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During depolarization, which gradient(s) move(s) Na+ into the cell?
Yes, a positive ion is driven into the cell because the inside of the cell is negative compared to the outside of the cell, and Na+ is driven into the cell because the concentration of Na+ is greater outside the cell.
The action potential is a transient change in the resting membrane potential from -70 mV to +30 mV, then back to -70 mV. This change is caused by the opening of first _____ then _____ voltage-gated channels.
What area(s) of the neuron generate local signals that open the voltage-gated channels in the first part of the axon, thus causing an action potential to begin?
As the axon hillock depolarizes, Voltage-gated Na+ channels open and Na+ moves (into or out of) __________ the cell causing further (depolarization or repolarization) __________.
If depolarization reaches -55 mV, an action potential will be generated. What is this -55 mV trigger point called?
At the end of the depolarization phase, what voltage-gated channels open to help restore the resting membrane potential?
Repolarization is caused by the movement of what ion (sodium or potassium), in what direction (into or out of the cell)?
After an action potential, the membrane becomes more negative than -70 mV. This period is called:
After a neuron has generated an action potential, it cannot generate another one for a while. This period is called:
The fastest conduction of an action potential would occur in an axon with which of the following characteristics?
When the nerve is stimulated at a voltage setting of 1.0 V, what is the response observed on the oscilloscope?
What is the threshold voltage of this nerver to produce an action potential?
Do not get this confused with threshold membrane potential of the neuron which is required to start the action potential down the axon. This is just demonstrating that you need a threshold voltage—enough stimulations of the receptors of the nerve —to then cause the action potential.
If the voltage is increased by 0.5 over threshold, and Single Stimulus is clicked, how does this change the tracing?
The maximal voltage at which an increase in response is no longer observed is:
Why did the action potential strength increase with increasing voltage?
So this is just showing that you can increase the action potential reading by activating more neurons in a nerve—but REMEMBER an action potential in a NEURON is an ALL or Nothing event—it is not gradated like muscle force.
When the rod is positioned to touch the nerve, what do you see on the oscilloscope?
How does the tracing (in response to the rod) compare to other tracings previously generated?
What happens when the heated rod is brought into contact with the nerve?
How does the tracing generated when the heated rod touches the nerve compare to the tracing you observed with the unheated rod?
Which of the following conclusions would you make, based on your experiments using the heated and unheated rods?
When a nerve is exposed to sodium chloride, is an action potential generated?
How does the tracing of the nerve exposed to sodium chloride differ from that of the original threshold stimulus tracing?
What happens when the nerve is exposed to hydrochloric acid?
How does the tracing of the nerve exposed to hydrochloric acid differ from that of the original threshold stimulus tracing?
What is the likely explanation for the results seen with both the sodium chloride and the hydrochloric acid?
Based on all your results so far, which type(s) of stimuli were observed to elicit an action potential?
How would you describe the trace that is generated when the nerve is exposed to ether and then stimulated with adequate voltage? Thus ether had what effect on nerves ability to produce an action potential?
How long does it take the nerve to return to normal?
How would you describe the trace that is generated when the nerve is exposed to curare and then stimulated with adequate voltage? Thus curare had what effect on nerves ability to produce an action potential?
How would you explain the effect of curare on the action potential?
How would you describe the trace that is generated when the nerve is exposed to lidocaine and then stimulated with adequate voltage? Thus lidocaine had what effect on nerves ability to produce an action potential?
At what level of the nerve does lidocaine have its effect?
What was the threshold voltage and approximate conductance velocity of rat nerve number 1?
Of the four nerves tested, which had the slowest conduction velocity?
Based on your results, what can you infer about nerve size and conduction velocity?
Which of the following is true?
In this graph a membrane potential of -55 mV is indicating what?
How is the resting membrane potential of a neuron maintained? (Choose all that apply)
When a neuron reaches threshold, what are opened on a cell membrane? (Choose all that apply)
What is the relationship between the diameter of the nerve and the conduction velocity? (Choose all that apply)
If a nerve is myelinated, its conduction velocity is faster than it would be if it was not myelinated. T or F
In this graph the letter “E” is indicating what?
The ability of a neuron to respond to stimuli and convert it into a nerve pulse is called its___________
At what phase(s) on the graph below are the voltage regulated Na+ and K+ channels closed in the axon?
