The Urinary System or Urinary Apparatus is responsible for the production and elimination of urine, has the function of filtering the “impurities” of the blood that circulates in the body.
The Urinary System consists of two kidneys and the urinary tract , formed by two ureters , the urinary bladder and the urethra .
Rins
The kidneys are organs located at the back of the abdominal cavity, located one on each side of the spine. They are dark red in color and have the shape similar to a bean grain and the approximate size of a closed hand.
The kidneys are connected to the circulatory system via the renal artery and renal vein, and to the urinary tract via the ureters. Renal arteries are very thin branches that form small tangles called glomeruli . Each glomerulus is surrounded by a round structure called the glomerular capsule or Bowman’s capsule .
Detail of a Kidney, showing the Nephron in detail.
Therefore, the basic unit of blood filtration is called the nephron , which is formed by the glomeruli, the glomerular capsule and the renal tubule.
Forced by blood pressure, part of the plasma (water and small particles dissolved in it, such as mineral salts, urea, uric acid, glucose) leaves the capillaries that form the glomeruli and falls into the glomerular capsule. It then passes into the renal tubule.
Useful substances such as water, glucose and mineral salts, contained in this liquid, cross the wall of the renal tubule and return to the bloodstream. Thus, what remains in the tubules is a small amount of water and waste, such as urea, uric acid and ammonia : it is urine , which goes to the urinary tract. Observe in the diagram below the phases of formation of urine within the nephron.
Urinary Tracts
The urinary tract consists of the bladder, ureters and urethra.
Urinary bladder
Elastic muscular organ, a kind of bag, which is located in the lower part of the abdomen with the function of accumulating the urine that arrives from the ureters. Therefore, the bladder temporarily receives and stores the urine and when the volume reaches about 300 ml, the nerve sensors in the bladder wall send messages to the nervous system, making us want to urinate.
At the bottom of the bladder is a sphincter – a circular muscle that closes off the urethra and controls urination. When the bladder is full, the sphincter contracts, pushing the urine towards the urethra, where it is then released from the body. The maximum capacity of urine in the bladder is approximately 1 liter.
ureters
There are two tubes, approximately 20 cm long each, which carry urine from the kidneys to the bladder.
urethra
Muscular tube that carries urine from the bladder out of the body. The female urethra measures about 5 cm in length and carries only urine. The male urethra measures about 20 cm and carries urine out of the body, as well as sperm.
Male Urinary System
Male Anatomy showing the organs of the urinary and reproductive system.
The male urinary system differs from the female in that the urethra , the channel that conducts urine from the bladder to the outside, is also used to release sperm during ejaculation . Divided into three parts: prostatic, cavernous and membranous, the male urethra measures approximately 20 cm and extends from the internal urethral orifice in the urinary bladder to the external urethral orifice at the end of the penis .
Also read about:
- Male Reproductive System
- Prostate
Female Urinary System
Female anatomy showing organs of the urinary and reproductive system.
The urethral canal in the female urinary system, which extends from the bladder to the external orifice in the vestibule, is much smaller than the male, measuring approximately 5 cm . This characteristic of the female anatomy, short urethral canal, facilitates the occurrence of urinary infections in women.
Diseases of the Urinary System
Many diseases are associated with the urinary system, whether in the kidneys or in the urinary tract (ureters, bladder and urethra).
Kidney Diseases
Nephritis
Nephritis is an infection of the nephrons, resulting from several factors, for example, overdose of medication and the presence of certain toxic substances in the body, such as mercury, which can damage or destroy the nephrons, causing pain, reduced production of urine, cloudy appearance of urine and increased pressure.
High Blood Pressure and Kidney Problems
When the kidneys do not work efficiently, excess salts and water build up in the blood, causing high blood pressure. The kidney filtering process in hypertensive people is deficient, which can result in the development of kidney disease.
Bacterial Infections
In particular the bacteria Escherichia coli , which can enter the urinary system through the urethra causing bacterial infection.
Illnesses in the Urinary Tracts
kidney stones
Scheme of the formation and location of a stone in the kidney.
Popularly known as “kidney stone”, kidney stones can lodge in the kidneys, ureters or bladder. They are formed as there is a high concentration of calcium or other types of salt contained in body fluids (in this case, urine).
Cystitis
Cystitis is an infection or inflammation of the urinary bladder. The patient feels a burning sensation in the urethra when urinating and because he is unable to retain the urine, he releases it in small amounts.
Uretite
Urethitis is an infection in the urethra developed by bacteria that usually occurs along with cystitis.
