Autonomic nervous system questions and answers pdf

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Autonomic nervous system

The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. Disorders of the autonomic nervous system can affect any body part or process. Autonomic disorders may be reversible or progressive. 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.

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. The balance of water and electrolytes such as sodium and calcium. 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.

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. 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. 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.

The speed at which energy is used to perform body functions while a person is at rest basal metabolic rate. Two chemical messengers neurotransmitters are used to communicate within the autonomic nervous system:. Nerve fibers that secrete acetylcholine are called cholinergic fibers. Fibers that secrete norepinephrine are called adrenergic fibers. Generally, acetylcholine has parasympathetic inhibiting effects and norepinephrine has sympathetic stimulating effects.

However, acetylcholine has some sympathetic effects. For example, it sometimes stimulates sweating or makes the hair stand on end. Autonomic disorders may result from disorders that damage autonomic nerves or parts of the brain that help control body processes, or they may occur on their own, without a clear cause. Diabetes the most common cause. Peripheral nerve disorders. Parkinson disease. Autonomic neuropathies.

Multiple system atrophy. Pure autonomic failure. Spinal cord disorders. Disorders of the neuromuscular junction where nerves connect with muscles , such as botulism and Lambert-Eaton syndrome. In men, difficulty initiating and maintaining an erection erectile dysfunction can be an early symptom of an autonomic disorder.

Autonomic disorders commonly cause dizziness or light-headedness due to an excessive decrease in blood pressure when a person stands orthostatic hypotension. People may sweat less or not at all and thus become intolerant of heat. The eyes and mouth may be dry. After eating, a person with an autonomic disorder may feel prematurely full or even vomit because the stomach empties very slowly called gastroparesis.

Some people pass urine involuntarily urinary incontinence , often because the bladder is overactive. Other people have difficulty emptying the bladder urine retention because the bladder is underactive. Constipation may occur, or control of bowel movements may be lost. During the physical examination, doctors can check for signs of autonomic disorders, such as orthostatic hypotension. For example, they measure blood pressure and heart rate while a person is lying down or sitting and after the person stands to check how blood pressure changes when position is changed.

When a person stands up, gravity makes it harder for blood from the legs to get back to the heart. Thus, blood pressure decreases. To compensate, the heart pumps harder, and the heart rate increases.

However, the changes in heart rate and blood pressure are slight and brief. If the changes are larger or last longer, the person may have orthostatic hypotension.

Blood pressure is also measured continuously while the person does a Valsalva maneuver forcefully trying to exhale without letting air escape through the nose or mouth—similar to straining during a bowel movement. Electrocardiography is done to determine whether the heart rate changes as it normally does during deep breathing and the Valsalva maneuver. A tilt table test may be done to check how blood pressure and heart rate change when position is changed.

In this test, blood pressure is measured before and after the person, who is lying flat on a pivoting table, is tilted into an upright position. The tilt table test and the Valsalva maneuver, done together, can help doctors determine whether a decrease in blood pressure is due to an autonomic nervous system disorder.

Sweat testing is also done. For one sweat test, the sweat glands are stimulated by electrodes that are filled with acetylcholine and placed on the legs and forearm.

Then, the volume of sweat is measured to determine whether sweat production is normal. A slight burning sensation may be felt during the test. In the thermoregulatory sweat test, a dye is applied to the skin, and a person is placed in a closed, heated compartment to stimulate sweating. Sweat causes the dye to change color. Doctors can then evaluate the pattern of sweat loss, which may help them determine the cause of the autonomic nervous system disorder. Disorders that may be contributing to the autonomic disorder are treated.

If no other disorders are present or if such disorders cannot be treated, the focus is on relieving symptoms. Orthostatic hypotension: People are advised to elevate the head of the bed by about 4 inches 10 centimeters and to stand up slowly. Wearing a compression or support garment, such as an abdominal binder or compression stockings, may help. Consuming more salt and water helps maintain the volume of blood in the bloodstream and thus blood pressure.

Sometimes drugs are used. Fludrocortisone helps maintain blood volume and thus blood pressure. Midodrine helps maintain blood pressure by causing arteries to narrow constrict. These drugs are taken by mouth. Decreased or absent sweating: If sweating is reduced or absent, avoiding warm environments is useful. Urinary retention: If urinary retention occurs because the bladder cannot contract normally, people can be taught to insert a catheter a thin rubber tube through the urethra and into the bladder themselves.

