NU 545 Unit 2 EXAM | QUESTIONS AND ANSWERS | VERIFIED AND
WELL DETAILED ANSWERS | ALREADY HIGHLY RATED | LATEST
EXAM UPDATE
Review the anatomy of the brain. Which portion is responsible for keeping you
awake, controlling thought, speech, emotions and behavior, maintaining balance
and posture? - CORRECT ANSWER - The reticular formation is a large
network of diffuse nuclei that connect the brainstem to the cortex and control
vital reflexes. It is essential for maintaining wakefulness and is referred to as the
reticular activating system. Some nuclei within the reticular formation support
specific motor movements, such as balance and posture (p448). The cerebellum
is responsible for maintaining balance and posture (p452). The prefrontal area is
responsible for the elaboration of thought (pg 449). The Broca speech area is on
the inferior frontal gyrus (Brodmann 44, 45). It is usually on the left hemisphere
and is responsible for motor aspects of speech. Broca Area in the inferior frontal
lobe (Brodmann areas 44, 45) is an important center for speech and language
processing. This area, rostral to the inferior edge of the premotor area
(Brodmann area 6). Injury to this area results in difficulty forming or inability to
for words (expressive aphasia or dysphasia). Wernicke (posterior Brodmann 22)
and adjacent portions of the parietal lobe are a sensory speech area, responsible
for reception and interpretation of speech (aphasia/dysphasia). Insula (insular
lobe) between hemispheres temporal and frontal lobes, processes emotional
information (pg 450). The basal ganglia nuclei are important for emotional
functions (pg 451). Cerebrum > forebrain/hindbrain
Broca's area = difficulty writing and finding words, See chart 17.10 (p523)
Know the function of the arachnoid villi. - CORRECT ANSWER - The
arachnoid villi protrude from the arachnoid space, through the dura mater, and
lie within the blood flow of the venous sinuses. The villi function as one-way
valves directing CSF outflow into the blood but preventing blood flow into the
subarachnoid space. Thus CSF is formed from the blood and, after circulating
throughout the CNS, it returns to the blood. Absorbs CSF (pg 459)
,Where is the primary defect in Parkinson's disease and Huntington's? -
CORRECT ANSWER - Extrapyramidal system; controls motor system
(involuntary movement) (pg 451). Substantia nigra (of the midbrain)
synthesizes dopamine. The dysfunction of dopamine neurons is associated with
PD and Huntington's
What is the function of the CSF? Where is it produced? Where is it absorbed? -
CORRECT ANSWER - Cerebrospinal fluid (CSF) is a clear, colorless fluid
similar to blood plasma and interstitial fluid. The intracranial and spinal cord
structures float in CSF and are thereby partially protected from jolts and blows.
The buoyant properties of the CSF also prevent the brain from tugging on
meninges, nerve roots, and blood vessels. Appx 600mL is produced daily (457).
Ependymal cells in the choroid plexuses are the structures that produce CSF;
they arise from the pia mater. The arachnoid villi reabsorb the CSF (p458)
Review blood flow to the brain. - CORRECT ANSWER - The brain receives
approximately 20% of the cardiac output, or 800 to 1000 mL of blood flow per
minute. Autoregulated to maintain a stable flow during fluctuating perfusion
pressures. Carbon dioxide serves as a primary regulator for blood flow within
the CNS. It is a potent vasodilator in the CNS, and its effects ensure an adequate
blood supply. The brain derives its arterial supply from the internal carotid
arteries (anterior circulation) and the vertebral arteries (posterior circulation)
(Fig. 15.20). The internal carotid arteries supply a proportionately greater
amount of blood flow. They originate at the common carotid arteries, enter the
cranium through the base of the skull, and pass through the cavernous sinus.
After entering the skull, these arteries divide into the anterior and middle
cerebral arteries (Fig. 15.21). The vertebral arteries originate at the subclavian
arteries and pass through the transverse foramina of the cervical vertebrae,
entering the cranium through the foramen magnum. They join at the junction of
the pons and medulla oblongata to form the basilar artery. The basilar artery
divides at the level of the midbrain to form paired posterior cerebral arteries
(459). When one of the routes is obstructed, the circle of Willis is an alternate
route.
What is the gate control theory of pain? - CORRECT ANSWER - Gate control
theory (GCT) integrates and builds upon features of the other theories to explain
the complex multidimensional aspects of pain perception and pain modulation.
