KIDNEY AND HIS FAILURE

The kidneys are bean shaped organs that serve several essential regulatory roles in vertebrate animals. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and regulation of blood pressure (via maintaining salt and water balance). They serve the body as a natural filter of the blood, and remove water soluble wastes, which are diverted to the urinary bladder. In producing urine, the kidneys excrete wastes such as urea and ammonium, and they are also responsible for the reabsorption of water, glucose, and amino acids. The kidneys also produce hormones including calcitriol, erythropoietin, and the enzyme renin.

LOCATION

In humans the kidneys are located in the abdominal cavity, more specifically in the paravertebral
The upper (cranial) parts of the kidneys are partially protected by the eleventh and twelfth ribs, and each whole kidney and adrenal gland are surrounded by two layers of fat (the perirenal and pararenal fat) and the renal fascia. Each adult kidney weighs between 125 and 170 grams in males and between 115 and 155 grams in females. The left kidney is usually slightly larger than the right kidney.

gutter and lie in a retroperitoneal position at a slightly oblique angle. There are two kidneys. One is on each side of the spine. The asymmetry within the abdominal cavity caused by the liver typically results in the right kidney being slightly lower than the left, and left kidney being located slightly more medial than the right. The left kidney is approximately at the vertebral level T12 to L3, and the right slightly lower. The right kidney sits just below the diaphragm and posterior to the liver, the left below the diaphragm and posterior to the spleen. Resting on top of each kidney is an adrenal gland.

INNERVATION
The kidney and nervous system communicate via the renal plexus, whose fibers course along the renal arteries to reach each kidney. Input from the sympathetic nervous system triggers vasoconstriction in the kidney, thereby reducing renal blood flow. The kidney also receives input from the parasympathetic nervous system, by way of the renal branches of the vagus nerve (cranial nerve X); the function of this is yet unclear. Sensory input from the kidney travels to the T10-11 levels of the spinal cord and is sensed in the corresponding dermatome. Thus, pain in the flank region may be referred from corresponding kidney.

FUNCTIONS
The kidney participates in whole-body homeostasis, regulating acid-base balance, electrolyte concentrations, extracellular fluid volume, and regulation of blood pressure. The kidney accomplishes these homeostatic functions both independently and in concert with other organs, particularly those of the endocrine system. Various endocrine hormones coordinate these endocrine functions; these include renin, angiotensin II, aldosterone, antidiuretic hormone, and atrial natriuretic peptide, among others.

Many of the kidney's functions are accomplished by relatively simple mechanisms of filtration, reabsorption, and secretion, which take place in the nephron. Filtration, which takes place at the renal corpuscle, is the process by which cells and large proteins are filtered from the blood to make an ultrafiltrate that eventually becomes urine. The kidney generates 180 liters of filtrate a day, while reabsorbing a large percentage, allowing for the generation of only approximately 2 liters of urine. Reabsorption is the transport of molecules from this ultrafiltrate and into the blood. Secretion is the reverse process, in which molecules are transported in the opposite direction, from the blood into the urine.


RENAL FAILURE

Renal failure (also kidney failure or renal insufficiency) is a medical condition in which the kidneys

Renal failure is mainly determined by a decrease in glomerular filtration rate, the rate at which blood is filtered in the glomeruli of the kidney. This is detected by a decrease in or absence of urine production or determination of waste products (creatinine or urea) in the blood. Depending on the cause, hematuria (blood loss in the urine) and proteinuria (protein loss in the urine) may be noted.

In renal failure, there may be problems with increased fluid in the body (leading to swelling), increased acid levels, raised levels of potassium, decreased levels of calcium, increased levels of phosphate, and in later stages anemia. Bone health may also be affected. Long-term kidney problems are associated with an increased risk of cardiovascular disease.

fail to adequately filter waste products from the blood. The two main forms are acute kidney injury, which is often reversible with adequate treatment, and chronic kidney disease, which is often not reversible. In both cases, there is usually an underlying cause.

ACUTE KIDNEY INJURY

Acute kidney injury (previously known as acute renal failure) - or AKI - usually occurs when the blood supply to the kidneys is suddenly interrupted or when the kidneys become overloaded with toxins. Causes of acute kidney injury include accidents, injuries, or complications from surgeries in which the kidneys are deprived of normal blood flow for extended periods of time. Heart-bypass surgery is an example of one such procedure.

Drug overdoses, accidental or from chemical overloads of drugs such as antibiotics or chemotherapy, may also cause the onset of acute kidney injury. Unlike chronic kidney disease, however, the kidneys can often recover from acute kidney injury, allowing the patient to resume a normal life. People suffering from acute kidney injury require supportive treatment until their kidneys recover function, and they often remain at increased risk of developing future kidney failure.

Among the accidental causes of renal failure is the crush syndrome, when large amounts of toxins are suddenly released in the blood circulation after a long compressed limb is suddenly relieved from the pressure obstructing the blood flow through its tissues, causing ischemia. The resulting overload can lead to the clogging and the destruction of the kidneys. It is a reperfusion injury that appears after the release of the crushing pressure. The mechanism is believed to be the release into the bloodstream of muscle breakdown products – notably myoglobin, potassium, and phosphorus – that are the products of rhabdomyolysis (the breakdown of skeletal muscle damaged by ischemic conditions). The specific action on the kidneys is not fully understood, but may be due in part to nephrotoxic metabolites of myoglobin.
So for all these we can conclude that acute kidney failure is causes with three mains:

• A sudden, serious drop in blood flow to the kidneys. Heavy blood loss, an injury, or a bad infection called sepsis can reduce blood flow to the kidneys. Not enough fluid in the body (dehydration) also can harm the kidneys.
• Damage from some medicines, poisons, or infections. Most people don't have any kidney problems from taking medicines. But people who have serious, long-term health problems are more likely than other people to have a kidney problem from medicines. Examples of medicines that can sometimes harm the kidneys include:

1. Antibiotics, such as gentamicin and streptomycin.
2. Pain medicines, such as naproxen and ibuprofen.
3. Some blood pressure medicines, such as ACE inhibitors.   
4. The dyes used in some X-ray tests.

