Practical 3 Self-test S19

Nervous System Structures and Functions

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1. Neuron Anatomy

  • Types of Neurons

    • Motor Neuron: Transmits impulses from the central nervous system to muscles.

    • Sensory Neuron: Carries signals from sensory receptors to the central nervous system.

    • Interneuron: Connects other neurons, primarily found in the brain and spinal cord.

  • Parts of a Neuron

    • Soma (Cell Body): Contains the nucleus and organelles.

    • Dendrites: Branch-like structures that receive messages from other neurons.

    • Axon: Long projection that transmits impulses away from the soma.

    • Axon Bulb: The terminal end of the axon that releases neurotransmitters.

    • Node of Ranvier: Gaps in the myelin sheath where action potentials are regenerated.

    • Myelin Sheath: Covers axons and insulates them to enhance signal speed.

2. Neuroglia and Support Cells

  • Schwann Cell: Type of glial cell that provides myelin for peripheral nervous system axons.

  • Neuroglia: Supportive cells in the nervous system; not involved in transmitting impulses.

3. Coverings and Connective Tissues

  • Meninges

    • Dura Mater: Tough outer layer covering the brain and spinal cord.

    • Arachnoid Mater: Middle layer with a web-like structure.

    • Pia Mater: Thin inner layer closely adhering to the surface of the brain and spinal cord.

  • Epineurium: The outermost layer of connective tissue surrounding nerves.

  • Perineurium: Encases bundles of nerve fibers (fascicles).

  • Endoneurium: Surrounds individual nerve fibers within a fascicle.

4. Brain Structures

  • Cerebrum: Largest part of the brain responsible for higher brain functions such as thought and action.

  • Cerebellum: Coordinates muscle movements, posture, and balance.

  • Brain Stem: Controls automatic functions such as breathing and heart rate.

    • Midbrain: Associated with vision, hearing, motor control, and alertness.

    • Pons: Connects parts of the brain and carries messages between them.

    • Medulla Oblongata: Controls vital functions and reflexes.

  • Thalamus: Relay motor and sensory signals to the cerebral cortex.

  • Hypothalamus: Regulates body temperature, hunger, thirst, and circadian cycles.

  • Corpus Callosum: Connects the left and right hemispheres of the brain.

  • Pituitary Gland: Master endocrine gland controlling hormonal regulation.

  • Pineal Gland: Regulates sleep patterns by producing melatonin.

5. Fissures and Sulci in the Brain

  • Longitudinal Fissure: Divides the brain into left and right hemispheres.

  • Transverse Fissure: Separates the cerebrum from the cerebellum.

  • Central Sulcus: Separates the frontal and parietal lobes.

  • Dorsal Median Sulcus: A longitudinal groove on the spinal cord.

6. Spinal Cord Anatomy

  • Describe components such as

    • Cervical, Thoracic, Lumbar, Sacral, and Coccygeal Regions.

  • Grey Matter: Contains neuronal cell bodies, dendrites, and synapses. It processes information.

  • White Matter: Composed of myelinated axons that transmit signals across different regions of the central nervous system.

7. Peripheral Nervous System (PNS)

  • Components

    • Cranial Nerves: Emanating directly from the brain.

    • Spinal Nerves: Emanating from the spinal cord.