neurons and electrical potentials Flashcards
1
Q
properties of neurons
A
- irritability
- conductivity
- cell membrane is electrically unstable
- communicates using electrical potentials
2
Q
sensory neurones
A
- afferent
- pseudounipolar or bipolar
3
Q
motor neurons
A
- efferent
- multipolar
4
Q
interneurons
A
- connect sensory and motor neurons in CNS
- multipolar
5
Q
Glial cells
A
- support neurons
- do not produce electric potentials
6
Q
schwann cells
A
- glial cells
- wrap around axons to form myelin sheath
- nodes of ranvier
- help regrowth of neurons
7
Q
Equilibrium potential of an ion (Eion)
A
the voltage across a membrane when the ion is at electrochemical equilibrium
8
Q
electrochemical equilibrium of a ion
A
balance between voltage and concentration where there is no net movement of the ion across the membrane
9
Q
Nernst equation
A
- calculating Eion
- proportional to the log of the ratio of the concentrations either side of the membrane
- a larger chemical gradient requires a larger voltage to offset ion movement
10
Q
Vrest of neurons
A
- voltage of neuron at rest
- -70mV (polarised)
- closer to Eion of K+ as there are more K+ leakage channels than Na+
11
Q
graded potential
A
- involve ion channels that are opened by stimulus energy
- electrical impulse proportional to stimulus
- occur in dendrites or ‘passive membrane’
- decrease in amplitude with distance
12
Q
passive vs active membrane
A
active membranes contain voltage-gated ion channels
13
Q
action potential
A
- triggered by voltage change from stimulus or graded potential at axon hillock (active membrane)
- all or nothing, depolarisation has to reach threshold
- able to carry information long distance, constantly triggering action potentials along axon
14
Q
neurons that only use graded potentials
A
- 2nd order L-neurons in locust
- detect light intensity
- large, only relatively short transmission distance
