The Renal System

The Renal System

The renal system is concerned with the osmotic balance. Essentially, kidney physiology boils down to a simple equation: what goes in must be the same as what goes out. Despite a variable load from dissolved substances and solvent intake, the kidneys can finely regulate the osmotic balance. Several cotransporters, antiporters, and Na+ channels serve to reabsorb Na+ along the nephron to create the osmotic gradient required for water reabsorption.

Physicians have a vast arsenal of drugs at their disposal to bypass water and Nab retention, particularly in conditions such as congestive heart failure where retained fluid needs to be removed. Administration of these drugs (diuretics) causes both diuresis (water loss) and natriuresis (Na+ loss). Diuretics increase the rate of urine production. As urine volume increases, there is a net loss of water and accompanying solutes. The net loss of electrolytes varies between diuretics depending on the drug’s site of action. Because of their role in water and salt regulation, diuretics have been used to treat conditions such as hypertension, congestive heart failure, edema, hypercalciuria, and historically glaucoma.

The urinary system, also known as the renal system, produces, stores, and eliminates urine, the waste fluid excreted by the kidneys. The kidneys produce urine by filtering waste and extra water from the blood. Urine travels from the kidneys through two thin tubes called ureters and fills the bladder. When the bladder is full, the person urinates through the urethra to remove waste.

The urinary system is susceptible to a variety of infections and other problems, including obstructions and injuries. These can be treated by a urologist or other healthcare professional who specializes in the kidney system.

Description of the Urinary System

The urinary system works with the lungs, skin, and intestines to maintain the balance of chemicals and water in the body. Adults excrete about 27 to 68 fluid ounces (800 to 2,000 millilitres) per day, based on the typical daily fluid intake of 68 ounces (2 litres), National Institutes of Health (NIH). Other factors in the functioning of the urinary system include loss of fluid through sweating and breathing. In addition, certain types of medications, such as B. diuretics, which are sometimes used to treat high blood pressure, also affect the amount of urine a person produces and passes. Some beverages, such as coffee and alcohol, can also cause increased urination in some people.

The main organs of the urinary system are the kidneys, which are bean-shaped organs that sit just below the rib cage in the centre of the back. The kidneys remove urea, a waste product from the breakdown of proteins, from the blood through small filtering units called nephrons. Each nephron consists of a sphere made up of small blood capillaries called glomeruli and a small tube called the renal tubule. Urea, along with water and other waste materials, forms the urine as it passes through the kidney’s nephrons and renal tubules. From the kidneys, urine travels to the bladder through two thin tubes called ureters. The ureters are 8 to 10 inches long (20 to 25 centimetres).

According to the NIH, the muscles in the walls of the ureter continuously contract and relax to push urine out of the kidneys. A build-up of urine can cause a kidney infection. A small amount of urine empties from the ureters into the bladder about every 10 to 15 seconds.

The bladder is a balloon-shaped hollow organ in the pelvis. It’s held in place by ligaments attached to other organs and the pelvic bones, according to the Kidney and Urology Foundation of America. The bladder stores urine until the brain tells the bladder the person is ready to void it. A normal, healthy bladder can easily hold up to 16 ounces (almost a pint) of urine for two to five hours.

To prevent leakage, circular muscles called sphincters close tightly around the bladder’s opening into the urethra, the tube that allows urine to exit the body. According to the Merck Manuals, the only difference between the male and female urinary systems is the length of the urethra. In women, the urethra is about 1.5 to 2 inches long (3.8 to 5.1 cm) and is located between the clitoris and vagina. In males, it is about 20 cm long, runs the length of the penis, and opens at the end of the penis. The male urethra is used to drain urine and semen during ejaculation.

Kidney and Parts of the Urinary System and Their Functions

1) Two kidneys

This pair of purplish-brown organs are located below the ribs towards the mid-back. Its job is to: 

Remove waste products and drugs from the body 

  • Balance body fluids 
  • Balance a variety of electrolytes 
  • Release hormones to control blood pressure 
  • Release hormone to control red blood cell production 
  • Support bone health to control calcium and phosphorus 

The kidneys remove urea from the blood through small filtering units called nephrons. Each nephron consists of a sphere made up of small blood capillaries (glomerulus) and a small tube called the renal tubule. Urea, along with water and other waste materials, forms the urine as it passes through the kidney’s nephrons and renal tubules.

2) Two ureters

These narrow tubes carry urine from the kidneys to the bladder. The muscles in the walls of the ureter continue to contract and relax. This forces the urine down, away from the kidneys. When urine pools or stagnates, a kidney infection can develop. Small amounts of urine are released from the ureters into the bladder about every 10 to 15 seconds.

3) Bladder

This hollow, triangular organ is in the lower abdomen. It is held in place by ligaments that attach to other organs and the pelvic bones. The bladder walls relax and expand to hold urine. They contract and flatten to empty urine through the urethra. The typical healthy adult bladder can hold up to 2 cups of urine for 2 to 5 hours.

4) Two sphincters

These circular muscles prevent urine from leaking out by closing tightly around the opening of the bladder like a rubber band.

5) Nerves in the Bladder

The nerves alert a person when it is time to urinate or empty the bladder.

6) Urethra

This tube allows urine to pass out of the body. The brain tells the bladder muscles to contract. This forces urine out of the bladder. At the same time, the brain signals the sphincters to relax, allowing urine to exit the bladder through the urethra. When all the signals occur in the correct order, normal urination occurs.

