The kidneys filter blood to produce urine and are located between vertebrae T12-L3. Each kidney contains an outer cortex where filtering occurs and an inner medulla composed of renal pyramids. Blood enters the kidneys through the renal artery and leaves through the renal vein, undergoing filtration in structures called nephrons. Urine flows from nephrons through collecting ducts into minor calyces, major calyces, the renal pelvis, ureters, bladder, and urethra to exit the body. The ureters are muscular tubes that carry urine from kidneys to bladder. The bladder is a muscular reservoir organ where urine is stored before exiting through the urethra.

1. Urinary System

2. Kidneys: external 1. Paired, located between T12-L3 3. Convex lateral surface 4. Concave medial surface 5. Covered by 3 layers a. Renal fascia, c.t. = outside adipose capsulea b. Adipose capsule = middle c. Renal capsule, c.t. = innermost

3. Kidneys: internal 1. Cortex: This is where the blood is filtered. The filtrate flows into medulla 2. Medulla is composed of 8-15 conically-shaped Renal Pyramids. 3. The Renal Papillae are surrounded by funnel-shaped tubes

4. Renal Blood Vessels Aorta Renal Artery Glomerulus = a mass of capillaries. Some of the plasma (= filtrate) leaves the blood stream at this point Renal vein Inferior Vena Cava

5. Nephrons Functional units of kidney. The nephrons modify the filtrate. Composed of: GLOMERULUS RENAL TUBULE.

6. Urine Flow The urine flows into a Collecting Duct which ends at the tip of the renal pyramid The urine flows next into the minor calyx--> major calyx---> renal pelvis---> ureter---> bladder---> urethra

7. Ureters Paired, tubular organs, 10" long Histology: 3 layers 1. Mucosa - innermost, transitional epi. 2. Muscularis - middle, 2-3 layers of smooth muscle (peristalsis) 3.Adventitia - c.t.

8. Urinary Bladder Urine reservoir Histology: 3 layers 1. Mucosa - inner, transitional epi. a. Large folds = rugae b. Smooth area = trigone 2. Muscularis - 3 layers of smooth muscle = Detrusor Muscle. The muscle is modified at neck of bladder = Internal Sphincter (involuntary) 3. Serosa

9. Urethra Muscular tube - from bladder to body's exterior Pierces urogenital diaphragm. The skeletal muscle there is modified to form the External Sphincter (voluntary) around Urethra Female urethra - 1 ½ inches long Male urethra - 8 inches long Prostatic - through prostate Membranous - from prostate to bulb of penis Penile (Spongy) - through penis