Nerves

The flow of _____ ion is the most common cause of depolarization.

Sodium

An action potential cannot be initiated during the absolute refractory period because _____.

Sodium channels are inactived, and this can not open

Which of the following membrane transports are present throughout the membrane of a neuron?

Sodium leak channels Na+/K+ pumps Potassium leak channels

A change in membrane potential insufficient to cause an action potential is known as a

Subthreshold value

Neurons integrate multiple synaptic inputs by the process of _____.

Summation

The process by which postsynaptic potentials are added together at the initial segment is known as _____.

Summation

Neurotransmitters are store in ______.

Synaptic vesicles

"An action potential either happens or it doesn't". This statement could also be called

The all-or-none law

Which describes the propagation of depolarization down an axon?

The flow of Na+ to downstream regions causes depolarization of adjacent region

If summated PSPs reach threshold, an action potential begins first in _____.

The initial segment

The voltage-gated sodium channels undergo changed in activity during the depolarization phase of an action potential. Place these in order from first to last.

The membrane potential is -70 mv Sodium ions flow into the neuron The membrane potential becomes more positive Voltage-gated sodium ion channels open

The all-or-none law refers to the fact that action potentials will only occur if the initial segment reaches _____.

Threshold

In the initial segment, an action potential is generated if the membrane potential reaches the _____ _____.

Threshold Value

Voltage-gated calcium channels are found mostly in the ______ segment of a typical neuron.

Transmissive

In the ______ of a neuron, you would be likely to find voltage-gated calcium channels.

Transmissive segment

If an analogy is drawn between action potential and shooting a gun, then the initial segment is analogous to the _____.

Trigger

True or False: In most cases, a single EPSP is not sufficient to cause a neuron to reach the threshold potential.

True

True or False: Most voltage-gated ion channels are closed until the electrical potential across a membrane changes.

True

True or False: There are more potassium leak channels in a neuron membrane than sodium leak channels.

True

True or False: Voltage-gated sodium ion channels are closed initially and the membrane potential is -70mv.

True

______ are unique channels in that they have three states; resting, activation, and inactivation.

Voltage-gated channels

______ are not commonly found in the receptive segment of a neuron.

Voltage-gated ion channels

_____ and are the cause of hyperpolarization in an action potential.

Voltage-gated potassium channels remain open

According to Ohm's law, the current is directly related to ______, and inversely directed to ______.

Voltage; Resistance.

_____ there would be no net movement of K+ ions through an open K+ leak channel.

When the electrical gradient and chemical gradient balance each other

If a subthreshold value is reached on an axon membrane, an action potential ______.

Will not occur

Channels that allow an ungated flow of specific ions from regions of high concentration to regions of low concentration are called ______ channels.

leak

Place the events of synaptic transmission from earliest to latest.

1. Action potential reaches synaptic knob 2. Voltage-gated calcium channels open 3. Calcium enters the synaptic knob 4. Calcium triggers exocytosis of vesicles 5. The neurotransmitter diffuses across the synaptic cleft 6. The neurotransmitter binds to polysynaptic receptors

Place the events of an EPSP in order

1. Excitatory neurotransmitter binds to chemically gated cation channel 2. More Na+ enters the postsynaptic cell than K+ leaves 3. The inside of the cell becomes more positive 4. The local current of Na+ becomes weaker as it moves towards the axon hillock

Match the location with the larger concentration of ions. 1. Extracellular 2. Intracellular

1. Sodium 2. Organic ions

Place the events of a chloride-based IPSP in order from earliest to latest

1. The inhibitory neurotransmitter binds to postsynaptic chemically gated chloride channels 2. Chloride moves from outside the cell to the inside 3. the inside of the postsynaptic cell becomes more negative 4. The local chloride current become weaker as it moved away from the neurotransmitter binding site.

Membrane pumps require ______ energy.

A lot of

______ is a type of membrane transport protein that increases the potential energy across a membrane.

A pump

The leak of potassium ion tends to drive the membrane potential to -90millivolts, and yet the normal resting membrane potential (RMP) of a neuron is around -70 millivolts. What is the reason for this difference?

A small leak of sodium ion makes the RMP more positive

Before a vesicle of neurotransmitter can be released which of the following must occur?

Action potential reaches synaptic knob Voltage-gated calcium channel open

The refractory period occurs immediately _____ an action potential.

After

The relative refractory period occurs _____ the absolute refractory peroid.

After

Current is measured in

Amps

The nerve impulse causes _____ in the number of calcium ions that enter the synaptic knob.

An increase

The voltage-gated sodium channels _____ during repolarization.

Are inactivated

The voltage-gated potassium channels _____ during repolarization.

Are open

Voltage-gated sodium channels _____ during the relative refractory period.

Are returning to the resting state

The synapse is located ______ the presynaptic neuron and postsynaptic neuron.

Between

A synapse is a junction ______.

Between a neuron and another cell

Many excitatory neurotransmitters cause the opening of channels that allow for the flow of ______.

Both Na+ and K+

The presence of _____ ions causes the synaptic vesicles to bind to the membrane, allowing neurotransmitters to be released.

Calcium

Most synapses in the human body are ______ synapses.

Chemical

______ use neurotransmitters.

Chemical synapses

A ______ is a channel that is usually closed but which opens in response to binding a neurotransmitter.

Chemically gated channel

The total length of the axon is called the _____ segment.

