MS- Neurophysiology.txt

Information carried by nerves is coded by __________; therefore, _______ and ________ are invariable.

To increase strength of contraction, the signal does not become larger, but the __________ becomes greater.

The voltage that exists b/w the inside and the outside of the cell, across the cell membrane.

With respect to resting membrane potential, we assign a ________ value to the interior of the cell with respect to the outside of the cell.

The voltage at which there is no net diffusion taking place.

The equation that relates elecrical gradient and chemical gradient to calculate the membrane potential in a cell.

The equilibrium potential is totally dependent on the ___________ of the ___________.

(Membrane semipermeable to K+ only) Net diffusion is K+ down its ___________ gradient until equilibrium is reached, at which time the tendency for K+ to diffuse down its _________ equal its tendency to diffuse the other way, down its _________.

_______ plays a major role in the membrane potential of most animal cells.

________ is passively distributed across the cell membrane according to the potential established by the diffusion of ________ out of the cell, creating a negative charge from the fixed anions within the cell.

_________ maintains electroneutrality for sodium that is outside the cell.

The equation that considers not only the concentration ratios of sodium, chloride, and potassium, but also takes their respective permeabilities into account in the calculation of equilibrium potential.

The Na-K ATPase pump carries ________ back into the cell while removing _______ from the cell.

Electrogenic pumping of the Na-K ATPase pump occurs when the pump exchanges _________ for ______, resulting in a net loss of __________, generating a current.

Electrogenic pumping of the Na-K ATPase pump contributes to the __________ of the cell.

What are the 4 factors that describe the genesis of membrane potential?

The membrane potential of excitable cells.

Membrane potential during which the membrane actively responds with a conducted impulse, usually resulting in some action.

Term describing the fact that even during the inactive or resting condition, ions are constantly leaking down their concentration gradients.

Location where the release of a neurotransmitter substance acts to stimulate the receptors.

The ease with which the events leading from the application of the stimulus to the initiation of the action potential take place.

When a stimulus is applied, the membrane potential is displaced from its normal level of __________.

If current is added to the membrane potential, it becomes more ___________; if current subtracts from the membrane potential, it becomes more _________.

When the current is depolarizing and the stimulus is adequate to elicit an action potential, _________ has been reached and ___________ has occurred.

The point at which activation of the membrane takes place, resulting in the regenerative phases of an action potential and a conducted impulse.

Stimuli that fail to elicit an action potential.

Passive changes in the membrane, which are a result of a subthreshold stimulus.

Generator potential, synaptic potential, and electrotonic potential are examples of __________.

The greater the voltage difference b/w the threshold and the resting potential, the _____ excitable the tissue because...

Hypocalcemia results in the membrane becoming ___________, threshold is ________, and excitability ________.

Hypercalcemia results in the membrane becoming __________, threshold is _________, and excitability _________.

Hyperkalemia _________ the resting potential by ________ the gradient for potassium to diffuse out of the cell and _________ excitability.

Hypokalemia __________ resting potential, and ________ excitability because the gradient for potassium to diffuse out of the cell is _________.

If hyperkalemic depolarization is severe, the membrane remains depolarized, is unable to be __________, and may become ______ excitable.

Condition in which the membrane remains inexcitable due to persistent or gradual depolarization, such as in the case of severe hyperkalemia.

Activation of the membrane takes place when... (2)

Change in membrane resistance.

Ion channels have the property of selectivity and undergo a pattern of ______________.

Sodium channels are responsible for the ________ of the membrane.

Potassium channels are responsible for the __________ of the membrane.

Sodium and potassium channels are _____-gated.

Channels whose activation/opening is dependent upon a change in the voltage of the membrane, which occurs with a depolarizing stimulus.

Voltage-gated channels are activated/opened with a ________ stimulus.

As soon as the voltage inside becomes less _______ (__________), some voltage-gated sodium channels begin to activate/open.

A sodium channels open due to depolarization, more sodium ions rush in, causing the inside to become less negative and more depolarized to its threshold. This is known as a process of __________.

Rapid sodium influx drives the membrane potential toward and even past _______; this rapid depolarization increases the __________ so that sodium conductance may increase up to 10,000 times the resting value.

What 2 things occur to immediately oppose the sudden influx of sodium and depolarization of the membrane?

At the same time the depolarization starts to open sodium channels, it also opens __________, which also tend to oppose the sodium channel activation.

Voltage-gated potassium channels open _________ than sodium channels and are open for a _______ period of time.

During repolarization, potassium enters the cell at a _______ rate than sodium and for a _______ period of time.

The outward movement of potassium carrying positive charges restores the __________ to its original ___________, which also brings about ___________.

Potassium efflux is a process of __________.

Every time an impulse passes along the surface of an excitable cell, the changes in membrane conductances underlying an action potential causes a slight gain of __________ and loss of _________. The __________ operates in the background to restore the gradients.

Hypernatremia and hyponatremia result in changes in the _______ and _______ of _______________.

Because the velocity of impulse conduction is directly dependent on the rapid phase of ___________, conditions resulting in ___________ can alter impulse conduction.

Conditions of ________ alter resting membrane potential, excitability, and normal repolarization of the membrane, thus lengthening the amount of time the membrane is refractory (cannot conduct an impulse).

Undiminished in size over a distance.

Frequency coding is an ________ signal that is the same ______ every time.

The energy to maintain a signal over the relatively long distances of very thin nerve fibers.

