The Nervous System allows the horse to perform highly complex activities in addition to being the main control system for internal processes. It manages reasoned and co-ordinated movement. The Nervous System stores information and evaluates situations based on experience and instinct. Thus making decisions and sending messages to the muscles.
The Nervous System influences a horse's reaction to the world around. Changes in light, temperature etcetera produce a reaction. A stimulus or change is received from the Sensory System, this is then conducted to the control system ie: Central Nervous System, this interprets the stimulus or change and in turn coordinates an appropriate response. Look out for future blogs about the senses.
The Central Nervous System (CNS) consists of the brain and the spinal cord. The brain is safely encased inside the horse's skull. The spinal cord is a cylinder of tissue which goes from the brain and down the back.
The brain receives all the messages from the sensory system via the sensory nerves. It then integrates this information to form an understanding of the immediate environment. The information is also stored as an 'experience' which will then allow the horse to anticipate events in the future.
Once the stimulus is interpreted by the brain, messages are sent to the body via the cranial nerves in the skull and then through the spinal cord to the spinal nerves which go to all parts of the body. The spinal cord runs down the centre of the spinal column, see my Horse's Skeleton blog. The spinal nerves emerge between each vertebrae. The spinal cord sends the messages on to the peripheral nervous system.
The Peripheral Nervous System (PNS) consists of the cranial and spinal nerves and nervous tissue outside of the brain and spinal cord. Nerves may contain sensory and motor neurons. The PNS forms a huge network of sensory and motor pathways. The sensory pathways transmit messages from the sensory receptors to the CNS. The motor pathways carry messages from the CNS to the muscles and glands. The PNS is divided into the Somatic (voluntary) and Autonomic (involuntary) nervous systems.
The Somatic Nervous System: includes the sensory nerves which transmit information from the peripheral sensory receptors to the CNS and the motor nerves which send the nerve impulses to the skeletal muscles. Many of the actions which this system is involved with can be consciously controlled ie: moving a leg!
The Autonomic Nervous System: is involuntary as this allows internal organs to function properly, usually unconsciously controlled. The autonomic nervous system controls the digestive system, the movement of blood by the heart, some of gland activities and much of the urino-genital system. This system is again divided into the parasympathetic nervous system and the sympathetic nervous system, these have opposing actions.
The Parasympathetic nervous system maintains normal functioning of the body when in non-threatening situations. So this helps keep the body in a relaxed and unstressed condition, so keeping the heart rate low, constricting the pupils. The Sympathetic nervous system effects physiological reactions to threatening situations ie: fight or flight. This system increases the heart rate, dilates the pupils and constricts blood vessels going to the gut. These 2 systems work in opposition to each other and as no horse is fully relaxed or fully active the levels are appropriate to any given situation.
The Nervous System is obviously of vital importance and some understanding will in turn help us to understand our horses and their actions.
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