Conductive

The main activity of the _____ is the propagation of an action potential along the axolemma.

Conductive segment

Of Ohm's law is rearranged to Voltage = "A" X resistance, the term "A" should be

Current

What is the movement of charged particles called?

Current

The electrical gradient in a resting neuron is such that the ______ of the cell is negative relative to the ______.

Cytosol, outside

A positive change in the membrane potential is called _____.

Depolarization

The event that occurs when the inside of the cell becomes more positive (less negative) than the resting membrane potential is called _____.

Depolarization

Membrane channels provide the means to move a substance ______ its concentration gradient.

Down

Numerous _____ must be generated and arrive at the initial segment at nearly the same moment if threshold is to be reached.

EPSPs

Creating and transmitting ___________ currents is central to the function of neuron physiology.

Electrical

A difference in the number of charged particles between two sides of the membrane forms a(n) ______.

Electrical gradient

Gap junctions are found in ______.

Electrical synapses

______ allow ions to pass from one neuron to the other.

Electrical synapses

True or False: Ion channels use the energy of ATP to maintain concentration gradients across neuron membranes.

False

True or False: Many voltage-gated channels are found in the receptive segment of a neuron

False

True or False: The relative charge across a neuron's plasma membrane is negative outside the cell relative to the inside of the cell.

False

The flow of sodium ions through sodium channels is best described as ______.

From outside the cell to inside

Negatively charged proteins and other large molecules are found in ______.

Greater amounts inside a neuron

The ______ the resistance, the ______ the current.

Higher, Lower

Immediately following the repolarization of an action potential, the membrane undergoes _____ before returning to the resting membrane potential.

Hyperpolarization

The event that occurs when the inside of a cell becomes more negative than the resting membrane potential is called _____.

Hyperpolarization

_____ is what underlies the absolute refractory period.

Inactivation of sodium channels

Many local anesthetics prevent the transmission of pain by _____.

Inhibiting voltage-gated sodium channels

The changes in membrane potential associated with both EPSP and IPSP inputs are "added" in the _____ to determine if an action potential is initiated and the theshold is reached.

Initial segment

Smooth muscle contraction is under ______ control of the nervous system.

Involuntary

During an action potential, voltage-gated potassium channels open after voltage-gated sodium channels. The effect this has on the membrane potential is _____.

It becomes less positive and more negative

The sequential opening of voltage-gated sodium channels is followed by he sequential opening of voltage-gated _____ channels.

K

The resting membrane potential is measured in

Millivolts

The threshold is reached when the _____ ions flow into the cell.

Na+

The nerve impulse has the voltage-gated ______ channels opened first followed by the opening of the voltage-gated ______ channels.

Na+, K+

Which of the following ions have leak channels on the plasma membrane?

Na+, K+

_____ to help return the membrane potential to the resting state following hyperpolarization.

Na+/K+ pumps restore gradients Voltage-gated potassium channels close

Which of the following pumps can you find in the plasma membrane?

Na+/K+, Ca2+

A _____ is the propagation of an action potential along an axon.

Nerve signal

Chemicals that are released from synaptic knobs and bind to receptors on postsynaptic membranes are called ______.

Neurotransmitter

In neurons, most chemically gated ion channels open in response to the binding of a(n)

Neurotransmitter

Which of the following would be likely to cause hyperpolarization of a neuron?

Opening of a chemically gated chloride channel Opening of a voltage-gated potassium channel

Which of the following would be likely to cause depolarization of a neuron?

Opening of a chemically gated sodium channel Opening of a voltage-gated sodium channel

When sodium ions flow into a cell through a leak channel they make the membrane potential more _____.

Positive

When sodium ions flow into a cell through a leak channel they make the membrane potential more ______.

Positive

An inhibitory neurotransmitter may cause the opening of a ______ channel.

Potassium Chloride

Voltage is a measure of relative ______ energy.

Potential

Voltage represents ______ energy.

Potential

A ______ transmits an impulse through its axon toward the synapse.

Presynaptic

Propagation of depolarization only flows away from the cell body towards the synaptic knob because _____.

Previous regions in the axon have sodium channels in the inactive state

If an analogy is drawn between action potential and shooting a gun, then reaching the threshold would be analogous to _____.

Pulling the trigger

An axon is either incapable of generating an action potential or requires a larger than normal stimulus during the _____ period.

Refractory

The period following an action potential in which an action potential can be inhibited with a larger stimulus is known as _____ _____ period.

Relative Refractory

A return of the membrane potential towards the resting membrane potential immediately the following depolarization is called.

Repolarizatioin

The opposition to the movement of electoral charge is known as ______.

Resistance

The relative difference in change across the plasma membrane of a resting neuron is known as the ______ ______ ______.

Resting membrane potential

The function of a neuron is dependent on ______.

Resting membrane potentials changing

Na+ and K+ leak channels and Na+/K+ pumps on the neuron are responsible for establishing and maintaining the ______ membrane ______.

Resting, Potential

______ is a typical resting membrane potential for a neuron.

-70 millivolts

Initially, the voltage-gated Na+ channels are closed and the membrane potential is ______ mV. As Na+ flows in the membrane potential changes to ______ mV and the threshold is reached.

-70; -55

If only K+ leak channels were present, the membrane potential would be ______.

-90mV

If only K+ leak channels were present, the membrane potential would be _________.

-90mV