The catheter allows the retained urine in the bladder to drain out, thus providing relief. People insert the catheter several times a day and remove it after the bladder is empty.

Bethanechol can be used to increase bladder tone and thus help the bladder empty. Constipation: A high-fiber diet and stool softeners are recommended.

If constipation persists, enemas may be necessary. Erectile dysfunction: Usually, treatment consists of drugs such as sildenafil , tadalafil , or vardenafil taken by mouth. Stool softeners such as docusate, lactulose , or polyethylene glycol. Fiber supplements add bulk to the stool and thus stimulate the natural contractions of the intestine. Fiber supplements and stool softeners help move food through the intestine more quickly.

These drugs stimulate contractions in the digestive tract and thus help move food through it more quickly. Erectile dysfunction. Orthostatic hypotension an excessive decrease in blood pressure when a person stands. These drugs cause small arteries arterioles to narrow constrict and thus helps maintain blood pressure. Urinary incontinence. Urine retention.

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Nervous system questions

The autonomic nervous system ANS regulates the functions of our internal organs the viscera such as the heart, stomach and intestines. The ANS is part of the peripheral nervous system and it also controls some of the muscles within the body. We are often unaware of the ANS because it functions involuntary and reflexively. For example, we do not notice when blood vessels change size or when our heart beats faster. However, some people can be trained to control some functions of the ANS such as heart rate or blood pressure. The ANS is most important in two situations:.

Your autonomic nervous system is the part of your nervous system that controls involuntary actions, such as the beating of your heart and the widening or narrowing of your blood vessels. When something goes wrong in this system, it can cause serious problems, including. Autonomic nervous system disorders can occur alone or as the result of another disease, such as Parkinson's disease , alcoholism and diabetes. Problems can affect either part of the system, as in complex regional pain syndromes , or all of the system. Some types are temporary, but many worsen over time. When they affect your breathing or heart function, these disorders can be life-threatening. Some autonomic nervous system disorders get better when an underlying disease is treated.


8) Thermoregulatory responses to increased heat are mediated by the sympathetic nervous division. 13) The sympathetic and parasympathetic divisions of the.


Human Anatomy and Physiology : Peripheral Nervous System

Some sympathetic fibers pass through the paravertebral ganglia of the sympathetic trunk; other sympathetic fibers synapse there. Some sympathetic fibers pass through the paravertebral ganglia of the sympathetic trunk, while other sympathetic fibers synapse there. Parasympathetic nerves are associated with cranial nerves, and the dilation of blood vessels in skin of the back and limbs the sympathetic system constricts these vessels. Preganglionic neurons originate in the thoracolumbar region of the spinal cord T2 to L1 then travel to a paravertebral ganglion or prevertebral ganglion, where they synapse with a postganglionic neruon. The paravertebral ganglion are found throughout the length of the spinal cord, including the cervical, thoracic, lumbar, and sacral areas.

Autonomic nervous system , in vertebrates , the part of the nervous system that controls and regulates the internal organs without any conscious recognition or effort by the organism. The autonomic nervous system comprises two antagonistic sets of nerves, the sympathetic and parasympathetic nervous systems. The sympathetic nervous system connects the internal organs to the brain by spinal nerves. When stimulated, these nerves prepare the organism for stress by increasing the heart rate, increasing blood flow to the muscles , and decreasing blood flow to the skin.

If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus. Please consult the latest official manual style if you have any questions regarding the format accuracy. After studying this chapter, you should be able to:. Describe the location of the cell bodies and axonal trajectories of preganglionic and postganglionic sympathetic and parasympathetic neurons.

Overview of the Autonomic Nervous System

The autonomic nervous system regulates a variety of body process that takes place without conscious effort. The autonomic system is the part of the peripheral nervous system that is responsible for regulating involuntary body functions, such as heartbeat, blood flow, breathing, and digestion. This system is further divided into three branches: the sympathetic system, the parasympathetic system, and the enteric nervous system. The autonomic nervous system operates by receiving information from the environment and from other parts of the body. The sympathetic and parasympathetic systems tend to have opposing actions in which one system will stimulate a response where the other will inhibit it.

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Nervous System Quiz. 1. The term central nervous system refers to the: A) autonomic and peripheral nervous systems. B) brain, spinal cord.


Overview of the Autonomic Nervous System

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