Ch. 7.12 Urinary system
Urinary System (Excretory System)
The body system responsible for removing waste and excess water from the body, maintaining acid-base balance, and regulating the body's electrolyte and blood volume.
Kidneys
Two bean-shaped organs located on either side of the vertebral column, behind the upper part of the abdominal cavity. They are responsible for filtering blood to produce urine.
Cortex
The outer section of the kidney which contains most of the nephrons.
Medulla
The inner section of the kidney that contains most of the collecting tubules, which carry urine from the nephrons through the kidney.
Nephrons
The microscopic filtering units of the kidney. There are over one million per kidney.
Glomerulus
A cluster of capillaries within the nephron where the initial filtration of blood takes place. Water, mineral salts, glucose, and metabolic products are filtered out here.
Bowman's Capsule:
A C-shaped structure that surrounds the glomerulus and marks the start of the convoluted tubule. It picks up the materials filtered from the blood.
Ureters
Two muscular tubes, approximately 10-12 inches long, that extend from the kidneys to the bladder. They use peristalsis (rhythmic muscle contractions) to move urine.
Bladder
A hollow, muscular sac that acts as a reservoir for urine. It is lined with mucous membrane arranged in folds called rugae, which disappear as the bladder expands.
Urethra
The tube that carries urine from the bladder to the outside of the body.
Urinary Meatus
The external opening of the urethra.
Homeostasis
A state of equilibrium or constant state of natural balance in the internal environment of the body.
Voiding (Micturition)
The act of urinating or emptying the bladder.
Urine
The liquid waste product produced by the urinary system, consisting of approximately 95% water along with urea, uric acid, creatinine, mineral salts, and pigments.
Cystitis
nflammation of the bladder, usually caused by pathogens entering the urinary meatus.
Glomerulonephritis
Inflammation of the glomerulus of the kidney, which can be acute (often following a streptococcal infection) or chronic.
Pyelonephritis
Inflammation of the kidney tissue and renal pelvis, usually caused by pyogenic (pus-forming) bacteria.
Renal Calculus
A kidney stone formed when salts in the urine settle and precipitate out of solution.
Renal Failure
The failure of the kidneys to function properly, which can be acute (sudden onset) or chronic (progressive loss of function).
Uremia
A toxic condition (urinary waste in the blood) that occurs when the kidneys fail and urinary waste products are present in the bloodstream.
Urethritis
Inflammation of the urethra, usually caused by bacteria, viruses, or chemicals.