his
CONDUCTSSSSS
the waves of electrical impulses to purkyne tissue in the right and left ventricle
what does the purkyne tissue do
Carries the wave of electrical impulses into the muscular walls of the right+left ventricle causing them to contract simultaneously, from the bottom up.
what does an electro cardiograph do
Records the heart’s electrical activity
when the heart muscle contracts does it depolarise or repolarise
It DEpolarises, ( loses electrical charge when contracts) BUT Repolarises ( Gain electrical charge when it relaxes)
what is an ECG
Electrocardiogram
ECG graph details:
1) P wave is caused by contraction of the atria
2) Main beat of the heart peak in the middle with the dips on either side
- This is called a QRS complex and is caused by contraction of the ventricles
3) T wave is due to the relaxation of the ventricles
- Also the bigger the wave the stronger the contraction, and the more electrical charge that passes through the heart
what is the graph called for a person who has a fast and slow heart beat
Tachycardia ( fast) (120bpm), at rest this shows that the heart isn’t pumping blood efficiently
Bradycardia (slow) (below 60bpm)
what is the graph called of a person who had an extra heart beat
Ectopic heart beat ( extra heart beat)
- caused by an early contraction of the atria
However, it can also be caused by early contraction of the ventricles too.
what is the graph called for a person with an irregular heart beat
FIbrillation
- irregular heart beats, BECAUSE atria or ventricles COMPLETELY lose their rhythm and stop contracting properly
- This can result from anything to chest pain, fainting , lack of pulse or even dead.
