NU 545 EXAM 3 Study Guide QUESTIONS
AND ANSWERS VERIFIED 2024
CORRECT!
A
Review the anatomy of the brain. Which portion is responsible for keeping
you awake, controlling thought, speech, emotions and behavior, maintaining
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balance and posture? CH 15 pg 440
The three major structural divisions of the brain are 1) the forebrain
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(prosencephalon) which includes the telencephalon and diencephalon. 2) the
midbrain (the mesencephalon, which connects the pons to the
diencephalic;pn and the includes the corpora quadrigemina, tegmenjtum and
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cerebral peduncles; and 3). the hind brain (rhombencephalon), which
connects the hemispheres of the brain, cerebellum and spinal cord.
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Reticular formation: is collection of nuclei within the brainstem collectively,
and is a large network of diffuse nuclei that connect the brainstem to the
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cortex and control vital reflexes, such as CV function and respiration. It is
essential for maintains wakefulness and attention and thus us referred to as
A
the reticular activating system.
N
Cerebral hemisphere: Part frontal lobe: prefrontal area is responsible for goal
oriented behavior/ the ability to concentrate, short term memory recall, and
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the elaboration of thought and inhibition on the limbic (emotional) areas of
the CNS.
The premotor area is involved in programming motor movements.
,The Broca area in the inferior frontal lobe is an important center for speech
and language processing. Injury to this area results in difficulty to form words
(expressive aphasia/ or dysphasia)
The hind brain: the cerebellum is responsible for reflexive, involuntary fine
tuning of motor control and for maintaining balance and posture through
extensive neural connections with the medulla and with the midbrain
A
VI
What nerves are capable of regeneration? CH 15 pg 435-437
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Myelinated axons ONLY in the PNS.
When an axon is severed wallerian degeneration occurs in the portion of the
axon distal to the cut:
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1) a characteristic swelling appears
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2) the neurofilaments hypertrophy
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3) the myelin sheath shrinks and disintegrates
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4) this axon portion degenerates and disappears.
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The myelin sheaths reform into Schwann cells that line up in a column
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between the cut and the effector organ. At the proximal end of the injured
axon, similar changes occur but only as far back as the next node of Ranvier.
The cell body responds to trauma by swelling and then dispersing the Nissl
substance (chrmatolysis). During the repair process the cell increases in
metabolic activity, protein synthesis, and mitochondrial activity. This process
is limited to myelinated fibers and generally doesn't occur outside of the
PNS. The regeneration of axonal constituents in the CNS is limited by
,increased scar formation and the different nature of myelin formation by the
oligodendrocyte. Nerve regeneration depends on many factors, such as
location of injury, type of injury, the inflammatory responses, and the process
of scarring. The closer the cell body of the nerve, the greater the chances that
the nerve cell will die and not regenerate. A crushing injury allows recovery
more fully than a cut. Crushed nerves sometimes recover whereas, cut nerves
often form connective tissue scars that block or slow regenerating axonal
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branches.
VI
Know the function of the arachnoid villi. CH 15 pg 451
CSF is reabsorbed in venous circulation through a pressure gradient between
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the arachnoid villi and the cerebral venous sinuses. The arachnoid villi
protrude from the arachnoid space, through the dura mater, and lie within the
blood flow of the venous sinuses. The vili function as one way valves
directing CSF outflow into the blood but preventing blood flow into the
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subarachnoid space.
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What is the function of the CSF? Where is it produced? Where is it absorbed?
CH 15 pg 450
Is a clear colorless fluid. the intracranial and spinal cord structures float in
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CSF and are thus protected by this fluid from jolts and blows. The buoyant
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properties of CSF also prevent the brain from tugging on the meninges ,
nerve roots, and blood vessels. Aprox 600 ml of CSF is produced daily.
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The choroid plexus in the lateral, third and fourth ventricles produce the
major portion of CSF.
The CSF exerts pressure within the brain and spinal cord. CSF flor results
from the pressure gradient between the arterial system and the CSF filled
cavities.
, Beginning in the lateral ventricles the CSF flows through the intraventricular
foramen into the third ventricle and then pass through the cerebral aqueduct
into the fourth ventricle. From the ventricle , the CSF may pass through either
the paired lateral apertures or the median aperture before communicating
with the subarachnoid spaces of the brain and spinal cord. CSF is produced
continually but does not accumulate. Instead it is reabsorbed in the venous
A
circulation through a pressure gradient between the arachnoid villi and the
cerebral venous sinuses. Thus the CSF is formed from the blood and, after
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circulating throughout the CNS it returns to the blood.
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Review blood flow to the brain. pg 452 Ch 15
The brain derives its arterial supply from two systems: the internal carotid
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arteries (anterior circulation) and the vertebral arteries (posterior circulation)
The internal carotid arteries supply a proportionaly greater amount of blood
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flow. They originate at the common carotid arteries, enter the cranium
through the base of the skull and pass through the cavernous sinus. After
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entering the skull, these arteries divide into the anterior and middle cereal
arteries. The vertebral arteries originate at the subclavian arteries and pass
through the transverse foramina of the cervical vertebrae, entering the
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cranium through the foramen magnum. They join at the junction of the ins
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and medulla omblongata to form the basilar artery, the basil artery divides at
the level of the midbrain to form paired posterior cerebral arteries.
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Three major paired arteries perfuse the cerebellum and brainstem: the
posterior inferior cerebella artery, the anterior inferior cerbeller artery, and the
superior cerebella arteries. They originate from the basilar artery. The basilar
artery also gives rise to small pontine arteries. The large arteries on the
surface of the brain and their branches are called superficial arteries. Small
branches that project into the brain are term projecting arteries.
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