1. Kidneys E XCRETORY & U RINARY SYSTEM

2. T HE E XCRETORY O RGANS  Include the kidneys, lungs and skin  They all belong to different systems, but have 1 common goal: waste excretion  Excretion in the anatomical sense only refers to substances passing through a membrane to leave the body  Undigested food is eliminated by being expelled as feces from the body

4. T HE E XCRETORY O RGANS  The kidneys are the primary excretory organs and have the job of maintaining the homeostasis of body fluids  The lungs are the primary site of carbon dioxide excretion, carry out detoxification, & excrete volatile substances  The skin helps the kidneys control the salt composition of the blood through perspiration

5. K IDNEYS  Are bean shaped organs about the size of a fist  They are located behind the stomach and the liver  There are 3 main parts to its structure  Renal cortex  Renal medulla  Renal pelvis

7. Parts of the kidney: 1. Renal pyramid 2. Efferent vessel 3. Renal artery 4. Renal vein 5. Renal hilum 6. Renal pelvis 7. Ureter 8. Minor calyx 9. Renal capsule 10. Inferior renal capsule 11. Superior renal capsule 12. Afferent vessel 13. Nephron 14. Minor calyx 15. Major calyx 16. Renal papilla 17. Renal column

8. R ENAL C ORTEX  Is the outermost portion of the kidney  Makes up 1/3 of the kidney’s tissue mass 1.Lumen of Bowman’s capsule 2.Glomerulus 3.Squamous epithelial cell 4.Kidney tubule

9. R ENAL M EDULLA  Is the inner 2/3 of the kidney  The arrows point to kidney tubules, which consist of collecting ducts and loops of Henle  The cells of these tubules are simple cuboidal epithelial

10. R ENAL P ELVIS  Is a funnel-shaped structure in the center of the kidney  The ureters are connected to the renal pelvis  They are the ducts that carry urine from the kidneys to the urinary bladder Cross section of the ureter

11. R ENAL B LOOD V ESSELS Renal Artery  Supplies blood to the kidney  It transports  nutrients to be used for life processes  and wastes to be filtered out & processed  Most common metabolic waste is urea Renal Vein  The pathway by which clean filtered blood leaves the kidney

12. N EPHRONS  Are the structures that make urine  3 major processes take place here: filtration, re- absorption and secretion  Urine is an amber-colored liquid made up of toxins, urea, water and mineral salts  Nephrons are the functional units of the kidneys  They are tiny tubes at the end of which have a cup- shaped capsule called Bowman’s capsule  Inside of each Bowman’s capsule, there is a fine network of capillaries called a glomerulus

13. N EPHRONS  Fluid travels through the nephrons  Nutrients are reabsorbed in Bowman’s capsule into the bloodstream  The remaining fluid: water and waste products, form urine which passes out of the kidney through the ureters  Each kidney has more than a million nephrons  If stretched out the nephrons from both kidneys would measure 50 miles

14. R ENAL T UBULE  Is the pathway through which the material filtered out of the blood travels  It consists of 3 parts:  The proximal convoluted tubule  The loop of Henle  The distal convoluted tubule

15. N EPHRON

16. 3 M AIN P ROCESSES  The kidney produces urine and filters the blood with 3 main processes within the nephrons 1. Filtration 2. Reabsorption 3. Secretion

17. F ILTRATION  Happens in the glomerulus of Bowman’s capsule  Fluids & solutes (water, urea, glucose, vitamins & salts) are transferred from the glomerular capillaries along a pressure gradient into Bowman’s capsule  The filtration rate is different for male and females  Males: 125mL/min  Females:110mL/min

18. F ILTRATION

19. R EABSORPTION  The body needs to retain most of the substances that are removed from the blood by filtration (99%)  These materials are returned to the blood through selective reabsorption in the proximal convoluted tubules of the nephrons  75% of the water in the filtrate is reabsorbed through osmosis  Glucose and minerals (sodium, potassium, and calcium) are reabsorbed through active transport  A small percentage of the reabsorption happens in the distal convoluted tubule

21. S ECRETION  Occurs in the distal convoluted tubule  As the filtrate flows through the distal convoluted tubule, toxins and wastes pass from the blood into the filtrate  The pH of the blood is adjusted by hydrogen ions secreted from the blood into the filtrate

22. F ORMATION OF U RINE  The fluid and wastes that remain in the distal convoluted tubule form urine  Urine from several renal tubules flow into collecting ducts by osmosis

23. L OOP OF H ENLE ( HEN - LEE )  Its function is closely related to that of the collecting duct  A high concentration of sodium chloride is maintained by this structure to ensure the reabsorption of water from the collecting duct

24. E LIMINATION OF U RINE 1.Urine from the collecting ducts flows through the renal pelvis into the ureter 2.The ureter from each kidney goes to the urinary bladder  Urinary bladder is a muscular sac that stores urine 3.Muscular contractions of the bladder force urine out of the body through the urethra 4.At least 500 mL of urine must be eliminated every day 5.A normal adult eliminates 1.6 quarts to 2.4 quarts of urine a day

26. L UNGS  The lungs are the primary site of carbon dioxide excretion, carry out detoxification, & excrete volatile substances in onions, garlic & other spices  Carbon dioxide and water vapor are exhaled into the air

27. S KIN  The skin helps the kidneys control the salt composition of the blood through perspiration  The skin excretes nitrogen wastes (urea), salt and water in sweat  A person working in extreme heat can lose water through perspiration at the rate of 1 L per hour and 10-30 g of salt per day