The renal system filters blood and creates urine. There are three main functions: (i) the cortex has an outer layer of glomeruli for filtration, (ii) the medulla contains tubules and capillaries to concentrate urine, and (iii) the hilus deals with the lymphatic system and blood flow. Blood vessels and the exit of urine through the ureters. The kidneys and heart are connected by the renal artery.

The kidneys are involved in the autoregulation of glomerular filtration through most blood pressure fluctuations and blood pressure regulation. About 20% of cardiac output affects renal function, with the kidneys playing an important role in vasoconstriction. Hormones from the renin-angiotensin system and aldosterone from the adrenal cortex are involved in increases in blood pressure that contribute to heat stress. In TCM pathology, if the heart fire does not descend to warm the kidneys and the water in the kidneys does not rise to control the heart fire, there will be disharmony between the heart and kidneys.

Symptoms can include insomnia, palpitations, and edema. When the mind fails to control the essence and the essence to generate the mind, symptoms can include nocturnal emissions, sexual problems, difficulty concentrating and thinking, and decreased intelligence.

Complications related to the renal system are rare in the postoperative period. The most likely cause of low urine output (< 0.5 to 1 mL/kg per hour) is hypovolemia (eg, postoperative hypotension). Mechanical obstruction downstream of the kidneys may result from direct surgical intervention or from a poorly placed or malfunctioning urinary catheter (e.g., urinary catheter).B. blood clot or sprain). If the child has a regional anaesthetic (spinal or epidural) that contains an opiate and does not have a urinary catheter, placement of a straight Foley catheter may be indicated. Kidney failure is a rare possibility in children who have had major surgery or who have a systemic inflammatory disease.

Diseases of the urinary system

Different specialists treat urinary system ailments. Nephrologists treat kidney diseases, while urologists treat problems with the urinary tract, including the kidneys, adrenal glands, ureters, bladder, and urethra. Urologists also treat the male reproductive organs, while gynaecologists often treat urinary diseases or disorders in females, including yeast infections. Nephrologists and urologists often work with endocrinologists or oncologists, depending on the disease.

Urinary tract infections (UTIs) occur when bacteria enter the urinary tract; they can affect the urethra, bladder, or even the kidneys. While UTIs are more common in women, they can occur in men. UTIs are typically treated with antibiotics.

Incontinence is another common disease of the urinary system. The most common bladder problems seen in women are frequent urges to urinate and leakage of urine. The most common bladder problems in men are frequent urination at night and incomplete bladder emptying. This is usually due to an enlarged prostate causing obstruction of bladder emptying.

Problems can come in the form of a pelvic prolapse, which can result in leakage and can be the result of a vaginal delivery. Then there is the overactive bladder, which we see a lot and is not related to having children or trauma. A third condition involves overflow, in which the bladder does not completely empty.

Holding your urine for a short period of time, usually up to one hour, is typically okay. However protracted and repeated holding of urine may cause over-expansion of bladder capacity, the transmission of excess pressure into the kidneys, and the inability to completely empty the bladder. These problems in turn may lead to UTI [urinary tract infection], cystitis, and deterioration of kidney function.

Some common treatments involve medications, physical therapy, and pelvic mesh surgery. Vaginal laser surgery is also becoming a viable treatment option, he explained. In another 10 to 15 years, vaginal laser surgery will be another common option for the treatment of urinary conditions.

Interstitial cystitis (IC), also known as painful bladder syndrome, is a chronic bladder disorder that causes varying degrees of bladder pressure and pain, mainly in women, and sometimes pelvic pain. It can cause blister scars and make the bladder less elastic. Although the cause is unknown, many people with the condition also have a defect in the epithelium, the protective lining of the bladder.

Prostatitis is an inflammation of the prostate and can therefore only occur in men. Symptoms commonly caused by advancing age include urinary urgency and frequency, pelvic pain, and painful urination. Kidney stones are build-ups of calcium oxalate found anywhere in the urinary tract. Kidney stones form when chemicals in urine become so concentrated that they form a solid mass. They can cause back and side pain and blood in the urine. Many kidney stones can be treated with minimally invasive therapy, such as B. extracorporeal shock wave lithotripsy, in which kidney stones are shattered with shock waves.

Kidney failure, also known as kidney failure and chronic kidney disease, can be a temporary (often acute) condition or develop into a chronic condition that results in the kidneys not being able to filter waste from the blood. Other conditions such as diabetes and high blood pressure can cause chronic kidney disease.

Acute cases can be caused by trauma or other damage and improve over time with treatment. However, kidney disease can lead to chronic kidney failure, which may require dialysis treatments or even a kidney transplant. Bladder cancer is diagnosed in about 75,000 Americans each year and is more common in men and the elderly. 81,190 new cases of bladder cancer (about 62,380 in men and 18,810 in women) and about 17,240 deaths from bladder cancer are expected.


The renal system is an integral part of the cardiovascular system in health and disease. In acute heart failure, patients with a preserved renal function who do not develop significant reductions in acute heart failure enjoy a good response to diuretics and optimal outcomes. Patients with CKD at baseline who develop AKI during hospitalization for heart failure have a higher rate of hospital complications, including volume overload, hyperkalemia, and death.


Saravavan Nadarajan (Vanan)

Vanan, fitness expert and leader at EzFit Singapore, specializes in holistic training—home-based, boot camps, and corporate fitness—with over a decade of industry experience.

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