Electrophsiology Flashcards
(28 cards)
What is electrophysiology?
The study of the electrical activity of cells and tissues, using the principles of resting membrane potentials and action potentials.
What are the two environments in which electrophysiology can be studied?
In vivo (within organisms) and in vitro (outside organisms).
What is an electrograph?
Electrophysiology recordings.
What is the role of electrodes in electrophysiology?
To detect electrical activity and a monitor to display changes.
How many leads are typically used in electrocardiography (ECG)?
10 leads, although it is often referred to as ‘12 leads’.
What does an electroencephalogram (EEG) assess?
A variety of neurological conditions, such as epilepsy.
What is the purpose of electromyography (EMG)?
To assess muscular activity and nerve supply.
What condition can affect electromyograms?
Myasthenia gravis.
What is the resting potential generated at the RPE-PR interface in the eye?
60mV.
What does an electro-oculogram (EOG) measure?
The corneo-retinal standing potential using lateral eye movements.
What is the Arden ratio in EOG interpretation?
Light peak/dark trough.
What is considered a normal Arden ratio?
> 1.80-2.00.
What is a significant indicator of abnormal EOG results?
An Arden ratio < 1.50.
What does an electroretinogram (ERG) measure?
The cumulative electrical response to a light stimulus from all retinal elements.
What factors affect the electroretinogram (ERG)?
- Intensity of stimulus
- Duration of stimulus
- Stimulus wavelength
- Stimulus pattern
- Light/dark adaptation of the retina
What signifies hyperpolarization in the ERG?
A wave: Corneal -ve deflection.
What signifies depolarization of ON-centre bipolar cells in the ERG?
B wave: Corneal +ve deflection.
What does the C wave in ERG represent?
Transepithelial potential due to hyperpolarization of the innermost RPE.
What is indicated by a negative ERG?
Conditions affecting the inner retina only.
What is the purpose of multifocal ERG?
To assess localized retinal disease/macular disease.
What do visual evoked potentials (VEP) measure?
Visual cortex response to a visual stimulus.
What type of stimulus is usually used for pattern VEP?
Reverse checkerboard stimulus.
What is the advantage of using Flash VEP?
Useful in assessing vision in uncooperative, preverbal, or nonverbal patients.
True or False: The EOG measures the corneo-retinal standing potential in varying luminance conditions.
True.
