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Ch11-NervTis-Basics2
BIO201 - Ch 11 - NervSys Basics 2 - Signal Conduction - Marieb/Hoehn Rio Salado
| Question | Answer |
|---|---|
| The conducting region of the neuron. | Axon |
| The axon functions to __ & __. | Generates nerve impulses & transmits them. |
| In motor neurons, the nerve impulse is generated @ junction of __ & __. | Axon hillock & Axon (trigger zone). |
| After generation, nerve impulse is conducted along the __ to the __. | Axon to the axon terminals (secretory region). |
| When the impulse reaches the axon terminals, it causes __ to be released into extracellular space. | Neurotransmitters |
| Neurotransmitters either __ or __ neurons. | Excite or inhibit |
| Neurons receive & send to scores of other __ @ same time. | Neurons |
| Anerograde movement | Movement toward axon terminals |
| Retrograde movement | Movement away from axon terminals |
| Axolemma | Axon plasma membrane |
| Hyperpolarization | When membrane potential increases & becomes more negative than resting potential. |
| Graded potentials | Short-lived changes (local) in membrane potential - decrease in magnitude w/distance & varies according to stimulus strength. |
| 2 types of graded potentials | Receptor (generator) potential & post synaptic potential. |
| Postsynaptic potentials caused by? | Neurotransmitter released into synapse. |
| Receptor potential cause by? | Excited sensory neuron due to heat, light, etc. |
| In gradedpotentials how are local currents created? | Sm. patch of membrane depolarizes & as ions flow, adjacent areas become depolarized in a spreading wave of depolarization. |
| Which cell types can generate action potentials? | Neurons & muscle cells because they have excitable membranes. |
| In a neuron, an AP is also called __. | Nerve impulse |
| Where are nerve impulses generated? | Only in axons. |
| A stimulus changes the __ of the neuron's membrane by __. | Permeability - by opening specific voltage-gated channels on the axon. |
| The transition from local graded potential to AP takes place at the __. | Axon hillock |
| 3 phases of AP generation. | (1) resting - all gates closed, (2) Depolarizing Phase - Na+ channels open, (3) Replarization Phase - Na+ close & K+ opens. |
| Na+ channel has __ gate(s). | 2 - activation & inactivation gate. |
| Sodium-potassium pumps | Carrier proteins - span neuron's membrane & use ATP to actively transport K+ in & Na+ out. |
| __ must restore a neuron's action potential. | Ion pumps |
| Action potentials are __. | All or nothing - once positive-feedback cycle of opening Na+ gates starts, nothing stops its full spike. |
| About halfway through AP, __ open & __ flows out & restores original voltage difference across membrane. | Postassium channels, K+. |
| Synaptic integration | Summation of competing signals that reach input zone @ same time - signals are suppressed, reinforced, or sent onward to other body cells. |
| Saltatory Conduction | Action potentials jump from node to node. |
| Stretch reflex | Contracts muscle after load has caused it to stretch. |
| AP results when __ open & __ flows into a neuron. | Sodium gates, Na+ |
| Active transport of __ out of a neuron restores resting potential in a neuron. | Potassium (K+) |
| __ bridge synapses between all neurons & other cells. | Neuotransmitters |
| Endorphins are __. | Neuromodulators |
| Neuotransmitters are stored in __ in a cell's cytoplasm. | Synaptic vesicles |
| Neurotransmitters can __ or __ a receiving cell. | Excite or inhibit |
| How receiving cell responds to transmitter depends on several factors... | (1) type of, (2) amount of neurotrans., (3) kinds of receptors cell has, (4) types of channels, (5) input zone. |
| Neuromodulators | Can magnify or imede the effect of neuotransmitter. |
| Conduction velocity is affected by? | (1) axon diameter (bigger is faster), (2) degreeof myelination (naked is slower). |
| Briefly describe positive feedback cycle of AP. | Membrane potential depends on membrane permeability & vicea versa. |
| What 2 events contribute to replarization? | Abrupt decline in Na+ permeability & increased permeability to K+. |
| Threshold typicall reached when membrane deplarized by __ to __ mV. | 15 to 20 mV |
| Local anesthetics work by blocking __. | Voltage-gted Na+ channels - no AP. |
| Neurotransmitter receptors mediate __ potentials. | Graded |
| Chemically gated ion channels allow __ to diffuse simultaneously through membrane in opposite direction. | Na+ & K+ |
| The summation of __ influence the activity of a postsynaptic neuron. | EPSP excitatory postsynaptic potentials |
| Anxon hillock membranes function as __. | Neural integrators |
| When a motor neuron is at rest, its gated __ channels are closed, plasma membrane doesn't allow much __ to leak inward, but is more permeable to __. | Sodium channels, sodium, postassium (K+) |
| The cytoplasm next to membrane is __ charged. | Negatively |
| The membrane charge difference is called __. | Resting membrane potential - around -70 mV |
| When a signal arrives, __ open & __ rushes into the neuron. | Sodium gates, Na+ |
| Threshold level of stimulation. | Minimum around of voltage that shifts across plasma membrane before activation. |
| Action Potential | The "nerve impulse" - neuron's communication signal. |
| A neuron's trigger zone is riddled with __. | Sodium channels |
| Action potentials __ by themselves. | Spread/propagate |
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Ladystorm
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