Wikipedia - Kidney
(The Following are excerts from Wikipedia definition of the kidney. You can click on the link and it will take you straight to the page and you'll be able to read even more information.)
The kidneys are paired organs with several functions. They are seen in many types of animals, including vertebrates and some invertebrates. They are an essential part of the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid-base balance, and regulation of blood pressure. They serve the body as a natural filter of the blood, and remove wastes which are diverted to the urinary bladder. In producing urine, the kidneys excrete wastes such as urea and ammonium; the kidneys also are responsible for the reabsorption of water, glucose, and amino acids. The kidneys also produce hormones including calcitriol, renin, and erythropoietin.
Located at the rear of the abdominal cavity in the retroperitoneum, the kidneys receive blood from the paired renal arteries, and drain into the paired renal veins. Each kidney excretes urine into a ureter, itself a paired structure that empties into the urinary bladder.
Structure:
1. Renal pyramid • 2. Interlobular artery • 3. Renal artery • 4. Renal vein 5. Renal hilum • 6. Renal pelvis • 7. Ureter • 8. Minor calyx • 9. Renal capsule • 10. Inferior renal capsule • 11. Superior renal capsule • 12. Interlobular vein • 13. Nephron • 14. Minor calyx • 15. Major calyx • 16. Renal papilla • 17. Renal column
The kidney has a bean-shaped structure, each kidney has concave and convex surfaces. The concave surface, the renal hilum, is the point at which the renal artery enters the organ, and the renal vein and ureter leave. The kidney is surrounded by tough fibrous tissue, the renal capsule, which is itself surrounded by perinephric fat, renal fascia (of Gerota) and paranephric fat. The anterior (front) border of these tissues is the peritoneum, while the posterior (rear) border is the transversalis fascia.
The superior border of the right kidney is adjacent to the liver; and the spleen, for the left border. Therefore, both move down on inhalation.
The kidney is approximately 11–14 cm in length, 6 cm wide and 3 cm thick.
The substance, or parenchyma, of the kidney is divided into two major structures: superficial is the renal cortex and deep is the renal medulla. Grossly, these structures take the shape of 8 to 18 cone-shaped renal lobes, each containing renal cortex surrounding a portion of medulla called a renal pyramid (of Malpighi).[2] Between the renal pyramids are projections of cortex called renal columns (of Bertin). Nephrons, the urine-producing functional structures of the kidney, span the cortex and medulla. The initial filtering portion of a nephron is the renal corpuscle, located in the cortex, which is followed by a renal tubule that passes from the cortex deep into the medullary pyramids. Part of the renal cortex, a medullary ray is a collection of renal tubules that drain into a single collecting duct.
The tip, or papilla, of each pyramid empties urine into a minor calyx, minor calyces empty into major calyces, and major calyces empty into the renal pelvis, which becomes the ureter.
Functions
Renal physiology
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 will eventually become urine. The kidney generates 180 liters of filtrate a day, while reabsorbing a large percentage, allowing for only the generation of 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.
Excretion of wastes
The kidneys excrete a variety of waste products produced by metabolism. These include the nitrogenous wastes urea, from protein catabolism, and uric acid, from nucleic acid metabolism.
Acid-base homeostasis
Two organ systems, the kidneys and lungs, maintain acid-base homeostasis, which is the maintenance of pH around a relatively stable value. The kidneys contribute to acid-base homeostasis by regulating bicarbonate (HCO3-) concentration.
Osmolality regulation
Any significant rise or drop in plasma osmolality is detected by the hypothalamus, which communicates directly with the posterior pituitary gland. An increase in osmolality causes the gland to secrete antidiuretic hormone (ADH), resulting in water reabsorption by the kidney and an increase in urine concentration. The two factors work together to return the plasma osmolality to its normal levels.
ADH binds to principal cells in the collecting duct that translocate aquaporins to the membrane allowing water to leave the normally impermeable membrane and be reabsorbed into the body by the vasa recta, thus increasing the plasma volume of the body.
There are two systems that create a hyperosmotic medulla and thus increase the body plasma volume: Urea recycling and the 'single effect.'
Urea is usually excreted as a waste product from the kidneys. However, when plasma blood volume is low and ADH is released the aquaporins that are opened are also permeable to urea. This allows urea to leave the collecting duct into the medulla creating a hyperosmotic solution that 'attracts' water. Urea can then re-enter the nephron and be excreted or recycled again depending on whether ADH is still present or not.
The 'Single effect' describes the fact that the ascending thick limb of the loop of Henle is not permeable to water but is permeable to NaCl. This means that a countercurrent system is created whereby the medulla becomes increasingly concentrated setting up an osmotic gradient for water to follow should the aquaporins of the collecting duct be opened by ADH.
