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chapter 2 - Clemson University
neurons
41 Cards
Created on 2/8/10
motor neurons
carries commands to the muscles and organs. recieves info from other neurons, carries info to mucles or gland cells for output
multipolar throughout nervous system.
dendrites
extensions that branch out from the cell body to recieve info from other neurons. their structure allows them to collect info from many neurons.
axon
extends like a tail from the cell body and carries info to other locations.
myelin sheath
wraps around the axon to support and provide other benefit.
end bulbs or terminals
branches at the end of axons that culminate in swelling. contain neurotransmitters, which the neuron releases to communicate with muscle or organ or the next neuron in a chain.
sensory neurons
carry info from the body and from the outside world into the brain and spinal cord. can be unipolar ( outside brain) or bipolar (outside brain and spinal cord)
recieves a particular type of sensory info
"imput"
multipolar neuron
a motor neurons axon and dendrites extending in several different directions from the cell body.
interneurons
conducts info bt neurons in the same area
multipolar, brain and spinal cord.
glial cells
cells that provide structure and function
-oligodendrocytes build myelin around axons an brain and spinal cord
- schwann cells build myelin around axons in the periphery (fatty coating)
neurons
specialized cells that recieves info and sends it to other cells
- functional units
- carry info w/i the brain and throughout the brain
interneurons
connect 1 neuron to another in a particular part of the CNS
neural membrane
critical for the neurons ability to carry information
phospholipd molecules
fatty derivates
- heads are attracted to water - orient towards it
- tails are repelled by water- orient away from it
polarizations
difference in electrical charge (voltage) bt the inside and outside of the cell
resting potential
diff in electrical charge bt the inside and outside of the membrane of a neuron at rest
- serves vital and very adaptive function
what causes resting potential
unequal distribution of ions on the 2 sides of the membrane
- atoms or molecules that are + or - charged (ie lost or aquired electrons)
absolute refractory period
NA+ channels cannot reopen- cannot produce another action potentials
relative refractory preiod
only stimuli stronger than usual can produce action potential-- intensity of the stimulus is encoded by the rate of action potentials (rate law)
spontaneous activity
firing of a neuron at rest- firing of a neuron in absence of environmental stimulous
more action potentials if stimulus is stronger- rate law
action potentials
only happens at the axons ( not the dendrites or soma)
- its strenth is independent of of the intensity of the stimulus (all- or- none law)
- it does not decay as it travels down an axon ( non decremental)
graded potential
like a current going through a wire- directly relates to the stimuli that trigger them- travel very fast but short lived bc it decays
presynaptic neuron
sends info
postsynaptic neuron
recieves info
terminal button
presynaptic terminal
- the connections dont touch - synaptic cleft and presynaptic terminal
excitatory postsynaptic potential
partial depolarization (hypopolarization) of the postsynaptic membrane
- makes an action potential more likely to occure in the post- synaptic neuron- higher rate of firing
inhibitory postsynaptic potential
hyperpolarization of the postsynaptic membrane
- makes an action potential less likely to occure
temporal summation
combines psps arriving a short time apart
spatial summation
ions
atoms that are charged bc they have gained one or more electrons.
sodium and potassium ions
are positively charged
concentration gradient
ions move through the membrane to the side where they are less concentrated. result is electrical gradient
electrical gradient
ions are attracted to the side that is oppositely charged.
sodium- potassium pump
return the few ions that do make it through the membrane. consist of large protein molecules that move sodium ions through the cell membrane to the outside and potassium ions back inside.
action potential
effective for only short distances bc it dies out.
an excitory siginal causes a partial depolarization.polarity shifted toward zero. this disturbes the balance in the adjacent membrane. if it exceeds the threshold for activating that neuron, 10 mV more pos than resting potential then it will open the normally closed sodium channels.
action potential
abrupt depolarization of the membrane that allows the neuron to communicate over long distances.
graded potential
means that it varies in magnituide with the strength of the stimulus that produce it.
all-or-none law
means that it occurs at full strenght or it doesnt occure at all.
glutamate
excitory neurotransmitter in the brain and spinal cord. vitally involved in learning, and implicated in schizophrenia
GABA
INHABITORY nt. its receptorsrespond to alcohol and the class of tranquilizers called benzodiazepines. deficiency is one cause of epilepsy.
glycine
inhibitory transmitter in spinal cord and lower brain.
serotonin
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ED F REL BIOSC PSYCH CTE GEOL 324 663 880 456 315L 406