Section 2 Flashcards
Commotio Cordis
A blunt trauma to the chest during the second half of the t wave causing early depolarization sending pt into cardiac arrest
Role of electrolytes in cardiac function:
Sodium (Na+)
Flows into cell to initiate depolarization
Role of electrolytes in cardiac function:
Potassium (K+)
Flows out of cell to initiate repolarization
Role of electrolytes in cardiac function:
Hypokalemia
Increased myocardial irritability
Role of electrolytes in cardiac function:
Hyperkalemia
Decreased automaticity/conduction
Role of electrolytes in cardiac function:
Calcium (Ca++)
Maintains depolarization after initial Na+ influx and depolarization
Role of electrolytes in cardiac function:
Hypocalcemia
Decreased contractility and increased myocardial irritability
Role of electrolytes in cardiac function:
Hypercalcemia
Increased contractility
Role of electrolytes in cardiac function:
Magnesium (Mg++)
Stabilizes cell membrane;
Acts in concert with K+ and against Ca++
Role of electrolytes in cardiac function:
Hypomagnesemia
Decreased conduction
Role of electrolytes in cardiac function:
Hypermagnesemia
Increased myocardial irritability
Depolarization (Phase 0-2)
Electrical impulse that stimulates contraction
Stimulation causes Sodium ions to rush into cell, potassium ions start to leave while calcium enters the cell to maintain depolarization
Repolarization (phase 3-4)
Potassium ions (K+) exit cell rapidly,
Sodium exit, potassium enters, (Na/K pump puts everything back in place, restoring balance)
Refractory period (absolute/relative)
Period when cell is depolarized or in the process of repolarizing (T-wave)
Absolute: cardiac cells can’t respond to any stimulus
Relative: partial repolarization, may depolarize to stimulus
SA node supplied by what coronary artery?
RCA