When an impulse passes over the surface of a cell, there is a wave of _______ on the surface of the cell and a wave of _______ inside the cell.

The passive flow of positive charges depolarizing the membrane, causing the membrane directly in front of the impulse to become less ___________ until threshold is reached and _____________, allowing the regenerative depolarization-repolarization action potential cycle to continue.

The speed (velocity) with which an impulse is conducted is determined by the....

Factors that control the passive flow of charges in the local circuit (depolarization-repolarization in the forward direction, conducting an impulse).

As axon diameter increases, the resistance _______ and local flow can depolarize adjacent membrane areas _________.

If a membrane is better insulated and directs flow forward, local flow and depolarization are ______ and __________ is increased.

Myelinated nerves conduct ______ than unmyelinated nerves because....

Nerve fibers which are enveloped with special glial cells containing myelin, giving them better insulating qualities and faster conduction velocity.

The myelin of nerves is interrupted at intervals, allowing expose, uninsulated cell membrane areas, which are called ______________.

When an impulse spreads along a myelinated nerve, the nodes of Ranvier __________ readily, providing a ____________ driving force and added insulation b/w nodes forces the rapid flow of charges to ________________.

Two important properties which can be used to assess normal function in excitable tissues are...

Movement of an impulse jumping from node to node for more rapid conduction in a myelinated nerve.

_____________ requires that the time be determined that it takes for an impulse to be conducted over a known distance.

When determining refractoriness, if the stimulus producing the second impulse is maximal in strength, then the shortest interval would be the _____________.

hen determining refractoriness, if the stimulus is of just threshold strength, then the shortest interval would be the _____________.

The time difference b/w the absolute refractory period and the total refractory period.

A stimulus of greater than threshold strength can elicit a response during the _________.

Refractory periods prevent excitable tissue from...

Both excitation-secretion coupling and excitation-contraction coupling are ________-mediated processes.

Common features of neurotransmission at all chemical synapses in animals. (5)

The neurotransmitter at the neuromuscular junction.

Acetylcholine is synthesized within the prejunctional terminal from _______ and ________ by the enzyme choline acetyltransferase.

Choline acetyltransferase is produced in the __________ and is transported down the axon to the terminal by __________.

When an impulse originating in the CNS reaches the nerve terminal, the prejunctional membrane is rapidly _________ by _________.

When the prejunctional membrane is depolarized (as the impulse from the CNS is conducted to the nerve terminal), voltage-gated _________ open, and ________ enters the cytoplasm, causing...

When ACh is released into the junctional cleft, it rapidly diffuses toward the _________, which has __________ receptors, which are _______- gated channels, associated with ion channels.

When ACh binds to the ligand-gated channels on the motor end-plate, the end-plate is ___________ due to __________, initiating a __________.

The enzyme that terminates the action of ACh is ____________; it hydrolyzes ACh to ________ and _________.

Hypocalcemia can cause paralysis because...

Curare, a neuromuscular blocking drug, results in paralysis because it blocks ____________.

Inhibitors of acetylcholinesterase allow the ________________, which leads to continual ________ of the end-plate and _______.

Myasthenia gravis is an autoimmune disease that results in the destruction of ____________.

The functional unit of a striated muscle.

The sarcomere is the area lying between adjacent _______, which...

The sarcolemma in the muscle cell membrane, which conducts ________ along the cell surface.

__________ invaginate the cell surface and communicate with the extracellular fluid, carrying the electrical signal to the sarcomere.

The _________ surrounds each myofibril and controls the movement of calcium within the muscle.

Calcium is sequestered in the ______ after it is released from the terminal cisternae.

The sarcomere contains myofilaments of ________ surrounded by _______ in a hexagonal array.

Each actin filament is attached to the _________, producing the light area called the ______.

The myosin filaments are attached to the ______.

The H-band, centered around the M-line, contains only ________.

The area where actin and myosin overlap.

Troponin and tropomyosin respond to changes in ________.

The cross-bridges on the head of each myosin molecule contain _________, which hydrolyzes _____, and the released energy is used to...

What are the 8 steps in muscle contraction?

What are the 3 steps in muscle relaxation?

A contraction when the external length of the muscle does not shorten during contraction.

A contraction when the external shortening occurs while tension remains approximately constant.

When the load imposed by a muscle exceeds the force developed by the muscle, ________ is minimal and little or no _______ is detected.

The length-tension relationship is based on the amount of....

The greater the degree of overlap between myosin and actin, the greater the number of _______ and thus, the greater the ____________.

The velocity of muscle shortening is related inversely to the _______ so that as the speed at which actin and myosin slide past each other increases, the ________________ that can be formed decreases.

The force developed the stretching.

Force which results from cross-bridge formation and sarcomere shortening.

The tension developed each time the muscle is stimulated to contract at a new length.

The velocity of muscle shortening is inversely related to the...

Purposeful muscle contractions appear as smooth, sustained, forceful contractions because of... (3)

When the frequency becomes so fast that no relaxation occurs between contractions, and the contractions become fused.

As the demand for greater force of contraction is required of the muscle, more individual motor units containing more fibers per unit are made to contract. As individual motor units contract, they do so ___________ so that the contraction becomes smooth and sustained.

ADP is rephosphorylated to ATP by the transfer of phosphate from __________.

The total amount of energy available from creatinine phosphate must be replenished by _______ and _________.

Muscle fatigue closely parallels depletion of _________.

Red muscle contains the oxygen-storing protein ________; it is adapted for...

White muscle contains ________; it is adapted for...