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161 Cards in this Set
- Front
- Back
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Electrical charge across the membrane of cells with the interior of the cell negative with respect to the exterior.
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Resting potential
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What is the average resting potential for excitable cells?
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-70 mV
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What are the excitable cells?
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Neurons and Muscle cells
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What is the action potential known as in a nerve cell?
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Nerve impulse
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During the upstroke of an action potential, the cell depolarizes, or becomes _____ _____.
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Less negative
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Depolarization is caused by an inward current which is by definition the movement of _____ charge into the cell.
What ion causes this to happen? |
Na+
Positive |
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During initial depolarization how high can the membrane potential reach?
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+55mV
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What type of external stimuli can reduce the charge across the plasma membrane?
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Mechanical stimuli
Certain neurotransmitters |
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What is an EPSP?
What causes it? |
Excitatory postsynaptic potential
Diffusion of sodium into the cell reducing resting potential at spot of the cell |
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What is the threshold voltage required to cause an action potential?
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-50mV
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What kind of a response is an action potential?
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All or none response
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What is the thin membrane which spirally enwraps the myelin layers of certain fibers especially those of peripheral nerves, or axons of certain unmyelinated nerve fibers?
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Neurilemma (Schwann's membrane)
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What nervous system has all of its neurons wrapped in a myelin sheath?
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PNS
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What do the schwann cells form on the neurons?
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Myelin sheath
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What kind of lesion of the spinal cord results in loss of motor activity on the same side and pain and temperature sensations on the opposite side?
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Right sided lesions
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When you administer local anesthetics to your patients, what effect does this have on the nerve membrane?
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Decreases the membrane's permeability to sodium ions and reduces the membrane excitability.
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Local anesthetics bind to the _____ _____ of fast voltage-gated sodium channels, stabilizing them in a closed position, effectively prolonging the _____ _____ period.
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Inactivation gates
Absolute refractory |
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What conductances remain unchanged when a local anesthetic has been applied?
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Potassium
Calcium Chloride |
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What are the sensory types that are affected by a local anesthetic in order of first to last?
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Pain - touch - proprioception - skeletal muscle tone
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What are the largest ascending tracts of the spinal cord?
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Fasciculi gracilis and Cuneatus
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Ascending tracts are _____.
Descending tracts are _____. How do you know which is which? |
Sensory
Motor Name: These tracts are named from where they start to where they end. |
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What refers to the location of cell bodies of neurons from which the axons of a tract arise?
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Origin
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What refers to the structure in which the axons of the tract terminate?
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Termination
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What tract functions in pain, temp, crude touch on the opposite side of the body?
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Lateral spinothalamic
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What are the location, origin and termination of the lateral spinothalamic tract?
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Location: lateral white columns
Origin: Posterior gray column - opposite side Termination: Thalamus |
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What are the location, origin and termination of the anterior spinothalamic tract?
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Location: anterior white columns
Origin: Posterior gray column - opposite side Termination: Thalamus |
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What are the location, origin and termination of the Fasciculi gracilis and cuneatus tract?
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Location: posterior white columns
Origin: Spinal ganglia same side Termination: medulla |
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What are the location, origin and termination of the Anterior and posterior spinocerebellar tract?
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Location: lateral white columns
Origin: Anterior or posterior gray columns Termination: Cerebellum |
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Spatial summation occurs when what happens?
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Two excitatory inputs arrive at a postsynaptic neuron simultaneously
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Neurotransmitter molecules may have excitatory or inhibitory effects depending upon their binding to different _____ of _____.
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Subtypes
Receptors |
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What occurs when two excitatory inputs arrive at a postsynaptic neuron in rapid succession.
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Temporal summation
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In temporal summation, there is an _____ in the frequency of nerve impulses in a _____ presynaptic fiber.
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Increase
Single |
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Where will an action potential spread if it is initiated at the midpoint of the axon?
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Spreads to the cell body and nerve ending.
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What type of nerves has its impulse travel along the entire length of an unmyelinated axon?