Blood pressure regulation
Long-term regulation of blood pressure predominantly depends upon the kidney. This primarily occurs through maintenance of the extracellular fluid compartment, the size of which depends on the plasma sodium concentration. Although the kidney cannot directly sense blood pressure, changes in the delivery of sodium and chloride to the distal part of the nephron alter the kidney's secretion of the enzyme renin. When the extracellular fluid compartment is expanded and blood pressure is high, the delivery of these ions is increased and renin secretion is decreased. Similarly, when the extracellular fluid compartment is contracted and blood pressure is low, sodium and chloride delivery is decreased and renin secretion is increased in response.
Renin is the first in a series of important chemical messengers that comprise the renin-angiotensin system. Changes in renin ultimately alter the output of this system, principally the hormones angiotensin II and aldosterone. Each hormone acts via multiple mechanisms, but both increase the kidney's absorption of sodium chloride, thereby expanding the extracellular fluid compartment and raising blood pressure. When renin levels are elevated, the concentrations of angiotensin II and aldosterone increase, leading to increased sodium chloride reabsorption, expansion of the extracellular fluid compartment, and an increase in blood pressure. Conversely, when renin levels are low, angiotensin II and aldosterone levels decrease, contracting the extracellular fluid compartment, and decreasing blood pressure.
Hormone secretion
The kidneys secrete a variety of hormones, including erythropoietin, calcitriol, and renin. Erythropoietin is released in response to hypoxia (low levels of oxygen at tissue level) in the renal circulation. It stimulates erythropoiesis (production of red blood cells) in the bone marrow. Calcitriol, the activated form of vitamin D, promotes intestinal absorption of calcium and the renal reabsorption of phosphate. Part of the renin-angiotensin-aldosterone system, renin is an enzyme involved in the regulation of aldosterone levels.
Urinary system
1. Human urinary system: 2. Kidney, 3. Renal pelvis, 4. Ureter, 5. Urinary bladder, 6. Urethra. (Left side with frontal section), 7. Adrenal gland
Vessels: 8. Renal artery and vein, 9. Inferior vena cava, 10. Abdominal aorta, 11. Common iliac artery and vein
With transparency: 12. Liver, 13. Large intestine, 14. Pelvis
The Urinary System:
The urinary system (also called the excretory system) is the organ system that produces, stores, and eliminates urine. In humans it includes two kidneys, two ureters, the bladder, the urethra, and two sphincter muscles.
Kidney
The kidneys are bean-shaped organs that lie in the abdomen, retroperitoneal to the organs of digestion, around or just below the ribcage and close to the lumbar spine. The organ is about the size of a human fist and is surrounded by what is called Peri-nephric fat, and situated on the superior pole of each kidney is an adrenal gland. The kidneys receive their blood supply of 1.25 L/min (25% of the cardiac output) from the renal arteries which are fed by the abdominal aorta. This is important because the kidneys' main role is to filter water soluble waste products from the blood. The other attachment of the kidneys are at their functional endpoints the ureters, which lies more medial and runs down to the trigone of urinary bladder.
The kidneys perform a number of tasks, such as: concentrating urine, regulating electrolytes, and maintaining acid-base homeostasis. The kidney excretes and re-absorbs electrolytes (e.g. sodium, potassium and calcium) under the influence of local and systemic hormones. pH balance is regulated by the excretion of bound acids and ammonium ions. In addition, they remove urea, a nitrogenous waste product from the metabolism of amino acids. The end point is a hyperosmolar solution carrying waste for storage in the bladder prior to urination.
Humans produce about 2.9 liters of urine over 24 hours, although this amount may vary according to circumstances. Because the rate of filtration at the kidney is proportional to the glomerular filtration rate, which is in turn related to the blood flow through the kidney, changes in body fluid status can affect kidney function. Hormones exogenous and endogenous to the kidney alter the amount of blood flowing through the glomerulus. Some medications interfere directly or indirectly with urine production. Diuretics achieve this by altering the amount of absorbed or excreted electrolytes or osmalites, which causes a diuresis.
Kidney Cancer - AS Defined by the Wikipedia (link listed)
Wikipedia: Kidney Cancer
(The following are exerts from wikipedia. You may click on the above link and read the entire thing for further information.)
Kidney cancer is usually defined as any cancer that is determined to have arisen from the kidney. It usually does not include metastatic cancer of the kidney, i.e. cancer that arose outside of the kidney and has spread to it.
The two most common types of kidney cancer, reflecting their location within the kidney, are renal cell carcinoma (RCC) and urothelial cell carcinoma (UCC) of the renal pelvis.
The distinction between these two types (RCC and UCC) is important because their prognosis, staging, and management, i.e. treatment (e.g. surgery, chemotherapy etc.), is different.