• A sudden blockage that stops urine from flowing out of the kidneys.Kidney stones, a tumor, an injury, or an enlarged prostate gland can cause a blockage.

You have a greater chance of getting acute kidney injury if:

• You are an older adult.
• You have a long-term health problem such as kidney or liver disease, diabetes, high blood pressure, heart failure, or obesity.
• You are already very ill and are in the hospital or intensive care (ICU). Heart or belly surgery or a bone marrow transplant can make you more likely to have kidney problems.

And most important from acute kidney injury is most often diagnosed during a hospital stay for another cause. If you are already in the hospital, tests done for other problems may find your kidney problem.

If you're not in the hospital but have symptoms of kidney injury, your doctor will ask about your symptoms, what medicines you take, and what tests you have had. Your symptoms can help point to the cause of your kidney problem.

Blood and urine tests can check how well your kidneys are working. A chemistry screen can show if you have normal levels of sodium (salt), potassium, and calcium. You may also have an ultrasound. This imaging test lets your doctor see a picture of your kidneys.

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Warning For Passive Smoker

Secondhand smoke is the combination of smoke from a burning cigarette and smoke exhaled by a smoker. There are two types of secondhand smoke; side stream smoke comes directly from the burning tobacco product, and mainstream smoke is the smoke that the smoker inhales. The smoke that burns off the end of a cigarette or cigar actually contains more harmful substances than the smoke inhaled by the smoker, as there is no filter it must pass through.

HOW DOES SECONDHAND SMOKE AFFECT NON-SMOKERS?

If you are a non-smoker but are exposed to secondhand smoke on a regular basis, your body will still absorb nicotine and other harmful substances. Smoke contains more than 4000 chemical compounds, of which 250 are toxic and more than 50 are known cancer-causing agents. These dangerous substances linger in the air for approximately 4 hours and breathing in these particles for only minutes can harm you.

Exposure Time to Secondhand Smoke and Effects:

• 5 minutes – stiffens the aorta as much as smoking a cigarette
• 20-30 minutes – causes excess blood clotting, as well as increases the build up of fat deposits in blood vessels, increasing the risk of heart attack and stroke
• 2 hours – increases the chance of irregular heart beat (arrhythmia) and can trigger a fatal cardiac event or heart attack.

In addition, the longer you are around secondhand smoke, the greater the level of harmful substances in your body. As a result, you might have an increased risk of developing smoking-related disorders, including:

• Lung cancer and lung disease, including COPD, emphysema, asthma, and chronic bronchitis. Nonsmokers who live with a smoker have a 20% to 30% increased risk for developing lung cancer
• Heart disease
• Eye and nasal irritation; increased risk of sinus and respiratory infections

WHO IS AT GREATEST RISK OF BEING HARMED BY SECONDHAND SMOKE?

Although any person who spends time around those who smoke has an increased chance of developing a smoking-related illness, certain people are extremely susceptible to the harmful effects of secondhand smoke. These include:

Service industry workers, such as bartenders and restaurant servers. People who work in environments where they are constantly exposed to smokers might absorb carcinogens and other harmful substances from secondhand tobacco smoke on a regular basis. This puts them at greater risk of developing the health issues addressed above.

Pregnant women. Second hand-smoke harms not only the mother-to-be, but her unborn child as well. Smoke exposure during pregnancy increases the risk for problems such as placenta previa (low lying placenta), placental abruption (a medical emergency), as well as miscarriage, stillbirth, and ectopic pregnancy. It decreases the amount of oxygen available to mother and baby, increases the baby’s heart rate, and increases the likelihood that the baby will have a low birth weight or be born prematurely.

Infants and children (and pets! ) Because young children and animals can't choose to leave a smoke-filled environment, this constant exposure makes them especially vulnerable to the health risks of secondhand smoke. Infants and children who are regularly exposed to secondhand smoke have an increased chance of developing the following conditions:

• Frequent colds and respiratory infections (including bronchitis and pneumonia)
• May experience slow or incomplete lung growth and development
• Asthma and chronic coughs
• Chronic and/or recurrent ear infections
• SIDS (Sudden Infant Death Syndrome)
• High blood pressure
• Learning and behavior problems, including inattention and aggression.
• Cataracts
• Poor dental health
• Increased likelihood that the children themselves will become smokers
• Increased risk of tumors and cancer shown in cats, dogs, and birds.

WHAT CAN I DO TO AVOID SECONDHAND SMOKE?

The following suggestions might be helpful in reducing, or even eliminating, your and your family’s exposure to secondhand smoke:

• Whenever possible, ask visitors to your home to smoke outside and to use a “smoking coat” or sweatshirt so that they will not carry toxins on their clothes (this is actually known as “third-hand smoke”).
• Open windows and use fans to ventilate rooms in your home and work
• Don't keep ashtrays in your home.
• Tell babysitters and other caregivers not to smoke around your children, even if it is in their own home.
• If you are visiting a smoker’s home with your children, try to socialize outside whenever possible.
• If smoking is allowed where you work, talk to your employer about modifying the company’s smoking policy. Encourage them to support a program to help their employees quit!
• Ask to work near other non-smokers or as far away from smokers as possible.
• When staying in a hotel, ask for a non-smoking room.
• Stay informed about any changes in federal, state, and local smoking laws and become involved in strengthening those laws.

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