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Continuous conduction
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What is the distance between the nodes of ranvier on a myelinated neuron which allows for the jumping effect in saltatory conduction?
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0.2 and 2.0 mm
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Saltatory conduction is of value for two reaseons:
1. _____ velocity of nerve transmission in myelinated fibers. 2. _____ energy for axon because only the node _____. Thus it takes less energy for sodium/potassium ATPase to re-establish resting ion gradients |
Increases
Decreases, depolarizes |
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What does conduction velocity depend on in a nueron?
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Diameter of the nerve fiber: > diameter = > velocity
Presence of myelin sheath |
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What is the most abundant inhibitory neurotransmitter in the central nervous ssystem?
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GABA
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Inhibitory neurotransmitters encourage the _____ of the postsynaptic cell, making it less likely to generate an action potential.
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Hyperpolarization
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What determines whether a neurotransmitter will be excitatory or inhibitory?
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Reaction of the receptor it binds to so a neurotransmitter could have both effects on the same cell at different sites.
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What neurotransmitter involves voluntary movement of the skeletal muscles and movement of the viscera
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Acetylcholine
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What neurotransmitter is involved wakefulness or arousal - via the sympathetic pathways?
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Norepinephrine
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What neurotransmitter in large amounts are produced by the adrenal glands and are also known as adrenaline?
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Epinephrine
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What neurotransmitter involves involuntary movement and motivation, "wanting", pleasure, associated with addiction and love?
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Dopamine
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What neurotransmitter is involved with memory, emotion, wakefulness, sleep, and temperature regulation?
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Serotonin
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What are the most abundant neurotransmitters that are excitatory and found in the CNS?
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Glutamate
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What are the most abundant inhibitory neurotransmitters in the central nervous system?
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GABA
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What neurotransmitter is involved with spinal reflexes and motor behavior?
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Glycine
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What neurotransmitter is involved in the sleep/wake cycle and inflammatory response. This also has a modulating action on norepinephrine, serotonin, and acetylcholine?
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Histamine
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What is the enzyme that catalyzes the oxidative deamination of monoamines such as norepinephrine, serotonin, and epinephrine?
What does this process help in? |
Monoamine oxidase
Reducing excess neurotransmitters that build up at postsynaptic terminals |
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What are all of the basal ganglia?
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Caudate nucleus
Putamen Globus Pallidus |
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What structure is functionally important for controlling voluntary movements and establishing posture?
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Basal ganglia
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What is a classic sign of damage to the Basal ganglia?
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Involuntary movements
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What are the components of the corpus striatum?
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Caudate nucleus
Putamen Anterior limb of internal capsule |
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The shape of the putamen and globus pallidus resembles a _____, and they are collectively called the _____ _____.
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Lens
lenticular nucleus |
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What are the two large collections of nuclei that modify movement on a minute-to-minute basis?
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Basal ganglia
Cerebellum |
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The cerebral (motor) cortex sends information to both the basal ganglia and the cerebellum, and both structures send information back to the cortex via the _____.
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Thalamus
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The output of the cerebellum is _____, while the basal ganglia are _____.
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Excitatory
Inhibitory |
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What structure of the brain functions to maintain equilibrium and muscle coordination?
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Cerebellum
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What are the major parts of the the extrapyramidal system?
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Subcortical nuclei or Basal ganglia
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What are the two subclassifications of cholinergic receptors?
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Nicotinic and muscarinic receptors
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What receptors are membrane associated and located on autonomic postganglionic neurons or effector organs and are regulated by_____?
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Cholinergic receptors
acetylcholine |
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What are the characteristics of the nicotinic receptors?
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Stimulated by ACh and nicotine
Found at neuromuscular junction Found at all ganglionic synapses Blocked by hexamethonium |
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What are the characteristics of Muscarinic receptors?
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Stimulated by ACh and muscarine
Found at target organs after ACh release from postgang. neurons Selective stimulus (muscarine/bethanechol) Blocked by atropine |
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What types of neurons are cholinergic and thus uses ACh as a neurotransmitter?
