{A&P} Chapter 12

Suppose you were to treat a normal mammalian cell with a substance that inhibits the Na-K ATPase. Would be the most immediate effect upon the cell? A. There would be no change at all. B. The cell's osmotic balance were be disrupted, and the cell would begin to swell. C. The cell membrane potential would immediately drop to zero. D. The cell would very quickly run out of ATP. E. The cell could not create an action potential.

E. the cell could not create an action potential

True or False. Once initiated, action potentials decrease in strength over distance.

False

True or False. Saltatory conduction occurs because of the presence of salt (NaCl) around the neuron.

False

In response to a stimulus, if the membrane potential becomes more negative than the resting potential, we say the membrane is _______________.

Hyperpolarization

What is the difference between the absolute and relative refractory period?

In the relative period, generating another action potential is possible because sodium gates are closing and can be reopened. In absolute, there are no more sodium gates to open, so there will not be another action potential

A graded potential in an unmyelenated neuron is _______ (more or less) likely to decay.

More

The two ways ions may pass across a membrane involve using _____ channels and _____ channels.

Leaky, Gated

Movement of Cl- into a neuronal cell would make a neuron _____ (more or less) likely to fire an action potential.

Less

How are gated channels different than leaky channels?

leaky channels never close

Define threshold

-55mV, safety mechanism against noise

Name two ways action and graded potentials are different

Action potentials don't decay over time Action potentials are large charge changes while graded potentials are small

In class, we said that action potentials are anterograde. What does this mean?

APs only flow in one direction

Are action potentials negative or positive feedback systems? How do we know which of these they are?

Action potentials are negative because it eventually restores itself back to resting potential

Organophosphate chemicals such as nerve gas and sarin act by preventing acetylcholinesterase, the enzyme that removes acetylcholine (AcH). Atropine is a chemical given to patients or soldiers poisoned with organophosphates and nerve agents, to prevent their effects. Generally speaking, how do you think atropine does this?

Atopine stops organophosphate from blocking acetylcholinesterase, therefore blocking organophosphate from keeping the sodium channel open and allowing the neuron to function properly

Which portion of the neuron acts as the "conducting zone" for transmitting impulses?

Axon

Electrical impulses gather and accumulate in which specific part of a neuron, in order to initiate an action potential?

Axon Hillock

Cyanide poisoning inhibits ATP synthesis. Which specific neuron structure would be MOST affected by cyanide poisoning?

Axon hillock

What is acetylcholine affect on the postsynaptic membrane a. Neurotransmitter Hyperpolarizes the Post Synaptic membrane. b. Opens Na+ channels c. Causes Post Synaptic Inhibition d. Opens Cl- channels or K+ channels

B. Opens Na+ channels

To increase the amount of neurotransmitter released onto a postsynaptic cell, the presynaptic cell would have to: a. send action potentials with longer durations. b. send action potentials with higher frequency. c. send action potentials with higher voltage (higher amplitude). d. do nothing; no change is possible since the all-or-none law is in effect.

B. send action potentials with higher frequency

In response to a stimulus, if the membrane potential becomes more positive than the resting potential, we say the membrane is _______________.

Depolarization

Suxamethonium acts on post-synaptic receptors much like acetylcholine does. But suxamethonium stimulates the receptor for much longer, preventing acetylcholine from acting. After a few seconds, the muscle becomes paralysed. Which post-synaptic action potential stage does suxamethonium block? a. resting potential b. depolarization c. repolarization d. hyperpolarization

C. repolarization

What specific event leads to the release of neurotransmitter at the synapse?

Calcium must enter

Neurons cannot divide. They lack a specific organelle that is needed for cell division. What is the name of this organelle

Centrioles

What is the specific function of the structure from #25?

Connects soma to axon

A gap between Schwann cells in the peripheral system is called a(n) ________.

Nodes of Ranvier

An Alzheimer's patient most likely has defective _____________ cells.

Oligodendrocytes

In lecture, we used batteries to describe action potentials, which cell structure is similar to the battery barrier that separates charge?

