The respiratory system consists of the windpipe (trachea); bronchi (respiratory tree), which connects to the lungs; diaphragm (the main muscle of breathing); and the intercostal muscles (the muscles between the ribs that are used for coughing and deep breathing) (see Figure 14.1).
Protected by the breastbone, ribs, and spine, the lungs function primarily in breathing and filtering air. Air, which consists of nitrogen, oxygen, water, carbon dioxide, and other particles, enters through the nose and mouth; travels through the larynx (voice box); and proceeds down the trachea (windpipe), through the bronchi, and into the lungs. The lungs consist of mil-
Lungs Diaphragm lions of alveoli (air sacs) in which there are meshworks of capillaries where the exchange of oxygen and carbon dioxide takes place.
The act of breathing is controlled by the brain, normally about 10 to 20 times per minute, although you can consciously regulate the rate. Messages are sent from the respiratory center of the brain to the diaphragm and to certain rib muscles, which contract. This contraction pulls the lower surfaces of the lungs downward and air is inhaled. Stretch receptors in the lungs then send signals back to the brain, making the diaphragm and rib muscles relax, causing an upward movement and exhalation of air.
The respiratory muscles in the chest assist in breathing and ventilation by compressing and distending the lungs, causing an expansion and contraction of the alveoli. The lungs, which are elastic in nature, facilitate ventilation (or breathing), as does the presence of surfactant, a material found in the lungs of healthy individuals. This surfactant acts like a detergent and facilitates gas exchange.
The function of respiration is under the neurologic control of the medulla and pons, areas of the brain with nerves that affect functions such as chewing and swallowing. For this reason, people who have MS lesions in the medulla may not only have difficulty with breathing but with swallowing (dysphagia), which may predispose them to aspiration (drawing of foods and liquids into the lungs). Your respiratory rate or breathing rate can increase with fever, increased blood pressure, exercise, or anything that produces more carbon dioxide in your body. The rate decreases during sleep or periods of rest, or with a decrease in body temperature, blood pressure, or oxygen in the body.
Each lung is covered by a pleura, a lining that protects the lung and helps it expand and contract inside the chest. Lungs are spongy in consistency, light in weight, and can float in water. Normally, the lungs can avoid infection because the nose and respiratory system filter the air, and the trachea and bronchi produce mucus, which assists in trapping and carrying away contaminants. Cilia, small hairs that cover the entire respiratory tract, move the mucus and contaminants along by rapidly beating back and forth, in some areas at a rate of up to 1,000 times per minute.
Infections can cause your MS to feel worse, with intensified symptoms and increased weakness. Therefore, it is important to understand what types of infections can occur and how they can affect your ability to function. There are noninvasive devices that are helpful to people who are experiencing breathing difficulties on a continuous basis due to MS. BiPap™ machines and portable volume ventilators can help inflate the chest cavity when muscles are too weak to sufficiently contract. These devices can be used either throughout the night or on an as-needed basis. You should inform your healthcare provider if you feel you need mechanical assistance for breathing or clearing secretions in your throat.
Asthma is usually a chronic, inflammatory condition that can cause attacks of wheezing, dry coughing, or breathing difficulties. These attacks can be provoked by emotions, irritants, exercise, respiratory infections, fatigue, or allergies. When a person is exposed to a provoking agent, the overly sensitive bronchi respond by going into spasms and narrowing. The result is an asthma attack. People with asthma usually have little or no trouble breathing in (inspiring), but may have problems breathing out (expiring).
Bronchitis, Pneumonia, and Influenza The human body has natural defenses to prevent infection, such as the cilia that trap mucus and other contaminants. However, in people with underlying weakness and impaired ability to clear secretions, there may be a greater predisposition to react to infections, which can lead to bronchitis (inflammation of the bronchi) or pneumonia (inflammation of the lungs with accumulation of secretions).
Bronchitis, influenza, and pneumonia are lung-related conditions that occur more frequently in people with Ms who are inactive and do not breathe in and out deeply. These illnesses can occur in individuals who are minimally disabled as well. They are frequently caused by infectious organisms, such as bacteria or viruses, or by exposure to irritants, such as chemicals. People with Ms and other disabling diseases should talk to their physicians about obtaining a flu shot, which is given annually, and a pneumonia vaccine, which is needed less frequently. These injections may help prevent or reduce the occurrence of influenza and pneumonia.
