Excretion – removes cellular waste Excretory System Excretion – removes cellular waste The process that collects & removes harmful or useless substances that form in the body or are taken into the body from the blood, tissues, and cells.

Excretory System Although the urinary system has a major role in excretion, other organs contribute to the excretory function.

Four Organs of the Excretory System The lungs in the respiratory system excrete some waste products, such as carbon dioxide and water. The skin is another excretory organ that rids the body of wastes through the sweat glands. The liver (via the intestines) excretes bile pigments that result from the destruction of hemoglobin. It also converts nitrogenous waste from the break down of proteins into urea. The major task of excretion still belongs to the kidneys, the major organ in the urinary system. If it fails the other organs cannot take over and compensate adequately.

Cellular Waste Heat Water Salts CO2 Urea W/O excretion poisonous wastes build up in blood, cells, and tissues. Could lead to serious illness & eventually DEATH!

Liver – Some Functions Functions in Excretion Detoxifies Blood Filters Bacteria, alcohol, drugs, toxic substances Changes them into inactive or less toxic forms. Excretes Bile Contains Worn-out RBC Bile salts Cholesterol

Liver Produces Urea Functions in Excretion Forms Urea Changes toxic wastes (ammonia – from break down of amino acids) to Urea. Urea  Blood  Kidneys Filtered out & excreted in Urine

Lungs –Main Function Alveoli - Exchange O2 & CO2 between air and blood (through process of diffusion) Lungs excrete CO2 when you EXHALE

Skin Sweat Glands Help cool body: Heat escapes through millions of pores in skin surface Excrete perspiration (evap. cooling) 99% H2O Mineral Salts Urea

human excretory system consists of the kidneys, ureters, urinary bladder, urethra and renal circuit (renal arteries and renal veins) kidney includes an outer cortex, middle medulla and the nephrons nephrons include a capsule and a looping tubule that joins others to form the collecting ducts, making up the pyramids which empty into the calyces - lead into the renal pelvis nephrons form urine, which passes from the collecting ducts to the renal pelvis.  The renal pelvis empties into the ureters, which conduct urine to the urinary bladder, and the urethra voids the urine from the body.

Kidneys & Urinary System Urinary System – excretes waste and maintains homeostasis of body fluids. Kidneys (main organ of the system) Ureters Bladder Urethra

blood and urine flow blood enters the kidneys via renal arteries, and leaves the kidneys via the renal veins wastes removed from the blood leave the kidneys by the ureter

primary organs of excretion

Kidneys & Urinary System Two Fist sized Bean shaped

Kidneys- Functional Units & Product Nephron (about one million per kidney) Microscopic units that filter blood of wastes. H2O and waste taken from blood into nephron Form URINE Glomerulus (clump of capillaries) At end of each nephron Network of coiled tubes – diffusion of wastes - while useful substances & water are reabsorbed Urine Pale yellow solution Urea, H20, salts, other trace solutions (toxins…)

parts of the nephron & functions 3 Collecting ducts.  Water leaves the collecting ducts in response to antidiuretic hormone (ADH), which is secreted by the posterior pituitary in response to osmotic conditions in the blood (actually detected by the hypothalamus).

kidney Learn the parts Functions of the kidneys excrete toxins and nitrogenous wastes regulate chemical levels in blood maintain water balance helps regulate blood pressure (renin)

Urinary System - continued Ureters Narrow muscular tubes Connect Kidney  Bladder Bladder Muscular sac Stores Urine Expand to fill Muscle relaxes Urine squeezed into Urethra

Urinary System - endpoint Urethra Tube leading from Bladder  outside of body

other organs ureters - long narrow tubes with expanded upper end (renal pelvis) located inside each kidney. Function is to drain the renal pelvis to urinary bladder urinary bladder- elastic muscular organ capable of great expansion. Function si storage of urine and voiding urethra – passage of urine from bladder to outside of body. Passage of semen from male body

Failures of Homeostasis Bladder & Kidney Infections caused by bacteria from colon/rectum entering urethra. Kidney Stones - crystallization of mineral salts & uric acid that block passage of urine Kidney Disease - caused by long term diabetes, infections, & chemical poisoning Gout – form of arthritis where excess production of uric acid leads to deposits of crystals in joints (esp. toes)