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The Neuron
A specialized cell that is directly involved in mental processes and behavior.
Most are present at birth
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The Neuron - Structure of the Neuron
Consists of dendrites, cell body (soma), and axon
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The Neuron - Structure of the Neuron - dendrites
receive information from other cells and conduct it toward the cell body
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The Neuron - Structure of the Neuron - Cell Body (Soma)
integrates information received from the dendrites and passes it on to the axon
contains several structures including the nucleus, mitochondria (power generator), ribosomes (creates new protein molecules), and Golgi complex (prepares neurotransmitters for secretion).
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The Neuron - Structure of the Neuron - Axon
Transmits information from the cell body to other cells.
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The Neuron - Communication Within and Between Neurons - Conduction
Messages within a neuron are transmitted from a neuron's dendrites to the end of its axon through this electrical process
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The Neuron - Communication Within and Between Neurons - Action Potential
An electrical impulse that travels quickly through the cell
Occurs after the dendrites of the cell receive sufficient information from other cells, sodium channels in the cell's membrane open, and positively charged sodium ions enter the cell to create depolarization
The cells resting state is negatively charged.
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The Neuron - Communication Within and Between Neurons - Action Potential - All-or-none Principle
Whenever the stimulation received by a neuron exceeds a given threshold, the resulting action potential will always be of the same intensity
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The Neuron - Communication Within and Between Neurons - Synaptic Transmission
The transmission of information from one nerve cell to another is usually chemically mediated and occurs when the action potential reaches the axon terminal with the release of a neurotransmitter into the synaptic cleft
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Neurotransmitters
Chemical substances that transmit signals from one neuron to another
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Neurotransmitters - Acetylcholine (ACh)
Found throughout the peripheral and central nervous systems and acts on two different types of receptors - muscarinic and nicotinic
In the peripheral nervous system it causes muscles to contract
In the central nervous system it is involved in REM sleep, the regulation of the sleep-wake cycle, and learning and memory.
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Neurotransmitters - Dopamine
Involved in a number if functions including personality, mood, memory, regulation of movements, and sleep.
Elevated levels have been linked to schizophrenia (dopamine hypothesis)
Linked to Tourette's and Parkinson's
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Neurotransmitters - Norepinephrine
Plays an important role in mood, attention, dreaming, learning, and certain autonomic functions.
the catecholamine hypothesis predicts that some forms of depression are due to lower than normal levels of norepinephrine
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Neurotransmitters - Serotonin (5-HT)
Usually exerts an inhibitory effect and has been implicated in mood, hunger, temperature regulation, sexual activity, arousal, sleep, aggression, and migraine headache.
Elevated levels contribute to schizophrenia, Autism, and food restriction associated with anorexia
Low levels play a role in aggression, depression, suicide, Bulimia, PTSD, and OCD
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Neurotransmitters - Gamma-Aminobutyric Acid (GABA)
an inhibitory neurotransmitter and play a role in eating, seizure, and anxiety disorders, motor control, vision, and sleep.
Low levels linked to anxiety disorders, and benzo's and other CNS depressants reduce anxiety bu enhancing the effects of GABA
Also been linked to Huntington's disease
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Neurotransmitters - Glutamate
Acts as an excitatory neurotransmitter and plays a role in learning and memory and, more specifically, in long-term potentiation (LTP), a brain mechanism that is believed to be responsible for the formation of long-term memories
Excessive amounts can lead to seizures and may contribute to stroke related brain damage., Huntington's disease, Alzheimer's disease, and other neurodegenerative disorders.
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Neurotransmitters - Endorphins
Inhibitory neuromodulators that lower the sensitivity of postsynaptic neurons and neurotransmitters.
May be responsible for the pain relief produced by acupuncture
Also implicated in certain pleasurable experiences (runner's high), emotions, memory and learning, and sexual behavior.
