The Urinary System

1. The Urinary System

2. Functions of the Urinary System • Three Major Functions • Excretion: The removal of organic waste products from body fluid. • Elimination: The discharge of fluid waste products into the environment.(urination) • Homeostasis: The regulation of the volume and solute concentration of blood plasma.

3. Functions of the Urinary System • Other functions of the urinary system: • Regulation Blood Volume & Blood Pressure. • Regulating Plasma Concentrations of Sodium, Potassium, Chloride, and other ions. • Helping Stabilize Blood pH. • Conserving Valuable Nutrients (glucose, amino acids). • These activities are carefully regulated to keep the composition of blood within acceptable limits.

4. Anatomical Structures of the Urinary System • Kidneys(2): Organ that produces urine. • Urine: Fluid containing water, ions, and small soluble compounds. • Urinary Tract(two paired ureters): Transports urine to the urinary bladder. • Urinary Bladder: Temporarily stores urine prior to elimination. • Urethra: Conducts urine to the exterior (in males also transports semen)

5. Urinary System

6. The Human Kidney • In the human body there are two kidneys, one located on either side of the vertebral column. • They are between the last thoracic and first lumbar vertebrae. • The right kidney is slightly lower than the left. • Each kidney is covered by a fibrous capsule and is packed in cushion of adipose tissue.

7. Anatomy of the Human Kidney • Each kidney is typically reddish-brown in color and about 4in. Long by 2.2in. Wide with a thickness of about 1.2in. • The kidney weighs in at about 5.5oz • Each kidney has a ureter connected to it at a indentation in the surface of the kidney called the hilum. • The hilum is also where the renal artery and nerve connect to each kidney.

8. Anatomy of the Human Kidney Continued • Each kidney is divided based on its inner and outer anatomy. • The outer portion is called the renal cortex. • The inner portion is called the renal medulla. • Divided into 6-18 conical shaped structures called renal pyramids. • Urine production occurs within the renal pyramids • The tip of each pyramid is called a renal papilla • Ducts within each papilla discharge urine into a drain called the minor calyx.

9. Anatomy of the Human Kidney Continued • 4-5 of the minor calyx will merge together to form a major calyces, which combine together form a funnel shaped chamber called the renal pelvis. • The renal pelvis is connected to the ureters and allows for urine to be drained out of the kidney.

10. The Kidney

11. Blood Supply to the Kidneys • Because the kidneys main function is to filter out waste from the blood it is highly vascular. • About 1200mL of blood flows through the kidneys each minute. • The main blood vessels of the kidney are the renal artery and renal vein.

12. Blood Supply

13. The Nephron & UrineProduction • In the renal cortex of the kidney are specialized microscopic tubular structures called nephrons. • Each kidney contains about 1.25 million nephrons. • The nephron is the basic functioning unit of the kidney. • Each nephron consists of two main parts the; renal corpuscle and the renal tubule.

14. The Nephron & Urine Production • The nephron is the location where the blood if filtered to produce urine. • The filtration process begins when the blood reaches the renal corpuscle and dissolved solutes are removed producing a fluid called filtrate. • The filtrate then enters the renal tubule where it is gradually changed into tubular fluid. • The fluid is then emptied into the collecting duct and eventually into the papillary duct. The papillary duct will empty the fluid now called urine into the renal pelvis of the kidney.

15. The Nephron & Urine Production • The Nephron has three main functions that it accomplishes via filtration and urine production. • Reabsorb useful organic molecules • Reabsorb water (~90%) • Secret waste products • Remove additional water and salt remove urine is released to the renal sinus.

16. The Nephron

18. Urine Production • The purpose for urine production is to maintain homeostasis(balance) in the body by regulating blood volume and composition. • The process also involves the excretion of three dissolved solids • Urea (most abundant, from breaking down amino acids.) • Creatinine (generated in skeletal muscle from energy production) • Uric Acid (produced from breaking down and recycling RNA) • To accomplish this goal the kidney does three specific functions: • Filtration • Reabsorption • Secretion

19. Nervous System & Hormonal Control • Several hormones are involved in regulating kidney function; • Angiotensin II • ADH (Antidiuretic Hormone) • Aldosterone • ANP (Atrial Natriuretic Peptide)

20. Ureters • A pair of muscular tubes that conduct urine from the kidneys to the urinary bladder. • Each is about 12in long. • About every 30 seconds a peristaltic contraction begins at the renal pelvis and sweeps along the ureters all the way to the bladder forcing urine into the bladder.

21. Urinary Bladder • A hollow muscular organ that stores urine prior to urination. • A full bladder can hold up to a liter of urine • (Micturition reflex) Stretch receptors in the bladder signal when the bladder is full and start a chain reaction of neurological activity that makes us consciously aware of our full bladder. • Eventually muscle contraction and relaxation of internal and external sphincters allow for the bladder to empty and urination to occur.

22. Ureter & Bladder

23. Urethra • Short tube that extends from the bladder to the exterior body that allows the urine to exit the bladder and the body. • The urethra is shorter in females(1in) than in males (7-8in). • In males it is also involved in the transportation of semen.

24. Balance & Homeostasis • Many dynamics exits between the urinary system and other systems in the body due to balance and exchange of fluid between the internal and external environment. • Homeostasis involves the balance of fluid volume, solute concentration, and pH. • Fluid Balance • Electrolyte Balance • Acid-Base Balance • Sodium Balance • Potassium Balance

25. Diseases & Disorders • Kidney Diseases • Kidney Stones • Incontinence • Urinary Tract Infection • Renal or Kidney Failure • Bladder Infection • ETC.