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A&P II - Neurophysio
A&P I - Human Neurophysiology
| Question | Answer |
|---|---|
| all neurons are ______________ and respond to stimuli | excitable |
| stimuli generates ____________________ __________________ across neuron plasma membrane | electrical changes |
| what are the two forms of electrical changes in neurons | local (graded) potentials and action potentials |
| membrane potential is synonymous with what term | resting potential |
| this potential is temporary, localized change in resting potential | graded potential |
| this potential is an electrical impulse, produced by graded potential, and propagates along surface of axon to synapse | action potential |
| Describe synaptic activity | the release of neurotransmitters at presynaptic membrane which produces a graded potential in post synaptic membrane |
| what is information processing | integration of stimuli ( response) of postsynaptic cell |
| _______________ is the measure of potential energy generated by separated charge | voltage |
| voltage is always measured between ____________ point(s) and it is called - ___________________ or portential | 2 points; potential difference |
| the greater the difference between the 2 points the (higher/lower) the voltage | higher |
| _______________ is the flow of electrical charge between two points | current |
| the flow of electical charges (current) can be used to perform ________________ | work |
| _________________ is a material's opposition to the flow of electric current | resistance |
| ___________________ is a substance with high electrical resistance | insulator |
| a ________________________ is a substance with low electrical resistance | conductor |
| what is the general charge of the human body | neutral (same number of positive and negative charges) |
| (same/opposite) charges attract | opposite |
| __________________________ is required to separated opposite charges across a membrane | energy |
| in the physics current reflects the flow of _________________; but in the human body current is reflected by the flow of _________________ | electrons (physics); ions (human body) |
| there is a potential on either side of membranes when : _______________________________ and _________________________________ | number of ions is different across the membrane; membrane provides a resistance to ion flow |
| ion channels are __________________ | membrane protiens |
| how do membrane proteins allow ions into/out of a cell | they change shape to open/close the channel |
| __________________________ channels are always open | passive/leakage/non-gated |
| _______________________ - gated channels open with binding of specific chemical (neurotransmitter in case of the nervous tissue) | chemically/ligand - gated channels |
| ________________________ channels open and close in response to membrane potential | voltage -gated |
| ________________________ channels open and close in response to physical deformation of receptors | mechanically gated |
| what is the voltage of resting membrane potential | -70mV |
| the membrane of a cell is polarized because | there is a potential voltage difference (of -70mV) across the membrane of a resting neuron |
| what does the minus sign on the -70mV signify on the membrane potential | the inside of the membrane is negatively charged |
| the inside of the membrane is (negatively/positively) charged and the outside of the membrane is (negatively/positively) charged | inside = negative; outside = positive |
| resting membrane potential (exists only across the membrance/in the entire cell) | RMP exists only across the membrane potential; generally most of the solution in the cell are neutral |
| describe the membrane permeability to protien anions, sodium cations, potassium cations, and chloride ions. | Protien anions = impermiable, Na+ = Slightly permeable, K+ = 75X more permeable than Na+, Cl- = freely permeable |
| why is there no equilibrium in the ion concentration of ECF and ICF | ATP-driven sodium/potassium pump |
| in the sodium/potassium ion pump, (2/3) sodium are (ejected/imported) to the cell while (2/3) potassium ions are (ejected/imported) the the cell | 3 sodium ejected; 2 potassium imported |
| what three major events cause the membrane potential to change in a cell | depolarization, repolarization, and hyperpolarization |
| during depolarization; the membrane potential becomes (more/less) negative than resting membrane potential | less |
| what happens during repolarization | the membrane returns to its membrane potential |
| during hyperpolarization the membrane potential becomes (more/less) negative than resting membrane potential | more |
| Membrane potential changes are produced by: ______________________ and _________________________ | membrane permeability changes to ions, alterations of ion concentrations across the membrane |
| name the two types of membrane signals | graded potentials and action potentials |
| ___________________ potentials are incoming signals over short distances; while _____________________ potentials are over a long distance | graded potentials (short); action potentials (long) |
| graded potential, occurs on a small area of the neuron membrane and depolarizes by _____________________ | graded potential depolarizes by a stimulus |
