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• hree basic parts to a Neuron
• The main function of the nervous system
• Nursing Diagnosis: Impaired Gas Exchange Ventilation or Perfusion Imbalance
• Corneal ulcers and infections
• Low blood pressure or hypotension
• Addison’s disease,Symptoms,Risk factors, treatment Addison’s disease

hree basic parts to a Neuron Posted: 18 Jan 2011 04:48 AM PST The Neurons Has many functions and vary in size and in length. Three basic parts to a Neuron a. cell body b. axon c. dendrites Each Neuron has one cell body with a nucleus. Neurons cannot divide and multiply by mitosis like other cells in the body. Once the body is destroyed it is gone forever. The axon is an extension that carries impulses away from the neuron cell body. Some have a covering called myelin and others do not. Myelin sheath is a fatty covering. Those axons that have myelin are called myelinated axons. Myelinated axons conduct impulses more rapidly than unmyelinated axons. These sheaths help to insulate the nerve cell and conduct impulses easily and rapidly. Dendrites are the short, highly branched parts of the cell body. They carry impulses from the axon and send and receive impulses across the synapse. A synapse is the junction or space between the axon of one neuron and the dendrites of another. A nerve can only transmit impulses in only one direction because of the location of neruotransmitters. These are chemicals that the axon releases to allow nerve impulses to cross the synapse and reach the next nerves dendrites. The dendrites release opposing chemicals to slow down impulses. Neurons can be classified as follows: a. Sensory ( afferent) neurons- receive and send messages to the central nervous system from all parts of the body. b. Motor ( efferent) – neurons receive and transmit messages from the central nervous system to all parts of the body. c. Interneurons ( connectory/ association neurons/ or integrators) can be thought of as a link between the two other types of neurons. They are interconnecting neurons. Sensory neurons make up sensory nerves. Motor neurons make up motor nerves- which cause muscle activity and gland secretion. Put together, sensory and motor neurons make up Mixed nerves. source three basic parts to a Neuron

The main function of the nervous system Posted: 18 Jan 2011 04:44 AM PST The main function of the nervous system is communication and control. Communication 1. Monitors impressions and information from external stimuli 2. Monitors information from internal stimuli 3. Responds to danger, pain and other situations 4. Responds to internal and external changes 5. Helps maintain homeostasis 6. Responds to conscious decisions and thoughts 7. Coordinates the process of new learning Control 1. Directs all body activities 2. maintains blood pressure, respiration and other vital functions 3. Regulates body systems 4. coordinates reflexes 5. Controls instinctual behavior 6. Controls conscious movement and activities 7. Stores unconscious thoughts source The main function of the nervous system

Nursing Diagnosis: Impaired Gas Exchange Ventilation or Perfusion Imbalance Posted: 18 Jan 2011 04:32 AM PST NOC Outcomes (Nursing Outcomes Classification) Suggested NOC Labels * Respiratory Status * Gas Exchange NIC Interventions (Nursing Interventions Classification) Suggested NIC Labels * Respiratory Monitoring * Oxygen Therapy * Airway Management NANDA Definition: Excess or deficit in oxygenation and/or carbon dioxide elimination at the alveolar-capillary membrane By the process of diffusion the exchange of oxygen and carbon dioxide occurs in the alveolar-capillary membrane area. The relationship between ventilation (airflow) and perfusion (blood flow) affects the efficiency of the gas exchange. Normally there is a balance between ventilation and perfusion; however, certain conditions can offset this balance, resulting in impaired gas exchange. Altered blood flow from a pulmonary embolus, or decreased cardiac output or shock can cause ventilation without perfusion. Conditions that cause changes or collapse of the alveoli (e.g., atelectasis, pneumonia, pulmonary edema, and adult respiratory distress syndrome [ARDS]) impair ventilation. Other factors affecting gas exchange include high altitudes, hypoventilation, and altered oxygen-carrying capacity of the blood from reduced hemoglobin. Elderly patients have a decrease in pulmonary blood flow and diffusion as well as reduced ventilation in the dependent regions of the