LS 12

A flow of electrical current called an _________ ___________ is generated within the initial segment of a neuron

action potential

The __________ of the functional division of the nervous system provides involuntary control of smooth muscle

autonomic motor

The postsynaptic potential immediately follows the binding of neurotransmitter molecules that can

be both excitatory and inhibitory

The somatic sensory division detected stimuli that are __________ detected

consciously

The epineurium is made of _________ connective tissue

dense irregular

The tissues that receive nerve impulses from motor neurons are called

effectors

A difference in the number of charged particles between two sides of membrane forms a

electrical gradient

The electrochemical gradient is formed from a combination of the ________ gradient and the _________ gradient

electrical, chemical

A ______ is a cluster of neuron cell bodies with the peripheral nervous system

ganglion

The sensory division of the nervous system is responsible for

input

charged particles

ions

Type B

medium conduction velocity

voltage

membrane potential

The resting membrane potential is measured in ___________

millivolts

__________ neurons are most common

multipolar

The presence of a ________ sheath increases the rate of impulse conduction

myelin

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

neurotransmitter

The neuron cell body hoses both the ________ and the cytoplasm

nucleus

bipolar neurons have one axon and ______ dendrite

one

The motor nervous system is responsible for ________

output

A fascicle is surrounded by a layer of dense irregular connective tissue called _______

perineurium

resistance

plasma membrane

A graded potential that occurs in a postsynaptic neuron is known as a

postsynaptic potential

The sequential opening of voltage-gated sodium channels is followed by the sequential opening of voltage-gated ________ channels

potassium

intracellular

potassium, organic anions

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

repolarization

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

summation

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

the all-or-none law

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

threshold potential

Sensory nerves carry information

to the central nervous system

________ are NOT commonly found in receptive segment of a neuron

voltage gated ion channels

According to Ohms law, current is related to ________, and inversely directed to _______

voltage, resistance

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

K+, Na+

A unipolar neuron has one extension. a bipolar neuron has ____ extensions

2

Place the events of synaptic transmission from earliest to latest

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

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

Na+/K+ pumps, sodium leak channels, potassium leak channels

If several EPSP's occur at different synapses, they undergo ________ at the initial segment.

Spatial summation

The refractory period occurs immediately ________ an action potential

after

Action potentials are always propagated along an axon at the same _______ but _______ can vary depending on the strength of the stimulus

amplitude, frequency

A substance synthesized at the cell body must undergo________ transport to reach the synaptic knobs

anterograde

_________ neurons have a single, short neuron process that emerges from the cell body and branches like a T.

Unipolar

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

Voltage-gated channels

The plasma membrane of an axon is called the

axolemma

Extracellular ions

chloride, sodium

Type A

conduction velocity up to 150 meters per second

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

conductive segment

________ nerves extend from the brain, while _______ nerves extend from the spinal cord

cranial, spinal

An individual axon is wrapped in a connective tissue covering called the

endoneurium

The "E" is EPSP stands for __________, meaning that the potential makes the inside of the postsynaptic cell more __________

excitatory, positive

When chemically or voltage gated channels open, there is a change in ion _______ across a membrane

flow

current

flow of ions through the ion channels

If you were moving across a neurons membrane from the receptive segment toward the transmissive segment, in the _________ is where you would first encounter large numbers of voltage-gated Na+ and K+ channels

initial segment

The brain interprets the increased frequency of nerve signals as a ________ stimulus

more intense

The opposite to the movement of electrical charge is known as

resistance

Interneurons facilitate communication between ________ neurons and ________ neurons

sensory and motor

________ are found in mixed nerves

sensory and motor axons

which of the following are functional classes of neurons?

sensory neurons, motor neurons, interneurons

Which of the following are considered types of effectors?

skeletal muscle, cardiac muscle, glands

Type C

slowest conduction velocity

The flow of _______ ion is the most common cause of depolarization

sodium

___________ are voltage-gated ion channels that have two gates

sodium channels

Which two are divisions of the sensory nervous system

somatic division and visceral division

If several EPSP's occur at different synapses, they undergo ________ at the initial segment

spatial summation

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

subthreshold value

The components of the somatic sensory division are

taste, joints and muscles, hearing

If several EPSP's occur at a synapse over a short period of time, they undergo _________ at the initial segment

temporal summation

Which of the following segments of a neuron contain large numbers of voltage-gated potassium channels and voltage-gated sodium channels?

the initial segment and conductive segment

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

threshold value

Dendrites transfer information ________ the cell body

toward

Voltage-gated calcium channels are found mostly in the _________ segment

transmissive

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

true

Most channels have ____ gates, but a sodium channel has ______ gates

two, three

Most afferent neurons are classified functionally as

unipolar

The _________ division of the nervous system detects nerve impulses from blood vessels and internal organs

visceral sensory division

_____________ are membrane molecules that use the energy of ATP to move ions against a concentration gradient

Pumps

_________ is a typical resting membrane potential for a neuron

-70 millivolts

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

A pump