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Preganglionic Autonomic neurons
Postganglionic parasympathetic neurons |
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What is the cholinergic effect of preganglionic autonomic neurons?
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Excitatory
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What are the cholinergic effects of postganglionic parasympathetic fibers?
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Excitatory or inhibitory
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Where is the voluntary pyramidal motor system located?
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Cortex
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This group of fibers carriers messages for voluntary motor movement to the lower motor neurons in the brain stem and spinal cord.
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The pyramidal tract
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Approximately _____ of the cell bodies of the pyramidal tract are located on the _____ _____ of the _____ _____, which is also known as the motor strip.
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80%
Precentral gyrus Frontal lobe |
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Approxiamtely _____ of the pyramidal tract fibers also originate in the _____ _____ of the _____ _____.
What area is this known as? |
20%
Postcentral gyrus parietal lobe Brodemann's area 1,2,3 |
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The pyramidal tract is _____ and _____, meaning that the axons of its neurons do not synapse with other cells until they reach their final destination in the brain stem or spinal cord.
Why is this set up this way? |
Direct
Monosynaptic Allows for faster transmission |
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What tract is formed when the pyramidal tract synapses with cranial nerves located in the brain stem?
What is this tract important for? |
Corticobulbar tract
Speech and swallowing |
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What tract is formed when the pyramidal tract synapses with spinal nerves sending information about voluntary movement to the skeletal muscles?
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Corticospinal tract
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What percentage of the corticospinal tract fibers decussate or cross to the other side of the brain at the inferior part of the medulla?
What are these tracts called after crossing? |
85-90%
Lateral corticospinal tract |
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What percentage of the corticospinal tract continues to descend ipsilaterally after it reaches the medulla?
What are these fibers called at this point? |
10-15%
Direct pyramidal tract or anterior corticospinal tract |
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Where are synapses of the ANS neurons made?
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Autonomic ganglia
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What ANS ganglia are located in the paravertebral chain or prevertebral ganglia?
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Sympathetic ganglia
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What ANS ganglia are located in or near the effector organs?
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Parasympathetic ganglia
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What are the two types of motor neurons?
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Preganglionic neurons
Postganglionic neurons |
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What type of motor neuron has its cell bodies in the CNS and synapse in the autonomic ganglia?
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Preganglionic neurons
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Where do preganglionic neurons of the sympathetic nervous system originate?
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Spinal cord segments T1-L2
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Where do the preganglionic neurons of the parasympathetic nervous system originate?
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Nuclei of cranial nerves in spinal cord segments S2-S4
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What type of motor neurons of both sympathetic and parasympathetic systems have their cell bodies in the autonomic ganglia and synapse on effector organs?
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Postganglionic neurons
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The majority of sympathetic postganglionic neurons are _____, which means they release _____ as the neurotransmitter.
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Noradrenergic
Norepinephrine |
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What causes the hyperpolarization that takes place a few milliseconds after the action potential is over?
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Potassium channels remain open for several milliseconds after repolarization of the membrane is complete
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The importance of hyperpolarization is that the cell remains in a "hypoexcitable state", or the _____ _____ _____.
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Relative refractory period
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During what period of a stimulus will the membrane not respond to any additional stimulus?
During what period of a stimulus will only a very strong stimulus elicit a response in the membrane? |
Absolute refractory period
Relative refractory period |
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Nerve impulses travel in only one direction because of the fact that synapses are _____.
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Polarized
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What is rare in the CNS but common in the cardiac and smooth muscle?
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Electrical synapses
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The CNS neurons are connected by _____ _____, which allow local electrical currents resulting from action potentials in the presynaptic neuron to _____ _____ to the postsynaptic neuron.
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Gap junctions
Pass directly |
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What blocks the effects of adrenaline on the body's beta receptors?
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Beta blockers
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Beta blockers _____ the nerve impulses that travel through the heart.
Beta blockers also block impulses that can cause _____. |
Slows
Arrhythmia |
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What are the two main beta receptors?
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Beta 1 and Beta 2
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Some beta blockers are _____.
