1. 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.

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

3. 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.

4. 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!

5. 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

6. 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

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

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

9. 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.

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

11. 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

12. primary organs of excretion

13. Kidneys & Urinary System
Two
Fist sized
Bean shaped

14. 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…)

15. 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).

16. 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)

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

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

19. 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

20. 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)