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Divisions of the Nervous System - Central Nervous System (CNS)
consists of the brain and spinal cord
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Divisions of the Nervous System - Central Nervous System (CNS) - Spinal Cord
Made up of bundles of myelinated axons as well as dendrites, cell bodies, and interneurons. It carries information between the brain and the peripheral nervous system, coordinates activities of the left and right sides of the body, and controls simple reflexes that do not involve the brain
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Divisions of the Nervous System - Central Nervous System (CNS) - Spinal Cord - quadriplegia
damage to the cervical portion of spinal cord
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Divisions of the Nervous System - Central Nervous System (CNS) - Spinal Cord - Paraplegia
Damage to the Thoracic portion of the spinal cord
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Divisions of the Nervous System - Central Nervous System (CNS) - Spinal Cord - hydrocephalus
Caused by an obstruction of the clow of cerebrospinal fluid that leads to a build-up of fluid and enlargement of the ventricles
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Divisions of the Nervous System - The Peripheral Nervous System (PNS)
Made up of nerves that relay messages between the central nervous system and the body's sensory organs, muscles, and glands.
Consists of 12 pairs of cranial nerves that connect directly to the brain and 31 sets of sensory and motor nerves that connect with the spinal cord
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Divisions of the Nervous System - The Peripheral Nervous System (PNS) - Somatic Nervous System (SNS)
Consists of sensory nerves that carry information from the body's sense receptors to the CNS and motor nerves that carry information from the CNS to the skeletal muscles
Governs activities that are ordinarily considered voluntary.
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Divisions of the Nervous System - The Peripheral Nervous System (PNS) - Autonomic Nervous System (ANS)
comprised of sensory nerves that convey signals from receptors in the viscera to the CNS and motor nerves that carry signals from the CNS to the smooth muscles, cardiac muscles, and glands.
Associated primarily with involuntary
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Divisions of the Nervous System - The Peripheral Nervous System (PNS) - Autonomic Nervous System (ANS) - Sympathetic Branch
associated with arousal and the expenditure of energy
In reaction to an external threat, causes dilation of the pupils, inhibition of peristalsis, dry mouth, sweating, and increased blood pressure and heart rate in order to ready the body for fight or flight.
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Divisions of the Nervous System - The Peripheral Nervous System (PNS) - Autonomic Nervous System (ANS) - Parasympathetic Branch
Involves in the conservation of energy and is active during digestion and periods of rest and relaxation
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Development of the Central Nervous System - Proliferation
New cells are produced inside the neural tube beginning when the embryo is about 2.5 weeks old
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Development of the Central Nervous System - Migration
Immature neurons migrate to their final destination in the brain beginning at about 8 weeks. Once they reach their destination, they begin to aggregate with other cells to form the structures of the brain.
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Development of the Central Nervous System - Differentiation
Neurons initially look very much lie other cells of the body but, following migration, develop axons and dendrites
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Development of the Central Nervous System - Myelination
The axons of some neurons myelinate, which occurs when glial cells form an insulating sheath around the cell's axon. Much myelination occurs postnatally
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Development of the Central Nervous System - Synaptogenesis
The time of synaptogenesis depends on the specific areas of the brain, but most occurs postnatally. Appears to be influences by both endogenous (genetic) and exogenous (experience) factors.
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Evaluation of Spinal Cord and Brain - Evaluation of Spinal Cord Injuries and Disease
XRAY - Bone issues
MRI - evaluation of soft tissues
EMG or SSEP - evaluate conduction of nerve signals
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Evaluation of Spinal Cord and Brain - Neuroimaging Techniques
CT and MRI - provide information on the physical structure of the brain
PET, SPECT, fMRI - provide information on brain activity
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Most neurons consist of three distinct components: the branch-like _________ receive information from other cells and conduct it toward the __________, which integrates information received from the dendrites and passes it on to the __________. Most neurons have a single axon that divides into numerous branches (collaterals), and many axons are covered by a myelin sheath that is made up of _________ cells.
dendrites
cell body
axon
glial
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Conduction of information with neurons is an ________ process. With sufficient stimulation, the interior of the neuron becomes less negative and triggers an __________, which operates on the _________ principle. Communication between neurons usually involves the release of a _______ by the presynaptic cell into the synaptic cleft
electrical
action potential
all or none
neurotransmitter
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In the peripheral nervous system, the neurotransmitter _________ is released into the neuromuscular junction where it causes muscles to contract; and, in the central nervous system, it's involved in the regulation of the sleep-wake cycle and learning and memory
ACh
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_________ plays a role in Schizophrenia and is involved in the regulation of movement and has been linked to several disorders with prominent motor symptoms including Tourette's Disorder and Parkinson's Disease.
dopamine
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Elevated levels of ________ contribute to Schizophrenia, Autism, and food restriction associated with Anorexia, while low levels play a role in aggression, depression, suicide, Bulimia, PTSD, and OCD
serotonin
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Benzodiazepines reduce anxiety by enhancing the effects of _________.