| name the four steps of graded potential depolarization | 1) Na+ channels open, 2) Na+ ions enter cell, 3) Membrane potential rises, and 4) depolarization occurs |
| during graded potential flow only occurs on (one/both) sides of the membrane | potential occurs on both sides of the membrane |
| during graded potentials, most of the charge is lost through __________________________ | most of the charge is lost through leak channels |
| graded potential is _____________________ | decremental |
| define decremental | dies with increasing distance |
| where on the neuron does localized changes (graded potential) usually occur | dentrites |
| define the term graded | the magnitude of response is proportional to the stiumlus |
| graded potential are decremental, which means the intensity | the intensity decreases with distance |
| the ____________________ of a graded potential varies directly with the strength of the stimulus | magnitude |
| with graded potential, the stronger the stimulus, the more _______________ changes and the _________________ the current flows | stronger stimuli, more voltage change, farther flow |
| what type of graded potential can initiate action potential | a graded potential that is sufficiently strong enough can start an action potential |
| a subthreshold stimulus is | a week local depolarization that does not reach threshold |
| a threshold stimulus is | a stimulus that is strong enough to push the membrane potential toward and beyond the axon hillock |
| the (action/graded) potential is an all-or-none phenomenon | action potential is an all or none phenomenon |
| this concept about action potential describes the aspect that action potential either happen completely or do not happen at all | all or none phenomenon |
| when does depolarization become self-generating | when the potential reaches threshold |
| during depolarization, the Na+ permeability is ____________________ times higher than a resting cell | 1000 |
| at the end of depolarization the internal charge is now (positive/negative) and the actual numerical charge is ______________ mV | positive; +30mV |
| subthreshold depolarization (will/will not) results in an action potential | subthreshold WILL NOT results in action potential |
| action potential begins when (chemically/voltage)-gated NA+ channels open at the trigger zone | action potential begins when VOLTAGE-gated Na+ channels open |
| a graded potential becomes an action potential at ___________ | trigger zone/axon hillock |
| the amplitude of action potential is _________ mV | 100 mV |
| action potentials (do/do not) decrease in strength over distance | Action potentials DO NOT decrease in strength |
| because it does not decrease in strength over distances, ____________________ are great mechanisms for sending signals over long distances | action potentials are ideal mechanisms for sending signals over long distances |
| the action potential in the axon of a neuron is called | a nerve impules |
| during resting states voltage-gated Na+ and voltage-gated K+ channels are (open/closed) | during resting states voltage-gated Na+ and voltage-gated K+ channels are CLOSED |
| during resting state leak channels (passive) are open which allows for | small movements of Na+ and K+ between ECF and ICF |
| activation gates (voltage-gated Na+ channels) are (fast/slow); during resting state they are (open/closed) and respond to depolarization by (opening/closing) | fast; closed; opening |
| inactivation gates (voltage-gated Na+ channels) are (fast/slow); during resting state they are (open/closed) and during depolarization the channel is (opened/closed) | slow; open; closed (or blocked during depolarization) |
| during depolarization the channel opens and then ___________________ Na+ channels | deactivates (it's blocked) |
| name the three states of a voltage-gated Na+ channel | 1) inactivation gate open, and activation gate closed, 2) activation gate and inactivation gate is open, 3) activation gate is open but inactivation gate is closed |
| name the two states of voltage-gated K+ channels | activation gate closed and activation gate open |
| local/graded potential uses (chemically/voltage)-gated Na+ channels to depolarize a cell | graded potential uses chemically-gated Na+ channels |
| as membrane potential goes from -70 mV to -55 mV (threshold) what gates are open | from -70 mV to -55 mV chemically-gated Na+ channels |
| at threshold (-55 mV) what gates open | at threshold voltage-gated Na+ channels activate and gate opens until membrane potential becomes +30 mV |
| at +30mV, what is the gated activity | voltage-gated Na+ channels inactivate and voltage-gated K+ channels open and K+ leaves the ICF |
| the depolarization of an axon is an example of a (positive/negative) feedback system | positive feedback system |
| at what voltage point do voltage-gated Na+ channels open on an axon | -55mV (at threshold stimulus) |
| what major event occurs when voltage-gated Na+ channels open | Na+ diffused into the cell |
| what major action(s) occur during repolarization | voltage-gated Na+ channels become inactive and the voltage-gated K+ channels open |
| at what voltage-point does voltage-gated K+ channels open | +30 mV |
| what major event occurs when voltage-gated K+ channels open | K+ rushes out of the neuron |
| slower voltage-gated K+ channels stay open and cause _________________________ with a voltage of -90mV | hyperpolarization |
