Urinary System Structures and Functions

Functions of the Urinary System To remove certain salts and nitrogenous wastes (wastes made by cellular processes)

To maintain normal concentrations of water and electrolytes through urine output

3. To regulate the pH of body fluids.

Kidneys- Maintain homeostasis by regulating the composition, volume and pH of extracellular fluid Structure Function 2 12 cm long, 6 cm wide located on posterior abdominal wall Surrounded by connective and adipose tissue Connects kidneys to body wall and serves as protection for kidneys

Kidney- continued Structure Function Covered by a heavy capsule of dense connective tissue Functional units are called nephrons Prevents kidney from swelling, forcing urine outward Produce urine Remove wastes, water, salts, and bile pigments from blood Important role in maintaining homeostasis- balance water, pH, salts

Ureters Structure Function 2 tubes Made of 3 muscular layers Transport the urine made in the kidneys to the bladder Contract in peristaltic waves

Bladder Structure Function Hollow sac in pelvic cavity Muscular Pressure receptors Stores urine Allows bladder to expand and contract Send messages urging urination at 200 mL, at 400mL you feel like you will burst

Urethra Structures Function Tube 3.8 cm long in females 20 cm long in males Carries urine from the bladder to the urinary meatus.

Kidney Structure and Function

FOCUS ON THE KIDNEYS

Functions: Filter wastes: Every day, kidneys process about 200 quarts of blood to filter out about 2 quarts of waste products and extra water Regulate composition of electrolytes: The kidneys measure out chemicals like sodium, phosphorus, and potassium and release them back to the blood to return to the body. In this way, the kidneys regulate the body’s level of these substances. Maintain pH: filter H+ ions Secrete hormones and enzymes: -erythropoietin: stimulates the bone marrow to make red blood cells (hormone) -renin: regulates blood pressure (enzyme) -calcitriol: helps maintain proper calcium levels (hormone)

Kidneys and urine formation Blood enters the kidney through the renal artery Identify: -kidney -abdominal aorta -renal artery

Blood enters the functional unit of the kidney called the nephron. One kidney contains about one million nephrons. Stop and take the kidney quiz

3 Filtration of the blood takes place in the renal corpuscle which is made of a glomerulus and a glomerular capsule.  

3. The filtrate goes into the glomerular capsule and includes water, amino acids, vitamins, glucose, and nitrogenous wastes. Cells and large proteins are left in the arteriole.

Tubular reabsorption The blood reabsorbs needed substances from the proximal convoluted tubule -water -amino acids -glucose -ions: Na, Cl, Ca, K -bicarbonate -some urea The glomeruli and tubules together make up long and extremely fine tubes which, if connected, would run for 50 miles. 

Additional items are added to the forming urine. 5. Tubular Secretion Additional items are added to the forming urine. -H+ -ammonia -urea -potassium Link- Use this to review

Filtered blood exits the kidneys by way of the renal vein Identify the renal vein and inferior vena cava

7. Wastes removed by the kidney pass through collecting ducts then the ureter to the bladder.

8. When the bladder is full, the urine passes out of the body through the urethra. Summary

What can go wrong?

High Blood Pressure What part of the nephron would be damaged by high blood pressure? What does the glomerulus do? Filters blood.

Diseases of the glomerulus What is in the urine that should not be?

Polycystic kidney disease (inherited)

. Trauma- such as a direct and forceful blow to the kidneys, can lead to kidney disease Ingestions of poisons

What happens when kidneys fail completely? The body fills with extra water and waste products (uremia). Hands or feet may swell. A person will feel tired and weak because the body needs clean blood to function properly. 2. Untreated uremia may lead to seizures or coma and will ultimately result in death. 3. A person whose kidneys stop working completely will need to undergo dialysis or kidney transplantation.

Treatment Dialysis Transplant Home dialysis Preview to transplant