How the Urinary System Works – Anatomy and Functions

How the Urinary System Works - Anatomy and Functions

The Urinary System is a group of organs in the body concerned with filtering out excess fluid and other substances from the bloodstream. The substances are filtered out from the body in the form of urine.

Urine is a liquid produced by the kidneys, collected in the bladder and excreted through the urethra. Urine is used to extracting excess minerals or vitamins as well as blood corpuscles from the body.

The Urinary organs include the kidneys, ureters, bladder, and urethra. The  Urinary system works with the other systems of the body to help maintain homeostasis.

The kidneys are the main organs of homeostasis because they maintain the acid-base balance and the water-salt balance of the blood. If the kidneys fail, these functions are compromised or lost altogether, with devastating effects on homeostasis.

The affected individual might experience weakness, lethargy, shortness of breath, anemia, widespread edema (swelling), metabolic acidosis, rising potassium levels, heart arrhythmias, and more.

Each of these functions is vital to your well-being and survival. The urinary system, controlled by the nervous system, also stores urine until a convenient time for disposal and then provides the anatomical structures to transport this waste liquid to the outside of the body.

Failure of nervous control or the anatomical structures leading to a loss of control of urination results in a condition called incontinence.

 Also read: Human Reproductive system- Formation of Gametes, Organs Overview and Function

Functions of the urinary system

  • Excretion – removal of waste material from the blood plasma and the disposal of this waste in the urine. 
  • Elimination – removal of waste from other organ systems. From the digestive system – undigested food, water, salt, ions drugs. From respiratory system – CO2, H+, water, toxins. From skin – water, NaCl, nitrogenous wastes (urea, uric acid, ammonia, creatinine). 
  • water balance – kidney tubules regulate water reassertion and urine concentration. 
  •  Regulation of pH – volume, and composition of body fluids. 
  • Production of erythropoietin: for hematopoiesis, and renin for blood pressure regulation.

Anatomy of the Urinary System

The urinary system consists of the kidneys, ureters, urinary bladder and urethra. The kidneys form the urine and account for the other functions attributed to the urinary system.

The ureters carry the urine away from kidneys to the urinary bladder, which is a temporary reservoir for the urine. The urethra is a tubular structure that carries the urine from the urinary bladder to the outside. 

  • kidneys – a pair of bean-shaped organs located retroperitoneal, responsible for blood filtering and urine formation.
  •  Renal capsule – a layer of fibrous connective tissue covering the kidneys.
  • Renal cortex – the outer region of the kidneys where most enthrones are located.
  •  Renal medulla – an inner region of the kidneys where some enthrones is located, also where urine is collected to be excreted outward.
  • Renal calyx – duct-like sections of renal medulla for collecting urine from nephrons and direct urine into the renal pelvis’
  • Renal pyramid – connective tissues in the renal medulla binding various structures together.
  • Renal pelvis – central urine collecting area of the renal medulla.
  • Hilum – concave notch of kidneys where renal artery, renal vein, ureter, nerves, and lymphatic vessels converge. 
  • Ureter – a tubule that transports urine (mainly by peristalsis) from the kidney to the urinary bladder. 
  •  Urinary bladder – a spherical storage organ that contains up to 400 ml of urine.
  • Urethra – a tubule that excretes urine out of the urinary bladder to the outside, through the urethral orifice.

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Frequently Asked Questions (FAQs)

What are the three primary components of the urinary system?

The urinary system consists of three main parts: the kidneys, ureters, and bladder. The kidneys filter waste and excess fluids from the blood to produce urine, which then travels through the ureters to the bladder for storage. The bladder can then be voluntarily emptied through the urethra during urination.

What is the urinary system called?

The urinary system is also commonly known as the renal system or the genitourinary system. The term “renal” comes from the Latin word “renes,” which means kidneys, while “genitourinary” refers to the organs of the urinary tract and the reproductive system. The system is responsible for removing waste products and excess fluids from the body, maintaining electrolyte balance, and regulating blood pressure.

What is the urinary system in simple terms?

The urinary system is the body’s drainage system for removing waste and excess fluids. It includes the kidneys, which filter the blood to produce urine, the ureters, which transport urine from the kidneys to the bladder, the bladder, which stores urine until it is voluntarily released through the urethra during urination. The urinary system plays a vital role in maintaining the body’s fluid and electrolyte balance and removing harmful waste products from the body.

Where is urine stored?

Urine is stored in the bladder, a muscular sac located in the lower abdomen. The bladder can expand and contract to hold varying amounts of urine, depending on the volume of fluid intake and the frequency of urination. When the bladder is full, it sends signals to the brain indicating the need to urinate. At that point, the bladder contracts and the urine is expelled through the urethra, a tube that carries urine from the bladder out of the body.

Where is urine formed?

Urine is formed in the kidneys, a pair of bean-shaped organs located on either side of the spine, just below the ribcage. The kidneys filter the blood to remove waste products, excess water, and electrolytes, and produce urine as a result. Urine formation involves a complex process of filtration, reabsorption, and secretion, in which the kidneys selectively remove waste products and excess fluids while retaining essential substances such as glucose and electrolytes in the bloodstream. The urine then travels down the ureters to the bladder, where it is stored until it is expelled during urination.

What is urine made of?

Urine is primarily composed of water, accounting for about 95% of its volume. The remaining 5% consists of waste products, including urea, creatinine, uric acid, and ammonia, as well as electrolytes such as sodium, potassium, chloride, and bicarbonate. The color and odor of urine can vary depending on factors such as hydration status, diet, and the presence of certain medications or medical conditions. Normally, urine is pale yellow to amber in color, and has a relatively mild odor.

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