Urinary System Structure and Function

Urinary System Structure and Function

Urinary System

Basic Structure

  • The urinary system consists of two kidneys, two ureters, a urinary bladder, and a urethra.
  • Kidneys are bean-shaped organs located at the back of the abdominal cavity. They remove waste substances from the blood through filtration and secretion.
  • Ureters are tubes that connect the kidneys to the bladder. They transport urine from the kidneys to the urinary bladder.
  • The bladder is a hollow, muscular organ that stores urine. It can expand and contract, depending on the volume of urine it contains.

Key Function

  • The primary function of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH.

Filter Function

  • The nephrons in the kidney are the functional units for filtration. It is here that water and solutes are filtered out from the blood based on their size and charge.
  • Smaller molecules like water, glucose, and urea pass through the philtre, while larger molecules like proteins and blood cells do not.
  • Urine formation involves three main processes – glomerular filtration, reabsorption in the renal tubules, and secretion.

Urine Excretion

  • The urine formed in the kidneys passes down through the ureters by the process of peristalsis to the urinary bladder.
  • When the bladder is full, urine is excreted through the urethra, which is controlled by sphincter muscles.

Kidney Regulation

  • The kidneys regulate the body’s fluid volume, mineral composition, and acidity by adjusting the amount of urine that is excreted daily.
  • Kidneys also produce hormones that influence the function of other organs.
  • Erythropoietin and renin are the two important hormones produced by the kidney which help in red blood cell production and blood pressure regulation respectively.

Remember, the kidney’s major functions are to clean the blood and produce urine for excretion of waste substances. It is essential to understand its structure and how each component contributes to its overall function.