Cigarette smoking is known to damage the respiratory system, blood vessels, heart, and other organs. Men who smoke have a 70 percent higher death rate from diseases of the heart and respiratory system than men who do not. Smoking interferes with the lungs' natural ability to rid themselves of pollutants. Smoking is associated with increased coughing, breathing problems, respiratory infections, pneumonia, stroke, hardening of the arteries (arteriosclerosis), gastrointestinal ulcers, and cancer of the mouth, throat, esophagus, lungs, kidneys, bladder, and pancreas. Smoking during pregnancy increases the risk of miscarriage and fetal death. Secondhand smoke has been reported to increase the risk of respiratory and middle-ear infections in children and to cause about 3,000 deaths from lung cancer and about 36,000 deaths from heart disease each year.
Self-Care Strategies for Respiratory Health
• Treat upper respiratory infections promptly with fluids and decongestants. Contact your healthcare professional if a fever develops or if a cold or sore throat does not go away within a week.
• If your mobility is decreased, remember to take deep breaths throughout the day to aerate your lungs. Breathe in as deeply as you can, count to three, and push all the air out. Do this 5 to 10 times each session.
• Try to avoid known pollutants such as dust, mold, fumes, and dangerous chemicals. They can damage or destroy the cilia that protect your lungs.
The circulatory system consists of the heart, blood, blood vessels, and lymphatic vessels. its purpose is to deliver oxygen and nutrients to all parts of the body and to pick up waste materials and poisons that the body eliminates. The various types of blood vessels are: arteries, arterioles (smaller arteries), veins, venules (smaller veins), and capillaries. These vessels are part of what is generally considered to be two systems: the systemic circulatory system, which carries oxygen-rich blood from the heart to the organs and tissues, and the pulmonary circulatory system, which carries oxygen-poor blood and other materials to the lungs where carbon dioxide is released and oxygen is picked up. The blood then returns to the heart to be pumped out to the body (see Figure 14.2).
Veins (shown at left)
Arteries (shown at right)
Blood transports oxygen and waste products, keeps the body's temperature stable, promotes defense against infection, and facilitates hearing. Blood is channeled through the arteries, which are thick walled and carry blood with a high concentration of oxygen. The largest artery is the aorta, which rises directly from the heart. The coronary arteries rise directly from the beginning of the aorta and feed blood directly back to the heart. Arteries can be narrowed by deposits of fatty substances within the vessels (atherosclerosis), or they can become brittle and stiff (arteriosclerosis). These changes can occur because of age, obesity, or poor dietary habits, which might include a high intake of fats.
Veins are thin-walled vessels that carry blood with a lower concentration of oxygen. One exception is the pulmonary veins, which carry blood that is full of oxygen from the lungs to the heart.
Your heart is composed of muscles that work together as a pump. The heart has four compartments: two atria, or upper chambers, and two ventricles, or lower chambers. Blood is returned from the body to the heart by two large veins—the superior and inferior vena cava on the right side of the heart—and from the lungs by the pulmonary veins to the left side of the heart.
Your heartbeat is sustained by a part of the heart that functions as a pacemaker. A healthy heart has a regular beat of 60 to 100 beats per minute. Heart rate varies with age, sex, physical activity, and emotions. During checkups, your physician listens to your heart with a stethoscope, measures your blood pressure, and checks your pulse. Blood pressure is a measure of the force with which your blood goes through your veins. It is regulated by how well your heart pumps blood and how much tension is in your arteries. A wide range of blood pressures is considered normal. A stable blood pressure is one that remains within a consis tent range. Your personal physician is in the best position to determine what blood pressure is normal for you. In general, 140/90 is often considered borderline for high blood pressure and should be further investigated by a visit to your doctor.
The nervous system controls the diameter of the blood vessels, adjusting it to body position and level of activity. When you move from sitting to standing or from standing to lying down, the diameter changes to accommodate blood flow. Some people with MS develop swelling (edema) in the legs. This may be associated with changes of color (mottling) of the skin and with changes of skin temperature (frequently cool to very cold). Edema can be reduced by wearing compression or support hose, maintaining the regular range of motion of the legs, and elevating the legs frequently during the day.
To determine the health of your circulatory system, your physician may order a range of tests, such as electrocardiograms, echocardiograms, stress tests, and blood counts. As with most tests, none of these is 100 percent accurate in determining heart disease, although each can provide your doctor with valuable information about your body's ability to function.
• Reduce your intake of dietary fats and increase your intake of complex carbohydrates, such as grains, oats, rice, pasta, and barley; fresh fruits and vegetables; and lean meats, fish, chicken, and turkey.
• Maintain your body weight to within 5 pounds of the ideal.
• Keep your alcohol consumption moderate.
• Avoid cigar and cigarette smoke.
• Exercise to the best of your ability.
• Monitor your cholesterol level regularly.
• Check your blood pressure regularly.
An additional resource is the American Heart Association, which provides information on the prevention and treatment of heart disease. Call the Consumer Nutrition
Hotline, which is run by the American Dietetic Association, at (800) 366-1655 for information about diet and nutrition.
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