Central Nervous System and Brain Structure Flashcards

Central Nervous System

Brain Structure and Function Overview

• Brain Divisions and Functions:
  • Cerebrum: Higher mental functions, sensory interpretation, movement planning.
  • Diencephalon: Processes and relays information, maintains homeostasis, regulates rhythms.
  • Cerebellum: Monitors and coordinates movement.
  • Brainstem: Controls reflexes, monitors movement, relays information.

Brain Matter

• Gray Matter: Unmyelinated axons, dendrites, cell bodies (e.g., basal nuclei, cortex).
• White Matter: Myelinated axons within the CNS (tracts).
• Tract Types:
  • Commissural: Connects right and left hemispheres.
  • Association: Connects areas within a hemisphere.
  • Projection: Connects upper and lower areas, forming corona radiata.

Cerebrum Folding

• Folding increases processing area.
• Sulcus (sulci): Depression or groove.
• Central Sulcus: Separates frontal and parietal lobes.
• Gyrus (gyri): Ridge.
• Precentral Gyrus: Anterior to the central sulcus.
• Postcentral Gyrus: Posterior to the central sulcus.
• Fissures: Deeper grooves.
• Longitudinal Fissure: Separates left and right hemispheres.
• Lateral Fissure

Lobes of the Brain

• Frontal Lobe: Voluntary motor movements, cognitive functions, personality.
• Parietal Lobe: Interprets general senses, written and spoken language.
• Temporal Lobe: Processes hearing and smell, integrates memories and sensations.
• Occipital Lobe: Receives and processes visual information.
• Insula: Processes taste (gustatory).

Meninges

• Three connective tissue layers lining the CNS.
  • Dura Mater: Outer layer, dense irregular tissue. Includes meningeal (inner) and periosteal (external) layers.
  • Arachnoid Mater: Middle layer, collagen and elastin fibers. Contains arachnoid granulations protruding into dura mater.
  • Pia Mater: Areolar connective tissue, thin membrane.
• Subarachnoid Space: Below arachnoid mater for CSF circulation.
• Meningitis: Inflammation of meningeal layers due to infection.

Ventricles and Cerebrospinal Fluid (CSF)

• Ventricles: Chambers lined by ependymal cells, filled with CSF.
  • Lateral: In cerebral hemispheres, largest and paired.
  • Third: Within the lower cerebral hemisphere.
  • Fourth: Continuous with the third, connects to the spinal cord.
• CSF Formation: Formed in the choroid plexus in ventricle walls, filtered blood.
• CSF Circulation: Fills ventricles and subarachnoid space.
• CSF Absorption: Reabsorbed into blood in dural sinuses via arachnoid granulations.
• CSF Composition: Contains glucose, oxygen, vitamins, and ions.
• Hydrocephalus: Blockage in CSF flow.

Blood-Brain Barrier

• Regulated by astrocytes around brain capillaries.
• Limits solutes entering brain ECF.

Cerebral Cortex

• Outer gray matter for conscious processing.
• Primary Motor Areas: Initiate movement.
• Primary Sensory Areas: Receive stimuli.
• Primary Motor Cortex: In frontal lobe, initiates voluntary movement in upper motor neurons.
  • Somatotopy: Body mapped as an upside-down representation.
• Premotor Cortex: Plans, guides, and coordinates movement.
• Frontal Eye Fields: Motor area for lateral eye movements.
• Primary Somatosensory Area: Receives information from somatic senses; contains somatotopic map.
• Somatosensory Association Cortex: Interprets information from the primary somatosensory area.
• Primary Visual Cortex: In occipital lobe, receives visual input.
• Visual Association Area: Interprets vision, processes color, movement, and depth.
• Primary Auditory Cortex: In temporal lobe, receives auditory stimuli.
• Auditory Association Area: Interprets auditory stimuli.
• Gustatory Cortex: Processes taste.
• Olfactory Cortex: Processes smell.
• Multimodal Areas: Process multiple tasks, where thoughts, emotions and sensations become conscious.
• Broca's Area: Initiates speech.
• Wernicke's Area: Integrates speech for understanding.
• Prefrontal Cortex: Modulates behavior, personality, learning, working memory, and psychological state.

Limbic System

• "Visceral brain" regulating emotional responses.
• Limbic Lobe: Grey matter involved in memory formation, retrieval, and learning.
• Hippocampus: Grey matter involved in learning and memory.
• Amygdala: Grey matter involved in expressing fear.
• Fornix: Output tracts for the limbic system.

Diencephalon

• Physical center of the brain.
• Thalamus: Gateway to cerebrum, filters information.
• Hypothalamus: Regulates ANS, secretes hormones, regulates visceral functions.
• Epithalamus: Contains pineal gland; regulates wake-sleep via melatonin.

Midbrain

• Part of the brainstem, regulates startle reflexes.
• Corpora Quadrigemina:
  • Superior colliculi: Visual tracking.
  • Inferior colliculi: Auditory tracking.

Hindbrain

• Pons: Connects, "bridge"; aids in breathing.
• Medulla Oblongata: Connects to spinal cord, contains pyramids (decussation), maintains equilibrium. Contains cardiac and respiratory centers.
• Cerebellum: Coordinates ongoing movement.
  • Arbor vitae: white matter.
  • Folia: outer ridges of grey matter.
  • Vermis: worm-like bridge, separates hemispheres.
• Fine-tunes skeletal muscle movements, contains blueprint of body position.
• Receives motor information, evaluates body position, coordinates planned movement, sends information to cerebral motor cortex and brain stem nuclei.

Reticular Formation

• Functions in sleep, pain transmission, mood, regulates breathing and blood pressure.

Cranial Nerves

• Transmit information to and from the brain; can be sensory, motor, or both.

Basal Nuclei

• Deep gray matter that inhibit involuntary movement and initiate voluntary movement.
• Parkinson's disease is related to diminished dopamine levels.

Sleep

• Temporary unconsciousness
• Control: cerebral cortex, thalamus, hypothalamus, reticular formation

Brain Communication

• Uses projections, commissures, and association tracts to allow areas to communicate.