What is the range of the resting membrane potential?
-60 to -100 mV
What is the peak value of an action potential?
20 mV
What is the duration of an action potential in nerve and skeletal muscle cells?
Cardiac muscle cells?
nerve cells - 1 ms
cardiac muscle - 150-300 ms
What is the Absolute Refractory Period?
How long is it in nerve cells?
the period during depolarization and repolarization when further stimulus can not cause further action potentials
about 1 ms in nerve cells
What is the Relative Refractory Period?
How long in nerve cells?
The refractory period caused by hyperpolarization during which a stronger stimulus is required to create an action potential
- several ms in nerve cells
What is ENG?
Electroneurogram
a signal observed as a stimulus and the associated nerve action potential propagating over the nerve’s length
How are ENGs measured?
What amplitudes are generally measured?
What can they diagnose?
- concentric needle electrodes or Ag-AgCl electrodes
(ex: above elbow, below elbow + wrist electrodes) - strong short stimulus to minimize muscle contraction
- amplitudes approx. 10 μV
- diagnose neural disease (slower transmission)
What is EMG?
Electromyogram
- measures electrical activity of skeletal muscles
- measures electric potential of muscles when they are electrically or neurologically activated
What is SMUAP?
How many phases does it have generally?
Duration?
Amplitude?
Single Motor Unit Action Potential
- bi- or triphasic
- 3-15 ms
- 100-300 μV
What is EEG?
Electroencephalogram
- records electrical activity along the scalp to detect electrical activity of neurons in the brain
- used for diagnosis of epilepsy primarily
What are the 4 main frequency ranges of brain waves?
- Delta - deep sleep (delta = deep)
- Theta - beginning stage of sleep
- Alpha - principal resting rhythm (alpha = principal)
- Beta - background activity when tense or anxious (beta = background)
What is EGG?
Electrogastrogram
- measurement of the rhythmic deploarization/repolarization of gastric smooth muscle (starting in mid-corpus every ~20 sec)
- recorded by abdomen electrodes… 3 along antral axis and one reference electrode
What is Carotid Pulse measurement?
It has 4 parts… what are they?
Carotid Pulse (CP)
- measurement of pressure over the carotid artery
- P (Percussion) Wave - left ventricle ejection
- T (Tidal) Wave - reflected pulse from upper body
- D (Dicrotic) Notch - closure of aortic valve
- DW (Dicrotic Wave) - reflected pulse from lower body
What is VMG?
How is it detected?
Vibromyogram
- mechanical measurement of skeletal muscle contraction
- detected with contact microphones or accelerometers
What is VAG?
vibroarthrogram
- recording of vibration signal from a joint during articulation
- arthritic or other diseased joints may produce grinding sounds
