NU 545 Unit 2 Study Guide: CNS
Anatomy and Disorders
Anatomy and Functions of the Brain
Brain Structures and Their Functions
• The brainstem's Reticular Formation is crucial for wakefulness, attention, and vital
reflexes like cardiovascular function and respiration (pg. 448).
• The prefrontal area is involved in goal-oriented behavior, short-term memory, thought
elaboration, and inhibition of limbic areas (pg. 449).
• Broca's area, located in the inferior frontal gyrus (Brodmann areas 44, 45), is primarily
responsible for the motor aspects of speech, typically found in the left hemisphere (pg.
449).
• The basal ganglia nuclei play a significant role in voluntary movement and
cognitive/emotional functions, with the nucleus accumbens linked to pleasure and reward
(pg. 451).
• The limbic system is essential for mediating emotions and long-term memory, connecting
with the prefrontal cortex (pg. 451).
• The cerebellum fine-tunes motor control and maintains balance and posture through
extensive neural connections with the medulla and midbrain (pg. 452).
Cerebrospinal Fluid (CSF) Functions
• Arachnoid villi act as one-way valves for CSF outflow into the blood, preventing blood
from entering the subarachnoid space (pg. 458).
• CSF is produced by ependymal cells in the choroid plexuses of the lateral, third, and
fourth ventricles (pg. 458).
• The buoyant properties of CSF protect the brain from jolts and prevent it from tugging on
meninges and blood vessels (pg. 457).
• CSF is continuously produced and reabsorbed into the venous circulation, maintaining
homeostasis (pg. 458).
, • The pressure gradient between arachnoid villi and cerebral venous sinuses facilitates CSF
reabsorption (pg. 458).
• CSF plays a critical role in maintaining intracranial pressure and providing a stable
environment for the brain.
Blood Flow and Pain Perception
Blood Flow to the Brain
• The brain receives about 20% of cardiac output, approximately 800 to 1000 mL of blood
per minute, with autoregulation to maintain stable flow (pg. 459).
• The internal carotid and vertebral arteries supply blood to the brain, with the internal
carotid arteries providing the majority (pg. 459).
• The Circle of Willis offers collateral blood flow, ensuring adequate perfusion even if one
artery is obstructed (pg. 459).
• Cerebral venous drainage does not parallel arterial supply, affecting intracranial pressure
significantly (pg. 460).
• Adequate venous outflow is crucial; head position can influence venous return and
intracranial pressure (pg. 460).
• The posterior inferior, anterior inferior, and superior cerebellar arteries perfuse the
cerebellum and brainstem (pg. 459).
Pain Perception and Theories
• The gate control theory of pain posits that pain perception is influenced by both
physiological signals and psychological factors (e.g., distraction can reduce pain
perception).
• Pain signals are transmitted through A-delta fibers (fast pain) and C fibers (slow pain),
with A-delta fibers being myelinated and larger (pg. 457).
• Pain perception occurs in the reticular and limbic systems and the cerebral cortex,
influenced by genetics, culture, and past experiences (pg. 476).
• Pain threshold is the minimum intensity of pain recognized, while pain tolerance is the
maximum intensity endured (pg. 476).
• Factors such as stress, fatigue, and emotional state can affect pain threshold and
tolerance, demonstrating the subjective nature of pain (pg. 476).
, • Perceptual dominance explains how intense pain in one area can mask pain in another,
affecting overall pain perception.
Clinical Aspects of Pain
Types of Pain and Their Characteristics
• Acute pain is typically short-term and directly related to tissue injury, while chronic pain
persists beyond normal healing time.
• Neuropathic pain arises from nerve damage and can be chronic, often described as
burning or tingling.
• Pain threshold varies among individuals and can be influenced by various factors,
including genetics and cultural perceptions (pg. 476).
• Pain tolerance can change over time and is affected by repeated exposure to pain,
emotional state, and other external factors (pg. 476).
• Understanding the differences between acute, chronic, and neuropathic pain is essential
for effective treatment and management.
• Clinical assessments of pain should consider both threshold and tolerance to tailor pain
management strategies.
Pain Mechanisms
Acute Pain (Nociceptive Pain)
• Acute pain serves as a protective mechanism, alerting individuals to harmful conditions
and prompting immediate action.
• It is typically transient, lasting from seconds to a maximum of 3 months, and is relieved
once the underlying cause is addressed.
• The autonomic nervous system's stimulation leads to physical symptoms such as
increased heart rate, hypertension, diaphoresis, and dilated pupils.
• Acute pain is often associated with inflammation, which activates pain receptors through
chemical mediators.
• Examples include post-surgical pain or pain from an injury, which usually resolves as
healing occurs.
