Vasoconstrictor drugs cause contraction of muscle cells in the walls of blood vessels, narrowing their internal diameter and raising blood pressure. This effect makes these medications useful for the treatment of low blood pressure, typically in an intensive care or surgical setting.
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Ticks commonly carry disease-causing bacteria, parasites and viruses. Bites from these spider-like pests often transmit infectious diseases to humans.
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Intestinal worms are parasites, deriving their nutrition from the human gut. Three types of worms can infest the human intestine: roundworms, tapeworms and flukes. The various species within these groups can live in different parts of the intestines, causing differing symptom patterns.
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The adrenal glands produce the hormone norepinephrine, a potent form of the “fight or flight” hormone epinephrine. Tumors of the adrenal glands called pheochromocytomas produce abnormally high levels of norepinephrine. The majority of pheochromocytomas are noncancerous.
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Viruses are interesting infectious organisms because they have no capacity to reproduce on their own. They infect the cells of living organisms from plants to people, hijacking the host’s cellular machinery to reproduce itself. Hundreds of viruses infect humans. Some infections are so mild they usually go unrecognized.
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Melanoma is a form of skin cancer. It arises from specialized skin cells called melanocytes, which produce the color (pigment) in our skin. Melanomas are pigmented lesions that resemble normal skin moles. However, melanomas usually have characteristics that distinguish them from moles.
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The circulatory system is the body’s transportation superhighway. As the blood circulates through the body, it brings oxygen and nutrients to the body tissues and picks up the waste products, delivering them to the kidneys and lungs to be expelled. The heart is the pump of this closed-circuit system.
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Temporary leg paralysis is a distressing symptom, which varies in severity from leg weakness to complete loss of movement in the affected limb. Abnormalities that affect the brain or nerves that control the leg muscles can cause temporary leg paralysis.
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Benign lung nodules are small, noncancerous masses of tissue typically discovered incidentally on a chest x-ray or CT scan. One out of every 500 to 1,000 chest x-rays reveals an unexpected lung nodule.
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People can experience two types of pain. "Normal" pain in response to bodily injury, such as a bruise, sprain or burn, is called nociceptive pain. In contrast, neuropathic pain arises when the nerves that transmit pain signals are damaged.
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Air hunger is one of the most distressing of all medical symptoms. Patients who can't derive enough oxygen from the air they breathe typically suffer from this symptom. Oxygen therapy involves supplying an increased concentration of oxygen to the lungs, helping alleviate breathlessness.
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Along with their desired actions, medications can also produce unwanted side effects. Many medications may cause an abnormal taste in the mouth, known as dysgeusia, which can interfere with the enjoyment of food and intake of adequate nutrition. A metallic taste is one of the most common types of dysgeusia.
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The brain is the primary controller of respiratory rate. It receives input from sensors that detect oxygen and carbon dioxide levels in the blood. Blood pH -- a reflection of its relative acidity or alkalinity -- also influences respiratory rate.
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Human viruses cause a variety of maladies, depending on the virus type and the tissues infected. All humans contract multiple viruses throughout the course of life. The severity of viral illnesses ranges from mild to lethal.
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When you go to the doctor, she checks your heart rate by feeling your pulse. With each beat of the heart, a wave of blood is pushed from the heart into the circulation. These waves can be felt as pulsations in arteries close to the skin surface, such as those in the wrist and neck.
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Nothing spoils a good meal quite like the gnawing pain of heartburn. The source of the pain is stomach acid flowing upward into the esophagus, the tube that transports swallowed food to your stomach.
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Although the kidneys occupy a protected area toward the back of the abdomen, these vital organs remain subject to traumatic injury. Motor vehicle accidents, falls, and other high-force trauma to the abdomen or back can cause kidney injury.
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Intestinal gas and loose stools often occur simultaneously with a variety of disorders and conditions. Incomplete digestion commonly leads to diarrhea. As undigested food reaches the large intestine, colonic bacteria break down the particles, producing gas.
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The colon normally absorbs the majority of water in fecal material, leaving soft, solid stool. Dietary intake, infections and digestive disorders can lead to increased water in expelled feces, or loose stools. The nutrient content of ingested foods and intestinal infections often cause transient episodes of diarrhea.
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Solid mineral crystals in your bones impart them with the strength and rigidity to support your body and withstand powerful physical stresses. Calcium and phosphorus are the most abundant minerals in your bones, together forming calcium phosphate crystals.
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