| when repolarization occurs the resting ionic conditions (have/have not) been returned back to normal | HAVE NOT, repolarization restores the resting electrical conditions of the neuron, however the resting ionic conditions are not restored |
| ionic redistribution of an axon after repolarization is brought back to resting conditions by ________________________ | sodium-potassium pump |
| ________________________ is the time period from beginning of action potential to return to resting state | refractory period |
| during the absolute refractory period, the membrane (will/will not) respond to additional stimuli | absolute refractory period will not respond to additional stimuli |
| describe the state of the voltage-gated Na+ channels during absolute refractory periods | voltage gated Na+ channels are either open or inactivated |
| describe the membrane potential during the relative refractory period | the membrane potential is almost normal |
| what type of stimulus is needed to initiate another action potential during the relative refractory period | very large stimulus |
| what are the three purposes of the absolute refractory period | 1) prevent neuron from generating action potential, 2) ensures that each action potential is separate, 3) enforces one-way transmission of nerve impulses |
| describe the voltage-gated channels during the relative refractory period. what phase or action potential is the axon in during the relative refractory period | voltage gated Na+ channels are closed, voltage-gated K+ channels are open, and the action potential is in repolarization |
| name the two different types of action potential propagations | continuous propagation and saltatory propagation |
| the action potential in unmyelinated axons are (continuous/saltatory); while the action potential in myelinated is (continuous/saltatory) | continuous = unmyelinated; saltatory = myelinated |
| conduction velocities (vary widely/are the same) among all neural axons | conduction velocities VARY WIDELY among all neural axons |
| what are the two factors that effect the rate of propagation | 1) presence of a myelin sheath, 2) axon diameter |
| the presence of a myelin sheath (increases/decreases) the impulse speed | presence of a myelin sheath increases the speed of an impulse |
| the (larger/smaller) the diameter of an axon, the faster the impulse | larger the diameter |
| in (saltatory/continuous) conduction the current passes though a myelinated axon only at the nodes of ranvier | SALTATORY conduction passes though a myelinated axon at the nodes of ranvier |
| in saltatory conduction, voltage-gated Na+ channels are concentrated at ______________________ | the nodes of ranvier |
| in this conduction type, the action potentials are triggered only at the nodes of ranvier and "jump" from one node to the next | saltatory action, action potential jumps from one node to another |
| ion movement is related to cytoplasm _______________________ | concentrations |
| increased axon diameter, the (higher/lower) the resistance | lower resistance |
| Axons are classified into 3 groups (A, B, and C), describe Type A axons | they are the larges axons and are highly myelinated. They can reach speeds of up to 150 m/s (or 300 mph) |
| what type of information does Type A axons carry to the CNS | information about balance, position, touch, and pressure sensations |
| motor neurons that control skeletal muscle movement are type ______________ fibers | motor neurons that control skeletal muscle are TYPE A fibers |
| what type division of the nervous system is controlled by Type B and C fibers | autonomic Nervous system |
| Type ____________ fibers are smaller myelinated and have an average propagation speed of 15 m/s (30 mph) | Type B fibers |
| Axons are classified into 3 groups (Types A, B, and C), this type is unmyelinated and have a propagation speed of 1 m/s (2mph) | Type C fibers |
| what information does type B and type C fibers carry to the CNS | temperature, pain and general touch sensations |
| type b and c motor fibers carry signals to what organs | smooth muscle, cardiac muscle, and glands |
| what is a synapse | a junction that mediates information transfer from one neuron to either another neuron or an effector cells |
| a (pre/post) synaptic neuron conducts impulses toward the synapse | the PREsynaptic neuron conducts impulses towards the synapse |
| the presynaptic neuron is an information _________________ | sender |
| the (pre/post) synaptic neuron transmits impulses away from the synapse | postsynaptic neuron transmits information away from the synapse |
| the postsynaptic neuron is the information _______________ | reciever |
| an axodendritic synapse is | between an axon of one neuron and a dendrite of another neuron |
| a __________________ synapse is between an axon of one neuron and the cell body (soma) of another neuron | axosomatic synapse |
| an axoaxonic synapse is | a synapse between the axon of one axon and another axon |
| __________________________ synapses include direct physical contact between cells | electrical |
| name the two different types of synapses | electrical and chemical synapses |
| a chemical synapse is | a signal transmitted across a gap by chemical neurotransmitters |
| in electronic synapses, what is the specific feature that allows the direct communication from the presynaptic cell to the postsynaptic cell | gap junctions |