Plasma Membrane

At resting potential, the ion distribution inside and outside of a neuron is such that __________ ions are most abundant on the outside of the cell, while __________ ions are most abundant on the inside of the cell.

Positive, Negative

Why does the action potential hyperpolarize? In other words, what is the structural explanation for hyperpolarizations?

Potassium channels take longer to close

Neurons store neurotransmitter molecules in vesicles located within _____.

Presynaptic neuron

In lecture, we used batteries to describe action potentials, which cell structure is similar to the battery pathway of electron flow?

Proteins/gates and pumps

How is temporal and spatial summation different?

Temporal~ an excitatory neuron fires rapidly, more than once Spacial~ 2 excitatory neurons fire at the same time

In class, we described all action potentials as having the same intensity. What does this mean?

That they will have the same strength/amplitude no matter how strong the stimulus, it will not change

Why is the absolute refractory period, 'absolute'?

There are a set number of gates and they are all already open during the absolute refractory period

Why does the nervous impulse travel faster when the nerve is covered with myelin?

There will be less channels for ions to leak out of, insulated

What happens to excess neurotransmitter produced by presynaptic neurons?

They are recycled by pumps

True or False. If the post-synaptic receptor allows sodium to move through it, an excitatory post-synaptic potential (EPSP) will be generated.

True

True or False. Strong stimuli cause the amplitude of action potentials generated to increase.

True

True or False. Threshold voltage (-55mV) is the same for every action potential regardless of location or neuron type.

True

If the stimulation of a cell is strong, the strength of the action potential produced will be _______ (higher than normal, lower than normal, or about the same.)

about the same

In class, we described axon potential velocity on an axon to a series of dominos. We said that once the first domino "falls" the rest of them falling is automatic. If action potentials are the same, which neuron structure "starts" the automatic generation of all action potentials on an axon?

axon hillock

Which part of the neuron has Schwann cells associated with it?

axon/myelin sheath

The impulse normally travels from the ____ to the ____ of a neuron. a. dendrite, dendrite b. dendrite, axon c. axon, axon d. axon, dendrite

b. dendrite, axon

Generally speaking, what is the function of the cell body?

biosynthetic center to make proteins

Place the events of the Action Potential in theIr correct sequence. A. Sodium Gates Close Potassium Gates Open B. DEPOLARIZATION C. Resting Potential Restored D. Potassium OUT - REPOLARIZATION E. Active Transport of Na+ & K+ F. All Sodium Gates OPEN a. A-B-C-D-E-F b. D-F-C-B-E-A c. F-B-A-D-E-C d. A-D-F-B-C-E e. F-E-D-C-A-B

c. F-B-A-D-E-C

An absolute refractory period in nerve stimulation is when the nerve a. Requires stronger stimulus to generate an action potential b. Requires weaker stimulus to generate an action potential c. There is no response of the neuron to any stimulus

c. There is no response of the neuron to any stimulus

When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs? a. temporal summation b. hyperpolarization c. spatial summation d. decrease in speed of impulse transmission e. inhibition of the impulse

c. spacial summation

The ion necessary to initiate the release of acetylcholine into the synaptic cleft is __________.

calcium

Opening and closing of ________________cause the characteristic phases of the action potential.

channels

What type of gate are the post-synaptic receptors

chemical

How do neurons alter their membrane potential? a. Proton pumps on the cell membrane are activated, which pump protons outside the cell. b. Neurons change the mitochondrial membrane potential, which is then propagated to the plasma membrane. c. Neurons selectively alter the permeability of their membranes to ions by changing the phospholipid composition of their membranes. d. Neurons selectively alter the permeability of their membranes to ions by opening and closing gated ion channels in the membrane.

d. Neurons selectively alter the permeability of their membranes to ions by opening and closing gated ion channels in the membrane.

