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29 Cards in this Set

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Absolute Refractory Period

The period immediately following the firing of a nerve fibre when it cannot be stimulated no matter how great a stimulus is applied

Acetylcholine

Neurotransmitter that is liberated at the PNS mostly. Exciters at the neuromuscular Junction, inhibitory at other synapses

Action Potential

An electrical signal that propagates along the membrane of a neuron/ muscle fibre. A rapid change in membrane potential that involves depolarisation then repolarization

After Hyper-polarisation:

(undershoot phase) The hyperpolarizing phase of a neuron's action potential where the cells membrane potential falls below the normal resting potential

Axon

Usually long, single process of a nerve cell that propagates a nerve impulse toward the axon terminals

Axon Terminal

Terminal branch of an axon where synaptic vesicles undergo exocytosis to release neurotransmitter molecules

Cell Body

The cell body of the neuron contains the nucleus and other usual organelles, along with Nissl bodies (clusters of RER) which produce protiens for cell growth and repair -esp the axon

Chemical Synapse

Specialised Junction through which neurons can signal to each other and non neuronal cells. Neurotransmitters molecules are released into the synaptic cleft to be recieved by another neuron. More abundant, slower and precise

Dendrites

A neuronal process that carries electrical signals (usually graded) toward the cell body

Depolarisation

An electrical state in an excitable cell where the inside of the cell is less negative than the outside

Electrical Synapses

A gap in which an ion current flows over a gap junction between neurons. Bidirectional and there is no delay (as no conversion to chemical energy occurs), however less control as it is a "all or nothing" response

End Plate

The flattened end of an axon of a motor neuron that contacts the muscle fibre

Equilibrium Potential

At a certain voltage there is no net flow of ions from one side to another (ie. Equilibrium)

Excitatory Post Synaptic Potentials

A neurotransmitter that causes an excitatory graded potential, this depolarizes the membrane

Excitatory Synapses

A synapse where the action potential in a presynaptic neuron increases the probability of an action potential occurring in a post synaptic cell


ACh and glutamic acid main neurotransmitters involved

Excitoxicity

The process in which nerve cells are killed by excessive stimulation by neurotransmitters

Glutamate (L- glutamic acid)

The main excitatory neurotransmitter in the CNS


Very important in brain function

Glutamate Transporters

Involved in the re-uptake of glutamate to inactivate the neurotransmitter


removal options:


- presynaptic terminals, astrocytes


- storage in synaptic vesicles



Goldman Equation

Calculates RMP (Resting Membrane Potential)


ADD IN PLZ

Hyperpolarisation

A change in a cell's membrane potential making it more negative. Increases the stimulus required to move the membrane potential to the action potential threshold.

Inhibitory Post Synaptic Potentials

Evoke hyperolarizations, making it harder for the membrane potential to be moved above the action potential threshold


- GABA or Glycine


Open K+ or Cl- channels


Cl- does not hyperpolarize, decreases the effect of the current induced by excitatory synpases

Inhibitory Synapses

A synapse where a nerve impulse in the presynaptic cell results in the release of inhibitory neurotransmitters causing the opening of channels that allow ions (K+ or Cl-) to flow in, hyper-polarising the membrane

Ligand Gated Ion Channel

Transmembrane ion channel proteins which open to allow ions (Na+, K+, Ca2+, or Cl− etc) to pass through the membrane in response to the binding of a neurotransmitter

Micro Electrode

A very small electrode that is able to be inserted into the membrane of a single cell

Passive Transmission

the action potential propagates passively to the nearby membranes *look at

Patch-Clamp Technique

Used to measure RMP, using intracellular micro electrodes and patch clamp pipettes

Myelination

the process of forming a myelin sheath around a nerve to allow nerve impulses to move more quickly

Na/K ATPase

Pumps sodium out of cells, while pumping potassium into cells. 3:2 Na:K

Nernst Equation

Calculates the equilibrium potential for an individual ion that contributes to RMP