lung where perfusion is greatest. Chronic conditions such as chronic obstructive pulmonary disease (COPD) put these patients at greater risk for hypoxia. Other patients at risk for impaired gas exchange include those with a history of smoking or pulmonary problems, obesity, prolonged periods of immobility, and chest or upper abdominal incisions. * Defining Characteristics: Confusion * Somnolence * Restlessness * Irritability * Inability to move secretions * Hypercapnia * Hypoxia * Related Factors: Altered oxygen supply * Alveolar-capillary membrane changes * Altered blood flow * Altered oxygen-carrying capacity of blood * Expected Outcomes Patient maintains optimal gas exchange as evidenced by normal arterial blood gases (ABGs) and alert responsive mentation or no further reduction in mental status. Ongoing Assessment * Assess respirations: note quality, rate, pattern, depth, and breathing effort. Both rapid, shallow breathing patterns and hypoventilation affect gas exchange. Shallow, “sighless” breathing patterns postsurgery (as a result of effect of anesthesia, pain, and immobility) reduce lung volume and decrease ventilation. * Assess lung sounds, noting areas of decreased ventilation and the presence of adventitious sounds. * Assess for signs and symptoms of hypoxemia: tachycardia, restlessness, diaphoresis, headache, lethargy, and confusion. * Assess for signs and symptoms of atelectasis: diminished chest excursion, limited diaphragm excursion, bronchial or tubular breath sounds, rales, tracheal shift to affected side. Collapse of alveoli increases physiological shunting. * Assess for signs or symptoms of pulmonary infarction: cough, hemoptysis, pleuritic pain, consolidation, pleural effusion, bronchial breathing, pleural friction rub, fever. * Monitor vital signs. With initial hypoxia and hypercapnia, blood pressure (BP), heart rate, and respiratory rate all rise. As the hypoxia and/or hypercapnia becomes more severe, BP may drop, heart rate tends to continue to be rapid with arrhythmias, and respiratory failure may ensue with the patient unable to maintain the rapid respiratory rate. * Assess for changes in orientation and behavior. Restlessness is an early sign of hypoxia. Chronic hypoxemia may result in cognitive changes such as memory changes. * Monitor ABGs and note changes. Increasing PaCO2 and decreasing PaO2 are signs of respiratory failure. As the patient begins to fail, the respiratory rate will decrease and PaCO2 will begin to rise. Some patients, such as those with COPD, have a significant decrease in pulmonary reserves, and any physiological stress may result in acute respiratory failure. * Use pulse oximetry to monitor oxygen saturation and pulse rate. Pulse oximetry is a useful tool to detect changes in oxygenation. Oxygen saturation should be maintained at 90% or greater. This tool can be especially helpful in the outpatient or rehabilitation setting where patients at risk for desaturation from chronic pulmonary diseases can monitor the effects of exercise or activity on their oxygen saturation levels. Home oxygen therapy can then be prescribed as indicated. Patients should be assessed for the need for oxygen both at rest and with activity. A higher liter flow of oxygen is generally required for activity versus rest (e.g., 2 L at rest, and 4 L with activity). Medicare guidelines for reimbursement for home oxygen require a PaCO2 less than 58 and/or oxygen saturation of 88% or less on room air. Oxygen delivery is then titrated to maintain an oxygen saturation of 90% or greater. * Assess skin color for development of cyanosis. For cyanosis to be present, 5 g of hemoglobin must desaturate. * Monitor chest x-ray reports. Chest x-rays may guide the etiological factors of the impaired gas exchange. Keep in mind that radiographic studies of lung water lag behind clinical presentation by 24 hours. * Monitor effects of position changes on oxygenation (SaO2, ABGs, SVO2, and end-tidal CO2). Putting the most congested lung areas in the dependent position (where perfusion is greatest) potentiates ventilation and perfusion imbalances. * Assess patient's ability to cough effectively to clear secretions. Note quantity, color, and consistency of sputum. Retained secretions impair gas exchange. Therapeutic Interventions * Maintain oxygen administration device as ordered, attempting to maintain oxygen saturation at 90% or greater. This provides for adequate oxygenation. Avoid high concentration of oxygen in patients with COPD. Hypoxia