Wed - fitz - neural communication Flashcards
How many different types of channels are there?
Hundres
4 types of ion channels
1 voltage gated
2 ligand gated (less specific)
3 mechanical (sensory receptors)
4 leak (don’t actually have gates)
What type of inactivation is only present in some transmembrane channels?
Inactivation ball.
all gated channels can close; only some can inactivate
Equilibrium (reversal) potential for Cl Ca Na K
Cl (-61)
Ca (+200)
Na (+60)
K (-88)
The amplitude of a graded potential ______ with time, and _______ with distance
decreases, decreases
Length constant applies to what types of potentials
Graded. (length until 37%)
When do action potentials peak?
When the voltage-gated Na channels inactivate and voltage-gated K channels open. (between 0 and 40 mV)
Two types of postsynaptic potentials
EPSP and IPSP
EPSP is the influx of cations into the cell
What is meant by all or none?
once Vm reaches the AP threshold, the cell will depolarize in a manner that is independent of the initiating stimulus.
Does NOT mean that all action potentials are all the same size or shape, it doesn’t say anything about the amplitude at all.
Why does the AP peak happen from 0 to 40 mV and not 60
because they are inactivated by the inactivation ball (this is sufficient enough to create the peak) THIS BEGINS REPOLARIZATION
plus chloride channels become more influential, and voltage gated K channels activate.
Two things hyperkalemia can do to action potentials
slight depolarization can cause depolarizations in the membrane potential to be more likely, leads to innapropriate aciton potentials (arrhythmias).
can also prevent action potentials from occurring, leading to cardiac arrest.
How do electrical synapses transfer their signals from cell to cell
through gap junctions made of connexin
Lambert-eaton syndrome. Treatment?
rare, autoimmune destruction of voltage gated Ca channels at the ends of axons. Muscle contraction increases with repeated stimulation
K+ channel blocker diaminopyridine. (leaves Na channels open longer)
Fast receptor activation name. slow?
Fast: ionotropic
slow: metabotropic
Three actions for terminating the actions of neurotransmitter?
diffusion: amino acid neurotransmitters like glutamate and GABA
enzymatic degradation (ACh)
reuptake (monoamines)
Function and chemical signal of these receptors
nicotinic AMPA NMDA 5HT3 GABA clycine
nicotinic - ACH, skeletal muscle contraction, autonomic ganglia
AMPA - glutamate, most excitatory neurotransmission in brain
NMDA - glutamate - mediates long-term potentiation (learning, memory)
5HT3 - serotonin, nociception in gut, nausea and vomiting, appetite, sleep, happiness
GABA - GABA, inhibitory neurotransmission in brain, activating GABA receptor results in more Cl influx and hyperpolarization.
Glycine - glycine, inhibitory neurotransmission in spinal cord
Effects of cocaine, amphetamine, tricyclic antidepressants?
effects of SSRIs?
block reuptake of all 3 monoamine neurotransmitters.
specific serotonin reuptake inhibitors block 5HT uptake
Myasthenia gravis
autoimmune disease results from the generation of antibodies to the nACh receptor found in skeletal muscle. muscle contraction rapidly fatigues.
Botulinum toxin
vs
tetanus
Both destroy components of the docking apparatus of vesicles.
Botulinum causes flaccid paralysis
Tetanus blocks release of inhibitory neurotransmitters.
