Autonomic Nervous System

Autonomic Nervous System The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person’s conscious effort. Disorders of the autonomic nervous system can affect any body part or process. Autonomic disorders may result from other disorders that damage autonomic nerves (such as diabetes), or they may occur on their own. Autonomic disorders may be reversible or progressive. Anatomy of the autonomic nervous system The autonomic nervous system is the part of the nervous system that supplies the internal organs, including the blood vessels, stomach, intestine, liver, kidneys, bladder, genitals, lungs, pupils, heart, and sweat, salivary, and digestive glands. The autonomic nervous system has two main divisions:   Sympathetic Parasympathetic After   the   autonomic   nervous   system   receives   information   about   the   body   and   external   environment,   it responds by stimulating body processes, usually through the sympathetic division, or inhibiting them, usually through the parasympathetic division. An autonomic nerve pathway involves two nerve cells. One cell is located in the brain stem or spinal cord. It is connected by nerve fibers to the other cell, which is located in a cluster of nerve cells (called an autonomic ganglion).   Nerve   fibers   from   these   ganglia   connect   with   internal   organs.   Most   of   the   ganglia   for   the sympathetic   division   are   located   just   outside   the   spinal   cord   on   both   sides   of   it.   The   ganglia   for   the parasympathetic division are located near or in the organs they connect with. Function of the autonomic nervous system The autonomic nervous system controls internal body processes such as the following:         Blood pressure Heart and breathing rates Body temperature Digestion Metabolism (thus affecting body weight) The balance of water and electrolytes (such as sodium and calcium) The production of body fluids (saliva, sweat, and tears) Urination   Defecation Sexual response Many organs are controlled primarily by either the sympathetic or the parasympathetic division. Sometimes the two divisions have opposite effects on the same organ. For example, the sympathetic division increases blood pressure, and the parasympathetic division decreases it. Overall, the two divisions work together to ensure that the body responds appropriately to different situations. Autonomic Nervous System Generally, the sympathetic division does the following:  Prepares the body for stressful or emergency situations—fight or flight Thus, the sympathetic division increases heart rate and the force of heart contractions and widens (dilates) the airways to make breathing easier. It causes the body to release stored energy. Muscular strength is increased. This division also causes palms to sweat, pupils to dilate, and hair to stand on end. It slows body processes that are less important in emergencies, such as digestion and urination. The parasympathetic division does the following:  Controls body process during ordinary situations. Generally, the parasympathetic division conserves and restores. It slows the heart rate and decreases blood pressure. It stimulates the digestive tract to process food and eliminate wastes. Energy from the processed food is used to restore and build tissues. Parasympathetic Innervation Both the sympathetic and parasympathetic divisions are involved in sexual activity, as are the parts of the nervous system that control voluntary actions and transmit sensation from the skin (somatic nervous system). Division Division Effects Effects Sympathetic Increases the following:  Heart rate and force of heart contractions  Release of energy stored in the liver  The speed at which energy is used to perform body functions while a person is  at rest (basal metabolic rate)  Muscle strength Widens the airways to make breathing easier Causes sweaty palms Decreases functions that are less important in an emergency (such as digestion and Division Division Effects Effects urination) Controls the release of semen (ejaculation) Parasympathetic Stimulates the digestive tract to process food and eliminate wastes (in bowel movements) Slows the heart rate Reduces blood pressure Controls erections disorder / расстройство, непорядок, неупорядоченность Dictionary:   [ d s ɪˈ ɔː ə .d r ]   reversible / обратимый, двусторонний, реверзибельный  [ r v .s .b  ]   ɪˈ ɜː ə ll intestine / кишечник   [  n tes.t n ]   ɪ ˈ ɪ bladder / пузырь [  blæd. r ]   ə ˈ lungs / легкие   [ l ŋ ]   ʌ salivary / слюнный   [  sæl. .v r.i ]   ɪ ə ˈ defecation / дефекация, осветление   [ de.f kæ n ]   ˌʃə əˈ division / отдел, разделение, раздел   [ d v n ]   ɪˈ ɪʒ ensure / обеспечивать   [  n ɪ ˈʃʊə (r) ]   appropriately / соответственно, правильно, уместно   [  pr əˈ əʊ .pri. ə t ] Tasks: Which of the following nervous systems can be further subdivided to form the  sympathetic and parasympathetic systems?    central somatic autonomic Which of the following nerves causes the adrenal medulla to release epinephrine and  norepinephrine?          somatic sympathetic parasympathetic Which of the following nerves generally “speed up” body activities? somatic sympathetic parasympathetic Which of the following consists of nerves that primarily branch from the brain area and  the sacral area only? somatic sympathetic parasympathetic Test your knowledge of the functions of the sympathetic and parasympathetic nervous systems by answering the following questions. If you get stuck on any of them, you'll find the answers in the article below. 1. The sympathetic and parasympathetic nervous systems are sub­systems of the  ______________ nervous system. 2. The ____________ nervous system provides is responsible for the "fight or flight"  reaction. 3. The "fight or flight" reaction __________ the blood pressure and heart rate. 4. The _______________ system increases blood supply to the skin and the  gastrointestinal tract. The   two   subsystems   of   the   autonomic   nervous   system,   the   sympathetic   and   the parasympathetic, work together in an essentially antagonistic way. The sympathetic nervous system provides responses needed to cope with stressful, "fight or flight" type situations such as fear or extremes of physical activity. In response to such stress, it raises the blood pressure and heart rate, diverts blood from the skin and gastrointestinal tract (to increase the blood supply to the skeletal muscles), dilates the pupils and the bronchioles (to provide improved vision and oxygenation), decreases salivary gland secretion (giving a dry and     mouth), activity. After such stressful situations, the body needs to recover, rest, and gain new energy. These tasks are under the control of the parasympathetic system, which lowers the blood pressure and heart rate, diverts blood back to the skin and the gastrointestinal tract, contracts the pupils and bronchioles, stimulates salivary gland secretion, and accelerates intestinal activity. decreases intestinal   Look carefully. What`s mistake in this picture? Explain the answer.