BIOL 213 Chapter 13 Study Guide Notes

BRAIN ORGANIZATION AND DEVELOPMENT

Overview of Brain Anatomy

  • Four Main Regions of the Brain:

    • Cerebrum: divided into left and right cerebral hemispheres; each hemisphere further divided into 5 lobes.
    • Diencephalon
    • Brainstem
    • Cerebellum

  • Brain Surface Features:

    • Gyri: folds of brain tissue in the outer portion of the brain.
    • Sulci: shallow depressions between gyri.
    • Fissures: deeper grooves between gyri.

  • Directional Terms:

    • Rostral: anterior or “toward the nose.”
    • Caudal: posterior or “toward the tail.”

Development of Brain Divisions

  • Neurulation:

    • Process forming the nervous system from the ectoderm, resulting in a neural tube that forms the CNS (brain and spinal cord).

  • Brain Development:

    • Develops from the cranial part of the neural tube into 3 primary brain vesicles:
    1. Telencephalon: forms the cerebrum.
    2. Diencephalon: forms the thalamus, hypothalamus, and epithalamus.
    3. Mesencephalon: forms the midbrain.
    4. Metencephalon: forms the pons and cerebellum.
    5. Myelencephalon: forms the medulla oblongata.

Gray Matter and White Matter Distribution

  • Gray Matter:

    • Contains neuron cell bodies, dendrites, unmyelinated axons.

  • White Matter:

    • Contains myelinated axons.

  • Distribution:

    • Identify gray and white matter distribution in the cerebrum and spinal cord using reference figures.

PROTECTION AND SUPPORT OF THE BRAIN

Cranial Bones

  • Provide rigid support to protect the brain.

Cranial Meninges

  • Three Connective Tissue Layers:
    1. Pia Mater:
    • Thin layer of delicate areolar connective tissue.
    • Tightly adheres to the brain.
    1. Arachnoid Mater:
    • Delicate layer of collagen and elastic fibers.
    • Subarachnoid space below it contains cerebrospinal fluid (CSF).
    • Contains a potential subdural space that can fill with blood/fluid (subdural hematoma).
    1. Dura Mater:
    • Strongest layer, composed of dense irregular connective tissue.
    • Potential epidural space may exist between the dura mater and skull bones.

Brain Ventricles

  • Ventricles: cavities within the brain lined with ependymal cells containing CSF.

Cerebrospinal Fluid (CSF)

  • Functions:
    • Buoyancy: allows the brain to float.
    • Protection: cushions the brain.
    • Environmental Stability: transports nutrients and removes wastes.
  • CSF Formation:
    • Formed by the choroid plexus via filtering blood plasma with different ionic compositions.

Blood-Brain Barrier (BBB)

  • Protects nervous tissue from the general circulation and regulates substance exchange.
  • Structural Features:
    • Endothelial cells with tight junctions.
    • Thickened basement membrane.
    • Astrocyte perivascular feet managing material passage.

CEREBRUM

Overview

  • Location of conscious thought, intellectual functions.

Cerebral Hemispheres

  • Composition: left and right hemispheres separated by the corpus callosum.
  • Cerebral Lateralization: different functions in each hemisphere (e.g., language in left hemisphere).

Lobes of the Cerebrum

  • Lobes:
    • Frontal, Parietal, Temporal, Occipital (4 visible)
    • Insula (5th lobe, not visible).

Functional Areas of the Cerebrum

  • Key areas include:
    • Primary Motor Cortex: controls voluntary muscle activity.
    • Broca Area: speech production.
    • Primary Somatosensory Cortex: processes sensory information from the skin.
    • Wernicke Area: involved in understanding language.

Cerebral Lateralization and Cerebral Nuclei

  • Functional Differences:
    • Left: language and analytical skills.
    • Right: creativity and spatial skills.
  • Cerebral Nuclei: regulate movement and associated with disorders like Huntington's disease.

DIENCEPHALON

Structure and Functions

  • Regions:
    • Epithalamus: includes pineal gland, regulates circadian rhythms.
    • Thalamus: relay for sensory information.
    • Hypothalamus: autonomic control and hormone regulation.

BRAINSTEM

Regions

  • Midbrain: movement control, visual/auditory reflex centers.
  • Pons: regulates breathing and connects brain/spinal cord.
  • Medulla Oblongata: autonomic functions like heart rate and breathing regulation.

CEREBELLUM

  • Coordinates skeletal muscle movements, maintains posture, and can be impaired by drugs or alcohol.

FUNCTIONAL BRAIN SYSTEMS

Limbic System

  • Processes and experiences emotions, involves structures like hippocampus and amygdala.

Reticular Formation

  • Regulates alertness and muscle tone, involved in arousal from sleep.

INTEGRATIVE FUNCTIONS

Memory Types

  • Sensory, Short-Term, Long-Term: varying durations and encoding processes.

Cranial Nerves

  • 12 pairs part of PNS, address sensory, motor, and mixed functions.

APPLICATION QUESTIONS

  1. What is meningitis and its dangers?
  2. Differentiate Broca’s and Wernicke’s aphasia.
  3. Phineas Gage's insights on prefrontal cortex.
  4. Predicting stroke effects due to hemisphere damage.
  5. Insights from HM’s surgery and aging-related diseases.