Types
In addition to renal cell carcinoma and renal pelvis carcinoma, other, less common types of kidney cancer include:
- Squamous cell carcinoma
- Juxtaglomerular cell tumor (reninoma)
- Angiomyolipoma
- Renal oncocytoma
- Bellini duct carcinoma
- Clear-cell sarcoma of the kidney
- Mesoblastic nephroma
- Wilms' tumor, usually is reported in children under the age of 5.
- Mixed epithelial stromal tumor
- Clear cell adenocarcinoma
- Transitional cell carcinoma
- Inverted papilloma
- Renal lymphoma
- Teratoma
- Carcinosarcoma
- Carcinoid tumor of the renal pelvis
Location within the kidney
Kidney cancer originates in the kidney in two principal locations: the renal tubule and the renal pelvis. Most cancers in the renal tubule are renal cell carcinoma and clear cell adenocarcinoma. Most cancers in the renal pelvis are transitional cell carcinoma.
Signs and symptoms
Common signs and symptoms of a kidney cancer include, in order of prevalence: palpable mass in the abdomen, hematuria, and hydronephrosis. However there may also be no signs or symptoms. A palpable mass is by far the most common sign.[5] The mass typically presents first in the anterior lumbar region, between the margins of the ribs and the crista ilii; it then grows forward to the umbilicus, upwards into the hypochondrium, and downwards into the iliac and inguinal regions. In extreme cases it fills the entire belly. The colon, and sometimes a portion of the small intestines, lies in front of it. This position of the colon furnishes an important diagnostic mark of all kidney cancers.
Treatment
Treatment for kidney cancer depends on the type and stage of the disease. In wilms tumor, chemotherapy, radiotherapy and nephrectomy are the accepted treatments. In renal cell carcinoma, treatment depends on the stage of the cancer, but typically does not involve chemotherapy and radiotherapy, as renal cell carcinoma is resistant to these therapies. Treatment for localized renal cell carcinoma consists of nephrectomy alone, with no adjuvant (post surgical) therapy. In metastatic renal cell carcinoma,treatment consists of Targeted therapy such as torisel, nexavar and sutent, the use of immunotherapy including interferon and interleukin-2, and in some cases, nephrectomy. Other rare forms of kidney cancer, such as sarcomatoid renal carcinoma, are not disscussed here.
NATIONAL CANCER INSTITUTE:
What You Need to Know About KidneyCancer
NCI: Introduction
NCI: The Kidneys
NCI: Understanding Cancer
NCI: Kidney Cancer: Who's At Risk
Kidney cancer develops most often in people over 40, but no one knows the exact causes of this disease. Doctors can seldom explain why one person develops kidney cancer and another does not. However, it is clear that kidney cancer is not contagious. No one can "catch" the disease from another person.
Research has shown that people with certain risk factors are more likely than others to develop kidney cancer. A risk factor is anything that increases a person's chance of developing a disease.
Studies have found the following risk factors for kidney cancer:
Smoking: Cigarette smoking is a major risk factor. Cigarette smokers are twice as likely as nonsmokers to develop kidney cancer. Cigar smoking also may increase the risk of this disease.
Obesity: People who are obese have an increased risk of kidney cancer.
High blood pressure: High blood pressure increases the risk of kidney cancer.
Long-term dialysis: Dialysis is a treatment for people whose kidneys do not work well. It removes wastes from the blood. Being on dialysis for many years is a risk factor for kidney cancer.
Von Hippel-Lindau (VHL) syndrome: VHL is a rare disease that runs in some families. It is caused by changes in the VHL gene. An abnormal VHL gene increases the risk of kidney cancer. It also can cause cysts or tumors in the eyes, brain, and other parts of the body. Family members of those with this syndrome can have a test to check for the abnormal VHL gene. For people with the abnormal VHL gene, doctors may suggest ways to improve the detection of kidney cancer and other diseases before symptoms develop.
Occupation: Some people have a higher risk of getting kidney cancer because they come in contact with certain chemicals or substances in their workplace. Coke oven workers in the iron and steel industry are at risk. Workers exposed to asbestos or cadmium also may be at risk.
Gender: Males are more likely than females to be diagnosed with kidney cancer. Each year in the United States, about 20,000 men and 12,000 women learn they have kidney cancer.
Most people who have these risk factors do not get kidney cancer. On the other hand, most people who do get the disease have no known risk factors. People who think they may be at risk should discuss this concern with their doctor. The doctor may be able to suggest ways to reduce the risk and can plan an appropriate schedule for checkups.
National Cancer Institute - Symptoms
Common symptoms of kidney cancer include:
- Blood in the urine (making the urine slightly rusty to deep red)
- Pain in the side that does not go away
- A lump or mass in the side or the abdomen
- Weight loss
- Fever
- Feeling very tired or having a general feeling of poor health
Most often, these symptoms do not mean cancer. An infection, a cyst, or another problem also can cause the same symptoms. A person with any of these symptoms should see a doctor so that any problem can be diagnosed and treated as early as possible.
