EMT 254 Flashcards
Automaticity
pacemaker cells can create their own electrical impulses
Excitability
ability of cardiac cells to respond to an electrical stimulus
Conductivity
ability for cardiac cells to receive an electrical stimulus and transmit it to other cardiac cells
Contractility
ability for cardiac cells to shorten and cause cardiac contraction
Myocardial cells are responsible for:
generating the physical contraction of the heart muscle
Pacemaker cells are responsible for:
controlling the rate and rhythm of the heart
Pacemaker cells have the ability to:
create their own electrical impulse without being stimulated
The three major cations that effect cardiac function:
Potassium (K), Sodium (Na) and Calcium (Ca)
Primary cations inside the cell:
Potassium, magnesium and calcium
A major cation outside the cell:
Sodium
At the resting state:
Potassium is greater inside the cell
Sodium is greater outside the cell
Cardiac depolarization it’s thought of as:
the period in which sodium ions rush into the cell
Sodium – potassium pump:
sodium returns outside of the cell and potassium returns inside the cell
The two stages of repolarization:
Absolutely refractory period (cell is unable to respond to a new electrical stimulus) from QRS - peak of T-wave
Relative refractory period (went repolarization is almost complete, the cell can be stimulated if the stimulus is stronger than normal), downward slope of the T-wave
5 step approach to reading ECG’s:
Herat rate, Heart rhythm, P-wave, PR Interval, QRS complex
PR Interval
0.12-0.20
QRS Interval
P-wave
Impulse spreads across the atria and triggers atrial contraction
QRS Complex
Impulse spreads across to ventricles, triggering ventricle contraction
T-wave
Ventricle returning to resting state
Which are bipolar leads
Leads I, II, III
V1 Placement
4th intercostal space, right of the sternum
V2 Placement
4th intercostal space, left of the sternum
V3 Placement
5th intercostal space, 1/2 way between V2 and V3
V4 Placement
5th intercostal space, left midclavicular
V5 Placement
5th intercostal space, left anterior axillary line
V6 Placement
5th intercostal space, left midaxillary line
What are the two leads used to access for axis deviation and what are you looking for:
I and aVF
The deflection of the QRS complex
What are the LCA’s:
Left Anterior Descending, Circumflex, marginal
What are theRCA’s:
Posterior descending, Marginal
Subendocardial infarctions:
Only a portion of the ventricle wall is involved, most commonly the subendocardial
* also known as nontransmural
Transmural infarctions:
Involve the entire thickness of the ventricle wall, from endocardium to the epicardial surface
Blue-bloaters
Chronic Bronchitis Pt, hypoxia and fluid retention
Pink-Puffers
Emphysema Pt, red faces during forced exhalation
Spontaneous Pneumothorax happens mostly to who:
seemingly healthy individuals 20-40, often tall men with long narrow chest
Type 1 and 2 blocks have what kind of QRS:
Narrow
Type 3 blocks have what kind of QRS:
Wide
Axis deviation is read from which two leads:
I and aVF
