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List 3 functions of the nervous system
- Sensory input-gathers information
- Integration-brain interpretation
- Motor output-activation of muscles affected by stimulus
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List the divisions of the nervous system
- Central nervous system: brain and spinal cord
- Peripheral nervous system: nerves (facial)
- -sensory, afferent division: towards the CNS
- -motor, efferent division: muscles and glands
- --somatic nervous system:voluntary
- --autonomic nervous system: involuntary
- ---sympathetic division: activity
- ---parasympathetic division: rest
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What are the two cell types of nervous tissue
neuroglia and neurons
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Neuroglia
- astrocytes- CNS, most abundant, support
- microglia- CNS, immune response
- oligodendrocytes- CNS, myelin sheath
- ependymal- CNS, cerebrospinal fluid
- satellite- PNS, surrounds neuronal cell bodies
- schwann-PNS, forms myelin sheath
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Collection of nerve cell bodies in CNS
nuclei
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Collection of nerve cell bodies in PNS
ganglia
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Bundles of nerve processes in CNS
tracts
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Bundles of nerve processes in PNS
nerves
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Glial cells utilize myelin sheathing in PNS
schwann
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Glial cells utilize myelin sheathing in CNS
oligodendrocytes
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Myelin Sheath does what?
increases in speed of signals
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Unique type of conduction that myelin sheathing does
Saltatory conduction, increase 30 times faster
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Nodes of ____ are present in both CNS and PNS
Ranvier
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Oligodendrocytes have rodes of ranvier. True or false
True
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White matter
myelinated fibers
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Gray matter
cell bodies and unmyelinated fibers
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3 structural classifications of neurons
- multipolar- most abundant in CNS
- bipolar - rare, found in special sensory organs
- unipolar - found mainly in PNS
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4 types of ion channels
- leakage or nongated - diffusion
- chemically gated or ligand gated- passive
- voltage gated channels - action potential,passive
- mechanically gated channels
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Which ion channels open in response to action potential
voltage gated channels
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Graded potential
short lived, depolarization and hyperpolarization
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Action potential
brief reversal of membrane potential
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Depolarization
sodium rushes in and decreases the membrane potential making it less negative
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Repolarization
potassium flows into the cell
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Hyperpolarization
excess potassium has left the cell and makes the membrane potential more negative
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Refractory period
recovering or resting period
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Absolute refractory period
no matter how strong the stimulus there will be no response
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Relative refractory period
requires a very strong stimulus
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What determines the nerve impulse conduction velocity?
axon diameter and degree of myelination (large axon faster, myelinated is faster)
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Steps of a synapse
- 1. action potential arrives at terminal
- 2. voltage calcium gates open and calcium enters
- 3. calcium entry causes synaptic vesicles to release neurotransmitters by exocytosis
- 4. neurotransmitter diffuses across synaptic and bonds to receptors on post synaptic membrane
- 5. binding of neurotransmitter opens ion channels
- 6. neurotransmitter effects are terminated by reuptake through transport proteins, enzymatic degradation or diffusion away from the synapse
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Post synaptic potential
graded potential, short distance
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two types of postsynaptic potentials
excitatory (EPSP) and inhibitory (IPSP)
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Which type of postsynaptic potential is associated with depolarization
EPSP (electrical)
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Which type of postsynaptic potential is associated with hyperpolarization
IPSP (inhibition)
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Temporal summation
2 exctatory stimuli close in time (in same spot) causes EPSPs that add together
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Spatial summation
2 simultaneous stimuli at different locations causes EPSPs to add together
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Which type of summation has a cumulative effect?
Temporal summation
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Which type of summation can have cancelling effects?
Spatial summation
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Threshold stimulus
point which has to be overcome to provide a stimulus
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how are neurotransmitters classified
chemically based on molecular structures
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Whether a neurotransmitter is excitatory or inhibitory depends on?
the specific receptor types with which they interact
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Types of circuits in neuronal pools
- diverging: one input into many outputs
- converging: many inputs into one output
- reverberating:travels through a chain
- parallel after-discharge: stimulates neurons arraged in parallel array
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Reflex
rapid automatic response to a stimulus
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What are the 5 components of reflex arc?
receptor, sensory neuron, CNS integration center (usually brain but sometimes spinal cord), motor neuron,and effector
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What do nerve cell adhesion molecules (N-CAMs) allow for?
development of neural connections
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CNS consists of:
brain and spinal cord
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PNS consists of:
sensory receptors, nerves, efferent motor endings
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In embryonic development, the neural plate forms from?