If the activity of the Ca2+ voltage gates decreased, then likelihood of a post synaptic potential would _________ (increase, decrease, or stay the same).

decrease

If the number of dendrites on a neuron decreases, the neuron's ability to generate an action potential _________ (increases, decreases, or stays the same).

decrease

If the number of post-synaptic receptors increased, then the likelihood of a post-synaptic potential would _________ (increase, decrease, or stay the same).

decrease

If the synapse between neurons is inhibitory, the probability of the next neuron firing, _____________ (increases, decreases, or remains the same).

decrease

If the amount of myelin wrapped around an axon decreases, then the neuron's ability to generate an action potential _________ (increases, decreases, or stays the same).

decreases

In Alzheimer's patients, the number of Nodes of Ranvier _________ (increases, decreases, or stays the same).

decreases

Which part of the action potential is produced by the rapid influx of sodium?

depolarization

Once a neurotransmitter has attached to it's receptor, how does it release from that receptor?

enzyme plucks it off

True or False. Neurotransmitters are destroyed after they have been used.

false

True or False. Neurotransmitters are specific to the post-synaptic receptors

false

Why do all action potentials have the same amplitude, regardless of neuron type or location?

fixed number of gates and fixed concentration of sodium

How are gated channels different than pumps?

gated channels don't use ATP

If the number of synaptic vesicles increased, then the likelihood of a post synaptic potential would _________ (increases decrease, or stay the same).

increase

If the number of voltage gates at the axon hillock increases, then the neuron's ability to generate an action potential _________ (increases, decreases, or stays the same).

increase

Generally speaking, there are _____ (more, less, or about the same) number of voltage gates and pumps on the dendrites and soma, as there are on the entire axon.

more

Unmyelinated axons require ________ (more, less, or about the same) ATP as myelinated axons.

more

The insulating lipid elaborated by oligodendrocytes centrally or Schwann cells peripherally that surrounds the axons is called ______.

myelin*

Generally speaking, relative to the outside of the cell, the neuron's interior is _________ (positive, negative, or neutral) charged.

negative

In class, we described axon potential velocity on an axon to a series of dominos. We said that once the first domino "falls" the rest of them falling is automatic. If action potentials are the same, which neuron structure represents each domino?

nodes of ranvier

Which cell organelle is responsible for separation of charge?

plasma membrane

In class we described action potentials as movement of ions along a neuron at specific locations, at discrete moments of time. Which specific structure is responsible for redistributing ions back to resting conditions?

pumps

What specific structure prevents action potentials from travelling retrograde?

pumps

Which specific structure prevents the action potential moving in "reverse" along an axon?

pumps

How does neurotransmitter return to its pre-synaptic vesicles?

pumps/active transporters

Myelinated axons have Nodes of Ranvier. What is the function of the Nodes of Ranvier?

recharge

During which part of action potential, the slow voltage gated K + channels close?

repolarization

Tetraethylammonium ion (TEA) inhibits K+ gated channels. If your patient consumed TEA they would die because they would no longer be able to generate an action potential. Which specific portion of their neuron action potentials would be missing?

repolarization

Which of the following cells would be likely to myelinate an axon in your leg?

schwann cells

Once released, neurotransmitters eventually bind to chemical gated receptors on the post-synaptic membrane. What specific force drives the neurotransmitter towards the post-synaptic receptors?

simple diffusion

Which ion crosses the neuron membrane through open gated ion channels to initiate a graded potential?

sodium

Which portion of the neuron release chemical neurotransmitters?

synapse/synaptic knob, telodendria

Where are neurotransmitters "stored", before the action potential arrives?

synaptic vesicles

What is the "All-or-None" phenomenon of action potentials?

the action potential will happen completely or not at all, there has to be a 15 mV change

If the interval between voltage gates and pumps on a dendrite decreases, then the signal most likely would ___________.

travel faster????

True or False. An excitatory post-synaptic potential (EPSP) would be cancelled out by an inhibitory of post-synaptic potential (IPSP) if their charges were equal in strength and occurred at the same time.

true

True or False. In animals, Na+ concentration is higher outside of the cell than inside.

true

In lecture, we used batteries to describe action potentials, which cell structure is similar the battery "on" and "off" switch?

voltage gates