A&P chapter 12

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

pumps

during ______ ______ an axon is either incapable of generating an action potential or requires a larger than normal stimulus

refractory period

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

repolarization

If several EPSPs occur at different synapses, they undergo ______ at the initial segment

spatial summation

Identify all of the components of the central nervous system

spinal cord and brain

Receptors detect changes in the external or internal environment. These changes are called

stimuli

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

summation

Axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

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

Dendrites transfer information ___ the cell body

toward

Which of the following are structural classifications of neurons

unipolar, bipolar, multipolar

Which two are divisions of the sensory nervous system?

visceral division, somatic division

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. Neurotransmitter diffuses across synaptic cleft 6. Neurotransmitter binds to postsynaptic receptors

Place the events of an EPSP in order

1. Excitatory neurotransmitter binds to chemically gated cation channel 2.more Na+ enters postsynaptic cell that 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

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

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

The voltage gates sodium channels undergo changes in activity during the depolarization phase of an action potential.

1. The membrane potential is -70 mv 2. Sodium ions flow into the neuron 3. The membrane potential becomes more positive 4. Voltage gated sodium ion channels open 5. -55mv threshold is reached

Sensory ___ neurons carry information ____ the central nervous system

Afferent/toward

Voltage-gated sodium channels ___ during the relative refractory period

Are returning to the resting state

The ____ division of the nervous system is subdivided into the sympathetic and parasympathetic division

Autonomic

The presence of ____ ions causes the synaptic vesicles to bind to the membrane, causing neurotransmitters to be released

Calcium

axon hillock

Cone shaped region of an axon where it joins the cell body.

Which terms are used for the structural classification of nerves

Cranial and spinal

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

Excitatory/positive

Match the location with the larger concentration or ions

Extracellular- chloride/sodium Intracellular-organic anions/potassium

___ describes the propagation of depolarization down an axon

Flow of Na+ to downstream regions causes depolarization of adjacent regions

Neuron cell bodied in the peripheral nervous system are found clustered in

Ganglia

A(n) ____ results in a swelling, or enlarged portion, along the length of the nerve, which is often large enough to be observed with the naked eye

Ganglion

Synapses occurs where axons contact which of the following

Gland cells, muscle cells and other neurons

____ is what underlines the absolute refractory period

Inactivation of sodium channels

The "I" in IPSP stands for ___, meaning that the potential makes the inside of the postsynaptic cell more ___

Inhibitory/ negative

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

Initial segment

____ cells wander through the CNS and replicate in response to an infection

Microglial

____ nerves contain both sensory and motor neurons

Mixed

Derived from certain amino acids

Monoamine

As more neurotransmitter is released, ___ channels open in the postsynaptic neuron

More

A (n) _____ is much more efficient because saltatory conduction occurs and less energy is required to maintain the RMP

Myelinated axon

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

Na+, K+

________________ is the propagation of an action potential along an axon

Nerve impulse

In the ___ there are a lot of ion channels and very little myelin

Neurofibril node

Chain of amino acids secreted as neurotransmitter

Neuropeptide

A toxin which interferes with the activity of neurons is called a ____

Neurotoxin

Bipolar neurons have one axon and ___ dendrites

One

When the inactivation gate of the V-gated Na+ channel closes the activation gate is

Open

fascicle is surrounded by

Perineurium

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

Potassium leak channels, sodium leak channels and Na+/K+ pumps

The period following an action potential in which an action potential can be initiated with a larger stimulus is known as the ____ ____ period

Relative refractory

A nerve impulse that "jumps" from node to node is called ___ conduction

Saltatory

___ help regulate fluid composition including the exchange of nutrients and waste in the nervous system

Satellite cells

A ___ neuron transmits stimuli to the interneuron

Sensory

Considered types of effectors

Skeletal muscle, cardiac muscle, glands

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

Sodium

____ are voltage gated ion channels that have two gates

Sodium channels

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

The conductive segment and initial segment

What must happen in order for a chemical signal to change the membrane potential of a neuron

There must be a change in ion flow across the membrane. There must be a change in the number of open ion channels

The conductive segment of a neuron is/are the ___

Total length of the axiom

Vesicles involves in retrograde transport are moving ____ the cell body

Toward

voltage-gated calcium channels are found mostly in the ___ segment

Transmissive

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

Trigger

In most cases, a single EPSP is not sufficient to cause a neuron to reach the threshold potential

True

___ 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 inactiviation

Voltage gated channels

___ are NOT commonly found in the receptive segment of a neuron

Voltage gated ion channels

Dendrites

a neuron's bushy, branching extensions that receive messages and conduct impulses toward the cell body

Building blocks of proteins secreted as neurotransmitters

amino acids

The plasma membrane of an axon is called the ___

axolemma

The central nervous system is made of the ____ and spinal ___

brain and cord

Soma is another name for

cell body

Sensory nerves carry information ____

central nervous system

Synapses are classified as:

chemical synapses and electrical synapses

axoplasm

cytoplasm of axon

A positive change in the membrane potential is called

depolarization

The tissues that receive nerve impulses from motor neurons are called

effectors

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

endoneurium

An entire nerve is surrounded by a connective tissue covering called the:

epineurium

The nervous system is composed of the brain, spinal cord, nerves and ___

ganglia

____ occurs when the inside of a cell becomes more negative than the resting membrane potential

hyperpolarization

Glial cells are found:

in both the central and peripheral nervous system

_____ are also called association cells because they link up sensory and motor neurons.

interneurons

Which of the following are functional classes of neurons

interneurons, motor neurons, sensory neurons

________ neurons are the most common class in the CNS.

multipolar

Oligodendrocytes create the ___ sheath in the central nervous system

myelin