The Urinary System: Structures and Functions

The urinary system include the two kidneys, two ureters, the urinary bladder (or simply, bladder), two sphincter muscles, and the urethra. These structures, including the nerves that control them, work in different ways. But generally, the urinary system works to form urine, store it, and carry it outside the body.

The different structures of the urinary system and their functions:

The Kidneys

The kidneys are two bean-shaped organs located near the middle of the back just below the rib cage. Each kidney is about the size of your fist.

The kidneys help to remove urea from the body. Urea is a waste product that forms when foods that contain protein are broken down in the body. Proteins are found in meat, poultry, and some vegetables. Urea, along with other waste products formed by cells is transported through the bloodstream to the kidneys.

Within the kidneys are tiny filtering structures called nephrons. The nephrons help eliminate urea, other waste products, and excess water from the body. The combination of waste products and excess water constitutes urine.

The Ureters

Once urine is formed in the kidneys, it flows into two thin, tube-like organs called ureters. Each ureter connects each kidney to the bladder.

The Bladder

The bladder, also called urinary bladder, is a hollow muscular organ that sits in the pelvis and held in place by structures attached to other organs and the pelvic bone.

The bladder receives the urine coming from the kidneys that passes through the ureters. It normally helps to store urine until you empty it during urination.

If you do not have problems with your urinary system, your bladder can hold up to 16 ounces, or 2 cups, of urine comfortably for up to 5 hours.

The Sphincters

To prevent leaking of urine, sphincter muscles in the opening of the bladder normally contract.

The Urethra

Urine flows to the urethra when sphincter muscles surrounding the tube just below the bladder relax. Urine exits the body through the opening of the urethra, called external urethral orifice.

The Nerves

Nerves play a vital role in “telling” the bladder when it is time to empty it, or urinate.

Normally, you may notice a feeling that you need to urinate as the bladder is filled with urine. This sensation grows stronger as the bladder continues to be filled. When it reaches its limit, nerves from the bladder inform the brain that the bladder is full. During this time, your urge to empty your bladder intensifies.

Urination

Urination occurs when the brain signals the muscles in the bladder to tighten. As a result, urine is squeezed out of the bladder. The brain also signals the sphincter muscles to relax allowing urine to pass and flow through the urethra.

Related Reading:  The Kidney: Structures and Functions

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Common Chronic Prostatitis Drug Not Effective in Reducing Symptoms

A commonly prescribed drug for chronic prostatitis, called alfuzosin, failed to significantly reduce symptoms of the condition. Chronic prostatitis is a painful disorder of the prostate gland and surrounding pelvic area.

According to the clinical trial sponsored by the National Institute of Diabetes and Digestive and Kidney Disease (NIDDK), a part of the National Institutes of Health NIH), alfuzosin failed to reduce symptoms in recently diagnosed men who had not been previously treated with the drug.

NIDDK Director Griffin P. Rodgers, M.D. said "Although these results are disappointing, it is just as important to find out what doesn’t work as it is to know what does." He further added, "We have conclusively shown that a drug commonly prescribed for men with chronic prostatitis did not significantly reduce symptoms compared to a placebo."

Chronic prostatitis is the most common type of prostatitis seen by physicians. Its cause is not fully understood making it difficult to find a uniform effective therapy. Men with the condition experience symptoms such as pain in the genital and urinary tract areas, lower urinary tract symptoms such as pain in the bladder area and during urination, and sexual problems that can severely affect their quality of life. Population-based surveys estimate that 6 percent to 12 percent of men have prostatitis-like symptoms.

In the clinical trial, a total of 272 men diagnosed with chronic prostatitis were randomly assigned to take either alfuzosin or an identical-looking placebo. Of these, 233 men have completed the trial. The primary outcome was a decrease (improvement) in the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) of at least four points over 12 weeks of treatment. A 4-point decrease in the NIH-CPSI score has been shown to be the minimal clinically significant difference perceived by patients as beneficial. The index measures the three most important symptoms of chronic prostatitis — pain, problems with urination, and negative effects on quality of life.

