Essentials of Human Anatomy Physiology Chapter 38 3

Essentials of Human Anatomy & Physiology Chapter 38 -3 The Excretory System Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

QUICK REVIEW OF ELIMINATION • Lungs eliminate CO 2 • Sweat glands eliminate excess heat, salt • Digestive tract- indigestible solids, bacteria • Urinary tract is the main system of elimination

Vocabulary Hints • • Uria or Ur - urine Nephr or renal - kidney Cyst - bladder Dys - painful Cystitis - inflammation of bladder Dysuria - painful urination Hematuria - blood in urine Hydronephrosis - water in kidney

The Urinary Tract • Urinary tract consists of 2 kidneys, 2 ureters, one bladder and one urethra. • Kidney location: – Retroperitoneal – Dorsal wall of abdominal cavity – 12 th thoracic and 3 rd lumbar vertebrae • Urethra – 1. 5 inches in women, – 8 inches in men

• Kidneys filter blood- 2, 000 L/day (500 gal) – remove waste products and reabsorb water, other valuable substances. – 1. 5 L of urine/day • Metabolism produces toxic substancesnitrogen containing waste as a by-product of protein breakdown • Nitrogen eliminated as urea - water soluble

Structure of Kidney • Outer layer- Cortex • Inner layer- Medulla • Calyx- collects urine as it is formed, join together to form the ureter

• The main functional unit of the kidney is called the nephron. • 1 million per kidney • Most of nephron located in renal cortex • Loop of Henle is located in the renal medulla

• Capillaries in glomerulus filter blood- Bowman’ capsule collects ultra filtrate • Through passive and active diffusion, 95% of water is reabsorbed, along with K, Na, Ca • Other things are actively excreted, like drugs. • Excretion is controlled by hormones such as ADH from hypothalamus

Urine is made in 4 steps 1. Filtration 2. Reabsorption 3. Secretion 4. Excretion A urinalysis is the most common non-invasive medical test ordered

Diseases of the Kidney • Acute Kidney failure– Causes: nephritis, shock, injury, heart failure or poisoning – Symptoms: anuria or oliguria. Uremia, nausea, coma, death • Chronic Kidney failure– gradual loss of function due to hypertension (high blood pressure) or endocrine disease Causes: nephritis, shock, injury, heart failure or poisoning – Symptoms: anuria or oliguria. Uremia, nausea, coma, death • Cystitis- inflammation of the urinary bladder

Kidney Dialysis

Dialysis, Kidney transplant • Hemodialysis- serves as an “artificial kidney” 2 -3 times per week for 2 -4 hours • Peritoneal dialysis- uses patient’s own peritoneal lining to filter blood • Kidney transplant- need suitable donor. Only need one, but must take antirejection drugs for the life of the patient