Chapter 2 : Electrophysiology Flashcards
What are the main positively charged ions in the body?
Sodium (NA+), potassium (K+), calcium (Ca++)
What is the main negative ion in the body?
Chloride (Cl-)
What is electrical potential?
Difference between the charges outside and inside of the cell wall
What is the bodies fuel pellet?
ATP
What moves ions around to maintain the resting concentration and charge of a cell?
ATPase pumps
What is the electrical potential of a resting myocyte?
-70 to -90 mV
Once the cell becomes so positive new channels open. What is this point called?
Threshold potential
What happens at Phase 0 in myocyte stimulation?
Sodium causes a rapid increase and the cell “spikes” or “fires”
What happens at Phase 1 of myocyte stimulation?
Cell is at its peak positive charge. Some negatively charged chloride ions enter and cause influx of sodium to slow. Slams shut the one way valve on the rapid sodium channels. Two more channels now open, slow sodium channels and calcium channels, slow plateau phase begins.
What happens in Phase 2 of myocyte stimulation?
The influx of calcium and the slow sodium help maintain the cell in the depolarized state. Calcium is needed for the cell to contract. Calcium is the key. Activating a key composed of the proteins troponin and tropomyosin. The clamp brings together two ratcheting proteins actin and myosin. The cell contracts.
What happens is Phase 3 of the myocyte stimulation?
Some potassium channels open and allow potassium to escape inside the cell. During this phase of rapid repolarization, the exit of positive ions imparts a relatively negative charge to the inside of the cell.
What does the CNS consist of?
Brain and spinal cord
What does the Peripheral Nervous System consist of?
All nervous tissue outside the brain and spinal cord
