Nervous System Terminology

The Nervous System

• The nervous system coordinates the body's involuntary and voluntary movements.
• It works in conjunction with the endocrine system to maintain homeostasis (a state of equilibrium).
• The nervous system has two main divisions: the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

Central Nervous System (CNS)

• The CNS consists of the brain and the spinal cord.
• The brain is separable into two hemispheres, each consisting of four lobes: frontal, parietal, occipital, and temporal.
• The CNS has three principal parts: the cell body, the dendrites, and the axon.
• The cell body contains the nucleus, and the dendrites project outward from the cell body.
• The axon is the part of the neuron that conducts electrical impulses.

Peripheral Nervous System (PNS)

• The PNS is divided into the somatic and autonomic nervous subsystems.
• When groups of neuron cell bodies occur within the PNS, each one is called a ganglion (plural: ganglia).
• Groupings of axons anywhere in the body are called nerves.

Synapse and Neurotransmitters

• The synapse is the connecting point between nerve cells or between a nerve cell and a receptor or effector cell.
• The stimulus between the two cells is usually passed by chemicals called neurotransmitters.
• Hormones are typical neurotransmitters.

Myelin Sheath and Ventricles

• The myelin sheath is a white fatty material that covers the axons, providing protection and electrical insulation to the nerves.
• Ventricles are cavities between the cerebrum and brain stem.

Parts of the Brain

• The cerebrum is the largest part of the brain, with an outer layer of grey matter called the cerebral cortex.
• The cerebellum is situated beneath the cerebrum and consists of two hemispheres.
• The diencephalon contains the thalamus and hypothalamus.
• The brain stem connects the cerebrum and cerebellum to the spinal cord.

Meninxes

• The meninxes are three-layered membranes surrounding the brain and spinal cord.
• They absorb physical shocks that may damage the neural tissue.
• The outer layer is termed the dura mater, the middle layer is the arachnoid, and the inner layer is the pia mater.

Disorders of the Nervous System

• Brain Trauma:
  • Concussion (cerebral concussion): violent shaking of the brain.
  • Subdural hematoma: a collection of blood trapped in the subdural space beneath the dura mater.
  • Epidural hematoma: a collection of blood between the dura mater and the skull.
• Vascular Insults:
  • Cerebrovascular accident (CVA): also known as a stroke.
  • Transient ischemic attack (TIA).
• Tumors:
  • Lesions or neoplasms that may cause localized dysfunction, producing an increase in intracranial pressure (ICP).
• Systemic Degenerative Diseases:
  • Multiple Sclerosis (MS).
  • Parkinson's disease.
  • Alzheimer's disease.
• Seizure Disorders:
  • Epilepsy: a chronic disorder characterized by recurrent seizures.
  • Grand mal seizures and petit mal seizures.
• Behavioral Disorders:
  • Anxiety disorders: obsessive-compulsive disorder (OCD) and phobia.
  • Mood disorders: depression.
  • Psychotic disorders: schizophrenia.

Procedures and Practitioners

• Imaging techniques:
  • Computed Tomography (CT).
  • Magnetic Resonance Imaging (MRI).
• Diagnostic tests:
  • Electroencephalography (EEG).
  • Lumbar Puncture (LP).
• Medical specialists:
  • Neurologists: diagnose and treat nervous system disorders.
  • Neurosurgeons: surgeons who specialize in operations on the nervous system.
  • Psychiatrists: medical doctors who specialize in the diagnosis and treatment of psychological disorders.
  • Psychologists: non-medical specialists in the diagnosis and treatment of psychological disorders.

Pharmacology

• Sedatives or hypnotics: drugs used to induce calming effects or sleep.
• Anticonvulsants: drugs used to treat seizure activity.