Neurophysiology Flashcards
Electricity
We create an electrical impulse through the movement of ions
An ions is an atom that has a positive or negative charge i.e., calcium = Ca2+, Sodium = Na+, potassium = k+
The production of a nerve impulse depends on two basic features of a plasma membrane:
- the existence of a resting membrane potential
2. the presence of specific types of ion channels
Diffusion
Movement of particles from an area of high concentration to an area of low concentration
Leak channel
Randomly open and close, only ions specific to that ion channel can move through when open
Ligand-gated channel
Ligand is a chemical, it will open in response to a ligand or a chemical stimulus e.g. a neurotransmitter or hormone
Mechanically-gated channel
Open in response to mechanical stimulation for example sound waves or touching of the skin
Mechanically-gated channel
Open in response to mechanical stimulation for example sound waves or touching of the skin
Voltage-gated channel
open in response in change in voltage, participate in generation and conduction of action potential in axons of all neurons
Action potential
rapid depolarization and repolarization of membrane potential
Order of action potential
Resting potential
Depolarization
Repolarization
Hyperpolarization
Refractory periods
a period of time during which a organ or cell is incapable of repeating an action
Absolute refractory period
during this time another action potential cannot be generated no matter the stimulus, during this time the voltage-gated sodium channels are either open and cannot open further or are inactive
relative refractory period
Another action potential can be generated but only by a larger than normal stimulus
Continuous propagation
Occurs in unmyelinated axons and muscle
moves down the axon
Saltatory propagation
Occurs in myelinated axons
can skip to nodes of ranvier
