Nervous System Flashcards
Polarised membrane
A membrane that has a potential difference across it
Depolarisation
The loss of polarisation across a membrane
When sodium ions are entering the cell
Generator potential
A small depolarisation of the membrane caused by sodium ions entering the cell
An action potential
Depolarisation of the membrane to about +40mV
Anatomy of a motor neurone
Cell body in the CNS
Long axon
Anatomy of sensory neurones
Cell body outside the CNS
Long dendron
Sort axon to CNS
List specialisations of neurone not including cell membrane
Many are very long to transmit an action potential over a long distance
Maintain a potential difference
Myelin sheath made of Schwann cell
Many dendrites to communicate with many other neurones
Specialisation of cell membrane
Channel proteins specific to sodium and potassium ions that are GATED to control permeability
Carrier proteins to actively transport sodium ions out and potassium in
Resting potential
Potential difference of a cell membrane at rest
Voltage-gated channels
Responds to changes in the potential difference across a cell membrane
Threshold potential
When the potential difference across a membrane increases by about +15mV from the resting potential
It is necessary for an action potential as it opens the voltage-gated channels
Refractory period
The time after an action potential when it’s impossible to stimulate the cell membrane to reach an action potential
Controls the frequency
Ensures 1D
Local currents
Diffusion of ions along the neurone
away from areas of high concentration
The movement of ions is called local current
Salatory conduction
Jumping conduction
The way the action potential appears to jump from one node of Ranvier to the next with elongated currents
Advantages of Schwann cells
Speeds up the transmission of action potentials
