How the Urinal System Works

Physiology and Functions 

The urinary system is composed of the two kidneys, two ureters, the urinary bladder, two sphincter muscles and urethra (Rizzo, 2015). The organs work together to produce, store and carry urine (Rizzo, 2015). When a human consumes food, some nutrients are absorbed into the body which aid in proper function and repair of tissues (Sherwood, 2015). The system expels urea from the blood. Usually, urea is produced when protein-rich foods are broken down in the body via the digestive system (Sherwood, 2015). Urea is transported to the kidneys through the bloodstream (Levey et al. 2015). In a nutshell, the kidneys filter the blood to remove wastes and produce urine. The ureters, urinary bladder, and urethra together form the urinary tract, which acts as a” plumbing system” to drain urine from the kidneys, store it, and then release it during urination (Levey et al., 2015). Apart from filtering and eliminating wastes from the body, the urinary system also maintains the homeostasis of water, ions, pH, blood pressure, calcium and red blood cells (Gossling et al. 2016). Gosling et al. (2016) state that the urinary system is connected to the lungs, skin, and intestines which similarly excrete wastes thereby maintaining a balance between water and the chemicals present in the body. 

The anatomy and structure of key or Primary organs 

Kidneys: it is a pair of bean-shaped organs located along the posterior muscular wall in the abdominal cavity (Gossling et al. 2016). The left kidney is a bit higher than the right one. Sherwood (2015) says that a layer of adipose tissue surrounds them and holds them in place to prevent physical damage. 

Ureters: is a thin muscular tube located in the abdominopelvic cavity (Gossling et al. 2016). Each is estimated to be around 8-10 inches long (Sherwood, 2015). The tubes are both on the left and right side of the body and run consonant to the vertebral column (Sherwood, 2015). The walls of ureter have muscles that unceasingly contract and relax thereby moving urine toward the urinary bladder at different intervals. 

Urinary Bladder : is a hollow muscular organ whose primary function is to store urine (Rizzo, 2015). The bladder is in the pelvis; held in place by ligaments that are integrated into other organs (Sherwood, 2015). Its muscular walls stretch to hold as much urine as possible. Studies show that for a healthy urinary system the bladder can hold up to about 16 ounces of urine for approximately 5 hours. The nerves of the bladder trigger urination. 

Sphincter Muscles. They are circular and control the exit of urine from the bladder. They close tightly around the opening of the bladder and into the urethra. Primarily, they prevent urine from leaking. Notably, both external and internal urethral sphincter muscles control the flow of urine in the urethra. 

Urethra: is a tube that urine from the bladder passes. In females, the tube stretches to the clitoris while in the male it forms part of the reproductive system by directing the sperm out of the body via the penis. As mentioned above the flow of urine in the urethra is controlled by the sphincter muscles. 

Key Processes 

There are four elemental processes in the urinary system that shall be discussed below. They include filtration reabsorption secretion and excretion. Filtration is the “mass movement of water and solutes from plasma to the renal tube” (Sherwood, 2015). The process takes place in the renal corpuscle. Inside the kidneys are tiny structures named nephrons. The nephron is “the functional unit of the kidney that filters blood to produce urine” (Sherwood, 2015). Arterioles in the kidneys remit blood to a myriad of capillaries surrounded by a capsule termed glomerulus (Levey et al. 2015). Here a significant proportion of the blood’s plasma is driven out of the capillaries and into the capsule (Levey et al. 2015). Blood cells and a smaller percentage of the plasma is left to continue flowing through the capillaries (Levey et al. 2015). The liquid filtrate in the capsule flows through a sequence of tubules embedded with filtering cells. The cells encircling the tubules selectively absorb water and substances from the filtrate and transfer it to the blood in the capillaries. Simultaneously, waste products in the blood are secreted into the filtrate (Levey et al. 2015). Consequentially, the filtrate in the tubule becomes urine containing waste products, water, and excess ions. The blood leaving the capillaries has reabsorbed all of the nutrients along with most of the water and ions that the body needs to function. 

