Neurons and Glia
Neurons and Glia
Terms in this set (63)
nervous system is made up of two types of cells
neurons and glia
A cell of the nervous system
that is specialized for information
processing and communication.
Cells in the nervous system that support the activities of neurons.
A small structure within a cell that carries out a specific function.
cell body / soma
main mass of a neuron, containing
the nucleus and many organelles.
The branch of a neuron
usually responsible for carrying
signals to other neurons.
The branch of a
neuron that generally receives
information from other neurons.
The primary task of any cell membrane is to form a boundary
between the cell and its external environment. The neural membrane must separate the intracellular fluid of the cell's interior from the extracellular fluid surrounding the neuron.
The fluid inside a cell.
The fluid surrounding a cell.
A property of
a substance that determines
the extent to which other
substances may pass through it.
The neural cytoskeleton provides structural support that maintains the shape of the neuron
The Neural Membrane
Membrane is a bi-layer composed largely of phospholipids and other lipids studded with proteins and other large molecules
Allow ions to diffuse down concentration gradient
Selective permeability to certain ions
Don't require additional energy
Actively move ions against concentration gradient
Create ion concentration gradients
Ion channels have the ability to open and close in response to stimuli in their immediate vicinity. Some ion channels, known as voltage-dependent channels, open and close in response to the electrical status of adjacent areas of membrane. These channels form an important part of our discussion of electrical signaling within the neuron
open when they come in contact with specific
chemicals. These chemicals are typically our naturally occurring chemical messengers but can be drugs from artificial sources as well
The junction between two neurons at which
information is transferred from one to another.
ion pump that uses energy to
transfer three sodium ions to
the extracellular fluid for every
two potassium ions retrieved
from the extracellular fluid.
structure embedded in the neural
membrane that uses energy to
move calcium ions out of the cell.
messenger that transfers
information across a synapse.
A network of filaments
that provides the internal
structure of a neuron.
cytoskeleton made up of
The largest fiber in the cell cytoskeleton, responsible for the transport of neurotransmitters and other products to and from the cell body.
A neural fiber
found in the cell cytoskeleton that is
responsible for structural support.
The smallest fiber found in the cell cytoskeleton
that may participate in the changing of the length and
shape of axons and dendrites.
of materials from the cell body
of a neuron to the axon terminal
along the microtubules.
of material from the axon terminal
back to the cell body via the
cell's system of microtubules.
Tau Phosphorylation Leads to Cell Death
In Alzheimer's disease, the tau levels become elevated
(Baas & Qiang, 2005). In response, an affected neuron adds molecules of phosphate
to the tau protein, which causes it to disconnect from the microtubules. As shown in
■ Figure 3.4, the disconnected tau begins to form tangles, hindering the cell's ability
to signal and maintain its structure. The neuron folds in on itself and collapses
Structural Features of Neurons
Cell body (soma) contains nucleus and other organelles
branches that serve as locations at which information from other neurons is received
are responsible for carrying neural messages to other neurons
Vary in diameter and length
Many covered by myelin
within a cell body that
contains the cell's DNA.
substructure within a cell nucleus
where ribosomes are produced.
An organelle in the cell body
involved with protein synthesis.
An organelle in the cell body that
participates in protein synthesis.
organelle in the cell body that
packages proteins in vesicles.
that provide energy to the cell
by transforming pyruvic acid
and oxygen into molecules of
adenosine triphosphate (ATP).
The tiny fluidfilled
space between neurons
forming a synapse.
A knob on the dendrite that provides additional
membrane area for the formation of synapses with other neurons.
The fatty insulating material covering some
axons that boosts the speed and
efficiency of electrical signaling.
The cone-shaped segment of axon located at the
junction of the axon and cell body that is specialized for the
generation of action potentials.
local circuit neuron
that communicates with neurons
in its immediate vicinity.
with a very long axon that
communicates with neurons in
distant areas of the nervous system.
The ends of many axons are divided into branches, known as collaterals. As a result, a neuron with only one axon may still communicate with a large number of other cells.
at the tip of an axon collateral
specialized for the release of
The axon terminal contains large numbers of both mitochondria and synaptic vesicles that contain chemical messengers. Synaptic vesicles are made from the same
double-lipid molecule structure as the cell membrane and are approximately 50 nm in diameter.
node of Ranvier
The uncovered section of
axon membrane between two
adjacent segments of myelin.
use of myelin
There are a number of important advantages to myelin. First of all, as mentioned earlier, myelin allows human axons to be smaller in diameter without sacrificing transmission speed. Space is a precious commodity in the nervous system. The smaller the diameter of our axons, the more neural tissue we can pack into our skulls, and the more information we can process. In addition, myelin reduces
the energy requirements of neurons by decreasing the amount of work done by sodium-potassium pumps. Myelin segments wrap so tightly around axons that there is little to no extracellular fluid between the myelin and the axon membrane.
mroe uses of myelin
As a result, there is no need for ion channels under a myelin sheath. The only places on a myelinated axon that have large numbers of ion channels are the axon hillock and the nodes of Ranvier. In contrast, an unmyelinated axon has ion channels along its entire length. During signaling, therefore, fewer ions move through the ion channels of a myelinated axon membrane than through an unmyelinated axon membrane of the same length. Because the sodium-potassium pumps work to restore ions to their pre-signaling locations, less of this work needs to be done in a
Structural Variations in Neurons
Single branch extending from the cell body
Two branches extending from the neural cell body: one axon and one dendrite
Many branches extending from the cell body; usually one axon and many dendrites
multipolar neurons Where are they found?
are specialized to receive information from the outside
world. Our senses of vision, hearing, touch, taste, and smell all depend on specialized
receptor neurons. These neurons can translate many types of information, such as light
or sound waves, into neural signals that the nervous system can process.
transmit commands from the central nervous system (the brain and spinal cord)
directly to muscles and glands.
The vast majority of neurons are known as interneurons.
Interneurons are not specialized for either sensory or motor functions but act as
bridges between the sensory and motor systems.
Large glial cells, including astrocytes, oligodendrocytes, and
Tiny, mobile glial
cells that migrate to areas of
damage and digest debris.
large, star shaped glial cell of
the central nervous system,
responsible for structural support,
isolation of the synapse, control
of the extracellular chemical
environment at the synapse,
and possibly communication.
A glial cell that
forms the myelin on central
nervous system axons.
A glial cell
that forms the myelin on axons in
the peripheral nervous system.
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