By Alex Dupille & Emmanuel Rivera The Urinary System By Alex Dupille & Emmanuel Rivera

What is the urinary system? The urinary system also known as renal system. -Produces, stores, and eliminates urine -Kidney filters blood to keep clean -Metabolic waste -Toxins -Excess water -Dispose of nitrogenous waste -Urea, Uric Acid, and Creatinine -Works with the lungs, skin, and intestines to maintain balance of water and chemicals in the body

What does it consist of? -Two pairs kidneys Two sets of ureters Bladder Sphincter Urethra

Functions & locations Kidney- removes urea and other toxics or wastes from the blood through tiny filtering units called nephrons Ureter-25 centimeter long which begins at the renal pelvis. Extends downward behind the parietal peritoneum and runs parallel to the vertebral column Bladder –hollow, muscular organ that stores urine and forces it into the urethra. Within the pelvic activity and beneath parietal peritoneum. Urethra- tube that directs urine from bladder to the outside. Within the pelvic cavity, goes medially, joining the urinary bladder from underneath.

Kidney Kidney is a bean-shaped organ that is about the size of a fist Kidneys are on both sides of the vertebral column, depression high on the posterior wall of the abdominal cavity Adipose tissue (fat) and connective tissue surround the kidneys and hold them in position The left kidney is usually 1.5-2.0 centimeters higher than the right one Is to help maintain homeostasis by regulating the composition, volume, and pH of extracellular fluid.

The Kidney Blood goes down the aorta valve to the kidneys Both the renal artery, renal vein, and ureter meet at the hilus. Blood, waste, and water leads into the Renal artery where filtration begins

Inside the Kidney Composed of two regions ~Renal medulla- has masses of tissue called renal pyramids ~Renal Cortex- Forms a shell around the medulla and between the renal pyramid, forming renal columns. ~ Renal Columns- Carry blood vessels to renal cortex ~Renal pyramids-Urine runs through small tubules collecting ducts which run down through here. Also it meets minor calyx ~Also runs through renal papilla before meeting the minor calyx in the renal pyramid. ~Minor calyx leads to major calyx which in turn empties into the renal pelvis. ~Urine in renal pelvis then into the ureter which leads into the bladder.

Inside the Kidney

Nephron A kidney has 1 million nephrons which each nephron has a renal corpuscle and renal tubule. Renal corpuscle is composed of blood capillaries called glomerulus. Glomerulus are high pressure capillaries which filters blood. They are incased in a thin-double wall capsule called bowman's capsule. Space inside the capsule and surrounding the glomerulus is Bowman’s space. Plasma like fluid is filtered from the capillary blood into Bowman’s space through the glomerulus filtration membrane. Which allows some particles to pass through.

Nephron (Cont.) Goes through a filtering process through the tubules system. Some are added to the filtrate as part of urine formation and some are reabsorbed into filtrate and passed into the blood. Filtrate passes through 4 segments before reaching the ureter ~Proximal Convoluted tubule-Drains bowman's capsule and complete absorption of nutritional importance substances takes place ~Loop of Henle-Reabsorbs water and ions from the urine and plays a role in controlling concentration of urine ~Distal convoluted tubule-Regulates potassium, sodium, and pH and where further dilution takes place. ~Collecting duct-Joins with other tubules, which collects filtrate Also where final sodium regulation takes place.

Renal Bloodflow Lobular arteries further subdivide to form interlobular arteries which branch off into afferent arterials. Blood flows into the glomerulus through the afferent arterials. Blood flows out of the glomerulus through the efferent arterials Both afferent and efferent arterials regulate glomerulus capillary pressure by dilating or constricting.

Renal Bloodflow (Cont.) Now filtered flows from the glomerulus via the efferent arterials into the peritubulary capillary network. Which is a low pressure, reabsorptive system surround the tubule. Arrangement allows rapid movement of solutes in water between the fluid in tubular lumen and blood in capillaries. Peritubular capillaries rejoin to form venous channels by which blood leaves the kidneys and empties into inferior vena cava.

