Anatomy Physiology

Anatomically speaking, the urinary system is composed of the two kidneys and two ureters and the urinary bladder in addition to the urethra.  The two kidneys are connected with the urinary bladder through two tubes which function as passage way fo the urine.  The bladder is a reservoir that contains the urine that can be evacuated to the outside of the body through the urethral orifice in the penis in males. 

The two kidneys are functionally the most important organs of the urinary system because they are the site where urine is formed.  Urine is usually formed by filtration of the blood from its waste products in the glomeruli if the kidney.  Formation of the final form if the urine is a complex process which involves in addition to filtration of the blood also reabsorption of many compounds in the tubules of the kidney back to the circulation and which are filtered in the glomeruli.

The composition of urine usually signifies if there is normal functioning of the urinary system or if there is certain pathological state.  Normal urine contains only water and urea in addition to some other compounds that are not harmful and are present in small concentration. 

Urea is the product of amino acids metabolism that is obtained by chemically modifying the base ammonia.  Ammonia is a toxic compound in high concentration and is obtained by a deamination process of amino acids.  Presence of ammonia in urine can signify a pathological state of the liver since the liver is the site of ammonia metabolism. 

Composition of urine is very important marker for kidney function and other organs of the urinary system.  For example, the presence of red blood cells in the urine can have several diagnostic possibilities.  These include damage to the kidney itself which allows blood cells to filter through the glomeruli of the kidneys.  This condition can occur for example in a condition which is called the nephritic syndrome.

Red blood cells in the urine can also signify pathology  elsewhere in the urinary system.  Prostate cancer can also have as one of its symptoms urine blood in addition to other symptoms such as urine retention and enlargement.  In addition passing small stones in the urethra that are lodged in the urinary bladder  and pass out of the body can injure the surface of the urethra causing little bleeding.  Also cancer of the bladder can be accompanied with urine blood.

Elevated level of creatinine and urea in the urine can also be indication to kidney disease.  Glucose urea or passing glucose in the urine is a marker for diabetes mellitus.  Patients who pass glucose in their urine should be evaluated for hyperglycemia or diabetes mellitus.  Microalbumin in the urine is also an indication for diabetes mellitus. 

Polyurea or passing often urine can be of various disorders.  One of them is kidney dysfunction in which it is unable to concentrate urine adequately.  Thus leading to polyurea.  Other cause to polyurea include nephrogenic diabetes insipidus in which the usual function of the water hormone which is called antidiuretic hormone is impaired due to the lack of appropriate response of the kidney tubules to this hormone.  Thus causing kidney inability to concentrate urine, passing diluted urine. 

Hyperglycemia of diabetes mellitus can also cause polyurea due to an osmotic effect that passing elevated amount of glucose in the urine makes.  Stones in the urinary system are a common clinical symptom to several disorders.  One of them is the presence of high concentration of calcium in the blood or hypercalcemia.  This can be caused due to several reasons.  One of them is administration of large quantity of calcium in the diet.  In addition, hyperparathyroidism can also cause stones in the urinary system.  Malignancies in the body can also cause hypercalcemia which in turn can cause to stones precipitation in the urinary tract. 

Stones are particularly liable to be trapped in the ureters causing urine retention and severe muscular pain.  Stones can also form in the urinary bladder impeding the flow of urine out of the bladder.  It can form due to precipitation of calcium salts.  Stones can be of several types including calcium oxalate and calcium phosphate in addition to stones that are cause by uric acid precipitation in the urinary system due to a disorder in the metabolism of one of the DNA bases.