Central Nervous System – Lecture Review

A comprehensive set of question-and-answer flashcards covering glial cell types and functions, CNS support structures, major brain regions and their roles, cortical areas, memory, learning, sleep physiology, and key neuroanatomical pathways.

What two major structures make up the central nervous system (CNS)?

The brain and spinal cord.

Approximately what percentage of cells in the CNS are glial cells?

About 90%.

Name the five main types of glial cells.

Astrocytes, microglia, ependymal cells, oligodendrocytes, and Schwann cells (in the PNS).

Which glial cell forms the myelin sheath in the CNS?

Oligodendrocytes.

Which glial cell type is responsible for phagocytosis of foreign matter in the CNS?

Microglia.

List three major functions of astrocytes.

blood-brain barrier,

removal of neurotransmitters from synaptic clefts,

maintaining extracellular ion balance,

modulating synaptic activity, and

protecting neurons from toxins/oxidative stress.

What fluid do ependymal cells secrete and where is it produced?

Cerebrospinal fluid (CSF) in the choroid plexus.

Name the three layers of the meninges from superficial to deep.

Dura mater, arachnoid mater, pia mater.

State two primary functions of cerebrospinal fluid (CSF).

Cushions the brain and maintains a stable interstitial fluid environment.

Roughly how much CSF is produced each day?

400–500 mL per day.

What percentage of the body’s total blood supply does the CNS receive?

Approximately 15%.

Why does the brain depend almost entirely on aerobic glycolysis for energy?

Because it has no glycogen stores and cannot use fatty acids; it relies on continuous delivery of glucose and oxygen.

What creates the blood-brain barrier in CNS capillaries?

Tight junctions between endothelial cells.

Name two substances that cross the blood-brain barrier easily.

Lipid-soluble substances such as oxygen, carbon dioxide, alcohol, steroids, and ketone bodies.

Differentiate gray matter and white matter in the CNS.

Gray matter contains neuron cell bodies, dendrites, and axon terminals; white matter consists mostly of myelinated axons.

List the three main subdivisions of the brain.

Cerebellum, brainstem, and forebrain.

Which brain structure provides fine control of motor activities and balance?

The cerebellum.

What are the components of the brainstem?

Midbrain, pons, medulla oblongata, and the reticular formation/reticular activating system.

Which cranial nerve functions are primarily processed in the brainstem?

10 of the 12 cranial nerves have nuclei in the brainstem.

State one major reflex function of the midbrain.

Reflex movements of the head and eyes in response to visual stimuli.

What two respiratory centers are located in the pons?

The apneustic and pneumotaxic centers (fine regulation of breathing).

Name three vital reflex centers located in the medulla oblongata.

Vasomotor center (blood pressure), cardiac center (heart rate/contractility), and respiratory center (rhythm generation).

Which brain region sends arousal signals that maintain wakefulness?

The reticular activating system (reticular formation).

What is the primary sensory relay station to the cerebral cortex?

The thalamus.

List four homeostatic functions regulated by the hypothalamus.

Autonomic nervous system, thirst/osmolarity, food intake, thermoregulation, endocrine link (pituitary control), circadian rhythms, emotions (rage/aggression).

Name the two layers of gray matter in the cerebrum.

The cerebral cortex and the basal nuclei.

What type of fibers connect the two cerebral hemispheres?

Commissural fibers (e.g., corpus callosum).

Which lobe of the cerebrum contains the primary motor cortex?

The frontal lobe (precentral gyrus).

What is the function of the premotor cortex?

Plans and coordinates stereotyped, sequential muscle movements.

Damage to Broca’s area results in what type of aphasia?

Broca’s (non-fluent) aphasia, characterized by slow, labored speech.

Where is Wernicke’s area located and what is its function?

On the left temporal/parietal region; it is responsible for comprehension of spoken and written language.

What sensory information is processed in the primary somatosensory cortex?

Touch, temperature, pressure, pain, and proprioception.

Which cortex distinguishes shape and color of visual stimuli?

The primary visual cortex (occipital lobe).

What area of the brain is responsible for perception of smell?

The olfactory cortex in the temporal lobe.

Which structures make up the limbic system?

Amygdala, hippocampus, fornix, cingulate gyrus, and parts of the thalamus and hypothalamus.

Give two functional specializations of the right cerebral hemisphere.

Creativity and spatial perception.

Define associative learning and give an example.

Learning that links two stimuli together; e.g., Pavlov’s dog associating a bell with food.

What type of memory is automatic and involves learned motor skills?

Procedural (implicit) memory.

Which brain structure is essential for consolidating short-term declarative memories into long-term memories?

The hippocampus.

During which sleep phase do most vivid dreams occur, and what neurotransmitter is involved in initiating it?

REM (paradoxical) sleep; acetylcholine release from the pons induces it.

List two EEG characteristics of slow-wave sleep.

High-amplitude, low-frequency (0.5–2 Hz) waves; decreased heart rate, blood pressure, and respiration.

What is the typical cycle length between REM periods during sleep?

About every 90 minutes.

Which glial cell forms myelin sheaths in the peripheral nervous system?

Schwann cells.

What is the normal total volume of CSF in an adult?

Approximately 125–150 mL.

Name the fiber type that connects cortical areas within the same cerebral hemisphere.

Association fibers.

Which brain lobe is primarily responsible for auditory perception?

The temporal lobe (primary auditory cortex).

What part of the brain sets overall voluntary activity plans and is linked to personality traits?

The prefrontal association cortex.

What sensory pathway feature explains why the right side of the brain perceives stimuli from the left side of the body?

Sensory pathways cross (decussate) before reaching the cortex.

Identify two behaviors regulated by the hypothalamic centers for food intake.

Appetite (hunger) and satiety (fullness).

Which structure suppresses unwanted movements and initiates learned complex motor patterns?

The basal nuclei (basal ganglia).

What are the three broad categories of the brain’s white-matter tracts?

Projection fibers, association fibers, and commissural fibers.

Define ‘stroke’ in relation to cerebral blood flow.

A loss of brain function due to decreased blood supply, either from vessel occlusion or hemorrhage.

Which EEG state is paradoxical because the brain is active but the person is asleep?

REM (rapid eye movement) sleep.

How many times is the entire CSF volume recycled each day?

About three times per day.

What is the role of the amygdala in the limbic system?

It is involved in emotion, especially fear and aggression.

Which neurotransmitter’s action is blocked by caffeine, thereby reducing sleepiness?

Adenosine.

Name two physiologic responses coordinated by the medulla’s autonomic reflex centers besides cardiovascular and respiratory control.

Regulation of vomiting, swallowing, coughing, and sneezing.

Which cortical area integrates complex sensory information and is pivotal for language comprehension?

Wernicke’s area.

Describe the main function of commissural fibers such as the corpus callosum.

They connect corresponding regions of the two cerebral hemispheres to facilitate interhemispheric communication.

What behavioral functions are localized predominantly in the left cerebral hemisphere?

Language, logic, and analytical reasoning.

What term refers to the CNS phenomenon of forming new synapses or modifying existing ones as part of learning and memory?

Neural plasticity.

Which part of the diencephalon acts as a major link between the nervous and endocrine systems?

The hypothalamus.

What are association fibers?

White-matter tracts that connect different areas of the cerebral cortex within the same hemisphere.

Which structure compares intended movements with actual body position to fine-tune motor output?

The cerebellum.

State one reason fatty acids are not used as an energy source by neurons.

Fatty acids cannot cross the blood-brain barrier readily and neurons rely on aerobic glycolysis of glucose.

Which phase of memory lasts seconds to hours and is susceptible to loss unless consolidated?

Short-term memory.