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NU 545 Unit 2 Exam With Complete Solution A+ Graded
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NU 545 Unit 2 Exam With Complete Solution A+Graded 2024-2025
Review the anatomy of the brain. What part of the brain keeps you awake, and also
allows you to control thought, speech, emotions and behaviour and balance and
posture? - ANSWER The reticular formation is a large diffuse network of nuclei
connected between the brainstem and cortex control vital reflexes. It plays an important
role in modulating wakefulness and alertness hence also known as the reticular
activating system. Some of the nuclei within the reticular formation support specific
motor movements including balance and posture, p448. The cerebellum maintains
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 the motor aspects of
speech. Broca Area of the inferior frontal lobe (Brodmann areas 44, 45) is an important
center for speech and language processing. The region is rostral to the inferior edge of
the premotor area (Brodmann area 6). Damage here causes a non-fluency problem or
an inability to form words, in other words, expressive aphasia or dysphasia. Wernicke's
posterior Brodmann 22 and adjacent portions of the parietal lobe is a sensory speech
area, responsible for the reception and interpretation of speech -aphasia/dysphasia.
Insula insular lobe between hemispheres temporal and frontal lobes, processes
emotional information p. 450. Basal ganglia nuclei p. 451 important to emotional
functions Cerebrum > forebrain/hindbrain
Broca's area = difficulty writing and finding words See chart 17.10 p523
Describe the purpose of arachnoid villi - ANSWER The arachnoid villi project from the
arachnoid space, through the dura mater, and sit within the bloodstream of the venous
sinuses. The villi are one-way valves that allow CSF outflow into blood but prevent blood
flow back into the subarachnoid space. In this way, CSF is produced from the blood and
after passing throughout the CNS it returns to the blood. Reabsorbs CSF (pg 459)
Where is the lesion in Parkinson's disease and Huntington's? - 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? -ANSWER
,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). The choroid plexuses are formed by ependymal cells, which are responsible for
the production of CSF; they originate from the pia mater. The CSF is reabsorbed by the
arachnoid villi (p458)
Review blood flow to the brain. - ANSWER The brain receives about 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 is a major factor in the
regulation of blood flow to the CNS. It is a potent CNS vasodilator and helps maintain an
appropriate blood supply through its effect. The arterial supply to the brain is derived
from the internal carotid arteries-anterior circulation-and the vertebral
arteries-posterior circulation-Fig. 15.20. A proportionately greater amount of blood flow
is derived from the internal carotid arteries. They arise from the common carotid
arteries, pass into the cranium through the base of the skull, and through the cavernous
sinus. The arteries then split into the anterior and middle cerebral arteries within the
skull as seen in Fig. 15.21. The vertebral arteries arise from the subclavian arteries and
pass through the transverse foramina of the cervical vertebrae into the cranium through
the foramen magnum. They converge at the junction of pons and medulla oblongata to
form basilar artery. Basilar artery branches at the mid brain level into paired posterior
cerebral arteries 459. In case one of the ways is blocked, circle of Willis is an alternative
route.
Circle of Willis
What is the gate control theory of pain? Answer: GCT embodies and extends the
concepts of the other theories in its attempt to account for the complex,
multidimensional components involved in 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 centres in the CNS. The large myelinated A-delta fibers and small
unmyelinated C fibers respond to most painful stimuli, including 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. This is done by the closure or partial closure of the spinal gates from
nonnociceptive stimulation-i.e., from touch sensors in the skin-carried on large A-beta
fibers. Pain theories 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 only activates certain pain
receptors and fibres that project to the brain. The intensity of the pain is directly related
to the amount of associated tissue injury. For example, pricking one's finger with a
needle would cause minimal pain, while cutting one's hand with a knife would produce
, more pain. When applied to specific injuries and the acute pain associated with them,
the theory is useful. This does not take into consideration the chronic pain or cognitive
and emotional factors that add to more complex pains. 5
Identify the type of nerve fibers that conduct pain impulses. Page 470 - ANSWER
Transduction begins when the nociceptors are activated by a painful stimulus opening
of ion channels, creating electrical impulses traveling down 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"
· excited by mechanoreceptors and mechanothermal nociceptors
· Cause reflexive withdrawal of the body from painful stimulus
C Fibers: most abundant, smaller, unmyelinated, slowly conduct dull, aching, burning
sensations that poorly localize, and are constant
· Excited by mechanical, thermal, and chemical nociceptors
A-beta fibers: NOT involved in transmitting pain, but function in pain modulation. Large,
myelinated fibers that transmit touch & vibration
Where is the perception of pain localized to in the CNS? -ANSWER In the reticular and
limbic systems and the cerebral cortex (p476)
It is the consciousness of one's pain; three systems must interact for this:
1. Sensory-discriminative system
Mediated through: the somatosensory cortex
Responsiveness: detection of presence, character, location and intensity of pain
2. Affective-motivational system
Mediated through: reticular formation, limbic system, and brainstem with projections to
the prefrontal cortex
Responsibility: individual conditioned avoidance behaviors and emotional responses to
pain
3. Cognitive-evaluative system
Mediated by: cerebral cortex
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