NURS 5315 - Advanced Pathophysiology: Altered Cellular Function and Cancer Module Core Concepts and Objectives with Advanced Organizers. Study
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N5315 Advanced Pathophysiology
Altered Cellular Function and Cancer
Module Core Concepts and Objectives with Advanced Organizers
Cellular Physiology
1. Analyze the steps of the action potential.
o Normal cell has a (-) charge inside and (+) charge outside with greatest Na+ outside and greatest K+ inside the cell. The difference in charges inside vs out = resting membrane potential (RMP) usually -70mv. Threshold potential (TP) is usually -55 to -60, which is the stimulus required to reach AP. Depolarization is usually when 0 to 30 is reached and is the change from (-) charge in cell to (+) charge in cell or neutralized. AP is the rapid reversal in polarity and is responsible for the signals carried across the nerve/muscle cells.
o RMP (-70) → Na+ rushes into cell → TP of -55 to 60 is reached → Depolarized 0 to 30 is reached → AP signal and absolute refractory period (no other stimulus will affect cell) → Repolarization to reestablish Na+/K+ levels and polarity (K+ channels open allowing K+ to leave cell and Na+ channels close) and relative refractory period (only strong stimulus will affect cell)
o Hyperpolarized if the inside cell is more (-) than RMP. Ex: -85 vs the RMP norm of -70
o Hypopolarized if the inside cell is less (-) than RMP. Ex: -65 vs the RMP norm of -70
2. Examine how the action potential is altered by calcium and potassium imbalances.
Topic
Describe the Action Potential
How is the action potential altered by a potassium imbalance?
How is the action potential altered by a calcium imbalance?
Action Potential Physiology
Rapid change in resting membrane potential (RMP) when nerve/muscle receives stimulus that exceeds membrane threshold potential (TP)
Hypokalemia causes hyperpolarization (inside the cell is more negative than RMP) causing greater distance between RMP and TP--harder time to reach action potential (AP). Ex: weakness, decrease in neuro muscle, cardiac dysrhythmias
Hyperkalemia (inside the cell is less negative than RMP) causing less distance between RMP and TP--easier to reach AP. If not corrected, can cause RMP to = TP which is BAD! No AP can take place! Ex: cardiac arrest, peaked T waves, as RMP begins to = TP it will stretch out QRS
Ca changes cell permeability.
Hypocalcemia causes less distance between RMP and AP by making TP to be more (-)--more excitable because it is easier to reach AP. Ex: tetany, muscle cramping, seizures, dysrhythmias
Hypercalcemia causes greater distance between RMP and AP by making TP more (+)--less excitable.Ex: weakness, fatigue, hyporeflexia, confusion, can be medical ER
Cellular Adaptation [Show Less]