Cell body containing nucleus and organelles, dendrites involved in conducting impulses towards cell body, axons conducting impulses away from cell body
Types of neurones
Sensory
Motor
Relay
Motor neurones
Transmit electrical impulses from central nervous system to muscles and glands
Sensory neurones
Transmit impulses from receptors to central nervous system
Relay neurones
Transmit electrical impulses from sensory neurones to motor neurones within central nervous system
Resting potential
70mV, due to imbalance of sodium and potassium ions across neurone membrane
Depolarisation
Sodium ion channels open, sodium ions diffuse in, potential reaches threshold of -55mV, more sodium channels open, potential reaches +30mV
Repolarisation
Sodium ion channels close, potassium ion channels open, potassium ions diffuse out, resting potential of -70mV restored
Refractory period
Short period where neurone membrane cannot be excited, ensures action potentials can only pass in one direction
Synaptic transmission
Action potential causes calcium ion channels to open, calcium ions enter, synaptic vesicles fuse and release neurotransmitter, neurotransmitter binds to receptors on postsynaptic membrane, sodium ions enter, postsynaptic membrane depolarises
Receptors
Cells specialised for detection of stimuli, able to convert one form of energy into another
Pacinian corpuscles
Pressure receptors in skin, convert mechanical energy into electrical energy
Action potentials have the same magnitude, frequency conveys strength of stimulus
