_______ is where a neuron is functionally connected to either another neuron or an effector.
Synapse
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What are the two types of synapses?
chemical and electrical
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_______ synapses are presynaptic neurons which release a neurotransmitter, and a postsynaptic neuron, which binds the neurotransmitter. they are physically separated by a synaptic cleft.
chemical
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_______ synapses are presynaptic neurons physically bound to postsynaptic neuron. no synaptic delay occurs and they are found in brain/eyes.
electrical
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What type of synapse has a space between the pre and postsynaptic neuron?
chemical
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What is the time between neurotransmitter from presynaptic neuron, its diffusion across the synaptic cleft, and binding of neurotransmitter by postsynaptic neuron?
synaptic delay
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Synaptic delay only occurs at chemical synapses. T/F?
true
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What is the plasma membrane of a neuron called?
cell membrane
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What are the three stages of voltage
gated Na+ channels?
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Inactivation gate is open, but activation gate is closed. entry of Na+ is prevented. what state is this?
resting state
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Both activation and inactivation gates are open. Na+ moves into the cell. what state is this?
activation state
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Activation gate is open, but inactivation gate is closed. entry of Na+ is prevented.
inactivation state
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What triggers voltage
gated Na+ channels to go from inactive state to resting state?
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What are the functional segments in a neuron?
receptive, initial, conductive, and transmissive
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What neuron structure makes up the receptive segment?
dendrites and cell body
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What neuron structure makes up the initial segment?
axon hillock
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What neuron structure makes up the conductive segment?
length of the axon
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What neuron structure makes up the transmissive segment?
synaptic knobs or synaptic bulbs
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What ions are more prevalent in the interstitial fluid? (outside the cell)
Na+
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What ions are more prevalent in the cytosol? (inside the cell)
K+
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What is the net electrochemical gradient of Na+?
Na+ would enter the cell
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What is the net electrochemical gradient of K+?
K+ would leave the cell
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What is a membrane potential?
electrical charge difference across the plasma membrane
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What are small, short
lived changes in the RMP that are caused by the movements of small amounts of ions across the plasma membrane?
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What involved depolarization and repolarization, and has the all
or
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What is the threshold for an action potential?
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What is the resting membrane potential for a neuron?
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What is the measure of the amount of difference in electrical between two areas?
voltage
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How is voltage measured?
in mV
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What is the movement of charged particles (ex. ions) across the barrier that separates this charge difference?
current
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How is current generated?
when ions diffuse across the plasma membrane through open channels
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What is the opposition to the movement of charged particles?
resistance
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Ohm's law
current = voltage/resistance
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What is the threshold potential?
minimum voltage change to initiate action potential, typically
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What is the sub
threshold potential?
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What is the gain of positive energy within a neuron that changes plasma membrane potential from negative to positive?
depolarization
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When does depolarization occur?
when voltage
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What is the return of polarity from positive back to negative?
repolarization
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When does repolarization occur?
when voltage
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What is the change in membrane potential to become more negative than
70mV?
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Why does hyperpolarization occur?
Because K+ cannels stay open for a long time. Which makes the cell become more negative (
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What is an excitatory postsynaptic potential?
graded, postsynaptic potentials that result in the neuron become more positive
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Why does the inside of a neuron become more positive with EPSPs?
Na+ flows into the neuron faster than K+ flows out (depolarization)
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What is an inhibitory postsynaptic potential?
graded, postsynaptic potentials that result in the neuron becoming more negative
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Why does the inside of a neuron become more negative with IPSPs?
K+ flows out of the neuron or Cl
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What is summation?
when graded potentials (EPSPs and IPSPs) are "summed" or added together in the initial segment to determine if an action potential is initiated
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What type of summation occurs when multiple locations on cell's receptive regions receive neurotransmitter simultaneously and generate postsynaptic potentials?
spatial summation
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What type of summation occurs when a single presynaptic neuron repeatedly releases neurotransmitter and produces multiple EPSPs within a very short period of time?
temporal summation
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What is propagation?
the process of sending nerve signals
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What are the types of propagation?
continuous and saltatory
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What type of propagation occurs on unmyelinated axons?
continuous
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What type of propagation occurs on myelinated axons?
saltatory
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Continuous conduction "jumps" from down the axon on the nodes of Ranvier (neurofibril nodes). T/F?
false
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What type of propagation is fastest and most efficient?
saltatory
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The ______ law requires that a threshold value be reached in order to initiate an action potential. if sub
threshold value is reached, no potential occurs.
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The All
or
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What must be reached for an action potential to occur? This demonstrates the __________ law.
Threshold; All
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What is the time period called where no stimulus can initiate a second action potential?
Absolute refractory period
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Propagation is also called: ___________
Nerve impulse or nerve signal
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What is the time period called where stimulus must be of sufficient strength to reverse hyperpolarization early to initiate an action potential?
relative refractory period
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What factors influence the velocity of a nerve signal?
Diameter of the axon and myelination of the axon
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________ are chemical messengers that carry, boost, and balance signals between neurons.
neurotransmitters
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This neurotransmitter is excitatory for skeletal muscle and inhibitory for cardiac muscle, smooth muscle and glands. It's the most common.
ACh, acetylcholine
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What are the four groups of neurotransmitters?
ACh, biogenic amines, amino acids, neuropeptides
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What are the two groups of biogenic amines?
catecholamines and indolamines
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What make up the catecholamines?
dopamine (mood and cognition), norepinephrine, and epinephrine (adrenaline)
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What make up the indolamines?
histamine and serotonin
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What are the amino acid neurotransmitters?
glutamate and aspartate (cognitive function), serine, glycine, GABA
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Chains of amino acids (2 to 40 amino acids long) including endorphins, substance P
Neuropeptides
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_______ is when chemicals alter responses of local neurons
Neuromodulation
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What breaks down ACh?
acetylcholinesterase
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What does acetylcholinesterase break ACh into?
Choline and Acetate
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Cranial nerves extend from the ________ while spinal nerves extend from the ___________.
brain; spinal cord
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Sensory nerves contain only __________ neurons.
sensory
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Motor nerves contain only ________ neurons.
motor
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What type of nerves carry both sensory and motor neurons?
mixed
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______ neurons bring info from periphery to CNS.
sensory (afferent)
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_______ neurons takes commands from CNS to periphery.
motor (efferent)
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_______________ neurons integrates info and facilitates communication between sensory and motor neurons.
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