The importance of the autonomic nervous system is the regulation of metabolism in tissues and organs for the purpose of adapting it to the needs of t

Autonomic nervous system structure and importance (picture)

The importance of the autonomic nervous system is the regulation of metabolism in tissues and organs for the purpose of adapting it to the needs of the whole organism activity and environmental conditions. It regulates the activity of internal (vegetative) organs and affects the intensity of metabolism in somatic muscle and nerve tissue. Since the activity of the autonomic nervous system is almost independent of our will and consciousness, it is also called autonomic. Anatomically and functionally autonomic nervous system is divided into the sympathetic and parasympathetic nervous system (diagram 156).

Structural feature of the autonomic nervous system is that the afferent pathway from the central nervous system to the working member consists of two neurons. Body of the first is in the CNS and its axon, placed beyond, transmits excitation to neurons whose bodies are in the peripheral ganglia. Due to these nodes, takes place the effect of expanding the influence of the nerve center on the working body. One neuron, incoming to the ganglion (prenode) usually transmits the excitement for a few neurons, coming out of it (postnode). The lower centers of the sympathetic nervous system are located in the lateral horns of the cervical, thoracic and lumbar spinal cord. Axons of prenode neurons after leaving the spinal cord approach the nervous chain located on both sides of the spine — the sympathetic nervous trunk. Part of axons switches to postnode neurons in the ganglia that are located further away from the spine. These are the abdominal (solar) plexus, cervical and mesenteric nodes.

The centers of the parasympathetic nervous system placed in the brain stem and in the sacral spinal cord. Prenode parasympathetic fibers come out of the central nervous system as part of cranial and spinal nerves. Switching to postnode neurons occurs at in ganglia that lie directly in the operating organ. The greatest parasympathetic nerve of the human body is a cranial nerve, called the vagus. It innervates almost all organs of the chest and abdomen. Almost every internal organ is innervated by both sympathetic and parasympathetic nerves (diagram 156). Blood vessels and skeletal muscles have only the sympathetic innervation. Taken from http://worldofschool.org

Diagram 156. The autonomic nervous system. The sympathetic nervous system: 1 — ciliary muscle relaxes, the lens focuses on distant objects, the pupil dilates; 2 — the salivary glands produce a thick secretion; 3 — the trachea expands; 4 — the bronchi dilate; 5 — pulmonary vessels dilate; 6 — the frequency and strength of heart contractions grow; 7 — adrenal gland produces stress hormones; 8 — the liver releases glucose; 9 — kidneys reduce urine output; 10 — stomach decreases the secretion of digestive enzymes; 11 — bowel movement slows down; 12 — bladder sphincter reduces; 13 — the blood vessels of the skin constrict, hair raises, sweat pores get opened; 14 — the blood vessels dilate. The parasympathetic nervous system: 15 — lacrimal glands secrete tears; 16 — eye ciliary muscle contracts, the lens focuses on near objects, the pupil narrows; 17 — nasal glands secrete slime; 18 — salivary glands secrete a liquid secretion; 19 — the muscles of the trachea and bronchi reduces; 20 — the frequency and strength of heart rate decreases; 21 — liver stores glucose; 22 — the work of the stomach activates; 23 — the pancreas secretes insulin and enzymes; 24 — bowel movement activates; 25 — the sphincter of the bladder relaxes; 26 — genitals are being stimulated
Questions:
  • What is the connection of sympathetic and parasympathetic nervous systems?

  • Explain the functional mechanism of the sympathetic nervous system.

  • Explain the functional mechanism of the parasympathetic nervous system.