, Pain transmission is modulated by a balance of impulses conducted to the spinal
cord where cells in the substantia gelatinosa function as a "gate." The spinal
gate regulates pain transmission to higher centers in the CNS. Large myelinated
A-delta fibers and small unmyelinated C fibers respond to a broad range of
painful stimuli (mechanical, thermal, and chemical). These fibers terminate on
interneurons in the substantia gelatinosa (laminae in the dorsal horn of the
spinal cord) and "open" the spinal gate to transmit the perception of pain.
Closure or partial closure of the spinal gates can occur from nonnociceptive
stimulation (i.e., from touch sensors in the skin) carried on large A-beta fibers
decreasing pain perception.
The theories of pain include the specificity theory, pattern theory, gate control
theory, and neuromatrix theory. 4 Specificity theory proposes that pain and
touch are carried on distinct pathways that project to distinct brain centers.
Injury activates only specific pain receptors and fibers that project to the brain.
Intensity of pain is directly related to the amount of associated tissue injury (i.e.,
pricking one's finger with a needle would cause minimal pain, whereas cutting
one's hand with a knife would produce more pain). The theory is useful when
applied to specific injuries and the acute pain associated with them. It does not
account for chronic pain or cognitive and emotional elements that contribute to
more complex types of pain. 5
Know the type of nerve fibers that transmit pain impulses. Page 470 -
CORRECT ANSWER - Transduction begins when nociceptors are activated
by a painful stimulus causing ion channels to open, creating electrical impulses
that travel through axons or two primary types. Pain impulses are conducted
along the A-delta and C fibers of nociceptors.
A-delta fibers: larger myelinated fibers that rapidly transmit sharp, well-
localized "fast" sensations (intense heat or pinprick) "reflex"
· stimulated by mechanoreceptors and mechanothermal nociceptors
· Responsible for causing reflex withdrawal of the body from the painful
stimulus
C Fibers: most numerous, smaller, unmyelinated, slowly transmit dull, aching,
burning sensations that are poorly localize and constant
· Stimulated by mechanical, thermal, and chemical nociceptors
A-beta fibers: NOT responsible to transmit pain, but play a role in pain
modulation. Large, myelinated fibers that transmit touch & vibration (p475)
WELL DETAILED ANSWERS | ALREADY HIGHLY RATED | LATEST
EXAM UPDATE
Review the anatomy of the brain. Which portion is responsible for keeping you
awake, controlling thought, speech, emotions and behavior, maintaining balance
and posture? - CORRECT ANSWER - The reticular formation is a large
network of diffuse nuclei that connect the brainstem to the cortex and control
vital reflexes. It is essential for maintaining wakefulness and is referred to as the
reticular activating system. Some nuclei within the reticular formation support
specific motor movements, such as balance and posture (p448). The cerebellum
is responsible for maintaining balance and posture (p452). The prefrontal area is
responsible for the elaboration of thought (pg 449). The Broca speech area is on
the inferior frontal gyrus (Brodmann 44, 45). It is usually on the left hemisphere
and is responsible for motor aspects of speech. Broca Area in the inferior frontal
lobe (Brodmann areas 44, 45) is an important center for speech and language
processing. This area, rostral to the inferior edge of the premotor area
(Brodmann area 6). Injury to this area results in difficulty forming or inability to
for words (expressive aphasia or dysphasia). Wernicke (posterior Brodmann 22)
and adjacent portions of the parietal lobe are a sensory speech area, responsible
for reception and interpretation of speech (aphasia/dysphasia). Insula (insular
lobe) between hemispheres temporal and frontal lobes, processes emotional
information (pg 450). The basal ganglia nuclei are important for emotional
functions (pg 451). Cerebrum > forebrain/hindbrain
Broca's area = difficulty writing and finding words, See chart 17.10 (p523)
Know the function of the arachnoid villi. - CORRECT ANSWER - The
arachnoid villi protrude from the arachnoid space, through the dura mater, and
lie within the blood flow of the venous sinuses. The villi function as one-way
valves directing CSF outflow into the blood but preventing blood flow into the
subarachnoid space. Thus CSF is formed from the blood and, after circulating
throughout the CNS, it returns to the blood. Absorbs CSF (pg 459)
,Where is the primary defect in Parkinson's disease and Huntington's? -
CORRECT ANSWER - Extrapyramidal system; controls motor system
(involuntary movement) (pg 451). Substantia nigra (of the midbrain)
synthesizes dopamine. The dysfunction of dopamine neurons is associated with
PD and Huntington's
What is the function of the CSF? Where is it produced? Where is it absorbed? -
CORRECT ANSWER - Cerebrospinal fluid (CSF) is a clear, colorless fluid
similar to blood plasma and interstitial fluid. The intracranial and spinal cord
structures float in CSF and are thereby partially protected from jolts and blows.
