Lecture 2a- Basic electrophysiology Flashcards
What is a neuron
A cell of the nervous system which conducts electrical impulses. These typically
have an axon, soma (cell body), and dendrites, which synapse with other cells
What is the human nervous system divided into
CNS and PNS
What are the components of the CNS
. The CNS comprises the brain and spinal
cord
What is the PNS
The PNS can be further divided in to the
autonomic and somatic nervous systems. The
autonomic NS is the part of the nervous
system responsible for functions which are
not consciously directed e.g. heartbeat,
peristalsis, breathing etc.
What is the somatic nervous system responsible for (PNS)
and what fibres is it divided into
Voluntary control of movements
Further divided into afferent sensory and efferent motor fibres.
What is the function of a resting membrane potential and what is the typical value
Typical value is 70mV
Function is for nerve fibres to carry electrical impulses.
- baseline for electrical signaling in cells
- maintains cellular homeostasis
- sets the threshold for cellular excitation, - facilitates neurotransmitter release
- supports cellular excitability
- regulates various cellular functions.
What happens when impulses arrive at the dendrites of a nerve cell
-The number of excitatory vs inhibitory impulses are summed
-If the membrane potential is depolarised sufficiently, then the nerve cell will propagate an all-or-nothing action potential along its axon towards the synapse
What is the impulse firing process mediated by
flow of…
flow of sodium and potassium ions through specialised pumps and channels
What do action potentials do and what is it described as
either occur or do not occur, they can be described as “all-or-nothing” responses,
and may also be thought of as digital signals.
What does digital transmission avoid
how long do the impulses last
crosstalk and external
interference
these impulses last for about 1 ms
How many impulses does the body use
~100 ips (impulses per second).
What is the shape and size of nerve fibres
Nerve fibres are long and thin (~10 µm diameter x 1 m long).
What are the types of fibres
Myelinated or unmyelinated
What is the function of a myelin sheath
Myelin sheaths insulate the axon and force action potentials to jump between the Nodes of Ranvier (small gaps in the myelin); this decreases the surface area to be depolarised, and increases conduction velocity.
What does myelination do
Myelination increases conduction velocity by ~ x 10 up to ~70m/s max, i.e. 241 kph (150
mph).
