CTL Week 8 Flashcards
(41 cards)
what does conduction velocity of neurons depend on
axon diameter (larger = faster)
degree of myelination
what is another function of myelination apart from making the conduction faster?
Myelin insulates and prevents leakage of charge
where are voltage gated Na channels located
areas that are unmyelinated
Nodes of Ranvier for myelinated axons, jumping from gap to gap (saltatory conduction)
where does the AP start on the neuron
axon hillock
when does voltage decay occur while travelling
on dendrites (no voltage gated channels located here)
when does voltage not decay
nonmyelinated axons - continuous conduction
myelinated axons - saltatory conduction
voltage gated channels are present along the axon = no decay in voltage
explain the process of neurotransmission
- Nerve impulse: AP arrives at axon terminal of presynaptic neuron, depolarising terminal causing…
- Voltage gated Ca2+ channels open – Ca2+ influx into cell
- Calcium triggers synaptic vesicles containing neurotransmitters to fuse with axon membrane
- Neurotransmitters diffuse across the synaptic cleft
- Binds to receptor on ligand gated (channel closed) on postsynaptic neuron
- Ligand gated channels open; Receptors are chemically gated ion channels or GPCRs
- Causes excitatory or inhibitory graded potential in neurons
- Post synaptic potential occurs
where is ACh neurotransmitter released and used?
Released at neuromuscular junction
synapses at: autonomic nervous system/CNS synapses
what are some catecholamine neurotransmitters and where are they released
o Include dopamine, norepinephrine and epinephrine
o Released at ANS and CNS synapses
what are some indolamine neurotransmitters
o Include serotonin and histamine
what are some amino acid neurotransmitters and where are they mainly used
o Include glutamate, GABA
o Major neurotransmitters in CNS
what are some other neurotransmitters
o Peptides, ATP, nitric oxide, endocannabinoids
what are the 2 effects a neurotransmitter has on receptors
excitatory - depolarizing
inhibitory - hyperpolarising
neurotransmitter action can be fast or slow depending on these 2 receptors it binds to
fast: ligand gated ion channel (ionotropic - fast); skeletal muscle
slow: GPCR (metabotropic)
what are some inhibitory neurotransmitters and where do they act
GABA, glycine, ACh
in cardiac muscle
what are some excitatory neurotransmitters and where are they used
Glutamate, ACh
at neuromuscular junction in skeletal muscle
which two hormones bind to at least two receptors with opposite effects
acetylcholine and norepinephrine
what causes more neurotransmitter to be released
more frequent AP’s at axon terminal
what are PSPs
in neurons, neurotransmitter receptors activate graded potentials (post-synaptic potential, PSPs)
what is the strength of PSP dependent on
Depends on amount of neurotransmitter released and time neurotransmitter stays in the area
what are excitatory and inhibitory PSPs and what do they cause
EPSPs – causes depolarization
IPSPs – causes hyperpolarisation
can a single EPSP induce an AP
no
how can a EPSP or IPSP influence a postsynaptic neurons response
by summation
what are the two types of summation
Temporal and spatial