How Urine Is Formed

How Urine is Formed Urine formation involves filtration of blood by the glomerulus to form type of urine Reabsorption of electrolytes of nutrients that’s needed to maintain constistency of internal environment Secretion of waste materials Begins at glomerulus and plasma moves from bowman’s space. Glomerular filtrate moves into tubular segments of the nephron. Through tubular reabsorption , electrolytes and nutrients move from the filtrate back into the blood stream. Here also through tubular secretion, substances move from the peritubular capillaries into the urine filtrate. The filtrate concentrates then finds its way renal pelvis and leads to the uretor.

Urine Composition Urine composition reflects the amount of water and solutes that the kidneys must eliminate from the body to maintain homeostasis Urine composition depends on dietary intake and physical activity Urine is about 95% water, and contains other chemicals -Traces of amino acids -Variety of electrolytes -Varies with the diet

Urine Composition

Urea and Uric acid Urea is a product of amino acid catabolism. Its plasma concentration reflects the amount of protein in the diet. Urea enters the renal tubule by filtration. Only about half is reabsorbed, and the remaining urea is excreted in urine. Uric acid is a product of metabolism of certain organic bases. Active transport reabsorbs all the uric acid in glomerular filtrate in the nephron. Small amount is secreted into the renal tubule and is excreted in urine.

Urine Elimination After urine forming, passes through the collecting ducts through openings in the renal papillae and enters the calyces of the kidney After which is passes through the renal pelvis, and moves it through the ureter to the urinary bladder Ureter is 25 centimeters long that begins at the renal pelvis Ureter wall has three layers -Mucous coat-(Inner layer)Lining with renal tubules and urinary bladder -Muscular coat-(Middle layer)Smooth muscle fibers also -Fibrious coat-(Outer layer)Connective tissue

Urine Elimination & Ureters Muscular walls of the ureters propel the urine Muscular peristaltic waves force urine along the length of the ureter. Once reached to the bladder, ureter ejects the urine into the bladder. A fold of mucous membrane covers the opening through which urine enters the bladder which acts as a valve preventing backing up.

Bladder Pressure of surrounding organs alter the shape from surrounding organs. The wall of the urinary bladder has four layers. -Mucous coat -Submucous coat -Muscular coat -Serous coat

Urination In micturition, the detrusor muscle contracts, as do muscles in the thoracic as do the muscles in the abdominal wall and pelvic floor. Muscle part of the urogenital diaphragm described, surrounds the urethra about 3 centimeters from the bladder and is composed of voluntary skeletal muscle tissue Tension between the bladder walls fills with urine which stimulates stretch receptors, triggering micturition reflex(Spinal cord). Triggering a sensation of urgency.

Urination and Urethra Urinary bladder holds as much as 600millimilters of urine before stimulating pain receptors, but awareness of begins at 150 milliliters. Within 300 millimilters or more, the sensation of fullness intensifies, and contractions of bladder wall due become more powerful. When triggered, the force is strong enough for internal urethral sphincter to open, which another relax signals the external urethral sphincter to relax, and the bladder can empty. External urethral sphincter is skeletal muscle, it is under conscious control. Nerve centers in the brainstem and cortex can inhibit the micturition reflex and aid this control.

Urination and Urethra When deciding to urinate, the external sphincter relaxes, and the micturition reflex is no longer inhibited The detrusor muscle contracts, and urine is excreted through the urethra. The detrusor muscle relaxes, and the bladder begins to fill with urine again Urethra is lined with mucous membrane and contains a thick layer of smooth muscle tissues. Urethral wall contains urethral glands, which secrete mucus into the urethral canal

Diseases or Disorders Hematuria-The presence of red blood cells in urine. Hematuria can be caused by the result of a tumor another serious issue. Urinary Tract Infection(UTI)-Caused when bacteria from the digestive tract clings to the opening of the urethra, the hollow tube that carries urine from the bladder to the outside of the body and begins to multiply. Bladder Cancer-Occurs when abnormal cancerous cells grow in the bladder. Bladder cancer attacks men four times more than women.

Work Cited http://www.livescience.com/27012-urinary-system.html http://nyp.org/health/urology-diseases.html http://medicalcenter.osu.edu/patientcare/healthcare_services/urinary_bladder_kidney/anatomy_urinary_system/Pages/index.aspx http://www.pc.maricopa.edu/Biology/pfinkenstadt/BIO202/202LessonBuilder/Urinary/index.html