stimulates the drive to breathe in the chronic CO2 retainer patient. When applying oxygen, close monitoring is imperative to prevent unsafe increases in the patient's PaO2, which could result in apnea. NOTE: If the patient is allowed to eat, oxygen still must be given to the patient but in a different manner (e.g., changing from mask to a nasal cannula). Eating is an activity and more oxygen will be consumed than when the patient is at rest. Immediately after the meal, the original oxygen delivery system should be returned. * For patients who should be ambulatory, provide extension tubing or portable oxygen apparatus. These promote activity and facilitate more effective ventilation. * Position with proper body alignment for optimal respiratory excursion (if tolerated, head of bed at 45 degrees). This promotes lung expansion and improves air exchange. * Routinely check the patient's position so that he or she does not slide down in bed. This would cause the abdomen to compress the diaphragm, which would cause respiratory embarrassment. * Position patient to facilitate ventilation/perfusion matching. Use upright, high-Fowler's position whenever possible. High-Fowler's position allows for optimal diaphragm excursion. When patient is positioned on side, the good side should be down (e.g., lung with pulmonary embolus or atelectasis should be up). * Pace activities and schedule rest periods to prevent fatigue. Even simple activities such as bathing during bed rest can cause fatigue and increase oxygen consumption. * Change patient's position every 2 hours. This facilitates secretion movement and drainage. * Suction as needed. Suction clears secretions if the patient is unable to effectively clear the airway. * Encourage deep breathing, using incentive spirometer as indicated. This reduces alveolar collapse. * For postoperative patients, assist with splinting the chest. Splinting optimizes deep breathing and coughing efforts. * Encourage or assist with ambulation as indicated. This promotes lung expansion, facilitates secretion clearance, and stimulates deep breathing. * Provide reassurance and allay anxiety: o Have an agreed-on method for the patient to call for assistance (e.g., call light, bell). o Stay with the patient during episodes of respiratory distress. * Anticipate need for intubation and mechanical ventilation if patient is unable to maintain adequate gas exchange. Early intubation and mechanical ventilation are recommended to prevent full decompensation of the patient. Mechanical ventilation provides supportive care to maintain adequate oxygenation and ventilation to the patient. Treatment also needs to focus on the underlying causal factor leading to respiratory failure. * Administer medications as prescribed. The type depends on the etiological factors of the problem (e.g., antibiotics for pneumonia, bronchodilators for COPD, anticoagulants/thrombolytics for pulmonary embolus, analgesics for thoracic pain). Education/Continuity of Care * Explain the need to restrict and pace activities to decrease oxygen consumption during the acute episode. * Explain the type of oxygen therapy being used and why its maintenance is important. Issues related to home oxygen use, storage, or precautions need to be addressed. * Teach the patient appropriate deep breathing and coughing techniques. These facilitate adequate air exchange and secretion clearance. * Assist patient in obtaining home nebulizer, as appropriate, and instruct in its use in collaboration with respiratory therapist. * Refer to home health services for nursing care or oxygen management as appropriate. source Nursing Diagnosis: Impaired Gas Exchange Ventilation or Perfusion Imbalance

Corneal ulcers and infections Posted: 18 Jan 2011 04:28 AM PST The cornea is the transparent area at the front of the eyeball. A corneal ulcer is an erosion or open sore in the outer layer of the cornea. It is associated with infection. Bacterial keratitis; Fungal keratitis; Acanthamoeba keratitis; Herpes simplex keratitis Causes Corneal ulcers are most commonly caused by an infection with bacteria, viruses, fungi, or parasite. Other causes include: * Abrasions (scratches) * Foreign bodies in the eye * Inadequate eyelid closure * Severely dry eyes * Severe allergic eye disease * Various inflammatory disorders Contact lens wear, especially soft contact lenses worn overnight, may cause a corneal ulcer. Herpes simplex keratitis is a serious viral infection. It may cause repeated attacks that are triggered by