What does this mean? |
Selective
They block beta 1 more than they block beta 2. |
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What beta receptors are responsible for heart rate and the strength of your heart beat?
What does it produce? |
Beta 1
Excitation |
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What kind of beta blockers block both beta 1 and beta 2 recpetors equally?
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Nonselective beta blockers
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What beta receptors are responsible for the function of your smooth muscles?
What does it produce? |
Beta 2
Relaxation (dilation) |
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_____ receptors are membrane receptors are membrane receptor proteins located on autonomic effector organs that are regulated by _____.
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Adrenergic
Catecholamines (epi. and norepi.) |
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What are the two types of adrenergic receptors?
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Alpha and Beta
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What receptors are located on smooth muscles and produce excitation (contraction or constriction)?
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Alpha1
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What receptors are located in presynaptic nerve terminals, platelets, fat cells, and the walls of the GI tract; produces inhibition (relaxation or dilation)?
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Alpha2
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_____ stimulates mainly alpha receptors.
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Norepinephrine
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_____ stimulates both alpha and beta receptors
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Epinephrine
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What results from an excess of positive ions on the outer surface of the plasma membrane? More _____ ions are on the outside of the membrane than _____ ions are on the inside of the membrane.
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Resting membrane potential
Na+ K+ |
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The resting membrane potential arises from what two activities?
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Resting potassium conductance
Sodium/Potassium pump |
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What type of cells lack a stable resting membrane potential?
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Visceral smooth muscle and cardiac pacemaker cells
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What are the afferent nerve ending in joints and tendons called?
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Proprioceptors
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Type of afferent nerve endings relaying information about body position and movement, the extent of stretch or force of muscle contraction.
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Proprioceptors
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What are the visceroreceptors that are associated with the viscera or organs and provide information about the internal environment?
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Interoreceptors
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What are the sensory nerve endings associated with the skin that provide information about the external environment?
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Exteroreceptors
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What is the decreased sensitivity to a continued stimulus?
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Adaptation
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What type of receptor responds to itch, movement, pain, and temperature?
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Free Nerve Endings
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What are some examples of free nerve endings?
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Nociceptors
Merkel discs Root hair plexuses |
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What type of receptors are sensitive to pressure or stretch, and are highly prone to adaptation from continued stimuli?
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Mechanoreceptors
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What are the mechanoreceptors?
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Pacinian corpuscles
Meissner's corpuscles Ruffini's end organs |
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What are nerve endings found in the hypodermis or deep in the dermis that sense deep cutaneous pressure, vibration, and proprioception?
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Pacinian corpuscles
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What are the nerve endings that are found in the dermal papillae and are associated with two-point discrimination?
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Meissner's corpuscles
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What are the nerve endings in the dermis of the skin that sense continuous touch or pressure?
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Ruffini's end organs
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What are the receptors that are free nerve endings sensitive to changes in temperature?
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Thermoreceptors
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What are receptors stimulated by various chemcals?
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Chemoreceptors
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What are the peripheral chemoreceptors?
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Carotid and aortic bodies
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What are the Central chemoreceptors?
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Medullary neurons
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What is the primary function of the peripheral and central chemoreceptors?
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Regulate respiratory activity?
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What are specialized receptors that are sensitive to light energy?
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Photoreceptors
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What are free nerve endings sensitive to painful stimuli. Generally, these have a higher activation threshold than other receptors?
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Nociceptors
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The actions of the ANS are largely _____.
How else does it differ from the somatic system? |
Involuntary
Uses 2 efferent neurons from CNS to effector |
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What are the two subdivisions of the PNS?
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Somatic nervous system
Autonomic nervous system |
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What consists of _____ pairs of cranial nerves and _____ pairs of spinal nerves and consists of both sensory and motor neurons?
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Somatic nervous system
12 31 |
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What does Somatic nervous system innervate?
What sensations does this include? |
Skeletal muscle
Touch, movement, temp, pain |
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What are the two subdivisions of the ANS?
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Sympathetic and parasympathetic nervous system
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What is the third division of the ANS that is a meshwork of nerve fibers which innervate the viscera?
