Exam (elaborations)
ECG CPO QUESTIONS AND ANSWERS 2024
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Exam of 14 pages for the course CPO at CPO (ECG CPO)
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ECG CPOWhat is the pattern of blood flow through the heart? - answer Right atrium - Tricuspid
valve - Right Ventricle - Pulmonic Valve - Pulmonary Arteries - To the Lungs -
Pulmonary Veins - Left atrium - Mitral Valve - Left ventricle - Aortic valve - Aorta
What is the atrial kick? - answer This is atrial systole - The atrial kick delivers 20-
30% of the blood volume from the atria to the ventricles. The atria is contracting in
response to the SA node
What is the pericardial cavity? - answer Between the parietal and visceral layers of
the heart is a potential space. It contains serious fluid (pericardial fluid) which reduces
friction.
What is the epicardium? - answer It is the outer surface of the heart or inner serous
layer of the pericardial asc
What is the myocardium? - answer It is the middle layer of the heart and it is the
muscular layer
What is the endocardium? - answer It is the inside layer that is nice and smooth. It
helps the blood to flow smoothly.
What are the five unique properties of myocardial tissue? - answer 1) Automaticity
2) Rhythmicity
3) Conductivity
4) Contractility
5) Excitability
What does 'automaticity' of cardiac cells refer to? - answer It refers to their ability to
initiate an impulse without an external source of stimulation
It works without your brain instructing it to
How is the action potential generated? - answer Phase 4: Resting membrane
potential. Inside the cell is a high concentration of K+. In this stage, K+ gates open and
it starts to leak out.
Phase 0: Depolarization phase. Na+ enters the cell via fast sodium channels - making
the inside of the cell positive. K+ gates close.
Phase 1: Early repolarization - fast sodium channels close
, Phase 2: Plateau phase - calcium moves into the cell, causing the cardiac contraction
along with the sodium. The influx helps to maintain the positive charge over this time
period.
Phase 3: Repolarization - K+ moves into the cell via the pump and the RMP is re-
established
What does the 'rhythmicity' of the cardiac cells refer to - answer It means that
impulses are formed at regular intervals. The sodium and potassium move at regular
rates and then the cycle is repeated - its regular
What does the 'conductivity' of the cardiac cells refer to? - answer Electrical impulses
travel quickly through the heart. Intercalated discs contain gap junctions that speed up
the conduction.
What does the 'contractility' of the heart refer to? - answer The cardiac fibers are
arranged in a circular pattern. Shortening of them reduces the chamber size and
increases chamber pressure. The contraction action produces the pumping effect of the
heart. To increase the force of contraction, fibers must shorten even more.
What does 'excitability' refer to? - answer The ability of the heart to respond to
outside stimuli? It can initiate an impulse (automaticity), but it is also affected by
external neurotransmitters, hormones and meds that can increase the rte and strength
of contraction of the heart
What are your SNS receptors? - answer They are adrenergic receptors: beta 1
receptors
What are the PNS receptors? - answer They are cholinergic receptors: Muscarinic
receptors
What is the main pacemaker of the heart? What is the rate? - answer SA node (60-
100 bpm)
Where is the SA node located? - answer Right atrial epicardium, near the opening of
the SVC
Where does the impulse go after the SA node initiates it? - answer It runs along the
intra-atrial tracts/internodal tracts. This carries the impulse throughout the right atria. It
will also go thru bachmann's bundle so that it can reach the left atrium.
What is after the intra-atrial tracts in the conduction pathway? - answer The AV node
What does the AV node do? - answer It filters out excess impulse from the atria, so
that they don't reach the ventricles. It also delays the impulse for 0.08-0.12 sec, which
allows for the atrial kick.
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