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Tachycardia?
More than 100 beats/min
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bradycardia
less than 60 beats/min
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layers of heart? (out to in)
- epicardium
- myocardium
- endocardium
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Heart chamber thicknesses:
- Right atrium: 2mm
- Left atrium: 3mm
- Right ventricle: 4-5mm
- Left ventricle: 8-15mm
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What is a pressure gradient and how does it relate to blood flow through the heart?
In order for blood to flow through a vessel or across a heart valve, there must be a force propelling the blood. This force is the difference in blood pressure (i.e., pressure gradient) across the vessel length or across the valve. Blood in the heart flows from a high pressure gradient to low pressure gradient.
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What is another name for the atrial contraction?
atrial 'kick' – pushes 30% more blood through
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Phase 1 of cardiac cycle?
- Ventricular filling: AV valves open
- -Occuring during mid to late diastole
- -Atrial kick
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Phase two of cardiac cycle?
- Systole has two periods
- -Isovolumetric contraction
- -Both AV valves and semilunar valves are closed
- -Ventricular contraction – semilunar valves open
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Phase 3 of cardiac cycle?
- Isovolumetric relaxation
- -Both AV valves and semilunar valves are closed
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Who was William Harvey?
first to describe correctly and in detail the systemic circulation and properties of blood being pumped to the body by the heart
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Who was Augustus Waller?
He created the first practical ECG machine with surface electrodes
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Who was Willem Einthoven?
He invented the first practical electrocardiogram (ECG or EKG) in 1903 and received the Nobel Prize in Medicine in 1924 for it. Inspired by waller.
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What is Bachmann's bundle?
The anterior internodal pathway. It spreads impulse of SA node to AV node and conducts impulses to the to the left atrium
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What is the difference in auto rhythmic and contractile cells?
Auto rhythmic- the ability of cardiac pacemaker cells to create an electrical impulse without being stimulated by a nerve
Contractile- the ability of myocardial cells to shorten in response to an impulse
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What are the two main types of heart cells we are discussing in class?
Myocardial cells- mechanical contractile cells
Pacemaker cells- conducting, automatic cells
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As depolarization advances PERPENDICULAR TO A lead, which way is the deflection on the tracing?
Biphasic waveform or straight line
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What does biphasic mean with an EKG deflection?
Partially positive and partially negative
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P wave?
atrial depolarization and the spread of electrical impulse throughout the right and left atria (repolarization is hidden by QRS)
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PR segment?
activation of AV node, his, branched, purkinje
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Q wave?
depolarization of intraventricular septum
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QRS complex?
ventricular depolarization
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ST segment?
early repolarization of right and left ventricles
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T wave?
ventricular repolarization
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P, Q, R, S, and T deflections from the baseline?
- P- upward
- Q- Downward
- R- Upward
- S- downward
- T- Upward
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What causes the delay in conduction at the AV node?
The SA node fires faster than the AV node and the delay gives the atria time to contract
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What is different from the right bundle branch and the left bundle branch?
Left bundle branch goes to the left ventricle (thicker) and interventricular septum. It divides into fascicles.
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There are 6 limb leads divided into two categories. What are they?
Standard and augments limb leads
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Which limb leads are bipolar (has a positive and negative electrode) and which are unipolar (single positive electrode reference point)?
Bipolar: I, II, III
Unipolar: AVF, AVL, AVR
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What are the precordial leads?
How many are there? Six, V1, V2, V3, V4, V5, V6
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Which leads would be described as left lateral?
I, AVL, V5, V6
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Which leads would be described as inferior leads?
II, III, AVF
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V1 and V2 provide electrical information from where on the heart?
Septal wall
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V3 and V4 provide electrical information from where on the heart?
Anterior wall of left ventrical
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V5 and V6 provide electrical information from where on the heart?
Lateral wall of left ventrical
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Normal P wave?
2.5 boxes both ways (measured from incline to decline)
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normal Q wave?
duration less than one box, amplitude, less than 1/3 the R wave
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normal QRS complex?
measured from point where the first wave of the complex begins to deviate from the baseline to where is levels out again. Around 2-2.5 boxes duration
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normal ST segment?
from baseline, shouldn’t depress more than ½ a small box, shouldn’t elevate more than one small box (amplitude)
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normal PR interval?
.12 - .2 seconds
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normal QR interval?
less than half the RR interval (under .38 sec)
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