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Enteric nervous system
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What is the neurotransmitter of the preganglionic sympathetic nervous system?
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Acetylcholine
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What is the neurotransmitter of the postganglionic sympathetic nervous system?
What does it bind too? |
Norepinephrine
alph/beta adrenergic receptors |
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What is the exception to binding sites of the postganglionic neurons?
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BV in muscle and Sweat glands use acetylcholine at muscarinic cholinergic receptors
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Where do sympathetic nerve fibers originate?
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Spinal cord between T1-L2
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What are the main nerves of the parasympathetic nervous system?
Where do they originate? |
Vagus nerves
Medulla oblongata |
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What is the neurotransmitter of both the pre and post ganglionic neurons of the parasympathetic nervous system?
What receptors do they bind too? |
Acetylcholine
Nicotinic cholinergic receptors |
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Nerves connect with muscles at the _____ _____. There, the ends of nerve fibers connect to special sites on the muscle's membrane called _____ _____ _____. These plates contain receptors that enable the muscle to respond to _____.
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Neuromuscular junction
Motor end plates Acetylcholine |
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_____ _____ catalyzes the formation of acetylcholine from _____ and _____ in the presynaptic terminal.
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Choline acetyltransferase
acetyl-CoA choline |
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What is the enzyme used to metabolize ACh after an motor action potential?
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Acetylcholineesterase
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What occurs if acetylcholinesterase is inhibited?
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Prolonged End-plate potential leading to tetanus
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When neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic cell is called _____ _____, and the time required is called the _____ _____.
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Synaptic transmission
Synaptic delay |
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What is the type of signal propagation between two neuron?
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Electrical - chemical - electrical
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Any stimulus strong enough to initiate a nerve impulse is referred to as a _____ _____.
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Threshold stimulus
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What principal states that if a stimulus is strong enough to generate a nerve action potential, the impulse is conducted along the entire neuron at maximum strength, unless conduction is altered by conditions such as toxic materials in cells or fatigue?
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All-or-none principal
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What is the single most important tract concerned with skilled voluntary activity?
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Corticospinal tract
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What spinal tract is involved in voluntary motor movement, contraction of individual or small groups of muscles, particularly those moving hands, fingers, feet, and toes of opposite side?
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Lateral corticospinal tract
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What spinal tract involves the same things as the lateral corticospinal tract but with muscles of the same side?
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Anterior corticospinal tract
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What spinal tract mainly has an influence on motor neurons to skeletal muscles?
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Lateral reticulospinal tract
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What spinal tract mainly has an inhibitory influence on motor neurons to the skeletal muscles?
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Medial reticulospinal
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What spinal tract involves coordination of body movement and posture?
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Rubrospinal tract
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What tract mediates the influences of the vestibular end organ and the cerebellum upon extensor muscle tone?
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Vestibulospinal tract
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_____ _____ is one important communicative behavior that is mediated by the extrapyramidal tract.
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Facial expression
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What are the extrapyramidal nuclei?
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Substantia Nigra
Basal Ganglia Thalamus Red nucleus Subthalamic nucleus |
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What extrapyramidal nuclei is especially affected by Parkinson's disease?
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Substantia nigra
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What are the extrapyramidal tracts?
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Rubrospinal tract
Reticulospinal tract Tectospinal tract Vestibulospinal tract |
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What tract originates in the red nucleus, and sends messages via the cerebellum to the spinal cord. This information is very important for somatic motor, or skeletal muscle control, and the regulation of muscle tone for posture?
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Rubrospinal tract
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What tract originates in the reticular nuclei of the pons and medulla to the spinal nerves and is involved in somatic motor control like rubrospinal tract and plays a major role in the control of autonomic functions?
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Reticulospinal tract
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What tract has points of origin throughout the brain stem, but especially in the midbrain area, and ends in the spinal nerves? This tract is involved in the control of neck muscles.
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Tectospinal tract
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What tract originates in the vestibular nuclei located in the lower pons and medulla to the spinal nerves? This tract is involved in balance.
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Vestibulospinal tract
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