Flashcards in Introduction to neurones, nerve conduction and synaptic transmission Deck (48)
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1
What is the purpose of a dendrite?
To receive inputs from other neurones and convey graded electrical signals passively to the soma
2
What is the purpose of the soma?
It is the synthetic and metabolic centre
Contains the nucleus, ribosomes, mitochondria and ER
It integrates incoming electrical signals that are conducted passively to the axon hillock
3
What is the axon hillock?
Site of initiation of the "all or nothing" action potential
4
What is the function of the axon?
Conducts output signals as action potentials to the presynaptic terminal
Mediates transport of materials between the soma and presynaptic terminal and vice versa by slow and fast axonal transport
5
What is the function of the synapse?
Point of chemical communication between neurones
6
What viruses will exploit retrograde transport to infect neurones?
Herpes
Polio
Rabies
7
What are the different types of neurones?
Unipolar
Pseudounipolar
Bipolar
Multipolar
8
Where can unipolar neurones be found?
Peripheral autonomic system
9
Where can pseudounipolar neurones be found?
Dorsal root ganglion
10
Where can bipolar neurones be found?
Retina
11
Where can multipolar neurones be found?
Lower motor system
12
What is the resting potential for a neurone?
-70 mV
13
What is the threshold for a neurone?
-60 mV
14
What channels allow for the upstroke and downstroke of the action potential in neurones?
Upstroke = Na+
Downstroke = K+
15
Why do passive signals in neurones not spread far from their site of origin?
Current loss across the membrane accompanied by a reduced change in potential
16
What are strategies utilised to increase passive current speed and therefore action potential velocity?
Decreased axial resistance of the axoplasm via increased axon diameter
Increased membrane resistance - addition of myelin provided by schwann cells in PNS and oligodendrocytes in CNS
17
What is saltatory conduction?
Action potential jumping from one node of ranvier to the next
18
What are examples of demyelinating disorders?
MS (CNS)
Guillan-Barre (PNS)
19
What separates the pre and post synaptic membranes?
Synaptic cleft
20
What holds the pre and post synaptic membranes together?
A matrix of fibrous extracellular protein within the cleft
21
Where are the neurotransmitters stored in the neurone?
Vesicles within the presynaptic terminal
22
What are the different types of synapses?
Axodendritic
Axosomatic
Axoaxonic
23
What is the most common type of synapse?
Axodendritic
24
What is the most common neurotransmitter of excitatory synapses in the CNS?
Glutamate
25
What will glutamate activate?
Post synaptic, cation selective, inotropic glutamate receptors resulting in a depolarisation; excitatory postsynaptic potential
26
What are the major amino acid neurotransmitters in the CNS?
Glutamate
GABA
Glycine
27
What is the most common neurotransmitter of inhibitory synapses in the CNS?
GABA or glycine
28
What will GABA/glycine activate?
Postsynaptic, anion selective, inotropic, GABA or glycine receptors generating a local, graded hyperpolarizaing post synaptic potential
29
What is spatial summation?
Many inputs converge upon a neurone to determine its output
30
