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Bio concepts 2
Neurons, Synapses, and Signaling
| Question | Answer |
|---|---|
| What are the two types of signals? | electrical and chemical |
| Neurons | Nerve cells that transfer |
| What are the three stages of neural signaling? | Input, Intergration, Output |
| Input | Sensation (stimulus)initiates neural signal |
| Intergration | processing of neural signal |
| output | neural signal stimulates effector responses |
| What are the three types of neurons? | Sensory neurons, Interneurons, motor neurons. |
| Sensory neurons | process sensory neural signals (input data) |
| interneurons | to ganglia to brain.these intergrate and process sensory data to motor signals (Out put) |
| motor neurons | exit the brain or ganglia via these that initiate appropriate responses (muscle activity) |
| Nervous system consists of what two smaller nervous systems? | Central nervous system and Peripheral nervous system |
| Central nervous system | receives and processes sensory neural signals (Brain and nerve cord) |
| Peripheral nervous system | transmits neural signals to and from CNS. |
| Dentrites | found on neurons.highly branched extensions that receive signals from other neurons or sensory cells |
| Axon | typically much longer extension of neuron that transmits signals to other neurons. |
| synapse | junction/space between an axon and another neuron |
| synaptic terminal | of one axon passes neural signals across synapse "encoded" as chemical messengers called neurotransmitters. |
| What is the path of the neural signal | presynaptic cell to postsynaptic cell |
| Membrane potential | every neurons has a difference in electrical charge(voltage)across its plasma membrane which acts as an insulator |
| How are neural signals transmitted? | as wave of charge in membrane potential |
| Resting potential | membrane potential of stable neuron, not sending neural signal.allows organism to deal with environment and not react to littlest detail. |
| Mammalian neuron at resting potential | K is greater inside the cell,while Na is greater outside cell creating a slight voltage |
| What concentration gradient occurs | Na and K.chemical potential energy which can be tapped to send neural signals. |
| Transmitting neural signals | when ion channels through the P.M. open chemical potential converted to an electrical potential.Neuron at resting potential contains many open K channels and fewer Na channels. |
| What are anions trapped inside the neuron? | they are large proteins that build up the internal negative charge. |
| Gated ion channels | found in neuron that open and close in response to various kinds of stimuli.Stimulus causes channels to open wide therefore changing the charge of the specific section of neuron. |
| When does the membrane potential change? | when K and Na channels open or close. |
| What happens when gated K channels open? | K diffuses out increasing strength of negative charge inside cell. |
| Hyperpolarization | the growing internal negative charge.as strength of membrane potential grow the axon becomes "primed" to discharge pulse of electricity. |
| What does the threshold determine? | If the signal is sent |
| Depolarization | a drop in strength of membrane potential.when gated Na channels open allowing Na to rapidly diffuse into cell.Stronger stimulus=stronger depolarization |
| Graded potential | magnitude of changes in polarization proportional to strength of stimulus |
| Production of action potential | voltage-gated Na and K channels respond to change in membrane potential.When stimulus depolarizes membrane Na channels open,allowing Na to diffuse into cell.Increases depolarization opening more Na channels.Strong stimulus result in action potential. |
| action potential | rapid change in membrane voltage.occurs when stimulus is strong enough to exceed threshold.rapid all or nothing.becomes neural signals that are then transmitted. |
| How many action potentials can a neuron produce in a second? | hundreds. Frequency reflects strength of stimulus. |
| At resting potential | most voltage gated Na and K channels are closed but some K channels are open. |
| When action potential is generated | voltage gated Na channels open first and Na flow into cell.During rising phase,threshold is crosses,and membrane potential increases.During falling phase,Voltage-gated Na channels inactivated;K channels open and K flows out. |
| Voltage-gated | respond to voltage change as suppose to gates that respond to concentration gradient. |
| During undershoot | membrane permeability to K at first higher than at rest(lag effect).then voltage gated K channels close.resting potential gradually restored as k builds up inside cell. |
| during Refractory period | after action potential,second action potential cannot be initiated immediately.Result from temporary brief inactivation of Na channels. |
| Conduction of Action Potential | action potential can travel long distances by propagating itself along the axon.where action potential is generated,usually axon hillock,an electrical current depolarizes neighboring region of axon membrane. |
| How is action potential prevented from traveling backwards? | Inactivated Na channels behind zone of depolarization.Action potentials can travel in only one direction toward synaptic terminals. |
| Conduction Speed | Speed of action potential proportional to Axons diameter. |
| Myelin sheath | in vertebrates.Insulates axons,which increases action potential's speed.made by glia.Oligodendrocytes in CNS and Schwann cells in PNS. |
| Nodes of ranvier | only place where action potentials will be seen.gaps in myelin sheath where voltage gates Na channels exist. |
| Saltatory conduction | Action potentials in Myelinated axons jump between nodes of Ranvier during process called this. |
| Gap junction | chemical synapses,chemical neurotransmitters carries neural signals across these.no physical touching. |
| Why is enzymatic breakdown of neurotransmitters important? | it stops the traveling of the signal. acts as off switch.if neurotransmitters were constantly on the receiving neuron would respond to phantom responses. |
| Synaptic Vesicle | where the presynaptic neuron synthesizes and packages neurotransmitters.these are concentrated in synaptic terminal. |
| Where do neurotransmitters diffuse across to postsynaptic cell? | synaptic cleft. |
| Direct synaptic transmitters involves the binding of what? | neurotransmitters to ligand-gates ion channels in postsynaptic cell.causes ion channels to open,generating a postsynaptic potential |
| What are the two categories of postsynaptic potential? | excitatory postsynaptic potentials and inhibitory postsynaptic potentials. |
| Excitatory postsynaptic potentials | are depolizations that bring membrane potential toward threshold. a single one is usually too small to trigger and action potential in postsynaptic neuron. |
| Inhibitory postsynaptic potentials | are hyperpolarizations that reduce membrane potential below threshold |
| What happens to the neurotransmitter after it has been released? | may diffuse out of synaptic cleft,may be taken up by surrounding cells,may be degraded by enzymes |
| How are postsynaptic potentials different than action potentials? | are graded and do not regenerate. |
| When does temporal summation occur? | if two EPSPs are produced by same synapse in rapid succession. |
| Spatial Summation | EPSPs produced nearly simultaneously by different synapses on same post synaptic neuron. |
| What can the connection of EPSPs through spatial and temporal summation trigger? | and action potential.Determine whether axon hillock will reach threshold and generate action potential along postsynaptic neuron. |
| Neurotransmitters | the same one can produce different types of neurons. |
| What are the five major classes of neurotransmitters? | acetylcholine,biogenic amined,amino acids, neuropeptides,gases |
| Acetylcholine | common neurotransmitter in vertebrates and invertebrates.in vertebrates usually excitatory transmitter |
| Biogenic amines | include epienephrine,norepinephrine,dopamine and serotonin. Active in CNS and PNS |
| Amino Acids | found in the CNS in the brain. Include gamma-aminobutyric acid (GABA) and glutamate. |
| Neuropeptides | relatively short chains of Amino acids,also function as neurotransmitters.include substance P and endorphine, opiates, cocaine. |
| Substance P and endorphins | both affect our preception of pain. |
| Opiates | bind to same receptors as endorphins and can be used as painkillers. |
| Gases | such as nitric oxide and carbon monoxide are local regulators in PNS. |
Created by:
ejohnson17
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