The rates of response of the NIH-CPSI in the alfuzosin group and placebo groups were the same — 49.4 percent. In addition, there were no significant differences between the two groups in the changes over time in most of the secondary outcomes, including the total NIH-CPSI score and a global response assessment.

Despite a lack of rigorous evidence supporting the use of antibiotics or alpha blockers for chronic prostatitis, more than three-fourths of primary care physicians often prescribe antibiotics and more than one-half regularly prescribe alpha blockers such as alfuzosin for the condition, according to a recent survey supported by NIDDK. Alpha blockers are a class of drugs that relax the smooth muscle of the bladder and prostate.

"Our findings do not support the use of alpha blockers for treating new cases of chronic prostatitis," said J. Curtis Nickel, M.D., of Queen’s University in Kingston, Ontario, Canada, and lead author of the study. "But the results of our study will inform future clinical trials of alpha blockers and other potential therapies."

Sanofi-Aventis, Paris, provided the study drug and placebo at no cost. The company was not involved in the design of the study, the analysis of data, or the preparation of the manuscript.

For more information on chronic prostatitis and other types of prostatitis, visit http://www.kidneyhealthcare.com/2008/10/prostatitis.html

Source:
NIH News: National Institutes of Health (December 17, 2008). Common Treatment for Chronic Prostatitis Fails to Reduce Symptoms. Available at: http://www.nih.gov/news/health/dec2008/niddk-17.htm

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Certain Bowel Cleansers and the Risk of Kidney Damage

The U.S. Food and Drug Administration has added a Boxed Warning on two prescription oral sodium phosphate (OSP) products: Visicol and OsmoPrep. The Boxed Warning helps to warn consumers about the risk of acute phosphate nephropathy (a kind of acute kidney injury or damage). OSP products are routinely used to cleanse the bowel before colon examination (colonoscopy) and other medical procedures.

In addition, the FDA has also directed the makers of these products to

 develop a risk evaluation and mitigation strategy (REMS)

 distribute a Medication Guide to alert patients to the risk of acute kidney injury associated with these products

 conduct a postmarketing clinical trial to further assess this risk.

The agency is also concerned about the risks associated with over-the-counter (OTC) OSP products when used at higher doses for bowel cleansing. Available data do not show a risk of acute kidney injury when OTC OSP products are used at lower doses as laxatives. However, these products present the same risk as prescription OSP products when used for bowel cleansing.

The FDA recommends that consumers should not use OTC OSP products for bowel cleansing. The agency plans to amend the labeling conditions for OTC OSP products to address this concern with bowel cleansing use.

FDA Safety Advice

OSP products should NOT be used

 by children under 18 years of age

 in combination with other laxative products containing sodium phosphate

OSP prescription products should be used with caution by people who are

 over 55 years of age

 suffering from dehydration, kidney disease, acute colitis, or delayed bowel emptying

 taking certain medicines that affect kidney function, such as diuretics (fluid pills), angiotensin converting enzyme inhibitors (medications that lower blood pressure) angiotensin receptor blockers, (used to treat high blood pressure, heart or kidney failure) and possibly nonsteroidal anti-inflammatory drugs (similar to ibuprofen and other arthritis medications).

To learn more about the News Release and Updates provided by the U.S. Food and Drug Administration:

FDA Requires New Safety Measures for Oral Sodium Phosphate Products to Reduce Risk of Acute Kidney Injury
Risk associated with both prescription and over-the-counter (OTC) products (Press Release - December 11, 2008)

Kidney Risk Spurs Warning on Bowel Cleansers (Consumer Update - December 16, 2008)

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Kidney Failure Treatments and Complications

Kidney failure treatments may cause complications that may require prompt treatment. But some of the kidney failure treatment complications or side effects of treatment may be prevented or easily treated. Let us have a look at some of the possible complications that may occur when undergoing treatment for total kidney failure.

Three treatment options are available for a patient whose kidneys totally fail to function. They are hemodialysis, peritoneal dialysis, and transplantation.

