Term
| What does the CNS consist of? |
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Definition
| The brain and spinal cord |
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Term
| Define sensory information |
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Definition
| Information about the state of the external environment |
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Term
| Define visceral information |
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Definition
| Information about the state of the internal environment (blood pH, fullness of stomach, blood pressure, etc) |
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Term
| What is the difference between the afferent and efferent divisions of the PNS? |
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Definition
| Afferent transmits information to the CNS, efferent transmits information from the CNS to effector organs |
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Term
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Definition
| A cell capable of producing an action potential |
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Term
| What percentage of cells in the nervous system are glial cells? |
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Definition
|
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Term
| What normal cell function can a neuron not perform? |
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Definition
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Term
| Where is an action potential generally started? |
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Definition
|
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Term
| Where are leak channels found on a neuron? |
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Definition
|
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Term
| Where are ligand-gated channels most densely located on a neuron? |
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Definition
|
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Term
| Where are voltage gated channels found the most densely in a neuron? |
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Definition
| In the axon, especially the axon hillock |
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Term
|
Definition
| Supporting cells of the nervous system |
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Term
| Where do oligodendrocytes form myelin? |
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Definition
| Around multiple axons in the CNS |
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Term
| Where do Schwann cells form myelin? |
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Definition
| Around a single axon in the PNS |
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Term
| What is the term for gaps in myelin? |
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Definition
|
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Term
| What is the resting membrane potential for a cell? |
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Definition
|
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Term
| What is the equilibrium potential (E) for potassium? |
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Definition
|
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Term
| What is the equilibrium potential (E) for sodium? |
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Definition
|
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Term
| Why is a cell's resting Vm closer to that of potassium's E? |
|
Definition
| A cell is 50 times more permeable to K+ than Na+ because of leak channels |
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Term
| Is a neuron in equilibrium? |
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Definition
| No, it is in a steady state, because energy is required to keep it there |
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Term
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Definition
| The value of membrane potential that must be met or exceeded if an action potential will be generated |
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Term
| Define electrotonic conduction |
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Definition
| Spread of voltage by passive charge movement, as in a graded potential |
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Term
| How positive can a cell get during depolarization? |
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Definition
|
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Term
| What channel types are involved in a graded potential? |
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Definition
| Ligand-gated or mechanically gated |
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Term
| What channel types are involved in an ation potential? |
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Definition
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|
Term
| How long does an action potential last? |
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Definition
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Term
| How long can after-hypolarization in a cell last? |
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Definition
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Term
| What is the form of a voltage-gated sodium channel when it is capable of being opened? |
|
Definition
| Activation gate closed, inactivation gate open |
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Term