The buoyant properties of the CSF also prevent the brain from tugging on
meninges, nerve roots, and blood vessels. Appx 600mL is produced daily (457).
Ependymal cells in the choroid plexuses are the structures that produce CSF;
they arise from the pia mater. The arachnoid villi reabsorb the CSF (p458)
Review blood flow to the brain. - CORRECT ANSWER - The brain receives
approximately 20% of the cardiac output, or 800 to 1000 mL of blood flow per
minute. Autoregulated to maintain a stable flow during fluctuating perfusion
pressures. Carbon dioxide serves as a primary regulator for blood flow within
the CNS. It is a potent vasodilator in the CNS, and its effects ensure an adequate
blood supply. The brain derives its arterial supply from the internal carotid
arteries (anterior circulation) and the vertebral arteries (posterior circulation)
(Fig. 15.20). The internal carotid arteries supply a proportionately greater
amount of blood flow. They originate at the common carotid arteries, enter the
cranium through the base of the skull, and pass through the cavernous sinus.
After entering the skull, these arteries divide into the anterior and middle
cerebral arteries (Fig. 15.21). The vertebral arteries originate at the subclavian
arteries and pass through the transverse foramina of the cervical vertebrae,
entering the cranium through the foramen magnum. They join at the junction of
the pons and medulla oblongata to form the basilar artery. The basilar artery
divides at the level of the midbrain to form paired posterior cerebral arteries
(459). When one of the routes is obstructed, the circle of Willis is an alternate
route.
What is the gate control theory of pain? - CORRECT ANSWER - Gate control
theory (GCT) integrates and builds upon features of the other theories to explain
the complex multidimensional aspects of pain perception and pain modulation.
, Pain transmission is modulated by a balance of impulses conducted to the spinal
cord where cells in the substantia gelatinosa function as a "gate." The spinal
gate regulates pain transmission to higher centers in the CNS. Large myelinated
A-delta fibers and small unmyelinated C fibers respond to a broad range of
painful stimuli (mechanical, thermal, and chemical). These fibers terminate on
interneurons in the substantia gelatinosa (laminae in the dorsal horn of the
spinal cord) and "open" the spinal gate to transmit the perception of pain.
Closure or partial closure of the spinal gates can occur from nonnociceptive
stimulation (i.e., from touch sensors in the skin) carried on large A-beta fibers
decreasing pain perception.
The theories of pain include the specificity theory, pattern theory, gate control
theory, and neuromatrix theory. 4 Specificity theory proposes that pain and
touch are carried on distinct pathways that project to distinct brain centers.
Injury activates only specific pain receptors and fibers that project to the brain.
Intensity of pain is directly related to the amount of associated tissue injury (i.e.,
pricking one's finger with a needle would cause minimal pain, whereas cutting
one's hand with a knife would produce more pain). The theory is useful when
applied to specific injuries and the acute pain associated with them. It does not
account for chronic pain or cognitive and emotional elements that contribute to
more complex types of pain. 5
Know the type of nerve fibers that transmit pain impulses. Page 470 -
CORRECT ANSWER - Transduction begins when nociceptors are activated
by a painful stimulus causing ion channels to open, creating electrical impulses
that travel through axons or two primary types. Pain impulses are conducted
along the A-delta and C fibers of nociceptors.
A-delta fibers: larger myelinated fibers that rapidly transmit sharp, well-
localized "fast" sensations (intense heat or pinprick) "reflex"
· stimulated by mechanoreceptors and mechanothermal nociceptors
· Responsible for causing reflex withdrawal of the body from the painful
stimulus
C Fibers: most numerous, smaller, unmyelinated, slowly transmit dull, aching,
burning sensations that are poorly localize and constant
· Stimulated by mechanical, thermal, and chemical nociceptors
A-beta fibers: NOT responsible to transmit pain, but play a role in pain
modulation. Large, myelinated fibers that transmit touch & vibration (p475)
