Neurones, Nerve Conduction And Synaptic Transmission Flashcards
What is the role of the soma?
Contains the nucleus and endoplasmic reticulum
The synthetic and metabolic centre
What is the role of the dendrite?
Receives inputs from neurones
Conveys signals to soma
What is the role of the axon?
Conducts output signals to other neurones
What is the role of the synapse?
Point of chemical communication between neurones
Give an example of a unipolar neurone?
Peripheral autonomic neurone
Give an example of a pseudounipolar neurone?
Dorsal root ganglion neurone
Give an example of a bipolar neurone
Retinal bipolar neurone
Give an example of a multipolar neurone
Motor neurone
What are the 4 functional regions of a neurone?
Input, integrative, conductile, output
What are the 3 types of synapse and their frequency?
Axodendritic- very common
Axosomatic- common
Axoaxonic- uncommon
What is the main transmitter in excitatory synapses?
Glutamate
What does glutamate do at the synapse?
Activates post synaptic cation selective ionotropic glutamate receptors to produce an excitatory postsynaptic potential
What are the main transmitter in inhibitory synapses?
Gamma-aminobutyric acid (GABA) or glycine
What do GABA and glycine do at the inhibitory synapse?
Activate postsynaptic anion selective ionotropic GABA or glycine receptors to produce an inhibitory postsynaptic potential
What are the steps of neurotransmission?
Uptake of precursor
Synthesis of transmitter
Storage of transmitter
Depolarisation by action potential
Ca2+ influx through voltage activated ion Ca2+ channels
Ca2+ induced release of transmitter (exocytosis)
Receptor activation
Enzyme mediated inactivation of transmitter
Reuptake of transmitter
What determines membrane potential?
Selective permeability of the membrane to certain ions
Concentration gradient of ions across membrane
The diffusion of ions down their concentration gradients generates a net electric potential which is the resting membrane potential.
What does Na+ influx cause?
Depolarisation
What does Ca2+ influx cause?
Depolarisation
What does K+ efflux cause?
Hyperpolarisation
What does Cl- influx cause?
Usually hyperpolarisation
What is the resting membrane potential?
~ -65mV
At rest, which ions is the neuronal membrane permeable to?
Na+ Cl-
What is the response of the membrane to current leak into the extracellular space?
Membrane potential decays exponentially with distance along the nerve process
How does length of nerve affect AP conduction velocity?
The longer the length the greater the local current spread and therefore the greater the AP conduction velocity.
Describe saltatory conduction?
The action potential ‘jumps’ from one node of Ranvier to the next
