2. Urinary System Anatomy and Physiology

3. Functions of Urinary System Regulate the volume, composition, and pH of body fluids Remove or add substances to the blood Form urine

4. Organs of the Urinary System Two kidneys Two ureters Bladder urethra

5. Kidneys Reddish brown; bean shaped on the posterior wall of the abdomen Inner region is the medulla; outer region is the cortex Nephrons are the working units

6. Ureters Tubes which drain the urine from the kidneys to the bladder Peristalsis moves the urine from the kidney to the bladder Can become inflamed in a urinary tract infection ureter

7. Bladder Hollow muscular organ Stores urine At the neck is the internal urethral sphincter muscle Can become inflamed in a urinary tract infection

8. Urethra Tube that takes the urine from the bladder to the outside Can become inflamed in a urinary tract infection Delivers both urine and semen in males

9. Urethra

10. Regulating substances and forming urine The nephrons of the kidneys filter the blood This means they remove substances from the blood The removed substances are called filtrate If these substances stay in the tubes of the urinary structures, they will be part of the urine and excreted

11. Regulating substances and forming urine The nephrons filter out some things we still need Part of the nephron’s job, then, is to put these wanted substances back into the blood Putting them back into the blood is called reabsorption This happens as the filtrate moves through the nephron structure

12. Nephron

14. One million nephrons in each kidney

15. Glomerulus Glomerulus: This is the filter.

16. Reabsorption Different substances are reabsorbed back into the bloodstream at specific locations along the nephron tubules. Some areas of the wall are more permeable to certain substances

17. Secretion Sometimes, to adjust the blood and the filtrate for homeostasis, certain substances are added back into the tubule This is called secretion

18. Dilute versus Concentrated Dilute urine contains lots of water, and not many dissolved particles. Light color Concentrated urine contains very little water, and lots of dissolved particles. Dark in color. Dehydrated! Kidneys make adjustments to the blood, which results in the composition of urine