Reabsorption process entails the movement of water and solutes back into the plasma (Levey et al. 2015). It occurs at varying degrees over the entire length of the renal tube. Solutes like glucose, amino acid and bicarbonates are “actively transported” out of the proximal tubule since they have a low concentration in the remaining fluid (Levey et al. 2015). Further reabsorption occurs in the loop of Henle; sodium being the prime solute (Levey et al. 2015). 

After filtration has taken place, the tubule continues to excrete additional substances through secretion (Levey et al. 2015). This enhances the kidney’s ability to eliminate toxins and certain waste. Secretion is essential to the regulation of plasma potassium concentrations and pH (Wahnginton et al. 2016). 

The final process is excretion after filtration, reabsorption, and secretion have taken place. The end product of these processes is urine. Urine is discharged from the urinary bladder through the urethra and out of the body (Rizzo, 2015). When this is done, excretion is said to have taken place. 

Homeostatic imbalance 

The kidney maintains homeostasis by controlling the excretion of substances out of the body (Sherwood, 2015). It controls the excretion of ions and seeks to maintain normalcy in their concentration levels (Levey et al. 2015). Also, the osmotic imbalance is maintained by the kidney. The amount of water filtered out of blood is regulated to ensure an isotonic environment for body cells (Sherwood, 2015). More so, blood pressure is monitored by the kidney. This achieved through reduction of water reabsorption into the blood when the pressure is high (Rizzo, 2015). When the pressure is low, renin enzyme is produced to constrict blood vessels and produce concentrated urine. 

Common diseases/disorders 

Complications in the urinary system can be as a result of different causes ranging from diseases, aging to injuries (nave,2014). The disorders are detected through a test known as urinalysis (Washington et al. 2016). Most common illnesses include Benign prostate hyperplasia (PBH) manifested in the enlargement of the prostate gland in men (Naveen, 2014). Kidney stones is another disease that more prone in men than women. The stones differ in size and could be found anywhere in the urinary system (Assimos, 2016). To remove them, both surgical and nonsurgical treatments are sought. Renal or kidney failure is also a common disorder associated with urinal system. It occurs when the kidney fails to discharge its primary role of intoxication. It is caused by injuries to the kidney, loss of blood and poison consumption (Naveen, 2014). Acute renal failure results in permanent kidney dysfunction (Naveen, 2014). For all the above-diseased treatment should be sought at an early stage. 

From the above discussion, it is reasonable to conclude that the urinary system plays a vital role in the well-being of the body. To ensure that the key organs of the system perform their functions to the fullest, healthy eating and living practices must be adhered to. To achieve full functionality, the renal system works parallel to another system, and together they maintain normalcy in the body cells and tissues. 

References 

Assimos, D., Krambeck, A., Miller, N. L., Monga, M., Murad, M. H., Nelson, C. P., ... & Razvi, H. (2016). Surgical management of stones: american urological association/endourological society guideline, Part I.  The Journal of urology ,  196 (4), 1153-1160. 

Gosling, J. A., Harris, P. F., Humpherson, J. R., Whitmore, I., & Willan, P. L. (2016).  Human Anatomy, Color Atlas and Textbook E-Book . Elsevier Health Sciences. 

Levey, A. S., Becker, C., & Inker, L. A. (2015). Glomerular filtration rate and albuminuria for detection and staging of acute and chronic kidney disease in adults: a systematic review.  Jama ,  313 (8), 837-846. 

Naveen, P. S. R. (2014). Definition of acute kidney injury.  Int J Health Modern Integr Med Sci ,  1 (1), 10-4. 

Nørregaard, R., Kwon, T. H., & Frøkiær, J. (2015). Physiology and pathophysiology of cyclooxygenase-2 and prostaglandin E2 in the kidney.  Kidney research and clinical practice ,  34 (4), 194-200. 

Rizzo, D. C. (2015).  Fundamentals of anatomy and physiology . Cengage Learning. 

Sherwood, L. (2015).  Human physiology: from cells to systems . Cengage learning. 

Washington, J. A., White, C. M., Laganiere, RN, M., & Smith, L. H. (2016). Detection of significant bacteriuria by microscopic examination of urine. Laboratory Medicine, 12(5), pp. 296-298