PHYS20008 Lecture Notes - Lecture 6: Depolarization, Phospholipid, Neuron (Software)
12 Jun 2018
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Lecture 6
PHYS20008 - HUMAN PHYSIOLOGY
LECTURE 6
SYNAPTIC TRANSMISSION
ANATOMY OF A NERVE CELL (NEURON)
CNS SYNAPSE (NEURON TO NEURON)
•When the AP reaches the calcium gate
the change in voltage opens the gate
and allows Ca2+ to move in freely.
•Synaptic vesicle walls are made of
phospholipid bilayers, which have a
high concentration of neurotransmitter.
•A series of events occurs with Ca2+
that allows synaptic vesicles to interact
with a series of proteins. The vesicle
comes down and fuses with the
membrane on the end, fusing and
opening into the omega shape, opening
to the outside world, and due to the
high concentration, the
neurotransmitter flows out into the
synaptic cleft.
•The pink receptors cause the response
in the post synaptic cell.
•There are specific types of receptor for
types of neurotransmitters.
•Many receptors are in and of
themselves ion channels. We can
pretend this one is a chemically gated
Na+ sodium channel (chemically gated
= closed until the neurotransmitter
comes into contact and then opens).
•The receptor will open up and allow some Na+ in, then it will close,
depolarising that section of the membrane.
•We will have all kinds of depolarisations because there are many
neurons and receptors.
•AP comes down - opens voltage gated Ca2+ channels - vesicles fuse
with protein - opens membrane to synaptic cleft - neurotransmitter
comes out - touches receptor - depolarises membrane.
Document Summary
We can pretend this one is a chemically gated. Phys20008 - human physiology: reuptake is a process that occurs whereby neurotransmitters not taken by the receptors are reabsorbed and reused, glial cells break down and metabolise other neurotransmitters left over. Types of neurotransmitter: excitatory: lead to a small depolarisation in the target cell. Bringing it closer to threshold, making post synaptic cell more likely to fire an ap: eg. Neuron that opens up na+ channel: inhibitory: lead to a small hyperpolarisation in the target cell. Glutamate has 8 excitatory and 1 inhibitory one so in general it"s called excitatory: mdma imitates serotonin; activates serotonin receptors and gets taken back up, telling cells to release more serotonin. Neuromuscular junction (neuron to skeleton muscle cell: unique synapse between neuron and skeletal muscle fibre. Skeletal muscle cells are similar to neurons; they fire ap and use voltage gated na+ and k+ channels: in order to contract we need to initiate an ap.
