The Human Nervous System Part Two

Today's post from helium.com (see link below) is the second part of a description of the human nervous system. Today's description is by a different author and you may notice one or two repetitions of information provided yesterday but that just helps to fix it in your brain. It's all very useful information and most certainly aids understanding of what your nervous system does and where it's going wrong if you have neuropathy. Both parts worth a read.
 

An overview on the human nervous system
by Jose Juan Gutierrez : Created on: October 23, 2011

 
The nervous system is the control center for all the processes occurring inside and outside of the human body, including all mental activity, such as learning, thinking, and memorizing. The nervous system monitors the organs, controls the movements of the muscles, processes data, and detects changes in temperature, among many other functions. The nervous system performs all these functions through the use of sensory receptors. Along with the endocrine system, the nervous system is responsible for maintaining homeostasis.

An overview on the human nervous system:

The nervous system is a communication network of nerve fibers, surrounded by a fatty substance known as myelin, and connective tissue that is constantly sending messages in and out of the human body. The complex activities performed by the nervous system include the motor, integrative, and sensory functions. The nervous system is classified into two subdivisions: the central nervous system (CNS), consisting of the brain and spinal cord; and the peripheral nervous system (PNS), consisting of nerves and ganglia (nerve cells outside the CNS).

The spinal cord and the brain form part of the CNS. The CNS is encased in bone for protection; the brain in the cranial vault and the spinal cord in the vertebral canal. The spinal cord is a long tube of nerve tissue that is located in the hollow channels of the vertebrae. The brain and spinal cord are surrounded by cerebro-spinal fluid (CSF) which protects the brain and spinal cord from injury. Membranes known as meninges prevent CSF from leaking to the outside.

The peripheral nervous system includes the nerve fibers that spread out from the spinal cord and the brain. These nerve fibers form the communication network between the CNS and the various organs of the body. The peripheral nervous system is subdivided into the somatic and the autonomic nervous systems. The somatic nervous system comprises the nerve fibers that connect to the skin and muscles and involves conscious activities. The autonomic nervous system includes the nerve fibers that communicate the CNS to organs, including the intestines, stomach, glands, and the heart, and involves unconscious actions.

Neurons are the nerve cells that carry out the functions of the nervous system; a neuron consists of a cell body (soma), a single axon, and one or more dendrites; neurons are classified as afferent, efferent, and inter-neurons; afferent (sensory) neurons carry signals from the peripheral sense receptors

to the CNS. Efferent (motor) neurons carry out signals from the CNS to organs, such as glands, or muscles. Inter-neurons (integration) neurons serve as connections between afferent and efferent neurons within the CNS.
Millions of sensory receptors detect changes occurring inside and outside of the body (sensory function); from the outside, they can detect changes, such as light, temperature, and sound; from the inside, they can detect carbon dioxide concentration, pH levels, and blood pressure. This information is known as sensory input; sensory input is changed into electrical signals (nerve impulses) which travel to the brain; once in the brain, these signals generate memory, thought, or decisions in a process known as (integration).

 

 Depending on the sensory input and integration, the nervous system reacts by signaling glands to secrete hormones, or muscles to contract; this is in response to an instruction from the nervous system, therefore, the muscles and glands are called effectors. This is known as the motor function of the nervous system.

Spinal reflex arc is a unit of the nervous system where responses to stimuli do not require conscious thought and as a consequence reactions occur more quickly than if the stimuli had travelled to the brain centers. There are two distinct types of reflex arc: one is autonomic reflex arc (having an effect on inner organs); and somatic reflex arc (having an effect on the muscles).

Al the systems in the human body are important to maintain the body in optimum functioning. The single movement of one leg involves the muscular, circulatory, and skeletal system; however it´s the nervous system which coordinates the activities of all these systems and without it, the human body wouldn´t be able to perform all its daily functions.

http://www.helium.com/items/2244685-an-overview-on-the-human-nervous-system