Define the following terms used to describe the Nervous System and explain how they interact with each other



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Neuroscience and Mental Health · S Tran

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Learning Objectives


  • Define the following terms used to describe the Nervous System and explain how they interact with each other:

Central Nervous System

Peripheral Nervous System

Autonomic nervous System

Somatic Nervous System

  • List the major causes of neurological disorders and give examples.

  • State the difference in the regenerative capacity of injured axons between the CNS and PNS.

  • Describe the main components of a standard neurological examination.

  • Outline the main electrophysiological and imaging techniques used in neurological diagnosis, noting the main advantages and disadvantages.


ession 1:
Neurological Disorders and their Main Causes

Parts of the Nervous System


  • Central Nervous System = Brain + Spinal Cord

    • ‘Housekeeping’ Functions. – Processing sensory + motor information

    • Supports higher functions: perceptions, cognition, emotion & memory.

  • Peripheral Nervous System = Peripheral nerves + Ganglia

    • Provides sensory & motor innervations to the body

  • Autonomic Nervous System = parts of the CNS + PNS.

    • Controls visceral function & homeostasis e.g. peristalsis & bladder release

    • Internal organs, blood vessels, glands, eye structures, genitalia.

  • Somatic Nervous System

    • Controls motor and sensory function for body wall

Causes of Neurological Disorders:


  1. Trauma

    • Spinal Cord Injury

      • Can cause paralysis

  1. Cerebrovascular Accident

    • Cerbrovascular Infarct / Stroke

      • Degeneration of neural tissue as no backup energy reserves like muscle

  1. Neoplasia

    • Meningioma

      • Pressure is an issue

      • Normally metastasis,

      • If primary then it’s normally connective tissue or glial

  1. Infection

  1. Metabolic Disorders

    • Diabetic Neuropathy e.g. Hypoglyceamia

      • Can result in comas

      • In peripheral nerves  Injury  tingling sensation

  1. Genetic Defects

  1. Environmental

    • Heavy Metal encepholopathies e.g. Lead Poisioning

    • Alcohol  fetal alcohol syndrome

    • ? Mobile Phones

    • Recreation Drugs etc

  1. Immunological

    • Multiple Sclerosis

      • D

        Neurological Examination


        1. Level of consciousness

        1. Speech

          • Talking to patient

        1. Mental state and cognitive function

          • Simple general knowledge/mathematical questions

        1. Sensory function

        1. Motor function

          • Twichage, feet touch, evaluation of strength of muscle groups

        1. Cranial nerve function

          • Eyelid strength, facial movement, gag reflex, smell, taste, hearing


        egeneration of neurones

Differences in regeneration capacity of the NS


  • No replacement of neurones

  • No axonal regeneration of CNS

  • High energy requirement – Low Energy Reserves

  • Little space inside the cranial cavity

  • In PNS, Regeneration may be functionally compromised

  • In CNS, regeneration is limited in distance therefore not viable

Investigations

Electrophysiology:


  • EEG: Electroencephalography measures the electrical potentials measured at scalp of underlying neurones Epilepsy & Coma.

  • EMG: Electromyography examines integrity of muscles e.g. motor neurone disease

  • NCS: Nerve Conduction Studies examines integrity of peripherphal nerves & lower motor neurones

Imaging


  • CT: Computerised Tomography uses x-ray sources. Shows hard tissue. Can’t be used too often. Cheap and Quick.

  • MRI: Magnetic Resonance Imaging is based on the behaviour of hydrogen protons to a externally applied magnetic field. Use for soft tissue differentiation. Time consuming. Can be used to give a functioning image: Functional MRI.

  • Angiography demonstrates cerebral vessels radiographically after a contrast medium injection.

Neuronal Dysfunction and Death


  • Neuronal Dysfunction = Epilepsy (abnormal synchronous firing)

  • Neuronal Death = Parkinson’s disease

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Learning Objectives


  • Draw and label a diagram of a typical neuron, identifying soma, dendrites, axon and terminals.

  • Define the role of each cellular component in the specialised function of the neuron.

  • Outline the organisation and functions of intracellular transport in the neuron.

  • Define the functional subtypes of neurons and list the ways in which they are organised collectively in the nervous system.

  • Describe the organisation of synapses.

  • Name the main classes of neuroglia and explain their functions in the nervous system.


ession 2:
Cells of the NS

Structure of a Neuron




  • Axon – Long extension of a neuron that carries nerve impulses away from the body of the cell.

  • Axon Terminals - The hair-like ends of the axon

  • Cell Body/Soma - The cell body of the neuron; it contains the nucleus

  • Dendrites - The branching structure of a neuron that receives messages on the Soma.

  • Myelin Sheath - The fatty substance that surrounds and protects some nerve fibers

  • Node of Ranvier – Gaps in the myelin sheath, allows salutatory conduction to occur

  • Nucleus - Organelle in the cell body of the neuron that contains the genetic material of the cell

  • Schwann's Cells - Cells that produce myelin - they are located within the myelin sheath.
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