stress, exposure to sunlight, or any condition that impairs the immune system. Fungal keratitis can occur after a corneal injury involving plant material, or in immunosuppressed people. Acanthamoeba keratitis occurs in contact lens users, especially those who attempt to make their own homemade cleaning solutions. Risk factors are dry eyes, severe allergies, history of inflammatory disorders, contact lens wear, immunosuppression, trauma, and generalized infection. Symptoms * Eye burning, itching and discharge * Eye pain * Eye redness * Impaired vision * Sensitivity to light (photophobia) * Watery eyes * White patch on the cornea Exams and Tests * Examination of scrapings from the ulcer * Fluorescein stain of the cornea * Keratometry (measurement of the cornea) * Pupillary reflex response * Refraction test * Slit-lamp examination * Tear test * Visual acuity Blood tests to check for inflammatory disorders may also be needed. Treatment Treating corneal ulcers and infections depends on the cause. They should be treated as soon as possible to prevent further injury to the cornea. Patients usually start treatment with an antibiotic that is effective against many bacteria. More specific antibiotic, antiviral, or antifungal eye drops are prescribed as soon as the cause of the ulcer has been identified. Corticosteroid eye drops may be used to reduce inflammation in certain conditions. Severe ulcers may need to be treated with corneal transplantation. Outlook (Prognosis) Untreated, a corneal ulcer or infection can permanently damage the cornea. Untreated corneal ulcers may also perforate the eye (cause holes), resulting in spread of the infection inside, increasing the risk of permanent visual problems. Possible Complications * Loss of the eye * Severe vision loss * Scars on the cornear When to Contact a Medical Professional Call your health care provider if you develop impaired vision, severe light sensitivity, or eye pain. Prevention Prompt, early attention by an ophthalmologist for an eye infection may prevent ulcers from forming. Wash hands and pay very close attention to cleanliness while handling contact lenses. Avoid wearing contact lenses overnight. References Butler FK. The eye in the wilderness. In: Auerbach PS, ed. Wilderness Medicine. 5th ed. St. Louis, Mo: Mosby; 2007:chap 25. source Corneal ulcers and infections

Low blood pressure or hypotension Posted: 18 Jan 2011 04:24 AM PST Definition Low blood pressure or hypotension Low blood pressure, or hypotension, occurs when blood pressure during and after each heartbeat is much lower than usual. This means the heart, brain, and other parts of the body do not get enough blood. See also: Blood pressure Alternative Names Low blood pressure; Blood pressure – low; Postprandial hypotension; Orthostatic hypotension; Neurally mediated hypotension; NMH Causes Blood pressure that is borderline low for one person may be normal for another. The most important factor is how the blood pressure changes from the normal condition. Most normal blood pressures fall in the range of 90/60 millimeters of mercury (mm Hg) to 130/80 mm Hg. But a significant drop, even as little as 20 mm Hg, can cause problems for some people. There are three main types of hypotension: * Orthostatic hypotension, including postprandial orthostatic hypotension * Neurally mediated hypotension (NMH) * Severe hypotension brought on by a sudden loss of blood (shock) Orthostatic hypotension is brought on by a sudden change in body position, usually when shifting from lying down to standing. This type of hypotension usually lasts only a few seconds or minutes. If this type of hypotension occurs after eating, it is called postprandial orthostatic hypotension. This form most commonly affects older adults, those with high blood pressure, and persons with Parkinson’s disease. NMH most often affects young adults and children. It occurs when a person has been standing for a long time. Children usually outgrow this type of hypotension. Low blood pressure is commonly caused by drugs such as: * Alcohol * Anti-anxiety medications * Certain antidepressants * Diuretics * Heart medicines, including those used to treat high blood pressure and coronary heart disease * Medications used for surgery * Painkillers Other causes of low blood pressure include: * Advanced diabetes * Anaphylaxis (a life-threatening allergic response) * Changes in heart rhythm (arrhythmias) * Dehydration * Fainting * Heart attack * Heart failure * Shock (from severe infection, stroke, anaphylaxis, major