| in electrical synapses, the changes in the transmembrane potential are transferred ___________________ between cells though local current | directly |
| in electrical synapses transmission is (fast/slow) | fast |
| what is the importance of electrical synapses | it gives the body the ability to synchronize several neurons together |
| define the term "electrically coupled" | two neurons that are joined together with electrical synapses |
| in electrical synapses, the axolemmmas of each cell are (not/nearly) touching | NEARLY touching |
| where in the body are most electrical synapses found | Found in the brain, cardiac, and visceral smooth muscle |
| in the brain, what are electrical synapses responsible for | programmed/automatic behaviors (i.e. breathing) |
| in cardiac and visceral smooth muscle what is the purpose of electrical synapses | coordinated muscle activity |
| for electrical synapses, electrical current can flow (directly/indirectly) from one axoplasm of on neuron to the next | DIRECTLY |
| name two unique features of electrical synapses | 1) transmission is bidirectional, 2) transmission is nearly instantaneous |
| neural synapses that are (electrical/chemical) are much faster than chemical synapses | Electrical synapses are much faster |
| neural synapses that are (electrical/chemical) are specialized for the release and receptions of Neurotransmitters | chemical synapses uses Neurotransmitters |
| the axonal termial of the ______________________ neuron contains synaptic vesicles (containing the Neurotransmitters) | presynaptic neuron contains synaptic vesicles |
| in chemical synapses, receptors on the postsynaptic neuron are located on ______________________ | soma or dendrites |
| for an action potential to be (or not to be) propagated to a post synaptic cell, depends on what two things | 1) amount of neurotransmitter released, 2) sensitivity of postsynaptic cell |
| what is the fluid filled space, separating the presynaptic and postsynaptic neurons in a chemical synapse | the synaptic cleft/gap |
| the transmission across the synaptic cleft has two characteristics: what are they | 1) it is a chemical event, 2) ensures unidirectional communication between neurons |
| name the eight steps for communication to occur across a chemical synapse | 1) action potential arrives, 2) voltage-gated Ca2+ channels open, 3) Ca2+ triggers exocytosis, 4) neurotransmitter diffuses and binds to receptor, 5) postsynaptic cell is either excited or inhibited, 6) degradation, 7) reuptake, 8) diffusion |
| after extended stimulation, the recycling of neurotransmitter unable to keep up with demand results in ______________________ | synaptic fatigue |
| what happens as a result of synaptic fatigue | the synapse weakens until neurotransmitter can be replenished |
| what is the synaptic delay | the amount of time between the release and the binding of a neurotransmitter |
| reflexes with fewer synapses are (faster/slower) than reflexes that require more synapses | fewer synapses the FASTER the reflexes |
| what two things are occurring as long as the neurotransmitter is bound to the postsynaptic receptor | 1) produces a continuous postsynaptic effect on permeability, 2) blocks reception of additional "messages." |
| name the three ways in which neurotransmitters are removed | 1) degradation by enzymes, 2) they are reabsorbed (by astrocytes), 3) they diffuse away from synaptic cleft |
| neurotransmitters are considered to be ____________________________ agents | paracrine |
| neurotransmitters are classified into what four categories | 1) amino acids, 2) monoamines, 3) soluble gases, 4) acetylcholine |
| name three excitatory neurotransmitters | 1) glutamate, 2) aspartate, 3) nitric oxide |
| name four inhibitory neurotransmitters | 1) glycine, 2) GABA, 3) serotonin, 4) dopamine |
| name two neurotransmitters that are both excitatory and inhbitory | 1) acetylcholine, 2) norepinephrine |
| four things that help to manipulate an neurotransmitter | 1) rate of synthesis, 2) rate of release, 3) blocking uptake, 4) blocking degredation |
| name five characteristics or neuromodulators | 1) effects are long term and slow to appear, 2) multiple steps, intermediary compounds, 3) alters nerve impulse transmission, 4) effect both pre/postsynaptic nerve, 5) released alone or with an NT |
| neuropeptides are __________________ | neuromodulators that bind to receptors and active enzymes |
| opioids are (neurotransmitters/neuromodulators) | opioids are neuromodulators |
| ________________ bind to the same receptors as opium or morphine | opioids bind to same receptors as opium/morphine |
| what is the purpose of opioids | relieve pain (endorphins) |
| the same neurotransmitter released in different locations will (always have the same influence/might have different influences) on effectors | might have different influences on effectors; example is ACh, usually promotes action potentials. but can also inhibit cardiac neuromuscular junctions |
| what can we conclude about neurotransmitters if the same neurotransmitter can have different effects on different tissues | there are different subtypes of receptors for neurotransmitters |
| the effect of a neurotransmitter on a postsynaptic membrane depends on | the properties of the receptors on the postsynaptic membrane |
| direct receptor mechanism in a postsynaptic channel | the neurotransmitter opens ion channels directly and promotes rapid response |