surface ectoderm
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Mesencephalon is more commonly called:
midbrain
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Diencephalon contains what 3 structures:
thalamus, hypothalamus, and epithalamus
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Four adult brain regions are:
cerebral hemispheres, diencephalon, brain stem (midbrain, pons, and medulla oblongata), and cerebellum
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Spinal cord is composed of:
Central Cavity, Inner Gray matter, Outer White Matter
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Outer white matter is composed of?
myelinated fiber tracts
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Fourth ventricle
descends into spinal cord
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Third ventricle
middle of the brain
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What fluid circulates in ventricles of the brain?
cerebrospinal fluid
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Ridges of the brain are called?
gyrus
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Shallow grooves of brain
Sulcus
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Deep grooves in brain
fissure
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5 lobes of the brain
parietal, frontal, occipital, temporal, insula
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Functional areas of brain
Motor area, Sensory area, and Association area
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Subdivisions of motor area
- primary motor cortex: conscious control, voluntary movement
- premotor cortex: planning of movement, repetitious learning skills
- broca's area: speech, left area of brain
- frontal eye field: voluntary eye movements
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Subdivisions of sensory area
- primary somatosensory cortex:recieves sensry information from sensory receptors (skin, muscles)
- somatosensory association cortex: integrates sensory input
- visual area: visual
- auditory area: hearing
- olfactory cortex: smell
- gustatory cortex: taste
- visceral sensory area: conscious perceptions of visceral sensations (ex. full bladder)
- vestibular cortex:conscious awareness of balance
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Subdivisions of association area
- anterior association area:working memory, reasoning, consciousness, complex learning abilities, intellect
- posterior association area: patterns, faces, understanding language
- limbic association: emotions, memories, senses danger
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Division of ______ between hemispheres
labor
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Most people are ______ hemisphere dominant
left
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Right hemisphere is responsible for:
insight, visual skills, intuition, musicale, artistic
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Left hemisphere is responsible for:
language, math, logic
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two hemispheres communicate via what structures:
commissural fibers (connect gray matter), association fibers, and projection fibers
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functions of basal nuclei
influence muscle control, help regulate attention and cognition, regulate intensity of slow movements, inhibit antagonistic or unnecessary movements
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3 structures of diencephalon
thalamus, hypothalamus, and epithalamus
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Function of Thalamus
sends messages to cerebral cortex, relays and sorts information
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Function of Hypothalamus
homeostasis, center for emotional response
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Function of Epithalamus
regulates sleep wake cycles
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3 structures of brain stem
midbrain, pons, and medulla oblogata
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Function of midbrain
visual, reflex, and auditory relay centers
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Function of pons
relays information between motor cortex and cerebellum
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Function of medulla oblogata
regulates cardiovascular and respiratory center, and autonomic reflex center
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What is the function of the cerebellum?
voluntary muscle contraction and consciously provides timely patterns of skeletal movement
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2 functional brain systems
limbic system and reticular formation
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Consciousness is defined by a response to?
stimuli
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Limbic system
emotional or affective
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Reticular system
consciousness, sends impulses to cerebral cortex, motor function
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4 subdivisions of the continuum of consciousness
- 1.alterness
- 2.drowsiness or lethargy
- 3.stupor
- 4.coma
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Is consciousness within the limbic or reticular functional system?
reticular
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Language occurs in what overlapping domains?
Broca's and Wernicke's
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What is STM?
short term memory, also called working memory
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What is LTM?
long term memory
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What factors affect the transfer from STM to LTM?
emotional state, rehearsal, association, and automatic memory
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2 categories of memory
declarative memory and nondeclarative memory
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Declarative memory
explicit information, factual knowledge -> names, faces, words
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Nondeclarative memory
acquired, hard to unlearn -> riding a bike, playing piano, driving a car
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Meninges
protective layers for the brain
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3 layers of meninges
dura mater, arachnoid mater, and pia mater
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What do spinocerebellar tracts do?
send information from the spine to the cerebellum
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Ascending pathway (afferent)
sending impulses towards and upward
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Descending pathway
motor neurons, send impulses from and away the spinal cord
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Descending pathways involve what 2 neurons
upper motor neurons and lower motor neurons
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Direct (pyramidal) system
originate with pyramid neurons in precentral gyri
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Flaccid paralysis
severe damage to the ventral root
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Spastic paralysis
damage to upper motor neurons
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