| What is the form of a voltage-gated sodium channel when it is incapable of being opened? |
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Definition
| Activation gate open (or briefly closed), inactivation gate closed |
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Term
| What type of mechanism is the opening of sodium activation gates? |
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Definition
| Regenerative because depolarization regenerates the trigger (depolarization) for other sodium activation gates |
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Term
| What type of feedback is the opening of sodium activation gates? |
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Definition
|
|
Term
| What phases does the absolute refractory period span? |
|
Definition
| Depolarization and most of repolarization (1-2msec) |
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Term
| When are potassium channels stimulated to open? |
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Definition
| Threshold, they're just slow |
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Term
| At rest phase: describe the positions of the sodium activation gate, the sodium inactivation gate, and the potassium channel, respectively |
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Definition
|
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Term
| At depolarization phase: describe the positions of the sodium activation gate, the sodium inactivation gate, and the potassium channel, respectively |
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Definition
|
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Term
| At repolarization phase: describe the positions of the sodium activation gate, the sodium inactivation gate, and the potassium channel, respectively |
|
Definition
|
|
Term
| At hyperpolarization phase: describe the positions of the sodium activation gate, the sodium inactivation gate, and the potassium channel, respectively |
|
Definition
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Term
| How does the diameter of an axon change the current in an axon? |
|
Definition
| The larger, the faster the current |
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Term
| What is the name for conduction in a myelinated axon? |
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Definition
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Term
| What are the terms for the first neuron and the second neuron which recieves the signal? |
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Definition
| Presynaptic neuron; postsynaptic neuron |
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Term
| What is the space between the presynaptic and postsynaptic neuron called? |
|
Definition
|
|
Term
| Is signaling across a synaptic cleft bidirectional? |
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Definition
|
|
Term
| What stores neurotransmitters in the presynaptic neuron? |
|
Definition
|
|
Term
| What triggers release of a synaptic vesicle? |
|
Definition
| Opening of a calcium channel after a depolarization |
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Term
| What type of receptors do neurotransmitters bind to? |
|
Definition
| Fast ligand gated ion channels or slow G-protein linked receptors |
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Term
| What are three ways to get rid of neurotransmitters in the synapse? |
|
Definition
| Degragation by enzymes, reuptake, or diffusion away from the synaptic cleft |
|
|
Term
| What causes synaptic delay? |
|
Definition
| Mostly the time it takes for calcium to trigger exocytosis of the neurotransmitter |
|
|
Term
| Are neurotransmitter effects always excitatory? |
|
Definition
| No, they can be inhibitory (hyperpolarizing) as well |
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|
Term
| What is the term for an excitatory response due to a neurotransmitter? |
|
Definition
| An excitatory post synaptic potential (EPSP) |
|
|
Term
| Are EPSPs and IPSPs graded? |
|
Definition
| Yes, they are strongest at the site of origin (usually a dendrite or cell body) |
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Term
| What two results can an inhibitory synapse cause in the posynaptic cell? |
|
Definition
| It can hyperpolarize it or stabalize the neuron at resting value |
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|
Term
| What is a "divergence" arrangement? |
|
Definition
| The axon of one neuron has several collaterals that bind to several other neurons |
|
|
Term
| What is a "convergence" arrangement? |
|
Definition
| A neuron recieves communication from 100s-1000s of ther neurons |
|
|
Term
| Define neural integration |
|
Definition
| The summation proccess from the 100s-1000s of signals arriving from all active synapses |
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Term
| Why will the membrane potential of a cell never reach -94mV, even if it is receiving a lot of IPSPs? |
|
Definition
| Even if all K+ channels are open, sodium will leak into the cell to counteract the movement of K+ |
|
|
Term
| What effect does increasing the amount of calcium in the cytosol of an axon terminal? |
|
Definition
| It increases the amount of neurotransmitter released |
|
|
Term
| What is the most abundant neurotransmitter in the PNS? |
|
Definition
|
|
Term
| From what is acetylcholine synthesized? |
|
Definition
|
|
Term
| What enzyme catalyzes the synthesis of acetylcholine? |
|
Definition
| Choline acetyl transferase |
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|
Term