National Cancer Institute: Diagnosis
If a patient has symptoms that suggest kidney cancer, the doctor may perform one or more of the following procedures:
- Physical exam: The doctor checks general signs of health and tests for fever and high blood pressure. The doctor also feels the abdomen and side for tumors.
- Urine tests: Urine is checked for blood and other signs of disease.
- Blood tests: The lab checks the blood to see how well the kidneys are working. The lab may check the level of several substances, such as creatinine. A high level of creatinine may mean the kidneys are not doing their job.
- Intravenous pyelogram (IVP): The doctor injects dye into a vein in the arm. The dye travels through the body and collects in the kidneys. The dye makes them show up on x-rays. A series of x-rays then tracks the dye as it moves through the kidneys to the ureters and bladder. The x-rays can show a kidney tumor or other problems.
- CT scan (CAT scan): An x-ray machine linked to a computer takes a series of detailed pictures of the kidneys. The patient may receive an injection of dye so the kidneys show up clearly in the pictures. A CT scan can show a kidney tumor.
- Ultrasound test: The ultrasound device uses sound waves that people cannot hear. The waves bounce off the kidneys, and a computer uses the echoes to create a picture called a sonogram. A solid tumor or cyst shows up on a sonogram.
- Biopsy: In some cases, the doctor may do a biopsy. A biopsy is the removal of tissue to look for cancer cells. The doctor inserts a thin needle through the skin into the kidney to remove a small amount of tissue. The doctor may use ultrasound or x-rays to guide the needle. A pathologist uses a microscope to look for cancer cells in the tissue.
- Surgery: In most cases, based on the results of the CT scan, ultrasound, and x-rays, the doctor has enough information to recommend surgery to remove part or all of the kidney. A pathologist makes the final diagnosis by examining the tissue under a microscope.
To plan the best treatment, the doctor needs to know the stage (extent) of the disease. The stage is based on the size of the tumor, whether the cancer has spread and, if so, to what parts of the body.
Staging may involve imaging tests such as an ultrasound or a CT scan. The doctor also may use an MRI. For this test, a powerful magnet linked to a computer makes detailed pictures of organs and blood vessels.
Doctors describe kidney cancer by the following stages:
Stage I - is an early stage of kidney cancer. The tumor measures up to 2 3/4 inches (7 centimeters). It is no bigger than a tennis ball. The cancer cells are found only in the kidney.
Stage II is also an early stage of kidney cancer, but the tumor measures more than 2 3/4 inches. The cancer cells are found only in the kidney.
Stage III is one of the following:
- The tumor does not extend beyond the kidney, but cancer cells have spread through the lymphatic system to one nearby lymph node; or
- The tumor has invaded the adrenal gland or the layers of fat and fibrous tissue that surround the kidney, but cancer cells have not spread beyond the fibrous tissue. Cancer cells may be found in one nearby lymph node; or
- The cancer cells have spread from the kidney to a nearby large blood vessel. Cancer cells may be found in one nearby lymph node.
- The tumor extends beyond the fibrous tissue that surrounds the kidney; or
- Cancer cells are found in more than one nearby lymph node; or
- The cancer has spread to other places in the body such as the lungs.
National Cancer Institute: Treatment and Getting a Second Opinion
National Cancer Institute: Side Effects of Treatment
- Surgery
- Arterial Embolization
- Radiation Therapy
- Biological Therapy
- Chemotherapy
NCI: Follow-up Care
NCI: Support for People With Kidney Cancer
Living with a serious disease such as kidney cancer is not easy. People with kidney cancer may worry about caring for their families, keeping their jobs, or continuing daily activities. Concerns about treatments and managing side effects, hospital stays, and medical bills are also common. Doctors, nurses, and other members of the health care team can answer questions about treatment, working, or other activities. Meeting with a social worker, counselor, or member of the clergy can be helpful to those who want to talk about their feelings or discuss their concerns. Often, a social worker can suggest resources for financial aid, transportation, home care, or emotional support.
Support groups also can help. In these groups, patients or their family members meet with other patients or their families to share what they have learned about coping with the disease and the effects of treatment. Groups may offer support in person, over the telephone, or on the Internet. Patients may want to talk with a member of their health care team about finding a support group.
The Cancer Information Service at 1-800-4-CANCER can provide information to help patients and their families locate programs, services, and publications.
NCI: The Promise of Cancer Research
National Cancer Institute Booklets
National Cancer Institue Information Resources
You may want more information for yourself, your family, and your doctor. The NCI offers comprehensive research-based information for patients and their families, health professionals, cancer researchers, advocates, and the public.
Call the NCI Cancer Information Service at 1-800-4-CANCER (1-800-422-6237)
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