Sharp ECG Study Guide
Study online at https://quizlet.com/_a5cj22
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 responsible 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 characteristics automaticity
of the heart excitability
conductivity
contractility
6. automaticity i. Specific to the pacemaker cells; ability to generate their own electrical
impulse spontaneously
, Sharp ECG Study Guide
Study online at https://quizlet.com/_a5cj22
7. excitability Ability of ALL cardiac cells to respond to an electrical impulse
8. conductivity i. Ability of ALL cardiac cells to conduct an electrical impulse
9. contractility i. Specific to muscle cells; ability to cause cardiac muscle contraction
10. electrons/ions responsi- Potassium
ble for depolarization/re- i. Primary ion inside the cell
polarization of the heart ii. Plays a role in depolarization and repolarization
muscle
Sodium
i. Primary ion outside the cell
ii. Major role in depolarization
11. sodium-potassium i. Actively transports ions across the membrane against the electro-
pump chemical gradient
ii. In a resting cardiac cell, there are more negative ions on the inside
than the outside. This is a resting, or polarized cell. No electrical activity
is occurring and there is an isoelectric (straight) line on ECG
12. depolarization i. When a cell is stimulated, potassium begins to leave the cell, increas-
ing permeability to sodium
ii. Sodium rushes in, causing the inside of the cell to be more positive
than negative
iii. Contraction is a mechanical process that FOLLOWS the electrical
event of depolarization
13. repolarization i. Sodium-potassium pump activated to transport sodium out of the cell
and move potassium back into the cell
ii. Inside becomes more negative again
Study online at https://quizlet.com/_a5cj22
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 responsible 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 characteristics automaticity
of the heart excitability
conductivity
contractility
6. automaticity i. Specific to the pacemaker cells; ability to generate their own electrical
impulse spontaneously
, Sharp ECG Study Guide
Study online at https://quizlet.com/_a5cj22
7. excitability Ability of ALL cardiac cells to respond to an electrical impulse
8. conductivity i. Ability of ALL cardiac cells to conduct an electrical impulse
9. contractility i. Specific to muscle cells; ability to cause cardiac muscle contraction
10. electrons/ions responsi- Potassium
ble for depolarization/re- i. Primary ion inside the cell
polarization of the heart ii. Plays a role in depolarization and repolarization
muscle
Sodium
i. Primary ion outside the cell
ii. Major role in depolarization
11. sodium-potassium i. Actively transports ions across the membrane against the electro-
pump chemical gradient
ii. In a resting cardiac cell, there are more negative ions on the inside
than the outside. This is a resting, or polarized cell. No electrical activity
is occurring and there is an isoelectric (straight) line on ECG
12. depolarization i. When a cell is stimulated, potassium begins to leave the cell, increas-
ing permeability to sodium
ii. Sodium rushes in, causing the inside of the cell to be more positive
than negative
iii. Contraction is a mechanical process that FOLLOWS the electrical
event of depolarization
13. repolarization i. Sodium-potassium pump activated to transport sodium out of the cell
and move potassium back into the cell
ii. Inside becomes more negative again
