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a neural impulse; a brief electrical charge that travels down an axon
action potential
nerves can be easily stimulated or depressed y chemical substances, mechanical stimulation, electrical stimulation, and temperature (true or false)
true
nerves consist of a big number of what
single neurons
registered action potential (compound action potential) is essentially a combination of what
single action potentials
the action potential is initiated where
axon hillock (trigger zone)
axon hillock contains a high density of what two channels
VOC sodium and potassium
action potential is also known as what
information
five major elements of action potential
depolarization, depolarization, threshold, all or none law, refractory period
major element of action potential:
increase in sodium permeability - opening of VOC sodium channels
depolarization
major element of action potential:
increase in potassium permeability - opening of VOC potassium channels
repolarization
major element of action potential:
critical membrane potential that must be reached before action potential
threshold
major element of action potential:
excitable membrane responds to stimuli with a maximal action potential
all or none law
major element of action potential:
a period when new action potential cannot be initiated
refractory period (absolute/relative)
depolarization occurs in approximately how fast
1 ms
depolarization and resting level is achieved in how long
1-2 ms
conduction by local currents, saltatory conduction, axon diameter, and myelin are all part of what effect
self propagating ("domino effect")
Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.
saltatory conduction
A gap between successive segments of the myelin sheath where the axon membrane is exposed.
node of ranvier
what are the axon classifications
group a, b, c, and squid giant axon
which axon classification is described:
myelinated, 15-130 m/s, 5-20 mm
group A
which axon classification is described:
ANS fibers, 3-15 m/s, 1-3 mm
group B
which axon classification is described:
unmyelinated, 1 m/s, 0.5-1 mm
group C
which axon classification is described:
unmyelinated, 25 m/s, 500 mm
squid giant axon
myelinated increases or decreases velocity
increases
increase in diameter of the axon increases or decreases velocity
increases
velocity of group A axon
15-130 m/s
velocity of group B axon
3-15 m/s
velocity of group C axon
1 m/s
velocity of squid giant axon
25 m/s
diameter of group a axon
5-20 mm
diameter of group b axon
1-3 mm
diameter of group c axon
0.5-1 mm
diameter of squid giant axon
500 mm
different physical factors (pressure, temperature) and chemical agents (general anesthetics, local anesthetics, and alcohol) can ____________ the ability of the neuron to propane action potential
inhibit
typical equipment to conduct nerve physiology may include electrical stimulator, oscilloscope, and a bio-amplifier (true or false)
true
who coined the term synapse in 1897
(charles) sherrington
who explained the mechanism of chemical synaptic transmission in 1921
(otto) loewi
how many neurons are in the human brain
100 billion
neuron branches in about how many presynaptic terminals
1000
neurons receives approximately __________ synaptic inputs from other neurons
1000
acetylcholine was first discovered when
1921
what are the two types of synapse
electrical and chemical
space between electrical synapses
2-4 nm
electric synapse includes what
gap junction
proteins that form gap junctions
connexin
how many protein connexins make up gap junction
12
synapses are found in cardiac muscle, some brain regions, and embryonic tissue (true or false)
true
gap junctions consists of what two channels
presynaptic and postsynaptic
gap junctions allow massage of metabolites, ions, and molecules less than ____________ dalton
1000
electrical synapses are unidirectional (true or false)
false (bidirectional)
a type of synapse at which a chemical (a neurotransmitter) is released from the axon of a neuron into the synaptic cleft, where it binds to receptors on the next structure (either another neuron or an organ)
chemical synapse
conducts impulses toward the synapse
presynaptic neuron
The narrow gap that separates the presynaptic neuron from the postsynaptic cell.
synaptic cleft
synaptic cleft length
20-40 nm
transmits impulses away from the synapse
postsynaptic neuron
typical elements of a chemical synaptic transmission:
neurotransmitters synthesis and storage in a _________
vesicle
typical elements of a chemical synaptic transmission:
neurotransmitter release in where
synapse
typical elements of a chemical synaptic transmission:
receptor activation on which neuron
postsynaptic
store various neurotransmitters that are released at the synapse
neurotransmitter vesicles
what is the size of a neurotransmitter vesicle?
30-150 nm
neurotransmitter vesicles use ___________ which is a dependent process to uptake and concentrate neurotransmitters
ATP
neurotransmitter vesicles do not contain other molecules (true or false)
false (contains other molecules that assist in packaging (often ATP))
the old theory about neurotransmitters is that majority of neurons contain multiple neurotransmitters (true or false)
false (that is the new theory, old theory is one neuron one neurotransmitter)
majority of neurons contain multiple neurotransmitters (true or false)
true
neurotransmitter release:
the release of a neurotransmitter is dependent on what secretory process
calcium
neurotransmitter release:
the calcium ion signal is detected by a vesicle associated Ca2+ binding protein which is called ________________
synaptotagmin
neurotransmitter release:
the vesicle associated calcium ion fuses with the ________________ membrane at an active zone
presynaptic
neurotransmitter release:
each vesicular packet represents a single _____________ of neurotransmitter
quantum
neurotransmitter release:
discarded vesicles are typically recycled by what process
endocytosis
what are the different types of termination of a neurotransmitter?
_____________ from the synapse, enzymatic degradation, and ___________ (neurons/neuroglia)
diffusion, reuptake
examples of neurotransmitters
acetylcholine, norepinephrine, dopamine, serotonin, histamine, amino acids, polypeptides, gases
what are the two most important neurotransmitters studied in this lecture
acetylcholine and norepinephrine
A neurotransmitter that enables learning and memory and also triggers muscle contraction
acetylcholine
A neurotransmitter involved in arousal, as well as in learning and mood regulation
norepinephrine
A neurotransmitter associated with movement, attention and learning and the brain's pleasure and reward system.
dopamine
A neurotransmitter that affects mood, hunger, sleep, and arousal; linked to depression and treated by Prozac.
serotonin
a neurotransmitter that plays an important role in stimulating wakefulness
histamine
what are the two groups under amino acid neurotransmitters?
excitatory and inhibitory
examples of excitatory amino acids
glutamic acid and aspartic acid
examples of inhibitory amino acids
GABA (gamma-aminobutryric acid) and glycine
examples of polypeptides
glucagon, insulin, endogenous opioids
examples og gases
nitric oxide and carbon monoxide
Acetylcholine undergoes what type of signal transduction
ligand operated
what is the duration of acetylcholine receptor interaction
2 ms
acetyl coa + choline
acetylcholine
what makes up acetylcholine?
acetyl coa and choline
after diffusion out of the synapse, Ach breaks up into what
acetate and choline
after Ach breaks up, ____________ diffuses and gets removed while __________ is reuptaken
acetate, choline
what breaks down Ach
acetylcholinesterase
insecticides, zarin, zoman, and neuromuscular relaxants inhibits what
Ach E
norepinephrine undergoes what type of signal transduction
protein coupled
a class of enzymes that destroy the monoamines: dopamine, norepinephrine, and serotonin
MAO (monoamine oxidase)
norepinephrine goes into what structure in the synapse
mitochondria
when norepinephrine goes through the synapse, how many types of reuptake are there
two
which reuptake is used more with norepinephrine
reuptake I
_______________ --> l-dopa
tyrosine
tyrosine --> ______________ --> dopamine
l-dopa
l-dopa --> _________________ --> norepinephrine (in the nerve)
dopamine
dopamine --> ___________________ --> epinephrine (in adrenal gland)
norepinephrine
norepinephrine --> _________________
epinephrine
