THE NERVOUS SYSTEM
“The Equine Nervous System is the most complex system in the body. It controls all of the other equine body systems – consisting of the brain, spinal cord, and sensory and motor nerves. It is also the system that feels pain or other sensations.”
Notes from folder
The nervous system controls and coordinates the equine body’s activities and responses to stimuli through nerve cells (neurons) and the messages they send (impulses). Irrespective of where they are in the body, they all fulfil the same function of transmit- ting information in the form of small electrical signals.
There are three main types of nerve cell or neuron, sensory, motor and intermediate.
The sensory neurons will pass information generated by receptor cells, on to the CNS. Motor neurons carry impulses from the CNS out to muscles and glands throughout the body. They can be extremely long, yet the information travels from the nerve cell out to the muscle or gland in milliseconds. Intermediate neurons connect sensory and motor neurons.
Generally, nerve cells have the same basic set up, a cell body with a nucleus, thin, branch-like growths called dendrites which receive information from other nerve cells, a long, single nerve fibre called an axon which is a transmitter and further branch-like growths at the end of the axon called terminal dendrites.
Neurones can talk to each other, they communicate at the junctions between one neurone’s terminal dendrite’s and another’s cell boy. This is called a synapse.
The Nervous System comprises of three main sub systems, the Central Nervous System (CNS), the Peripheral Nervous System (PNS) and the Autonomic Nervous System (ANS).
The CNS is….Literally the nerve centre of control in the horse – the horse’s “computer”. Made up of the brain and spinal cord, protected by the skull and spinal column.
The PNS is….The system that controls the sensory and motor nerves.
Connected to the CNS and runs throughout the body – the sensory nerves bring messages from sensory organs in to the CNS, the motor nerves take messages from the CNS out body parts, such as contractions of skeletal muscle.
The ANS is….Part of the PNS. Controls involuntary systems.
Made up of two additional sub systems, Sympathetic Nervous System and the Parasympathetic Nervous System.
The Sympathetic Nervous System governs the fight or flight mode in the horse. It will kick in in order to alert the horse to imminent danger, the presence of threats, predators etc. Once activated, the ANS shuts down un-necessary systems such as digestion and reproduction and concentrates on dilating the pupils, raising the horse’s blood pressure, heart rate and supply of oxygen-rich blood to the heart and lungs, ready for him to run.
The Parasympathetic Nervous System in contrast, governs the horse’s down time, the times when blood flow is increased and endorphins are released and he is safe to sleep, relax, digest, process, heal and deal with physical or emotional issues.
