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What is a neuron?
neuron-- functional unit of the NS responsible for receiving and transmitting electrochemical information
the basic building block of the NS
each one sends and receives signals
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Three major parts of the neuron
dendrites: branches that stem out from cell body and receive messages
axon: signal is sent down here to next neuron
cell body: has a semi-permeable membrane, nucleus, and mitochondria
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Additional parts of a neuron
myelin sheath: fatty substance that allows rapid transmission of messages
axon terminal branches: smaller branches coming off of the axon
Axon terminal buds: cap the branches
vesicles: inside the buttons and have NT that can be released
Neurotransmitter: cross the synapse, land on receptor sites of dendrites of next neuron
receptor sites
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How do neurons communicate?
- electrical and chemical language
- neurons transmit info--electrical messages received by the dendrites and cell body
- messages are passed along the axon in the form of a neuron impulse or action potential
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What is polarized?
outside of the membrane is positive and inside is negative
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Electrochemical potential:
sucks the positive ions in, depolarizing the membrane
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channels
special gates that the positive ions go into
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Depolarization
making the inside more positive
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All or none response
action potential either happens or doesnt
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refractory period
after AP, neuron rests before next AP
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Briefly explain neurotransmitter action at the synapse.
action potential reaches end of axon--> branches--> enters buds and pushes vesicles downward, causing release of NT into the synapse
At the membrane of the postsynaptic cell, NTs attach to proteins called receptors in a key into lock type of format--> post-synaptic potential
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Neurotransmitters
1) regulate __
2) Promote __
3) Affect __
- 1) actions of muscles and glands
- 2) sleep or stimulate mental/physical alertness
- 3) affect learning, memory, motivation, emotions, and psychological disorders
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serotonin
- mood (big part in disorder= depression)
- low levels lead to depression
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acetylcholine:
responsible for allowing memories to be processed
- low levels: Alzheimers
- also for muscle contraction
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Dopamine
pleasure enter [addiction caused by dopamine] (reward system)
schizo and parkinson's
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GABA
- number one inhibitory NT (relaxed)
- you have anxiety if you lack it
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endorphins
natural pain killers
coping mechanisms
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Explain division of the NS
CNS: brain and spinal cord; critical for ability to live; limited in plasticity; not a great ability to repair selves; reflexes
PNS: somatinc and autonomic; all neurons connecting the CNS to rest of body; carries messages from sensory--> CNS--> motor
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First division of PNS
somatic: takes in info from senses and sends to brain to let it be processed and perform action
divided into sensory (afferent) and motor (efferent)
- sensory takes in info
- motor allows action to be performed
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Second division of PNS
controls involuntary functions
Subdivided into sympathetic (fight or flight) and parasympathetic (rest and digest)
fight or flight: body is sped up: increased HR, breathing, blood flow
parasympathetic calms: when one up, one down
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Hindbrain
medulla: breathing; HR; automatic (damage leads to no breathing or HR)
cerebellum: finely coordinated movement and balance; smooth precise movements (alcohol affects this)
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Forebrain
largest
thalamus: sensory relay system; receives all sensory info except smell
hypothalamus: hunger, thirst, sex, aggression
limbic system: hippocampus--> short term memory/ amygdala: emotional memory and memory of others and self
cerebral cortex (next page)
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Cerebral cortex
- division?
- lobes
- functioning?
- structure?
two hemispheres
four types lobes (two of each): temporal, parietal, frontal, occipital
structure: wrinkled convolutions; biggest portion
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frontal
high complex functioning and thinking
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Parietal
- skin/ tactile senses
- pain, pressure, temp, and touch location
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laterilization
specialization of the left and right hemishperes of the brain for particular operations
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Left hemisphere vs Right
left: logical, analytical
right: emotion, risk-taking, creativity, etc.
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Genetic abnormalities
down syndrome
schizophrenia
alzheimer's Disease
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What are the steps of action potential?
1) inside cell body are positive and negative ions with positive being pumped out, leaving inside slightly negative (polarized/ resting state)
2) A force (electrochemical potential) pulls the positive ions back inside through special channels called gates
3) Depolarized once positive is back inside
4) Actional potential fires an all-or-none response (either fires or not)
5) refractory period (taking a rest)
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