Chapter 3 Flashcards
neurons
cells in the nervous system that communicate with one another to perform information processing tasks
neurons are complex structures that are composed of three basic parts:
the cell body, the dendrites, and the axon
cell body (also called the soma)
largest component of the neuron that coordinates information-processing tasks and keeps the cell alive
functions such as protein synthesis, energy production, and metabolism occur here
the cell body has a nucleus that contains DNA, and is surrounded by a semi-permeable membrane
dendrites
receive information from other neurons and relay it to the cell body
look like tree branches at the terminal ends
axon
carries information to other neurons, muscles, or glands
axons are very long and can stretch from the top of the spine to the big toe
synapse
the junction or region between the axon of one neuron and the dendrites or cell body of another
in many neurons, the axon is covered by a
myelin sheath
myelin sheath
an insulating layer of fatty material
the myelin sheath is composed of
glial glands
glial glands
support cells found in the nervous system.
some glial cells digest parts of dead neurons, others provide physical and nutritional support for neurons, and others form myelin to help the axon carry information more efficiently.
multiple sclerosis
deteriorating of the myelin sheath
there are three types of neurons, each performing a distinct function:
sensory neurons, motor neurons, and interneurons
sensory neurons
receive information from the external world and convey this information to the brain via the spinal cord
they have specialized endings on their dendrites that receive signals for light, sound, touch, taste, and smell
motor neurons
carry signals from the spinal cord to the muscles to produce movement
have long axons that can stretch to muscles in the extremities
most of the nervous system is composed of
interneurons
interneurons
they connect sensory neurons, motor neurons, and other interneurons
Some interneurons carry information from sensory neurons into the nervous system, others carry information from the nervous system to motor neurons, and still others perform a variety of information-processing functions within the nervous system
Which of the following is NOT a function of a neuron?
a processing information
b communicating with other neurons
c nutritional provision
d sending messages to body organs and muscles
c
Signals from other neurons are received and relayed to the cell body by
a the nucleus.
b dendrites.
c axons.
d glands.
b
Signals are transmitted from one neuron to another
a across a synapse.
b through a glial cell.
c by the myelin sheath.
d in the cell body.
a
Which type of neuron receives information from the external world and conveys this information to the brain via the spinal cord?
a sensory neuron
b motor neuron
c interneuron
d axon
a
Neurons have a natural electric charge called the
resting potential
resting potential
the difference in charge between the inside and outside of a neuron’s cell membrane
The resting potential arises from the difference in concentrations of________inside and outside the neuron’s cell membrane
ions
ions can carry a ______________charge
positive or negative
conduction
information travels inside a neuron via an electrical signal that travels from the dendrite to the cell body to the axon
transmission
a signal has to be transmitted from one neuron to another, usually via chemical messengers traveling across the synapse
In the resting state, there is a high concentration of a positively charged ion_______ as well as negatively charged ________inside the neuron’s cell membrane compared to outside it. By contrast, there is a high concentration of positively charged________and negatively charged_________outside the neuron’s cell membrane.
potassium (K+), protein ions (A–),
sodium ions (Na+), chloride ions (Cl–)
Electric stimulation causes an
action potential
resting potential is________because it creates the environment for a possible electrical impulse.
potential energy
The concentration of K+ inside and outside a neuron is controlled by channels in the cell membrane that allow K+ molecules to flow in and out of the neuron. In the resting state, the channels that allow K+ molecules to flow freely across the cell membrane are open, while channels that allow the flow of Na+ and the other ions are generally closed. Because of the naturally higher concentration of K+ molecules inside the neuron, some K+ molecules move out of the neuron through the open channels, leaving the inside of the neuron with a charge of about -70 millivolts relative to the outside
.
action potential
an electrical signal that is conducted along the length of a neuron’s axon to a synapse
The action potential occurs only when the electric shock reaches a certain level, or
threshold