trauma, or heart attack) Symptoms Symptoms may include: * Blurry vision * Confusion * Dizziness * Fainting (syncope) * Light-headedness * Sleepiness * Weakness Exams and Tests The health care provider will examine you and try to determine what is causing the low blood pressure. Your vital signs (temperature, pulse, rate of breathing, blood pressure) will be checked frequently. You may need to stay in the hospital for a while. The doctor will ask questions, including: * What is your normal blood pressure? * What medications do you take? * Have you been eating and drinking normally? * Have you had any recent illness, accident, or injury? * What other symptoms do you have? * Did you faint or become less alert? * Do you feel dizzy or light-headed when standing or sitting after lying down? The following tests may be done: * Blood cultures to check for infection * Complete blood count (CBC) and other blood tests, including blood differential * ECG * Urinalysis * X-ray of the abdomen * X-ray of the chest Treatment Hypotension in a healthy person that does not cause any problems usually doesn’t require treatment. If you have signs or symptoms of low blood pressure, you may need treatment. Treatment depends on the cause of your low blood pressure. Severe hypotension caused by shock is a medical emergency. You may be given blood through a needle (IV), medicines to increase blood pressure and improve heart strength, and other medicines, such as antibiotics. For more details, see the article on shock. If you have orthostatic hypotension caused by medicines, your doctor may change the dose or switch you to a different drug. DO NOT stop taking any medicine before talking to your doctor. Other treatments for orthostatic hypotension include increasing fluids to treat dehydration or wearing elastic hose to boost blood pressure in the lower part of the body. Those with NMH should avoid triggers, such as standing for a long period of time. Other treatments involve drinking plenty of fluids and increasing the amount of salt in your diet. (Ask your doctor about specific recommendations.) In severe cases, medicines such as fludrocortisone may be prescribed. Outlook (Prognosis) Low blood pressure can usually be treated with success. Possible Complications * Shock * Injury from falls due to fainting Falls are particularly dangerous for older adults. Fall-related injuries, such as a broken hip, can dramatically impact a person’s quality of life. Severe hypotension starves your body of oxygen, which can damage the heart, brain, and other organs. This type of hypotension can be life threatening if not immediately treated. When to Contact a Medical Professional When you have symptoms from a drop in blood pressure, you should immediately sit or lie down and raise your feet above heart level. If low blood pressure causes a person to pass out (become unconscious), seek immediate medical treatment or call the local emergency number (such as 911). If the person is not breathing or has no pulse, begin CPR. Call your doctor immediately if you have any of the following symptoms: * Black or maroon stools * Chest pain * Dizziness, lightheadedness * Fainting * Fever higher than 101 degrees * Irregular heartbeat * Shortness of breath Also call your doctor if you have: * Burning with urination or other urinary symptoms * Cough with phlegm * Inability to eat or drink * Prolonged diarrhea or vomiting Prevention If you have low blood pressure, your doctor may recommend certain steps to prevent or reduce your symptoms. This may include: * Avoiding alcohol * Avoiding standing for a long time (if you have NMH) * Drinking plenty of fluids * Getting up slowly after sitting or lying down * Using compression stockings to increase blood pressure in the legs References Calkins H, Zipes DP. Hypotension and syncope. In: Libby P, Bonow RO, Mann DL, eds. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 37. source Low blood pressure or hypotension