| what types of neurotransmitters open ion channels directly | ACh and amino acids |
| what is the indirect method of receptors in a postsynaptic channel | the neurotransmitter binds to a protein which activates a second-messenger and promotes long lasting effects |
| what are examples of a few neurotransmitters that used second-messenger mechanisms | biogenic amines, peptides, and dissolved gasses |
| G Protiens are (direct/indirect) mechanism of cell communication | G Protiens are INDIRECT |
| indirect effects of neurotransmitters work through _______________________ | second messengers |
| compared with direct effects of neurotransmitters, the indirect effects responses are _________________________________ | slower, more complex, more prolonged, and often diffuse |
| in indirect effects, the neurotransmitter | |
| give three examples of indirect neurotransmitters | muscarinic ACh receptors, neuropeptides, and those that bind biogenic amines |
| in an indirect effects, the neurotransmitter binds to the receptor and the G Protein is activated . What happens next | G Protien activates Adenylate cyclase to convert AT to Cyclic AMP, cAMP has several functions including (changing cell mem. permeability, activating enzymes, and activating genes) |
| receptors on postsynaptic cells are specialized in opening __________________-gated channels | receptors open CHEMICALLY-gated channels |
| chemically-gated channels are relatively (sensitive/insensitive) to changes in membrane potential | chemically-gated channels are INSENSITIVE to changes in membrane potential |
| why is it important to know that chemically-gated channels are insensitive to changes in membrane potential | because it makes them unable to become self-generating |
| when a neurotransmitter generates graded potential that depends on what? | the amount of neurotransmitter released |
| neurotransmitter receptors mediate changes in membrane potential according two what two things | 1) amount of neurotransmitter released, 2) amount of time the neurotransmitter is bound to receptors |
| name the two types of postsynaptic potentials | 1) EPSP (Excitatory postsynaptic potential), and 2) IPSP (inhibitory postsynaptic potential) |
| (EPSP/IPSP) can summate to reach threshold | EPSP can summate to reach threshold |
| (IPSP/EPSP) can summate with EPSP to cancel each other out | IPSP can cancel out an EPSP |
| what is summation | the amount of local potentials that add up to an action potential |
| if the summation of local potentials are excitatory then an action potential (is/is not) initiated | excitatory leads to an action potential that IS initiated |
| _________________________ summation is when one of more presynaptic neurons transmit impulses in rapid-fire order | temporal summation is when impulses arrive in rapid-fire order |
| in ______________________________ summation to be successful the first impulse produces a small EPSP and a second one arrives before the first disappears | temporal summation is when one impulse arrives and a second one arrives before the first disappears |
| __________________________ summation is when the postsynaptic neuron is stimulated by a large number of terminals at the same time | spatial summation |
| IPSP's (can/cannot) summate | IPSP's CAN summate both spacial and temporally |
| the neuron receives a many IPSP's and EPSP's simultaneously from different sources. the axon hillock of the neuron keeps "records" of all signals and acts as _______________________ | neural integrators |
| the CNS has millions of neurons are organized in _____________________ | neural pools |
| neural pools in the CNS have functional groups that | 1) integrate income information, 2) forwarding the processed information |
| this neural circuit amplifies the signal and diverges the signal into multiple tracts | Divergent |
| how does divergent neural circuits amplify signals | they spread the signal to an increasing number of neurons as it moves through successive orders of a neuronal pathways |
| this neural circuit receives input from many different presynaptic neurons; as a result, the neuron has a concentrating (funneling) effect | convergent circuit have a funneling effect and receives input from multiple sources |
| this specific neural circuit explains why different stimuli have the same effect | convergent explain why different stimuli have same effects |
| describe a reverberating/oscillating conferenced | incoming signal travels along chain of neurons containing collateral synapses with previous neurons in the chain |
| this particular feedback system is used in positive feedback when neural circuits re-excite the input of the same circuit | reverberating/oscillating neural circuit is used in positive feedback system |
| what stops a reverberating/oscillating neural circuit | progressive synaptic fatigue or inhibitory circuits |
| this particular feedback system gives a continuous signal involved in rhythmic activities such as (breathing and sleep-wake cycle) | reverberating/oscillating neural circuits is used for breathing |
| describe a parallel after-discharge neural circuit | an incoming neurons stimulate several neuron in parallel arrays that stimulate a common output cell |
| what is the function of parallel after-discharge neural circuit | precise activity (such as solving a math calculation) |
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