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What are the 4 properties of the heart?
What are the parts of the electrical conducting system?
- SA node
- AV node
- Purkinje's fibers
- HIS bundle
- Right and left bundle branches
What 2 kinds of cells make up the heart?
- Mechanical cells
- Cells of electrical system
The cells of electrical system are actually these
Modified cardiac muscle cells
What 2 things do interclated discs contain?
- Desmosomes - attach cells together
- Gap junctions - spread action potentials
What is the resting membrane potential in cardiac cells?
-80 to -90 mv
This ion generates resting membrane potential
What is the Nernst equation?
61.5 log10 (Xo / Xi)
These are 2 types of action potentials in the heart
Which cells have fast response action potentials?
- atrial cells
- ventricular cells
- His cells
- Purkinje cells
Which cells have slow action potentials?
- 0= Na influx
- 1= Na close and open specific K+ channels
- 2= open calcium channels
- 3= close calcium open K+
- 4= rest
The refractory period spans this time
depolarization half way down repolarization
- 1. K+ close, Naf open
- 2. Naf close, T-calcium open
- 3. T-calcium close, L-calcium open
- 4. L-calcium close, K+ open
The suppression of all other pacemakers by the SA node is called this
Conduction of AP
- 1. AP made in SA node
- 2. Rapid spread through atria
- 3. Delay
- 4. Goes through His bundle
- 5. Goes through ventricles
- 6. Rest
These cells have the largest diameter with most of gap junctions
These cells have small diameter and less gap junctions
AV node cells
Intercalated Disc between cells