Lecture 17 Flashcards
How do neurons communicate with each other
using synapses
What are the synapses
chemical synapse
Electrical synapse
How does chemical synapse work
The action potential in the presynaptic terminalcauses the creation off synaptic vesicle containing neurotransmitter then then released to the postsynaptic terminal of another neuron
how does electrical synapse communicate
The neurons and linked using gap junction channels and when there is a action potential, the signal will go through the gap junction channel and cause a coupling potential
What receptor are on the chemical synapse
ionotropic recepter, metabotropic receptor
What are the classical neurotransmitter material
• Acetylcholine • Dopamine • Norepinephrine • (noradrenaline) • Epinephrine (adrenaline) • Serotonin • Gamma-aminobutyric acid (GABA)
What are the neuropeptides
• Vasoactive intestinal peptide VIP • Cholecystokinin, Enkephalin • Somatostatin, Enkephalin, Neurotensin • Enkephalin • Substance P • Thyrotropin-releasing hormone
How does acetylcholine synapse work
Vesicle of acetycholine from pre-synaptic terminal will be released to the receptors of the post-synaptic cell. The released acetylcholine will broken down to choline using AChE, then enter the pre-synaptic terminal through a channel and convert back to acetylcholine using ChAT and acetyl-CoA
What is the neurotransmitter acetylcholine
A cholinergic synapse
What are the receptors in the postsynaptic neuron of The neurotransmitter acetylcholine
– Nicotinic
– Muscarinic
What is Muscarinic
• M1 decreases K+ permeability, drives membrane closer to
threshold (e.g. exocrine glands)
• M2 increases K+ permeability, drives membrane further from
threshold (e.g. Heart)
What is nicotinic receptor
increases Na+ permeability, drives membrane closer to threshold
What is the presynaptic attached to
the ending of the dentrite
What happens to the amplitude of the potential as it travels to the hillock axon
gradually reduce like a graded potential,
How does axon hillock receive signal
Spatial Summation of two post-synaptic potentials from different synapses at the same time to
reach threshold
What kind of presynaptic inputs are attached to the post synaptic cell
Excitatory and inhibitory presynaptic input
What is Excitatory postsynaptic potentials (EPSP) for
release positive potential into the receptors, bring it closer to the threshold
What is Inhibitory postsynaptic potentials
IPSPs
Releases negative potential into the receptor, ions like choride ions, bring it further away from threshold
What are the types of intergration of summation
a) no summation
b) temporal summation
c) spatial summation
d) EPSP - IPSP cancellation
What is temporal summmation
where the potential is caused by 2 signal from the same presynapse in quick succession
What is spatial summation
where the potential is cause by 2 different signal from different synapse
What is Tetanus toxin (tetanospasmin)
• Binds to presynaptic membrane and blocks the release of inhibitory neurotransmitters (GABA and glycine).
What happens when there is Tetanus toxin (tetanospasmin)
• Binds to presynaptic membrane and blocks the release of inhibitory neurotransmitters (GABA and glycine). • The excitatory signals in the postsynaptic neurons are unchecked
What are the effects of Tetanus toxin (tetanospasmin)
• Uncontrolled muscle
contractions and spasm
• Lockjaw
How is sensory nerve signal delivered to the nervous system
sensory nerve > lower motor neuron (LMN) > upper motor neuron (UMN)
What causes the voltage gated Ca2+ channels to open at the synaptic knob
when an action potential is detected
where does the neurotransmitter go
attached to the ligand channels
What is the synaptic delay
0.5 to 1.0 msec
What is the difference between graded potential and action potential
graded potential reduces over distance, there is no refractory period in graded potential
