CNS Structure and Function Quiz

CNS Structure and Function

• CNS comprises the brain and spinal cord.
• Major brain regions include the telencephalon, diencephalon, cerebellum, brainstem, midbrain, pons, and medulla oblongata.
• Grey matter consists of neuron cell bodies (soma).
• White matter consists of myelinated axons, acting as neural "wires."
• Ganglia are collections of grey matter cells, enabling electrochemical communication.

Neuronal Communication

• Action Potential: Neurons generate messages through electrical signals.
• At rest, the cell membrane maintains a negative potential (-70mV).
• Depolarization: Positive charge influx (sodium ions) triggers an action potential.
• Repolarization: Potassium ions exit the cell restoring polarity.
• Hyperpolarization: temporary overshoot of resting potential.
• Saltatory Conduction: Action potentials "jump" between nodes of Ranvier in myelinated neurons, increasing speed.
• Myelin Sheath: Fatty substance produced by oligodendrocytes (CNS) and Schwann cells (PNS), increasing conduction speed.
• Axons: Transmit messages between neurons; myelinated axons support fast transmission; unmyelinated axons support slow transmission (e.g., pain signals).
• Neurotransmitters: Chemical messengers passing signals between neurons.
• Receptors: Specialized structures, not neurons themselves, receive neurotransmitter signals.

Nervous System Development and Brain Organization

• Adult Brain Directions:
  • Caudal: Towards the tail
  • Dorsal: Posterior/Superior
  • Ventral: Anterior/Inferior
  • Rostral: Front
• Embryonic Development: The neural tube differentiates into structures like the telencephalon and diencephalon, forming the brain's major parts.
• Brain Regions:
  • Frontal Lobe: Motor, planning, cognition.
  • Parietal Lobe: Sensory processing.
  • Temporal Lobe: Language, comprehension.
  • Occipital Lobe: Vision.
  • Limbic System: Memory, emotions, homeostasis.
• Sulci and Gyri: Sulci (crevices) and gyri (bumps) are crucial brain surface features.
• Motor Planning and Execution: Premotor cortex and supplementary motor area plan movements; primary motor cortex executes them.
• Cerebellum: Refines and coordinates movements.
• Brain Environs: Skull, Meninges (dura mater, arachnoid, pia mater) surround and protect the brain; Ventricles contain cerebrospinal fluid (CSF).

Sensory and Motor Pathways (Spinal Cord and Brain)

• Spinal Cord:
  • Ventral: Motor information (LMN) flows down to the body.
  • Dorsal: Sensory information flows upward.
  • White matter in dorsal column conveys sensory information, while grey matter processes this information in the dorsal horn.
• Primary Motor Pathways: UMN in the primary motor cortex direct movement through the lateral and anterior corticospinal tracts to LMN in the spinal cord.
• Sensory Pathways:
  • DCML (dorsal column-medial lemniscal pathway): Conveys light touch, proprioception, vibration.
  • ALST (anterior lateral spinothalamic pathway): Conveys pain and temperature.
• Pyramidal Decussation: Crossover of corticospinal tracts in the medulla.
• Dorsal Root Ganglion: First neuron in sensory pathways; has two axons communicating information.

Muscle Contraction

• Neurotransmitters: ACh (Acetylcholine) stimulates muscle contraction.
• ATP: Essential for muscle contraction, Myosin head attaching to and pulling actin filaments.
• Excitation-contraction coupling: The chain of events that link electrical signals to muscle contractions.
• Types of Sensory Pathways: Myelinated (fast) versus unmyelinated (slow) pathways.
• Dermatomes: Specific segments of skin innervated by particular spinal nerves.
• Gate Theory of Pain: Explains how distraction can reduce perceived pain.

Test your knowledge on the structure and function of the Central Nervous System (CNS). This quiz covers major brain regions, neuronal communication, and the mechanics of action potentials. See how well you understand concepts like depolarization and saltatory conduction.