2025 SHARP ECG STUDY GUIDE | 45+ ACTUAL DETAILED CORRECT ANSWERED | COMPLETE GUDE | GRADED A+

1. Layers of the heart pericardium
myocardium
endocardium

2. pericardium outermost layer: fibrous and serous

fibrous
-outer sack that anchors the heart

serous
-inner, fluid secreting membrane with two layers
-parietal (lines inner surface of fibrous sac)
-visceral (AKA epicardium) lines myocardium
-between the two is the pericardial space, with
10-30ml of fluid to give the heart space to relax
and contract

3. myocardium i. Thick, middle muscular layer that makes up the
bulk of the heart wall

ii. Composed of cardiac muscle cells and is re-
sponsible for the heart's ability to contract

4. endocardium i. Thin layer of tissue that lines the inner surface of
heart muscle and heart chambers

ii. Extensions and folds of this tissue forms the
valves of the heart.



,5. 4 primary characteris- automaticity
tics of the heart excitability
conductivity
contractility

6. automaticity i. Specific to the pacemaker cells; ability to gener-
ate their own electrical impulse spontaneously

7. excitability Ability of ALL cardiac cells to respond to an elec-
trical impulse






, 8. conductivity i. Ability of ALL cardiac cells to conduct an
mm mm mm mm mm mm mm mm


electri-
mm


cal impulse
mm




9. contractility i. Specific to muscle cells; ability to cause
mm mm mm mm mm mm mm


mmcardiac muscle contraction mm mm




10. electrons/ions Potassium
mmresponsi- ble
mm for i. Primary ion inside the cell
mm mm mm mm mm


mmdepolarization/re- ii. Plays a role in depolarization and
mm mm mm mm mm


mmpolarization of mm the
mm repolarization
mm


mmheart muscle
mm


Sodium
i. Primary ion outside the cell mm mm mm mm


ii. Major role in depolarization
mm mm mm




11. sodium-potassium i. Actively transports ions across the
mm mm mm mm


mmpump mmmembrane against the electrochemical mm mm mm


mmgradient

ii. In a resting cardiac cell, there are more
mm mm mm mm mm mm mm


mmnega- tive ions on the inside than the
mm mm mm mm mm mm mm


mmoutside. This is a resting, or polarized cell.
mm mm mm mm mm mm mm


mmNo electrical activity is occurring and there
mm mm mm mm mm mm


mmis an isoelectric (straight) line on ECG
mm mm mm mm mm mm




12. depolarization i. When a cell is stimulated, potassium begins
mm mm mm mm mm mm mm


to mm


leave the cell, increasing permeability to sodium
mm mm mm mm mm mm




ii. Sodium rushes in, causing the inside of
mm mm mm mm mm mm


mmthe cell to be more positive than negative
mm mm mm mm mm mm mm




iii. Contraction is a mechanical process that mm mm mm mm mm


mmFOL- LOWS the electrical event of
mm mm mm mm mm


mmdepolarization

13. repolarization i. Sodium-potassium pump activated to transpor
mm mm mm mm mm


sodium out of the cell and move potassium
mm mm mm mm mm mm mm


mmback into the cellmm mm mm



3 m/
23