BIPN 100 Lecture Notes - Lecture 7: Meninges, Tight Junction, Arachnoid Granulation
26 Jun 2018
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BIPN100 Lecture 7 Notes 4/16/18
- Myasthenia gravis
oautoimmune system attacks receptors in NMJ and destroys them. Causes weakness in
muscle, mostly cranial. Problems focusing eyes or swallowing
oless receptors means less sodium can enter cell and less voltage-gated Na+ channels are
activated. Lower EPP created, so it takes longer to reach threshold, so less muscle action
potentials or no muscle action potentials are created
otreat using acetylcholinesterase inhibitor. As soon as the acetylcholine unbinds from the
receptor, AChE usually breaks it down. However, by inhibiting it, more acetylcholine
floats in the synaptic cleft. Though there are less receptors, most of those receptors will
have acetylcholine bound to it. That way, Na+ can flow into cell and EPP over threshold
and MAP will occur
oif too much inhibitor is added and AChE is totally inhibited, no acetylcholine is broken
down so there is way more acetylcholine present than normal. Acetylcholine
overflowing in synaptic cleft. ACh always bound to receptors so Na+ constantly flows in.
The voltage-gated Na+ channels open the activation gate due to depolarization. After a
certain time, the inactivation gate closes, blocking Na+ intake. To open the inactivation
gate, repolarization must occur. However, the continuous influx of Na+ doesn’t allow
repolarization of voltage-gated Na+ channels, so the inactivation gate is constantly
closed and there is a depolarization blockade. This causes a persistent EPP, which
cannot activate the MAP
- Post-synaptic potentials (PSPs): occur in post-synaptic cell
oChemical synapses can be excitatory (depolarizing) or
inhibitory (usually hyperpolarizing)
- Neuronal integration
oTypes of neurotransmitters
1) causes an excitatory post-synaptic potential (EPSP)
neurotransmitter (nt) -> cation influx -> post-synaptic neuron membrane
depolarization -> action potential (AP)
2) causes an inhibitory post-synaptic potential (IPSP)
neurotransmitter (nt) -> post-synaptic membrane potential further from
threshold -> reduces likelihood of AP
ex: activate Cl- channels to move Cl- into cell or K+ channels to move K+ out
- types of neurotransmitters
oacetylcholine
found in all motor neurons from the spinal cord
cholinergic: refers to acetylcholine
synthesis: choline + acetyl CoA by enzyme CAT
synthesized in the axon terminal (small/simple things synthesized in axon terminal)
cholinergic receptors
nicotinic: found on skeletal muscle in the NMJ, ANS (autonomic nervous system
in the PNS), and CNS. Excitatory
find more resources at oneclass.com
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muscarinic: tissue response varies with the receptor subtypes (5 subtypes).
Found in the CNS and autonomic parasympathetic division of the PNS. Can be
inhibitory or excitatory
obiogenic amines
contain nitrogen
derived originally from tyrosine
synthesized in the axon terminal
types of biogenic amines
epinephrine: produced from the adrenal medulla and released in the circulation
(neurohormone because produced by chromaffin cells which are like neurons)
norepinephrine: main neurotransmitter of ANS sympathetic division
dopamine: primarily in the midbrain region
serotonin: in many brainstem nuclei
histamine: hypothalamic nuclei and anti-inflammatory agent
oamino acids
found in the CNS
synthesized in the axon terminal
types of amino acids
glutamate: primary excitatory neurotransmitter in the CNS
aspartate: excitatory in some regions of the brain
gamma-aminobutyric acid (GABA): main inhibitory neurotransmitter in the brain
glycine: inhibitory neurotransmitter in the spinal cord
oneuro-active peptides
synthesized in the cell body (big things synthesized in cell body)
types of neuro-active peptides; modulate pathways
substance P: involved in some pain pathways
opioids: mediate pain relief
endorphins: pain control
ogases
nitric oxide (NO): diffuses quickly, crosses membranes and breakdowns easily
- types of synapses in terms of action
oone-to-one synapse (NMJ): one pre-synaptic neuron transmits information to one post-
synaptic neuron
odivergent pathway: one presynaptic neuron branches to affect a larger number of
postsynaptic neurons (some muscular systems)
oconvergent pathway: many presynaptic neurons provide to influence a smaller number
of postsynaptic neurons
find more resources at oneclass.com
find more resources at oneclass.com