What is section D in the graph below referred to as:
Together sections C and D in the graph below represent…
The physiological ability of a neuron to respond to stimuli and convert them into nerve impulses is its _______________.
The physiological ability of a neuron to transmit an impulse is its _______________.
What is section A in the graph below referred to as:
The difference in electrical charge across the membrane of a neuron that does not have any neural impulses present is the____________.
At what phase(s) on the graph below is the absolute refractory period?
The period of an action potential when the membrane is totally insensitive to additional stimuli is the ________________.
The speed of the action potential along a neural membrane is its_______
What is a white, fatty material, composed of lipids and lipoproteins, that surround the axons of nerves?
The two large categories of reflexes are:
The corneal reflex is mediated through which cranial nerve.
Any reflex observed on the side of the body stimulated is a(n) _____________ response.
___________ reflexes depend both on functional upper-motor pathways and on cord level reflexes.
Any reflex observed on the side of the body opposite from the side stimulated is a(n) _________________ response.
____________ is an example of a cranial nerve reflex
___________ reflexes are initiated by tapping a tendon.
Absence of the _____________reflex indicates damage to the brain stem.
Abdominal, cremaster, and planter reflexes are examples of what type of reflexes.
You have some damage to your nervous system, and you are lacking the ipsilateral response of this reflex but your contralateral response is still in tack.
Now you are walking around barefoot and start to step in a sharp rock, what happens:
You steady yourself in preparation for removing your foot, but you continue to step on the rock and damage your foot.
Which of the following are found in the skin? (Choose all that apply)
_______ react to stimuli in the external environment, and are typically found close to the body surface.
Which of these receptors responds chiefly to pain and temperature?
Which of the following are types of exteroreceptors (choose all that apply)
Place the following receptors from most superficial to deepest in the integument system.
_______ react to stimuli or changes within the body AND in the external environment.
_______ react to stimuli arising within the body, and are found in the internal visceral organs.
_______ include sight, hearing, equilibrium, smell and taste.
_______ react to internal stimuli, and are found in skeletal muscles, tendons, joints, ligaments, and connective tissue of bones and muscles.
_______ react to touch, pressure pain, heat, cold, stretch, vibrations, and position changes.
Which of the following receptors are not found in the skin?
These receptors are best suited to monitor high-frequency vibrations.
These receptors are encapsulated by connective tissue, respond to light touch and are located in the dermal papillae of glabrous skin only.
The least specialized and widely spread cutaneous receptors are the
the abil-ity to respond to stimuli and convert them into nerve impulses
the ability to transmit an impulse (in this case, to take the neural
impulse and pass it along the cell membrane
In the resting neuron (that is, a neu-ron that does not have any neural impulses), the exterior of the cell membrane ispositively charged and the interior is negatively charged relative to the outside.This difference in electrical charge across the plasma membrane is referred to asthe resting membrane potential,
sodium-potassium pump in the membrane maintains the difference in electricalcharge established by diffusion of ions. This active transport mechanism moves3 sodium ions (Na) out of the cell while moving in 2 potassium ions (K).Therefore, the major cation (positively charged ion) outside the cell in the extra-cellular fluid is Na, and the major cation inside the cell is K
When a neuron is activated by a stimulus of adequate inten-sity, known as a threshold stimulus, the membrane at itstrigger zone, typically the axon hillock, briefly becomes morepermeable to Na ions (sodium ion channels in the cell mem-brane open).
The interior surface of the membrane becomes less negative and the exterior surface becomes less positive, aphenomenon called depolarization
Whendepolarization reaches a certain point called threshold, anaction potential is initiated and the polarity ofthe membrane reverses.
The flow of K out ofthe cell causes the membrane potential to move in a nega-tive direction. This is referred to as repolarization
When the sodium ion channels are open, the membraneis totally insensitive to additional stimuli, regardless of theforce of stimulus. The cell is in what is called the absoluterefractory period. During repolarization, the membranemay be stimulated if a very strong stimulus is used. Thisperiod is called the relative refractory period.
When it reaches theaxon terminal, it triggers the release of neurotransmittersinto the synaptic cleft. Depending on the situation, the neu-rotransmitter will either excite or inhibit the postsynapticneuron.
conduction velocity, that is, the velocity of theaction potential along a neural membrane