GABA
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The central nervous system (CNS) includes the brain and spinal cord. The consequences of damage to the spinal cord depend on its location and extent. For example, complete transection at the cervical level results in _________, while damage at the thoracic level causes __________.
quadriplegia
paraplegia
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The brain and spinal cord are protected by three meninges and the cerebrospinal fluid (CSF). Accumulation of CSF in the _________ as the result of obstruction can cause hydrocephalus.
cerebral ventricles
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There peripheral nervous system (PNS) is divided into the ________ nervous system, which carries information between the CNS and the body's sensory system and skeletal muscles, and the _________ nervous system, which regulates activities of the visceral muscles and glands
somatic
autonomic
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The autonomic nervous system has two subdivisions: The __________ branch prepares the body for fight or flight, while the __________ branch is associated with the conservation of energy and states of rest and relaxation.
sympathetic
parasympathetic
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The development of the CNS involves 5 stages. During the ________ stage, each cell moves to its ultimate destination in the nervous system
migration
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Computed tomography (CT) and magnetic resonance imaging (MRI) provide information on the _______ of the brain, while _______, SPECT, and fMRI provide information on the brain's _________ activities.
structure
PET
functional
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Memory loss associated with Alzheimer's dementia has been most consistently linked to abnormal levels of which of the following neurotransmitters?
A.Epinephrine
B.Norepinephrine
C.Serotonin
D.Acetylcholine
D
Acetylcholine (ACh) has been implicated in memory loss associated with Alzheimer's dementia. More specifically, degeneration of cholinergic (ACh) cells in the entorhinal cortex and other areas that communicate directly with the hippocampus has been linked to this disorder.
Answer A: Epinephrine is also called adrenaline. It is mainly produced by the adrenal glands and increases cardiac output and raises glucose levels in the blood.
Answer B: Norepinephrine plays an important role in mood, attention, dreaming, learning, and some autonomic functions. The catecholamine hypothesis predicts that some forms of depression are due to low norepinephrine.
Answer C: Serotonin is a neurotransmitter that exerts an inhibitory effect and is related to mood, hunger, temperature regulation, sexual activity, arousal, sleep, aggression, and migraines. Elevated levels of serotonin contribute to Schizophrenia and Autism Spectrum Disorder. Low levels of serotonin are associated with aggression, depression, suicide, PTSD, and OCD.
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Regional cerebral blood flow serves as an index of neural activity when using which of the following techniques?
A.EEG
B.PET
C.CT
D.MRI
B
Positron-emission tomography (PET) is a functional brain imaging technique that provides information on the functional activities of the brain (e.g. regional cerebral blood flow).
Answer A: An electroencephalogram (EEG) provides information about electrical activity in the brain.
Answer C: A CT scan is a structural imaging technique that uses x-rays to capture images within the body.
Answer D: Like a CT scan, an MRI is also a structural technique providing information on the physical structure (rather than the activity) of the brain. An MRI does this through radio waves, rather than through an x-ray, like a CT scan.
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Which of the following neurotransmitters plays a roll in the formation of long-term memories?
A.Endorphins
B.Serotonin
C.Acetylcholine
D.Glutamate
D
Glutamate acts as an excitatory neurotransmitter in many areas of the brain. It plays a role in learning and memory and, more specifically, in long-term potentiation (LTP), a brain mechanism that is believed to be responsible for the formation of long-term memories.
Answer A: Endorphins are inhibitory neuromodulators that lower the sensitivity of postsynaptic neurons to neurotransmitters. The endorphins have analgesic properties and may be responsible for the pain relief produced by acupuncture.
Answer B: Serotonin usually exerts an inhibitory effect and has been implicated in mood, hunger, temperature regulation, sexual activity, arousal, sleep, aggression, and migraine headache. Elevated levels of serotonin contribute to Schizophrenia, Autistic Disorder, and food restriction associated with Anorexia Nervosa, while low levels play a role in aggression, depression, suicide, Bulimia Nervosa, PTSD, and Obsessive-Compulsive Disorder.
