PSY2061 Lecture Notes - Lecture 4: Ligand-Gated Ion Channel, Myelin, Neurotransmitter
15 May 2018
School
Department
Course
Professor
Week 4
Systems of Neuroscience for biological psychology
Overarching Concept 5:
Communication in the nervous system has both short and long distance modes
1. Dendrites transmit messages from other neurones to the cell body
2. Axon carries the message to a nearby neurone, muscle or gland
3. Myelin. The myelin sheath provides insulation and increases the speed of the travelling
message or impulse
4. Terminal buttons: the impulse reaches the terminal buttons, releasing neurotransmitters
into the synaptic space which separates one neurone from another
5. Synaptic vesicles in the terminal buttons of a sending neurone release
neurotransmitters into the synaptic space
6. The neurotransmitters cross the synaptic space to the receiving neurone
7. After crossing the synaptic space the neurotransmitters fit into receptor sites located on
the dendrites or cell body of the receiving neurone
Two main receptor types
Overarching Concept 7:
Neural Transmission: Its a matter of Chemistry & Physics!
1. Resting Potential!
At rest there are more negative ions inside the neurone compared with the outside.
When a point on the semipermeable neural membrane is adequately stimulated by an
incoming message, the membrane opens at that point and positively charged ions flow
in!
2. Action Potential!
The process is repeated along the length of the membrane, creating the neural impulse
that travels down the axon, causing the neurones to fire
7 Steps in Neurotransmitter action:
1) Neurotransmitter molecules are synthesised from precursors under the influence of
enzymes
2) Neurotransmitter molecules are stored in vesicles
3) Neurotransmitter molecules that leak from the vesicles are destroyed by enzymes
4) Action potentials cause vesicles to fuse with the presynaptic membrane and release
their neurotransmitter molecules into the synapse
5) Released neurotransmitter molecules bind with auto receptors and inhibit subsequent
neurotransmitter release
An Ionotropic Receptor
A Metabotropic Receptor
Some neurotransmitter molecules bind to receptors
on ion channel when a neurotransmitter molecules
binds to an ionotropic receptor the channel opens
or closes thereby altering the flow of ions in or out of
the neurone
When a neurotransmitter molecule binds to a
metabotropic receptor, a subunit of the G-protein.
Breaks off into the neurone and either bind to an ion
channel or stimulates the synthesis of a second
messenger
Document Summary
Communication in the nervous system has both short and long distance modes: dendrites transmit messages from other neurones to the cell body, axon carries the message to a nearby neurone, muscle or gland, myelin. Some neurotransmitter molecules bind to receptors on ion channel when a neurotransmitter molecules binds to an ionotropic receptor the channel opens or closes thereby altering the ow of ions in or out of the neurone. When a neurotransmitter molecule binds to a metabotropic receptor, a subunit of the g-protein. Breaks off into the neurone and either bind to an ion channel or stimulates the synthesis of a second messenger. Neural transmission: its a matter of chemistry & physics: resting potential. At rest there are more negative ions inside the neurone compared with the outside. When a point on the semipermeable neural membrane is adequately stimulated by an incoming message, the membrane opens at that point and positively charged ions ow in: action potential.