Hemodialysis: Possible Complications

People on hemodialysis may experience problems with their vascular access. The vascular access is the site on the patient’s body where blood is removed and returned during dialysis. Problems with the vascular access include access infection and low blood flow due to blood clotting in the access.

Other problems may be caused by rapid changes in water and chemical balance during treatment. It may include muscle cramping and hypotension. Hypotension is the sudden drop in blood pressure, which can make a person feel weak and dizzy.

It takes time for a person to adjust to hemodialysis. People who undergo hemodialysis should report any side effects to their doctor and dialysis staff.

Following a proper diet, limiting fluid intake, and taking medications as prescribed by the doctor may prevent many of the side effects of hemodialysis.

Peritoneal Dialysis: Possible Complications

A common treatment complication encountered by patients who undergo peritoneal dialysis is peritonitis. Peritonitis is a serious abdominal infection, which occurs when the opening where the catheter enters the patient’s body becomes infected.

Signs of peritonitis may include fever, unusual color or cloudiness of the used fluid, and redness or pain around the catheter.

To prevent peritonitis in peritoneal dialysis, patients should carefully follow procedures exactly. In addition, a patient who experiences the signs of peritonitis should immediately inform his or her doctor for prompt treatment. Peritonitis can be treated with prescribed antibiotics.

Kidney Transplantation: Possible Complications

A possible treatment complication of kidney transplantation is kidney rejection. A common cause of rejection is not taking medications as prescribed by the doctor.

In order to prevent kidney rejection, the doctor will prescribe medicines called immunosuppressants. These kinds of medicines weaken the immune system, thus, preventing the possibility of rejection. However, the patient taking immunosuppressants will be prone to having infections because of the weakened immune system.

In some cases, the patient’s body may still reject the new kidney and he or she will need to go back on dialysis.

Note: Talk with your doctor about what treatment option is best for you and about the possible complications of each treatment.

See Also:

 Kidney Disease
 Total Kidney Failure: Treatment Options
 Kidney Failure Related and their Treatments

References:
National Kidney and Urologic Diseases Information Clearinghouse (February 2008). Vascular Access for Hemodialysis (NIH Publication No. 08—4554). National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD. Web URL: http://kidney.niddk.nih.gov/kudiseases/pubs/vascularaccess/. Accessed: November 30, 2008

National Kidney and Urologic Diseases Information Clearinghouse (November 2007). Kidney Failure: Choosing a Treatment That’s Right for You (NIH Publication No. 08—2412). National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD. Web URL: http://kidney.niddk.nih.gov/kudiseases/pubs/choosingtreatment/index.html. Accessed: November 30, 2008

National Kidney and Urologic Diseases Information Clearinghouse (May 2006). Treatment Methods for Kidney Failure: Kidney Transplantation (NIH Publication No. 06—4687). National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD. Web URL: http://kidney.niddk.nih.gov/kudiseases/pubs/transplant/. Accessed: November 30, 2008

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Page Last Revised: November 14, 2009

Prostate Problems

The prostate gland is a walnut-sized organ, located just below the bladder. It surrounds a portion of the urethra—a tube that carries urine during urination and carry semen during ejaculation, or sexual climax. The prostate produces fluid, which adds to the volume of semen.

Two common prostate problems are prostatitis and benign prostatic hyperplasia.

Prostatitis

When the prostate becomes inflamed, the condition is called prostatitis. It is the most common prostate problem encountered by men under the age of 50. Prostatitis may be caused by bacteria, which causes infection. In other cases, no other cause is found. It is important that you work with your health care provider to find a treatment that’s right for you.

Learn more about prostatitis, its causes, diagnosis, and treatment options. >>>

Benign Prostatic Hyperplasia (BPH) or Prostate Enlargement

Prostate enlargement is the most common prostate problem encountered by men over 50. Having problems with urination when you’re above 50 may indicate that you have an enlarged prostate, or BPH. The prostate normally enlarges, as a man grows older. However, sometimes, the enlargement may squeeze the urethra. As a result, bladder control problems and problems with urination may occur.

Learn more about this common prostate problem. >>>

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