Answer C: Acetylcholine (ACh) is found throughout the peripheral and central nervous systems and acts on two different types of receptors – muscarinic and nicotinic. In the peripheral nervous system, ACh is released into the neuromuscular junction where it causes muscles to contract. In the central nervous system, ACh is involved in REM sleep, the regulation of the sleep-wake cycle, and learning and memory.
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Hydrocephalus involves which of the following structures?
A.Cerebellum
B.Brain stem
C.Substantia nigra
D.Cerebral ventricles
D
Hydrocephalus ("water head") is caused by a build-up of cerebrospinal fluid in the cerebral ventricles in the brain.
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Spinal cord injury at the sacral level will cause:
A.Loss of control in the fingers
B.Loss of control in the arms and legs
C.Loss of functioning in the hips and legs
D.Poor trunk control
C
The 31 pairs of spinal nerves are divided into five groups or regions. These are, from top to bottom, cervical, thoracic, lumber, sacral, and coccygeal. Damage at the sacral level causes a loss of functioning in the hips and legs. Knowing that sacral nerves are near the spinal cord would have helped clarify this as the right response.
Answer A: Loss of control in the fingers and hands is caused by damage to a lower cervical nerve (C6 or C8) or by a combination of damage to a lower cervical nerve and T1 (the first thoracic nerve).
Answer B: Quadriplegia (loss of functioning in the arms and legs) results from damage at the cervical level.
Answer D: Loss of control of the trunk area is caused by damage at the thoracic level, especially T1-T8.
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The all-or-none principle applies to which of the following?
A.Neurotransmitter re-uptake
B.Action potential
C.Neurogenesis
D.Synaptogenesis
B
The neuron's action potential operates on an all-or-none principle. A neuron either fires completely or it does not fire at all. The all-or-none principle states that the magnitude of an action potential is independent of the intensity of the stimulation that produced it.
Answer A: The all-or-none principle is not relevant to the re-uptake of neurotransmitters.
Answer C: Neurogenesis refers to the creation of new neurons.
Answer D: Synaptogenesis is the term for the formation of synapses in the brain.
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After a particularly stressful day at work, Dan does some yoga, eats a healthy meal, and laughs while playing a game with his family. Which aspect of the nervous system is at work in his body during this time?
A.Parasympathetic
B.Autonomic
C.Sympathetic
D.Central
A
The parasympathetic system is a subdivision of the autonomic nervous system. It is involved in conservation of energy and is active during times of rest and relaxation.
Answer B: This answer may have been appealing because the parasympathetic nervous system (Answer A) is part of the autonomic nervous system (ANS). But Answer A is a better answer because the description clearly fits with only the parasympathetic system while the ANS includes both the parasympathetic and sympathetic nervous systems.
Answer C: The sympathetic nervous system is the opposite of what is described in this question. It is associated with arousal and expenditure of energy (e.g. sweating, increased heart rate, increased blood pressure, and preparing the body for "flight or fight").
Answer D: The central nervous system consists of the brain and the spinal cord.
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Which part of the body carries information to and from sense receptors, motor nerves, and skeletal muscles?
A.Central nervous system
B.Autonomic nervous system
C.Somatic nervous system
D.Peripheral nervous system
C
The somatic nervous system (SNS) is a division of the peripheral nervous system. The SNS governs activities that are considered voluntary. It consists of sensory nerves that carry information from the body's sense receptors to the central nervous system (CNS) and motor nerves that carry information from the CNS to the skeletal muscles.
Answer A: The central nervous system (CNS) consists of the brain and the spinal cord.
Answer B: The autonomic nervous system (ANS) is made up of sensory nerves that carry signals from the CNS to cardiac muscles and glands in the body.
Answer D: The peripheral nervous system (PNS) is made up of the nerves that relay messages between the CNS and the body's sensory organs, muscles, and glands. The PNS is divided into the somatic and autonomic nervous systems. Although the somatic nervous system is part of the PNS, Answer C is more specific and thus, the more appropriate answer to this question.
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