Anatomy and Disorders
Anatomy and Functions of the Brain
Brain Structures and Their Functions
• The brainstem's Reticular Formation is crucial for wakefulness, attention, and vital
reflexes like cardiovascular function and respiration (pg. 448).
• The prefrontal area is involved in goal-oriented behavior, short-term memory, thought
elaboration, and inhibition of limbic areas (pg. 449).
• Broca's area, located in the inferior frontal gyrus (Brodmann areas 44, 45), is primarily
responsible for the motor aspects of speech, typically found in the left hemisphere (pg.
449).
• The basal ganglia nuclei play a significant role in voluntary movement and
cognitive/emotional functions, with the nucleus accumbens linked to pleasure and reward
(pg. 451).
• The limbic system is essential for mediating emotions and long-term memory, connecting
with the prefrontal cortex (pg. 451).
• The cerebellum fine-tunes motor control and maintains balance and posture through
extensive neural connections with the medulla and midbrain (pg. 452).
Cerebrospinal Fluid (CSF) Functions
• Arachnoid villi act as one-way valves for CSF outflow into the blood, preventing blood
from entering the subarachnoid space (pg. 458).
• CSF is produced by ependymal cells in the choroid plexuses of the lateral, third, and
fourth ventricles (pg. 458).
• The buoyant properties of CSF protect the brain from jolts and prevent it from tugging on
meninges and blood vessels (pg. 457).
• CSF is continuously produced and reabsorbed into the venous circulation, maintaining
homeostasis (pg. 458).
, • The pressure gradient between arachnoid villi and cerebral venous sinuses facilitates CSF
reabsorption (pg. 458).
• CSF plays a critical role in maintaining intracranial pressure and providing a stable
environment for the brain.
Blood Flow and Pain Perception
Blood Flow to the Brain
• The brain receives about 20% of cardiac output, approximately 800 to 1000 mL of blood
per minute, with autoregulation to maintain stable flow (pg. 459).
• The internal carotid and vertebral arteries supply blood to the brain, with the internal
carotid arteries providing the majority (pg. 459).
• The Circle of Willis offers collateral blood flow, ensuring adequate perfusion even if one
artery is obstructed (pg. 459).
• Cerebral venous drainage does not parallel arterial supply, affecting intracranial pressure
significantly (pg. 460).
• Adequate venous outflow is crucial; head position can influence venous return and
intracranial pressure (pg. 460).
• The posterior inferior, anterior inferior, and superior cerebellar arteries perfuse the
cerebellum and brainstem (pg. 459).
Pain Perception and Theories
• The gate control theory of pain posits that pain perception is influenced by both
physiological signals and psychological factors (e.g., distraction can reduce pain
perception).
• Pain signals are transmitted through A-delta fibers (fast pain) and C fibers (slow pain),
with A-delta fibers being myelinated and larger (pg. 457).
• Pain perception occurs in the reticular and limbic systems and the cerebral cortex,
influenced by genetics, culture, and past experiences (pg. 476).
• Pain threshold is the minimum intensity of pain recognized, while pain tolerance is the
maximum intensity endured (pg. 476).
• Factors such as stress, fatigue, and emotional state can affect pain threshold and
tolerance, demonstrating the subjective nature of pain (pg. 476).
, • Perceptual dominance explains how intense pain in one area can mask pain in another,
affecting overall pain perception.
Clinical Aspects of Pain
Types of Pain and Their Characteristics
• Acute pain is typically short-term and directly related to tissue injury, while chronic pain
persists beyond normal healing time.
• Neuropathic pain arises from nerve damage and can be chronic, often described as
burning or tingling.
• Pain threshold varies among individuals and can be influenced by various factors,
including genetics and cultural perceptions (pg. 476).
• Pain tolerance can change over time and is affected by repeated exposure to pain,
emotional state, and other external factors (pg. 476).
• Understanding the differences between acute, chronic, and neuropathic pain is essential
for effective treatment and management.
• Clinical assessments of pain should consider both threshold and tolerance to tailor pain
management strategies.
Pain Mechanisms
Acute Pain (Nociceptive Pain)
• Acute pain serves as a protective mechanism, alerting individuals to harmful conditions
and prompting immediate action.
• It is typically transient, lasting from seconds to a maximum of 3 months, and is relieved
once the underlying cause is addressed.
• The autonomic nervous system's stimulation leads to physical symptoms such as
increased heart rate, hypertension, diaphoresis, and dilated pupils.
• Acute pain is often associated with inflammation, which activates pain receptors through
chemical mediators.
• Examples include post-surgical pain or pain from an injury, which usually resolves as
healing occurs.
