16 Electrophysiology of the Heart Flashcards
-this allows the cardiac muscle fibers to act as a functional syncytium so that the atria and ventricles can contract as a unit
-provides low resistance for the spread of excitation from one cell to another
gap junctions
Type of muscle that is involuntary and striated
Cardiac muscle
____ muscle fibers are shorter and less circular than ____ muscle fibers.
Cardiac
skeletal
-Adjacent cardiac myocytes are joined end to end by ____
-contain desmosomes and gap junctions
intercalated discs
What hold cells together
Desmosomes
In cardiac muscle cells, action potentials are conducted from ____ while in skeletal muscle cells, action potentials are conducted along the length of a ____
cell to cell
single fiber
Propagation is slow in this muscle because of gap junctions and the small diameter of fibers
cardiac muscle
Propagation is fast in this muscle because of the larger diameter fibers
skeletal muscle
The movement of extracellular Ca2+ through the plasma membrane and T tubules into sarcoplasm stimulates the release of Ca2+ from the sarcoplasmic reticulum
calcium-induced calcium release (CICR)
What are the Action Potential stages in Cardiac Muscle
Depolarization
Plateau
Repolarization
Refractory period
refers to all events associated with blood flow through the heart from the start of one heartbeat to the beginning of the next
The Cardiac Cycle
During a cardiac cycle, each
heart chamber goes through two divisions
systole
diastole
This represents ventricular filling
Diastole
This represents ventricular contraction/ejection
systole
Which valve closure causes the “lub” heart sound
Atrioventricular valves (tricuspid & mitral valve)