Nerve Conduction and Synapse Transmission Flashcards
What are Dendrites?
They receive inputs from other neurones and convey graded electrical signals passively to the soma
What is the Soma? (Perikaryon)
Synthetic and metabolic centre.
What does the Soma contain?
The nucleus
Ribosomes
Mitochondria
ER/RER
What happens at the Axon hillock and initial segment?
All or nothing action potential
What does the Axon do?
Conducts the output signals as action potentials to other neurones
mediates transport of materials between soma and presynaptic terminal
What is 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 (DRG)
Give an example of a Bipolar neurone
Retinal Bipolar neurone
Give an example of a Multipolar neurone
Lower Motor neurone (LMN)
What causes the upstroke in an action potential?
Voltage-activated Na+ channel
What causes the downstroke in an action potential?
Voltage gated K+ channel
How big may an axon be?
Up to 1 metre
The distance over which a current spreads depends upon what?
membrane resistance Axial resisitance (axoplasm)
True or False:
The longer the length in constant, the greater the local current spread?
TRUE
What does a Schwann cell surround?
A single axon
What does a Oligodendrocyte surround?
many axons
What is the name of the node that the action potential jumps from one to another?
Ranvier
In the CNS, what is the most common excitatory transmitter?
Glutamate
What are the excitatory and inhibatory responses?
Excitatory = depolarizing Inhibatory = hyperpolarizing
In the CNS, what is the most common inhibatory transmitter?
Gamma-Aminobutyric acid (GABA)
or
Glycine
What do the excitatory transmitters activate?
Postsynaptic cation sleective ionotrophic glutamate receptors
What do the inhibatory transmitters activate?
Posysynaptic anion selective ionotrophic receptors
What does e.p.s.p stand for?
Excitatory postsynaptic Potential
WHat does i.p.s.p stand for?
Inhibatory postsynaptic potential
What holds the pre and post synaptic cleft together?
A matrix of fibrous extracellular protein within the cleft
What receptors are involved in the excitatory process?
Sodium
What receptors are involved in the inhibatory process?
Chlorine
What happens in Spatial Summation?
Many inputs converge upon a neurone to determine its output
What happens in Temporal summation?
A single input may modulate output by variation in action potential frequency of that input
Where are amino acids and amines released from?
Synaptic vesicles
Where are peptides released from?
Secretory vesicles
How are enzymes transported in the body?
By axoplasmic transport along microtubules to the presynaptic terminal