Addison’s disease,Symptoms,Risk factors, treatment Addison’s disease Posted: 18 Jan 2011 04:21 AM PST Definition Addison’s disease Addison’s disease is a disorder that occurs when the adrenal glands do not produce enough of their hormones. Alternative Names Adrenocortical hypofunction; Chronic adrenocortical insufficiency; Primary adrenal insufficiency Causes The adrenal glands are small hormone-secreting organs located on top of each kidney. They consist of the outer portion (called the cortex) and the inner portion (called the medulla). The cortex produces three types of hormones: * The glucocorticoid hormones (such as cortisol) maintain sugar (glucose) control, decrease (suppress) immune response, and help the body respond to stress. * The mineralocorticoid hormones (such as aldosterone) regulate sodium and potassium balance. * The sex hormones, androgens (male) and estrogens (female), affect sexual development and sex drive. Addison’s disease results from damage to the adrenal cortex. The damage causes the cortex to produce less of its hormones. This damage may be caused by the following: * The immune system mistakenly attacking the gland (autoimmune disease) * Infections such as tuberculosis, HIV, or fungal infections * Hemorrhage, blood loss * Tumors * Use of blood-thinning drugs (anticoagulants) Risk factors for the autoimmune type of Addison’s disease include other autoimmune diseases: * Chronic thyroiditis * Dermatis herpetiformis * Graves’ disease * Hypoparathyroidism * Hypopituitarism * Myasthenia gravis * Pernicious anemia * Testicular dysfunction * Type I diabetes * Vitiligo Certain genetic defects may cause these conditions. Symptoms * Changes in blood pressure or heart rate * Chronic diarrhea * Darkening of the skin – patchy skin color * Unnaturally dark color in some places * Paleness * Extreme weakness * Fatigue * Loss of appetite * Mouth lesions on the inside of a cheek (buccal mucosa) * Nausea and vomiting * Salt craving * Slow, sluggish movement * Unintentional weight loss Exams and Tests Tests may show: * Increased potassium * Low blood pressure * Low cortisol level * Low serum sodium * Normal sex hormone levels Other tests may include: * Abdominal x-ray * Abdominal CT scan This disease may also change the results of the following tests: * 17-hydroxycorticosteroids * 17-ketosteroids * 24-hour urinary aldosterone excretion rate * ACTH * Aldosterone * Blood eosinophil count * CO2 * Cortrosyn stimulation test * Potassium test * Renin * Urine cortisol Treatment Treatment with replacement corticosteroids will control the symptoms of this disease. However, you will usually need to take these drugs for life. People often receive a combination of glucocorticoids (cortisone or hydrocortisone) and mineralocorticoids (fludrocortisone). Never skip doses of your medication for this condition, because life-threatening reactions may occur. The health care provider may increase the medication dose in times of: * Infection * Injury * Stress During an extreme form of adrenal insufficiency, adrenal crisis, you must inject hydrocortisone immediately. Supportive treatment for low blood pressure is usually needed as well. Some people with Addison’s disease are taught to give themselves an emergency injection of hydrocortisone during stressful situations. It is important for you to always carry a medical identification card that states the type of medication and the proper dose needed in case of an emergency. Additionally, your health care provider may advise you to always wear a Medic-Alert tag (such as a bracelet) alerting health care professionals that you have this condition in case of emergency. Outlook (Prognosis) With hormone replacement therapy, most people with Addison’s disease are able to lead normal lives. Possible Complications Complications can occur if you take too little or too much adrenal hormone supplement. Complications also may result from the following related illnesses: * Diabetes * Hashimoto’s thyroiditis (chronic thyroiditis) * Hypoparathyroidism * Ovarian hypofunction or testicular failure * Pernicious anemia * Thyrotoxicosis When to Contact a Medical Professional Call your health care provider if: * You are unable to keep your medication down due to vomiting. * You have been diagnosed with Addison’s disease, and you have stress such as infection, injury, trauma, or dehydration. You may need to have your medication adjusted. * Your weight increases over time. * Your ankles begin to swell. * You develop other new symptoms. If you have symptoms of adrenal crisis, give yourself an emergency injection of your prescribed medication. If it is not available, go to the nearest emergency room or call 911. Symptoms of adrenal crisis include: * Abdominal pain * Difficulty breathing * Low blood pressure * Reduced consciousness References Stewart PM. The adrenal cortex. In: Kronenberg H, Melmed S, Polonsky K, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders Elsevier; 2008:chap 14. source Addison’s disease

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