Equine_nervous_system-2025

Nervous System Overview

  • The equine nervous system is the most complex in the body.

  • It controls all other equine body systems.

Components of the Nervous System

  • Main components include:

    • Brain

    • Spinal cord

    • Spinal nerves

    • Cranial nerves

    • Vagus nerve

    • Network of nerves to forelimb

    • Autonomic nervous system

    • Sciatic nerve

Function of the Nervous System

  • Composed of billions of neurons.

  • Supplies information about internal and external environments.

  • Conveys sensation: impulses travel back and forth between the brain/spinal cord and body parts.

  • Acts as the body’s communication system, connecting various functions.

Division of the Nervous System

Central Nervous System (CNS)

  • Components:

    • Brain

    • Spinal Cord

  • Functions:

    • Controls conscious or voluntary actions.

    • Key structures of the CNS involve the brain which is responsible for numerous tasks:

      • Brain stem:

        • Controls heartbeat, respiration, and body temperature.

      • Cerebrum:

        • Involved in memory, intelligence, and emotional responses.

      • Cerebellum:

        • Manages muscular coordination, balance, and equilibrium

        • Spinal Cord: Reflex Arch (knee-jerk) and connects pns and the brain.

Peripheral Nervous System (PNS)

  • Function:

    • Connects CNS to limbs and organs.

    • Extends outside CNS and lacks the protective barriers present in CNS, making it vulnerable to damage.

  • Subdivisions:

    • Somatic Nervous System:

      • Coordinates body movements and responses to external stimuli.

      • Involves conscious control.

    • Autonomic Nervous System (ANS):

      • Controls involuntary functions (e.g., circulatory and respiratory systems).

      • Divided into:

        • Sympathetic Nervous System:

          • Activates the ‘Fight or Flight’ response.

          • Prepares the horse for danger or stress by increasing heart rate and blood pressure.

        • Parasympathetic Nervous System:

          • Manages 'Rest and Digest' functions when the horse is relaxed.

          • Promotes digestion and general maintenance of body systems.

Neuronal Communication

  • Neurons are the basic functional units:

    • Composed of:

      • Dendrites: Receive signals.

      • Cell Body: Contains the nucleus and organelles.

      • Axon: Sends messages away from the cell body.

  • Types of Neurons:

    • Sensory Neurons: Transmit impulses from sense receptors to CNS.

    • Motor Neurons: Send impulses from CNS to muscles or glands.

    • Relay Neurons: Connect sensory and motor neurons.

  • Synapse: Connection point between neurons for signal transfer, utilizing neurotransmitters (e.g., acetylcholine).

Reflex Actions

  • Reflexes operate independently of the brain; reactions occur instinctively.

  • Animals are born with reflexes, allowing immediate responses to stimuli.

Eastern Equine Encephalitis

  • A serious mosquito-borne viral disease affecting the central nervous system.

  • Symptoms range from mild (fever, headache) to severe (seizures, coma, brain damage, death).

  • No specific treatment is available, emphasizing the importance of preventive measures.

Relationship Between Sensory, Motor, and Relay Neurons

  • Nerve cells do not touch; there is a microscopic space between them called a synapse.

  • An impulse in the neuron before the synapse (sensory neuron) stimulates the production of chemicals called neurotransmitters (e.g., acetylcholine) into the synaptic gap.

  • Neurotransmitters diffuse across the gap.

  • Upon reaching the membrane of the next nerve cell (relay neuron), they stimulate a nervous impulse, facilitating communication between the sensory neuron and motor neuron through the relay neuron.

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