Phenytoin works by:
1. selectively inhibiting sodium entry into hyperactive neurons.
2. inhibiting calcium entry into all CNS neurons.
3. exciting healthy neurons to override hyperactive neurons.
4. blocking sodium entry into all CNS neurons at the time of seizure activity.
Question 2
A patient has taken phenytoin for 6 weeks. The nurse reviews the laboratory data and sees that the phenytoin level is 15. What is the nurse's best action?
1. This level is too low. Instruct the patient to increase the dose by 100 mg per day.
2. This level is in the therapeutic range. If the patient is seizure free and not experiencing significant, adverse events, the drug should be continued at this dose.
3. The serum level is above the therapeutic range. Instruct the patient to reduce the dose by 50 and avoid driving.
4. This dose is too high. Instruct the patient to stop the medication for 1 week, then return so that the level can be measured again.
Recording the membrane potential of neurons.
An example of sodium balance achieved by the coordinated actions of three hormones.
"Neurons" and "Neuroglia"
Potassium-Sodium Pump
Triumphal Entry, page from a manuscript of Firdawsi's Shahnamah, Persian, Safavid culture.
Time-of-entry mapping