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41 Cards in this Set
- Front
- Back
corpus callosum |
(area around the lateral ventricle) facilitates much of the communication between the 2 hemispheres; main function is to allow communication between the brain's left and right hemispheres |
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severed corpus callosum |
'split brain' when the corpus callosum connecting the 2 hemispheres is split to some degree |
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neuron |
an electrically excitable cell that processes and transmits information through electrical and chemical signals 100 billion in human brain; longest neuron is ~3 feet, info can travel through a neuron at top speed of ~250mph |
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parts of neuron |
input zone: cell body, dendrites conduction zone: axon output zone: axon terminals |
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types of glial cells (4) |
astrocyte, microglia, oligodendrocyte, Schwann cell |
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astrocyte (3) |
most common glial cells metabolic exchange between neurons and blood support BBB |
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microglia (3) |
type of glial cell immune defense / sense pathology clean up debris |
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oligodendrocyte (2) |
type of glial cell myelinate axons in CNS / supplies myelin sheath |
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Schwann cell (2) |
type of glial cell myelinate axons in PNS / supplies myelin sheath |
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multiple sclerosis |
demyelinating disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged this damage disrupts the ability of parts of the nervous system to communicate |
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what makes up gray matter and white matter? |
gray matter: cell bodies of neurons white matter: bundles of axons |
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How do signals travel through neurons? (5 steps) |
1. neuron at rest 2. input stimulates neuron 3. if large enough stimulus at axon hillock, an action potential is created 4. action potential propagates down axon 5. sends signal through synapse to other neurons |
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difference between electrical and chemical neuron signaling |
electrical: within neuron chemical: between neurons |
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potential resting potential |
difference or separation of charge neuron is prepared for action; resting potential is always negative (-40mV to -90mV0 |
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define: ion, cations, anions give examples of cations and anions |
ion: atom or molecule that has electrical charge cations: positively charged (Potassium K+, Sodium: Na+, Calcium, Ca2+) anions: negatively charged: (Chloride: Cl-, Protein: anion-) |
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membrane potential |
the difference in electric potential between the interior and the exterior of a biological cell |
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what generates membrane potentials? |
ion channels: passive, but open or closed based on voltage or chemical activity; when open, let specific ions in and out active/ion transporters (pumps): e.g., sodium potassium pump; they're active--require energy; bring ions in + take ions out |
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Are there many ions inside or outside of the cell for the following: Na+, K+, Cl-, Ca2+, anion proteins |
Na+: many outside K+: many inside Cl-: many outside Ca2+: many outside anion proteins: many inside |
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charge outside and inside of cell |
outside: + inside: - |
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what are the two forces acting on ions? describe them |
Diffusion: ions move from areas of high concentration to areas of low concentration electrostatic: like charges repel, opposites attract |
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What is the neuron membrane like when the neuron is at rest? |
Neuron shows selective permeability to potassium: K+ can enter and leave the cell freely Some channels are open all the time and allow only potassium ions to cross |
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Where does K+ want to go due to electrostatic forces and diffusion? |
electrostatic forces: inside diffusion: outside |
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Where does Na+ want to go due to electrostatic forces and diffusion |
electrostatic forces: inside diffusion: inside But neuron at rest is not nearly as permeable to sodium as it is to potassium, so only some sodium can pass through |
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What does the Na+/K+ pump (an active transporter) do? |
Pumps 3 Na+ out of cell and 2 K+ into the cell |
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What 4 factors does resting potential rely on? |
diffusion electrostatic forces selective permeability sodium-potassium pumps |
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receptor potential |
sensory neurons receive info from sensory receptors |
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post-synaptic potential |
neurons receive info from other neurons |
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What happens when Na+ comes into the cell? |
depolarization (reduction of membrane potential -- inside of cell becomes less negative) |
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depolarization |
reduction in membrane potential, making inside of cell less negative relative to outside, i.e., getting closer to 0 |
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Are action potentials graded? |
No, they are ALL or NONE, will propagate as is down an axon without decay depolarization across a threshold causes an action potential |
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action potential process (5) |
1. stimulus crosses threshold value 2. depolarization (Na+ enters) 3. repolarization (K+ leaves) 4. after-hyperpolarization (undershoot) 5. resting potential |
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in step 1 of action potential process, does it matter whether the stimulus is a little over threshold or a lot? |
No, as long as it is over threshold, it will generate the same action potential |
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what happens during step 2 of action potential process, "large depolarization"? |
voltage-gated Na+ channels open membrane potential passes 0, becomes more positive inside the neuron because of the huge influx of Na+ (Na+ enters, membrane potential becomes more positive) |
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what happens during step 3 of action potential process, "repolarization"? |
K+ channels open, K+ leaves the cell (because diffusion and electrostatic forces want it out of the cell) (K+ exits, membrane potential becomes more negative) |
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what happens during step 4 of action potential process, " after-hyperpolarization"? |
K+ channels take a little longer to close so more K+ rushes out bringing membrane potential briefly even more negative than resting potential (K+ keeps exiting a little too much, membrane potential briefly becomes even more negative than resting potential) |
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What happens to a sub-threshold stimulation as it propagates down an axon? What happens to a stimulation that produces an action potential as it propagates down the axon? |
when a sub-threshold stimulation propagates down an axon, the signal decays over time but otherwise, the signal remains as strong as it propagates down the axon because of channels and myelin |
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2 characteristics of action potential |
self-perpetuating: once it starts, it keeps going self-limiting: repolarizes, signal doesn't travel "backwards" |
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what part of the neuron receives the action potential signal? what part conducts? What part transmits? |
receives: dendrites, cell body conducts: axon transmits: synaptic terminals |
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Why doesn't the signal travel "backwards"? (2 reasons) |
absolute refractory period: second action potential cannot be initiated, no matter how large a stimulus is applied relative refractory period: initiation of second action potential is inhibited, though not impossible |
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How does myelination affect speed of propagation? |
myelin allows for faster conduction and greater energy efficiency |
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saltatory conduction |
saltare means jump or hop -- idea that the action potential gets boosted at these Nodes of Ranvier (areas without myelin that have ion channels) |