| Why is acetylcholine found in almost all cells of the body? |
|
Definition
| It is a 2-carbon molecule produced during energy catabolism and is the initial substrate for the Kreb cycle |
|
|
Term
| What enzyme degrades acetylcholine? |
|
Definition
|
|
Term
| What does acetylcholine break down into and what happens to those compounds? |
|
Definition
| Acetate (diffuses away into other cells for metabolic pathways)and choline (undergoes reuptake) |
|
|
Term
| Define anterograde axonal transport |
|
Definition
| Transport of material from cell body to nerve terminal |
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|
Term
| Define retrograde axonal transport |
|
Definition
| Transport of material from nerve terminal to cell body |
|
|
Term
| What are the four types of glia cells? |
|
Definition
| Oligodendrocytes, schwann cells, astroglia, and microglia |
|
|
Term
| What are the functions of astroglia? |
|
Definition
Remove waste products, stabilize concentrations of ECF around the CNS,
act as blood-brain barriers |
|
|
Term
| What is the function of microglia? |
|
Definition
| To be macrophage-like immune cells of the nervous system |
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|
Term
| What is threshold potential? |
|
Definition
| -55mV, when an action potential starts and sodium channels open |
|
|
Term
| What type of neurons are the fastest? |
|
Definition
|
|
Term
| What type of neurons are the slowest? |
|
Definition
|
|
Term
| What are the three groups of neurons we learned, in terms of speed? |
|
Definition
| Motor, skeletal muscle, cardiac |
|
|
Term
| Define absolute refractory period |
|
Definition
The time it takes the sodium channels
to go from the inactive state to the resting state |
|
|
Term
| Define the relative refractory period |
|
Definition
| When sodium channels are capable of being open but K+ channels are still open so it would take a higher level of stimulus |
|
|
Term
| What is the limit to the frequency of action potentials? |
|
Definition
|
|
Term
| How do action potentials travel down an axon? |
|
Definition
| The sodium channels downstream are triggered to open by the depolarization preceding them |
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|
Term
| How does the direction of propagation differ for muscles as opposed to nerves? |
|
Definition
| Action potentials propagate from the middle to the ends of the muscle fiber |
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|
Term
| Describe what causes Multiple sclerosis |
|
Definition
| Myelin is lost. Na and K channels are only located at the nodes so action potentials can no longer propagate down the axon. |
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|
Term
| Can nerves recover from damage? |
|
Definition
| Only in the periphery (Schwann cells will proliferate, form tube-like structures and secrete trophic factors), axons cannot repair in the CNS |
|
|
Term
| Why can't oligodendrocytes repair themselves? |
|
Definition
| Factors released from the oligodendrocytes inhibit axonal growth |
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|
Term
| Where are pacemaker potentials found? |
|
Definition
| In cardiac atrial and GI smooth muscle, and for respiration oscillation in medulla |
|
|
Term
| Define temporal summation |
|
Definition
| Multiple graded potentials adding together from a high frequency of action potentials from the same dendrite |
|
|
Term
|
Definition
| Multiple dendrities firing simultaneously to produce a larger graded potential |
|
|
Term
| Define generator potential |
|
Definition
Potentials produced by sensory nerve terminals to sensory neurons.
Stimuli can be physical (heat, touch, pressure, stretch), chemical or injury |
|
|
Term
| Define receptor potentials |
|
Definition
Graded potentials produced by special senses which generate action potentials.
Stimuli: sound, light, taste, smell |
|
|
Term
| Do graded potentials have thresholds or refractory periods? |
|
Definition
|
|
Term
|
Definition
| Neurons in the brain and spinal cord that innervate skeletal muscle fibers |
|
|
Term
|
Definition
| The motor neuron and the muscle fibers it innervates |
|
|
Term
|
Definition
| A specialized region of the muscle membrane (sarcolemma) in the center of a muscle fiber that makes a synapse with motor neurons. |
|
|
Term
| What is the postsynaptic receptor on a motor end plate? |
|
Definition
| A nicotinic cholinergic receptor (NAChR) |
|
|
Term
| What happens when the nicotinic cholinergic receptor is activated? |
|
Definition
| Na+ and K+ can diffuse across the cell membrane, increasing conductance, producing an end plate potential |
|
|
Term
| Does the NAChR produce an action potential in the endplate? |
|
Definition
| No, the endplate is not electrically excitable. The membrane surrounding the endplate is what has voltage-gated channels and is always excited to threshold. |
|
|
Term
| Why do graded potentials on the endplate always turn into action potentials on the surrounding sarcolemma? |
|
Definition
| A large amount of Acetylcholine (over 100 vesicles) is always released into the neuromuscular junction |
|
|
Term
| What is the magnitude of an end plate potential, and what does it depolarize the membrane to? |
|
Definition
The magnitude of an EPP is approximately 70 mV and depolarizes the membrane to
0 mV. |
|
|
Term
| How does an action potential in muscle fibers lead to muscle contraction? |
|
Definition
| Cytosolic calcium concentration rises, causing the muscle to contract (but more on that later) |
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