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Ch11-NervTis-Basics2

BIO201 - Ch 11 - NervSys Basics 2 - Signal Conduction - Marieb/Hoehn Rio Salado

QuestionAnswer
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
Created by: Ladystorm on 2007-06-11



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