Nervous System and Associated Diseases Notes

Nervous System Overview

• Main Divisions of the Nervous System

  • Central Nervous System (CNS)

  • Comprises the brain and spinal cord.

  • Peripheral Nervous System (PNS)

  • Comprises nerves extending from the CNS (cerebral & spinal nerves) and the autonomic nervous system.

Central Nervous System (CNS)

• Components:

  • Brain:

  • Medulla Oblongata: Controls involuntary functions such as breathing, chewing, swallowing, and heart rate.

  • Cerebellum: Responsible for movement coordination, balance, and motor control.

  • Cerebrum: Manages voluntary actions and cognitive functions.

  • Spinal Cord:

  • Pathway for transmitting neural signals between brain and body.

Peripheral Nervous System (PNS)

• Types of Nerves:

  • Cranial Nerves: 12 pairs that originate from the brain.

  • Spinal Nerves: Arise from the spinal cord and connect to body structures.

  • Autonomic Nervous System:

  • Parasympathetic Nervous System: Encourages restful functions (feed, breed, and rest).

  • Sympathetic Nervous System: Triggers fight or flight responses during stress.

Composition of Nervous System

• Neurons (Nerve Cells):

  • Specialized cells responsible for receiving/transmitting electrical and chemical signals.

  • Parts of a Neuron:

  • Cell Body (soma): Contains the nucleus.

  • Dendrite: Receives signals from other neurons.

  • Axon: Transmits impulses away from the cell body.

  • Myelin Sheath: Insulates the axon, speeding signal transmission.

  • Nodes of Ranvier: Gaps in the myelin sheath facilitating rapid impulse conduction.

  • Synapses: Junctions for signal transmission to other cells.

• Glial Cells (Neuroglia):

  • Support neurons, contribute to information processing, and aid in neurotransmitter exchanges.

Nervous System Disorders

• Encephalopathy: Disorders that affect brain function.

• Myelopathy: Affects the spinal cord leading to various dysfunctions.

• Neuropathy: Involves peripheral nerves, causing damage outside of the CNS.

Specific Conditions

• Tetanus:

  • Caused by toxin from Clostridium tetani, leading to muscle spasms and paralysis.

  • Highly sensitive in horses, sheep, and humans; affects heart and respiratory muscles.

• Rabies:

  • Viral disease affecting CNS, transferred via bites from infected animals.

  • Symptoms include aggression, drooling, abnormal behavior.

• Pseudorabies (PRV):

  • Contagious herpes virus primarily affecting pigs, leading to neurological disorders.

  • Symptoms vary by species, and effective vaccines exist for prevention.

• Eastern Equine Encephalomyelitis (EEE):

  • Mosquito-borne virus causing severe brain inflammation in horses.

  • Presents with fever, lethargy, neurological signs; vaccines available for prevention.

• Bovine Spongiform Encephalopathy (BSE):

  • Prion-related disease of cattle leading to severe CNS degeneration.

  • Progressively fatal; no treatment available, strict prevention measures are critical.

• Scrapie:

  • A TSE impacting sheep and goats causing incoordination and behavioral changes.

  • Not highly contagious; management involves flock depopulation and sanitation.

• Equine Protozoal Myeloencephalitis (EPM):

  • Protozoan-caused disease that can mimic various neurological conditions in horses.

  • Symptoms include ataxia, depression; treated with specific medications.

Summary of Nervous System Functionality

• CNS: Processes all sensory information, coordinates body movements, and integrates higher functions (thinking, memory).

• PNS: Transmits signals to/from CNS, regulates involuntary functions, and connects sense organs, muscles, and glands.

• Autonomic System: Manages involuntary actions necessary for survival, balancing responses between sympathetic (stress) and parasympathetic (rest) functions.

These notes are derived from the comprehensive overview of the nervous system and its associated disorders, summarizing the key structures, functions, and diseases relevant for academic study.