Lecture Notes: Introduction to the Brain

Overview

• Course Focus: Extensive discussion on brain structure and function.
• Prerequisite Knowledge: Anatomy and physiology, particularly central nervous system basics.

Brain Divisions

1. Hindbrain
   • Myelencephalon (Medulla)
   • Metencephalon (Pons and Cerebellum)
2. Midbrain
   • Mesencephalon
3. Forebrain
   • Diencephalon (Thalamus and Hypothalamus)
   • Telencephalon (Cerebral Hemispheres and Cerebral Cortex)

Evolutionary Context

• Three-Scoop Model:
  1. Old structures: Brainstem and cerebellum (Lizard brain)
  2. Middle layer: Limbic system (Rat brain)
  3. Top layer: Cortex (Monkey brain)

Neural Cells

• Neurons: Basic structure and action potential generation are assumed knowledge.
• Neuroglia (Glial Cells):
  1. Oligodendrocytes: Form myelin sheaths, speed up conduction along axon.
  2. Astrocytes: Support neurons, anchor them to nutrients, absorb and secrete substances.
  3. Microglial Cells: Monitor neuron health, perform phagocytosis.
  4. Ependymal Cells: Line brain and spinal cord cavities, form barrier between cerebrospinal fluid and other cellular fluids.

Brain Protection

• Cerebrospinal Fluid: Cushions brain, protects from physical trauma.
• Blood-Brain Barrier:
  • Prevents interference with neuronal firing by restricting permeability.
  • Allows necessary molecules (oxygen, glucose) through, restricts large molecules (proteins, many drugs).
  • Formed by tight junctions in endothelial cells of blood vessel walls.