A&P Ch 12 hmwk & quiz

Rank in order the events that occur when an action potential reaches the transmissive segment of an axon.

1- Action potential reaches synaptic knob 2- Voltage-gasted calcium channels open 3- Vesicles containing neurotransmitter merge with plasma membrane 4- Neurotransmitter diffuses across synaptic cleft

What is the correct order for the events of neurotransmitter release from the synaptic terminal? 1 - Extracellular Ca2+ enters terminal and binds to sensor protein in the cytoplasm 2 - Exocytosis of neurotransmitter into synaptic cleft 3 - Action potential reaches axon terminal 4 - Ca2+-protein complex stimulates fusion of the docked synaptic vesicle with the plasma membrane 5 - Voltage-gated Ca2+ channels open

3,5,1,4,2

What is produced when depolarization of a cell membrane reaches threshold?

A new action potential is produced

Which occurs first?

Absolute refractory period

The type of transport protein that moves a substance down its concentration gradient is a:

Channel

A decrease in the extracellular concentration of potassium

Depolarization

An increase in the number of sodium leak channels

Depolarization

Decrease in the membrane potential

Depolarization

Inside of the cell becomes more positive

Depolarization

Opening of voltage-gated sodium channels

Depolarization

When a neurotransmitter opens a chemically gated ion channel that allows sodium to enter the postsynaptic cell, the result is an:

EPSP

As it moves from the tip of a dendrite to the axon hillock, a postsynaptic potential will maintain a constant amplitude.

False

Channels require energy in order to function as transport proteins.

False

Ganglia are clusters of neuron cell bodies located within the CNS.

False

In neurons, protein pumps allow substances to move passively down their concentration gradients.

False

Neurons are unique in that they do not require glucose or oxygen to function.

False

Which is not characteristic of neurons?

High mitotic rate

An increase in the extracellulalar concentration of potassium

Hyperpolarization

Increase in the membrane potential

Hyperpolarization

Inside of the cell becomes more negative

Hyperpolarization

Opening of gated chloride channels

Hyperpolarization

When a neurotransmitter causes the opening of chemically gated potassium channels on the postsynaptic cell, the postsynaptic potential that results is an:

IPSP, which is a hyper polarization

Which functional class of neurons lies entirely within the central nervous system?

Interneurons

Check all that are a function of the nervous system.

Processing and evaluating information Collecting information Responding to information

Select all the appropriate classifications for a nerve that sends sensory information from the eye to the brain.

Sensory Cranial

Which part of the neuron contains the nucleus?

Soma

Select all that are true of inhibitory postsynaptic potentials.

The postsynaptic cell hyperpolarizes

Select all the characteristics of graded potentials.

They are the result of chemically-gated ion channels opening. The current generated is localized. The current generated decreases with distance.

What do all glial cells have in common?

They assist neurons in their respective functions

Which is not a function of the motor division of the nervous system?

Transmits impulses from the viscera

A postsynaptic potential is a graded potential.

True

Nerve impulses are only transmitted along exposed portions of an axon.

True

Postsynaptic neurons can generate both inhibitory and excitatory postsynaptic potentials simultaneously.

True

Sodium has a higher concentration outside the cell than within.

True

Some inhibitory neurotransmitters exert their effect by causing the opening of chloride channels, which results in the postsynaptic membrane becoming more negative.

True

Voltage-gated sodium channels at a neuron's initial segment are triggered to open when the membrane becomes more positive.

True

If extracellular calcium was absent, which would likely be true?

Vesicles containing neurotransmitter would not merge with the plasma membrane

Conductive activity in a neuron generally causes it to secrete:

a specific neurotransmitter that either excites or inhibits its target

A recently depolarized area of a cell membrane cannot generate an action potential because of the

absolute refractory period

The conductive segment of a neuron is its _______, a region that contains many _______ gated channels.

axon, voltage-

One dendrite and one axon:

bipolar neuron

When a nerve impulse reaches the transmissive segment of a neuron:

calcium diffuses into the neuron and neurotransmitter is released by exocytosis

When a neurotransmitter binds a protein channel, it opens and lets sodium diffuse down its concentration gradient. This is an example of a

chemically-gated sodium channel

The nervous system controls the activity of muscles and glands. Muscles and glands can generate changes and are therefore called:

effectors

Neurons that carry signals from the CNS to skeletal muscle for contraction would be classified as _____________ neurons.

efferent

On a graph of an action potential, the small depolarizations that lead to threshold are from

excitatory postsynaptic potentials (EPSPs)

If neurotransmitter from Neuron A causes Neuron B to hyperpolarize, this is an example of an

inhibitory postsynaptic potential

Based on function, 99 percent of neurons are:

interneurons

A nerve:

is a cable like bundle of parallel axons

Based on structure, the most common type of neuron is the _______ neuron.

multipolar

Many dendrites and a single axon:

multipolar neuron

A nerve impulse travels fastest along ________ axons of ______ diameter.

myelinated, large

In neurophysiology, the term summation refers to the addition of:

postysynaptic potentials at the initial segment

The afferent division of the nervous system is also known as the _____ division.

sensory

A mixed nerve refers to one that contains both:

sensory and motor neurons

The ___________ nervous system transmits information from receptors to the CNS, while the ___________ nervous system transmits information from the CNS to the rest of the body.

sensory; motor

The portion of the nervous system that conducts impulses from the skin, joints, skeletal muscles, and special senses is the ___________ division.

somatic sensory

A typical synapse in the CNS consists of a presynaptic neuron and a postsynaptic neuron, separated by a narrow space called the ___________.

synaptic cleft

When threshold is reached, depolarization occurs with the same amplitude of potential change. This is known as

the All-or-None Law

When transmission occurs at a synapse, neurotransmitter is released by:

the presynaptic neuron's synaptic knob into the synaptic cleft

The negative value of the resting membrane potential means

there are more negatively charged particles on the inside of the membrane than on the outside.

One process with two branches; one extending to the CNS, one extending to the periphery

unipolar neuron

A neuron conducting an impulse from the stomach wall to the CNS would be classified as a(n) __________ neuron.

visceral sensory