BIO 264 EXAM 3 SCRIPT COMPLETE
ANSWERS GRADED A+
◉ The Microglial Cell:
Answer: Microglial cells are rapidly activated in the CNS in
response to injury. Injury causes these cells to proliferate, change
shape, and become phagocytic. These cells are also very
important in presenting antigens to lymphocytes in response to
infection. Although these cells are an important component of the
CNS, it is believed that their activity is also toxic to neurons and
can result in long term damage. For this reason, medical
intervention in response to brain injury often involves factors that
inhibit microglial activity.
◉ The Schwann Cell:
Answer: The schwann cell is the mylenating cell of the PNS. In
contrast to the oligodendrocyte of the CNS, which uses multiple
processes to mylenate multiple segments of axons, a schwann cell
provides myelin for a single segment of an axon. Still, the
appearance and function of myelin in the PNS is exactly the same
as the CNS.
◉ The Satellite Cell:
Answer: Satellite glial cells help regulate the external chemical
environment around neurons of the PNS. In this way they are very
similar to the astrocyte of the CNS, but in addition are highly
sensitive to injury and inflammation.
,◉ Glial Cells of the PNS
Answer: The Schwann Cell: The Satellite Cell:
◉ what cell type is responsible for the formation of myelin within
the spinal cord?
Answer: Oligodendrocytes
◉ what cell type produces myelin sheaths within the peripheral
nervous system?
Answer: Schwann cells.
◉ what cell type produces myelin sheaths within the central
nervous system?
Answer: Oligodendrocytes
◉ Neurons have four specialized structures that allow for the
sending and receiving of information:
Answer: the cell body (soma), dendrites, axon and axon terminals
◉ Cell body or soma:
Answer: The cell body is the portion of the cell that surrounds the
nucleus and plays a major role in synthesizing proteins.
◉ Dendrites
,Answer: Dendrites are short, branched processes that extend
from the cell body. Dendrites function to receive information, and
do so through numerous receptors located in their membranes
that bind to chemicals, called neurotransmitters.
◉ Axon:
Answer: An axon is a large process that extends from the cell body
at a point of origin-called the axon hillock-and functions to send
information. In contrast to the shorter dendrites, the axon can
extend for more than a meter. Because of this length, the axon
contains microtubules and is surrounded by myelin. Microtubules
are arranged inside the axon as parallel arrays of long strands that
act as highways for the movement of materials to and from the
soma. Specialized motor proteins "walk" along the microtubules,
carrying material away from the soma (anterograde transport) or
back to the soma (retrograde transport). This system can move
materials down the axon at rates of 400mm/day. Myelin consists
of totally separate cells that coil and wrap their membranes
around the outside of the axon. These are essential for electrical
insulation and to speed up action potential propagation.
◉ Axon terminals:
Answer: Once an axon reaches a target, it terminates into multiple
endings, called axon terminals. The axon terminal is designed to
convert the electrical signal into a chemical signal in a process
called synaptic transmission
◉ which two regions are the exception to amitotic (lose their
ability to divide)?
, Answer: Exceptions to this rule are found in olfactory neurons
(those associated with smell) and hippocampal regions of the
brain.
◉ What will the body do if it detects that the neurons is not
receiving adequate amounts of nutrition?
Answer: Neurons also have exceptionally high metabolic rates and
subsequently require high levels of glucose and oxygen. The body
will go to great lengths to ensure that neurons are adequately fed;
in fact, if for some reason the brain detects that it is not receiving
adequate amounts of nutrition, the body will shut down
immediately (i.e., faint).
◉ Structural classification of neurons
Answer: multipolar, bipolar, and unipolar neurons.
◉ Multipolar neurons
Answer: Multipolar neurons are defined as having three or more
processes that extend out from the cell body. They comprise of
more than 99% of the neurons in humans, and are the major
neuron type found in the CNS and the efferent division of the PNS.
◉ Bipolar neurons
Answer: Bipolar neurons have only two processes that extend in
opposite directions from the cell body. One process is called a
dendrite, and another process is called the axon. Although rare,
these are found in the retina of the eye and the olfactory system.
