The Peripheral Nervous System
The nervous system is one of the smallest yet one of the, if not the most, complex systems in the human body. It can be broken down into two main subdivisions, the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system contains about 85 billion neurons and includes the spinal cord and brain. It is considered the control center of the body and processes all types of incoming sensory information. The peripheral nervous system is composed of all the other tissue outside of the central nervous system. It can be broken down into a somatic nervous system (SNS), an autonomic nervous system (ANS), and an enteric nervous system (ENT). Components that are involved in physical sensation come from both the central nervous system and the peripheral nervous system. To begin with, the somatic nervous system, which is part of the peripheral nervous system, is made up of nerve fibers that detect and carry information
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(or sensations), via sensory neurons, and bring that information up into the central nervous system. This is done through the many sensory receptors found throughout the body, and sense we are talking about physical touch, it is the touch receptors located in the skin. Once in the central nervous system will take part in a process known as integration. This is simply the processing of the information gained and making an appropriate response. A sensory impulse will carry the sensory information and will move throughout the body by traveling along neurons. The impulse will go from neuron to neuron passing through synapses until it reaches the central nervous system where it can be processed and an appropriate motor response can be made.
The components of the nervous system that are involved in skeletal muscle movements are similar to the components of the nervous system that are involved in physical touch.
In the peripheral nervous system, the somatic nervous system picks up a sensation, for example touching an extremely hot surface, and sends the information through sensory neurons, passing from neuron to neuron, until it reached the central nervous system. The central nervous system, consisting of the brain and spinal cord, acts as a “control center” of sorts and processes the information from the sensory neuron through cranial and spinal nerves and through a process called integration. In our example it receives the information that the surface is hot and will conduct an appropriate response, to yank your hand back form the hot surface. Now that the information has been integrated the nervous system will give feedback as a motor response and activate effectors that will contract the correct skeletal muscles to remove your hand from the hot
surface. A motor unit is composed of a somatic motor neuron, but also all of the skeletal muscle fibers that it will stimulate. A single motor neuron can make contact with hundreds and thousands of skeletal muscle fibers and when the muscle is contracted, all of the muscle fibers in the motor unit will or should be able to contract in unison. Usually muscle fibers that are part of a muscle unit are not clustered together and instead are scattered throughout muscle included in the motor unit.
(or sensations), via sensory neurons, and bring that information up into the central nervous system. This is done through the many sensory receptors found throughout the body, and sense we are talking about physical touch, it is the touch receptors located in the skin. Once in the central nervous system will take part in a process known as integration. This is simply the processing of the information gained and making an appropriate response. A sensory impulse will carry the sensory information and will move throughout the body by traveling along neurons. The impulse will go from neuron to neuron passing through synapses until it reaches the central nervous system where it can be processed and an appropriate motor response can be made.
The components of the nervous system that are involved in skeletal muscle movements are similar to the components of the nervous system that are involved in physical touch.
In the peripheral nervous system, the somatic nervous system picks up a sensation, for example touching an extremely hot surface, and sends the information through sensory neurons, passing from neuron to neuron, until it reached the central nervous system. The central nervous system, consisting of the brain and spinal cord, acts as a “control center” of sorts and processes the information from the sensory neuron through cranial and spinal nerves and through a process called integration. In our example it receives the information that the surface is hot and will conduct an appropriate response, to yank your hand back form the hot surface. Now that the information has been integrated the nervous system will give feedback as a motor response and activate effectors that will contract the correct skeletal muscles to remove your hand from the hot
surface. A motor unit is composed of a somatic motor neuron, but also all of the skeletal muscle fibers that it will stimulate. A single motor neuron can make contact with hundreds and thousands of skeletal muscle fibers and when the muscle is contracted, all of the muscle fibers in the motor unit will or should be able to contract in unison. Usually muscle fibers that are part of a muscle unit are not clustered together and instead are scattered throughout muscle included in the motor unit.