Excretory System

Functions Excretion removal of organic wastes from body fluid Elimination discharge of waste products Homeostatic regulation of blood plasma volume and solute concentration

Urinary System Kidney’s – create urine by filtering the blood Ureters – carry urine from kidney to urinary bladder Urinary bladder – stores urine Urethra – tube emptying the urinary bladder

Urinary Organs 2 Kidneys excrete urine Urinary tract: Ureters Urinary bladder Urethra

Kidneys Filter the blood and remove wastes Each contain 1-2 million nephrons

Blood Supply The kidneys continuously cleanse the blood and adjust its composition. Approximately one quarter of the total blood supply of the body passes through the kidneys each minute. The arterial supply of each kidney is the renal artery

Nephrons Each kidney contains over a million tiny structures called nephrons. They are the functional unit of the kidneys Make urine Control water balance Regulate blood pressure Filters 45 gallons of blood/day making 1 ml of urine/min

Each nephron consists of 2 main structures: Glomerulus Renal Tubule

Nephron Component Functions Glomerulus: mechanically filters blood Bowman's Capsule (Glomerular): Proximal Convoluted Tubule: reabsorbs 75% of the water, salts, glucose, and amino acids Loop of Henle: countercurrent exchange, which maintains the concentration gradient Distal Convoluted Tubule: tubular secretion of H ions, potassium, and certain drugs

Ureter Paired tubes Connects the kidney to the urinary bladder

Urinary Bladder Smooth muscle bag Stores waste solution - urine

Urethra Connects bladder to outside of the body Allows urine to pass out of the body

Basic Processes of Urine Formation Filtration Blood pressure Water and solutes across glomerular capillaries Reabsorption The removal of water and solutes from the filtrate Secretion Transport of solutes from the peritubular fluid into the tubular fluid

Urine Composition Urine is mostly water (about 95% water), however, the rest of the contents of urine can vary depending of what you’ve eaten, drank, breathed or been exposed to. The remainder of urine usually consists of urea, uric acid, ammonia, hormones, dead blood cells, proteins, salts and minerals, and toxins

Incontinence (urine leakage) More than 10 million Americans experience incontinence Most do not seek treatment Treatment can improve or eliminate the problem 90% of the time

Kidney Stones Solid mass of tiny crystals Form when urine contains too much of certain substances Dehydration

Urinary Tract Infection (UTI) Bacteria (E. coli) from the digestive tract get in the urinary tract multiply move from the urethra to the bladder to the kidneys More common in women than men