ANSWERS GRADED A+
◉ The Microglial Cell:
Answer: Microglial cells are rapidly activated in the CNS in
response to injury. Injury causes these cells to proliferate, change
shape, and become phagocytic. These cells are also very
important in presenting antigens to lymphocytes in response to
infection. Although these cells are an important component of the
CNS, it is believed that their activity is also toxic to neurons and
can result in long term damage. For this reason, medical
intervention in response to brain injury often involves factors that
inhibit microglial activity.
◉ The Schwann Cell:
Answer: The schwann cell is the mylenating cell of the PNS. In
contrast to the oligodendrocyte of the CNS, which uses multiple
processes to mylenate multiple segments of axons, a schwann cell
provides myelin for a single segment of an axon. Still, the
appearance and function of myelin in the PNS is exactly the same
as the CNS.
◉ The Satellite Cell:
Answer: Satellite glial cells help regulate the external chemical
environment around neurons of the PNS. In this way they are very
similar to the astrocyte of the CNS, but in addition are highly
sensitive to injury and inflammation.
,◉ Glial Cells of the PNS
Answer: The Schwann Cell: The Satellite Cell:
◉ what cell type is responsible for the formation of myelin within
the spinal cord?
Answer: Oligodendrocytes
◉ what cell type produces myelin sheaths within the peripheral
nervous system?
Answer: Schwann cells.
◉ what cell type produces myelin sheaths within the central
nervous system?
Answer: Oligodendrocytes
◉ Neurons have four specialized structures that allow for the
sending and receiving of information:
Answer: the cell body (soma), dendrites, axon and axon terminals
◉ Cell body or soma:
Answer: The cell body is the portion of the cell that surrounds the
nucleus and plays a major role in synthesizing proteins.
◉ Dendrites
,Answer: Dendrites are short, branched processes that extend
from the cell body. Dendrites function to receive information, and
do so through numerous receptors located in their membranes
that bind to chemicals, called neurotransmitters.
◉ Axon:
Answer: An axon is a large process that extends from the cell body
at a point of origin-called the axon hillock-and functions to send
information. In contrast to the shorter dendrites, the axon can
extend for more than a meter. Because of this length, the axon
contains microtubules and is surrounded by myelin. Microtubules
are arranged inside the axon as parallel arrays of long strands that
act as highways for the movement of materials to and from the
soma. Specialized motor proteins "walk" along the microtubules,
carrying material away from the soma (anterograde transport) or
back to the soma (retrograde transport). This system can move
materials down the axon at rates of 400mm/day. Myelin consists
of totally separate cells that coil and wrap their membranes
around the outside of the axon. These are essential for electrical
insulation and to speed up action potential propagation.
◉ Axon terminals:
Answer: Once an axon reaches a target, it terminates into multiple
endings, called axon terminals. The axon terminal is designed to
convert the electrical signal into a chemical signal in a process
called synaptic transmission
◉ which two regions are the exception to amitotic (lose their
ability to divide)?
, Answer: Exceptions to this rule are found in olfactory neurons
(those associated with smell) and hippocampal regions of the
brain.
◉ What will the body do if it detects that the neurons is not
receiving adequate amounts of nutrition?
Answer: Neurons also have exceptionally high metabolic rates and
subsequently require high levels of glucose and oxygen. The body
will go to great lengths to ensure that neurons are adequately fed;
in fact, if for some reason the brain detects that it is not receiving
adequate amounts of nutrition, the body will shut down
immediately (i.e., faint).
◉ Structural classification of neurons
Answer: multipolar, bipolar, and unipolar neurons.
◉ Multipolar neurons
Answer: Multipolar neurons are defined as having three or more
processes that extend out from the cell body. They comprise of
more than 99% of the neurons in humans, and are the major
neuron type found in the CNS and the efferent division of the PNS.
◉ Bipolar neurons
Answer: Bipolar neurons have only two processes that extend in
opposite directions from the cell body. One process is called a
dendrite, and another process is called the axon. Although rare,
these are found in the retina of the eye and the olfactory system.
