The autonomic nervous system (ANS) is a part of the nervous system that innervates the internal organs and maintains a constant internal environment. The second name of the ANS is autonomous, since its work takes place at an unconscious level and does not depend on the will of man.
Varieties
Conventionally, the system is divided into two departments - sympathetic (SNA) and parasympathetic (PSNS). The active substance is the first known adrenaline. The second neurotransmitter is acetylcholine. The longest nerve in the human body - the vagus - vagus (n. Vagus), implements the influence of parasympathetics.
Functions
So, what does the autonomic nervous system innervate and how does it manifest itself:
- Effect on the respiratory system. Vagal innervation causes a decrease in the lumen of the bronchi, a decrease in the frequency of respiratory movements per minute. The activity of the bronchial glands is increasing. An extreme degree of obstruction is observed in bronchial asthma. The SNS acts on the contrary: the smooth muscles of the bronchi relax, the patency of the bronchial tree increases, the production of mucus by the bronchial glands decreases. The respiratory volume of the lungs increases, and, as a result, gas exchange increases.
- Effects on the cardiovascular system. The autonomic nervous system innervates the blood vessels and heart. If parasympathetic prevails in the body, a person is prone to a rare pulse and low blood pressure. A high level of adrenaline, especially with stress, provokes vasospasm, with the exception of coronary arteries and vessels of skeletal muscles. Blood pressure rises, strength and heart rate increase.
- The autonomic nervous system innervates the digestive system. PSNS causes an increase in intestinal motility, relaxes the sphincters of the gastrointestinal tract, causes a reduction in the gall bladder, and stimulates the production of gastric juice. In patients with various diseases of the gastrointestinal tract, including peptic ulcer disease, an excessive tonus of the vagus nerve is often found. The sympathetic division has the exact opposite effect.
- The autonomic nervous system innervates the urinary system. The ANS primarily affects the bladder. The parasympathetic part causes relaxation of the sphincter of the bladder and the contraction of its wall. Urination occurs. Under the influence of sympathy, the sphincter comes in tone, and the tension of the muscle wall decreases. Atony occurs to an extreme degree.
- The autonomic nervous system innervates the pupil. Everyone remembers that in a state of excitement or anxiety, the pupil expands. The sympathetic division of the ANS is to blame for this. PSNS innervation leads, on the contrary, to muscle contraction - it narrows.
Sympathetic Division
In addition, the sympathetic division of the autonomic nervous system has an independent effect on a number of processes and metabolic parameters. It increases the level of glucose and blood lipids. Speeds up coagulation time. Stimulates the main exchange up to one hundred percent. An interesting fact: under the influence of the SNA, the spikelet muscles of the skin contract. Hence the expression "from fear, the hair stood on end". The parasympathetic department does not affect these processes.
Conclusion
What autonomic nervous system does the organs innervate? She innervates all the internal organs of man. Its two main departments are sympathetic and parasympathetic. These are two sides of the same coin. They mutually complement each other, ensuring the coordinated work of the whole organism. Depending on the environmental conditions, the influence of one of the departments may increase. In stressful, unfamiliar situations, sympathy dominates. The parasympathetic department is most active in routine activities.