The synapse Flashcards
(31 cards)
What is the function of the dendrites?
Receive inputs from other neurones and convey graded electrical signals passively to the soma
What is the function of the soma (cell body)?
Synthetic and metabolic centre. Contains the nucleus , ribosomes, mitochondria and endoplasmic reticulum. Intergrates incoming signals that are conducted passively to the axon hillock
What is the function of axon hillock and initial segment?
Site of initation of the ‘all or none’ action potential
What is the function of the axon?
Conducts output signals as action potentials to other neuroes (or other cells). Mediates transport of materials between the soma and presynaptic terminal and vice versa
What is the function of the synapse?
A point of chemical communication between neurones
What holds the pre- and post- synaptic membranes together?
A matrix of fibrous extracellular protein within the cleft
What does vesicles in the presynaptic terminal store ?
Neurotransmitter
What is the gray’s type 1 synapse?
Asymmetrical synapses in which the membrane differentiation on the postsynaptic side is thicker than the presynaptic side (usually excitatory in function)
What is the gray’s type 2 synapse?
Symmetrical synapses in which the membrane differentiations are of similar thickness (usually inhibitory in function)
What is a axodendritic synapse?
Axons joins at post synaptic dendrite
What is a axosomatic synapse?
Axon joins at the soma
What is a axoaxonic synapse?
Axon meets at axon
what two categories of synapses are there?
- excitatory
- inhibitory
What causes the excitatory postsynaptic potential?
Glutamate activates postsynaptic , cation selective, ionotropic, glutamate receptors generating a local, graded , excitatory (depolarising) response
What causes the inhibitory postsynaptic potential?
GABA, or glycine, activates postsynaptic, anion selective, ionotropic, GABAA, or glycine, receptors generating a local, graded, inhibitory (hyperpolarizing) response
What is spatial summation?
Many inputs converge upon a neurone to determine its output
What is temporal summation ?
A single input may modulate output by variation in action potential frequency of that input
What are released from synaptic vesicles ?
Amino acids and amines
What are released from secretory vesicles?
Peptides
What can activate ionotropic ligand-gated ion channels (LGiCs)?
- Glutamate
- GABA
- glycine
- acetylcholine
- 5-HT
What is the 9 steps of neurochemical transmission?
1) Upatke of precursor
2) Synthesis of transmitter
3) Storage of transmitter
4) Depolarization by action potential
5) Ca2+ influx through voltage-activated Ca2+ channels
6) Ca2+ induced release of transmitter (exocytosis)
7) Receptor activation
8) Enzyme-mediated inactivation of transmitter OR
9) Reuptake of transmitter
How are GABA and amines synthesised?
Must be synthesised by the neurones that release them,requiring specific enzymes
How are the enzymes synthesised in the cell body transported to the presynaptic terminal?
Axoplasmic transport
How are synaptic vesicles made?
- precursor molecule
- synthetic enzymes
- neurotransmitter molecule
- transporter protein
- synpatic vesicle made