Urinary System Cleaning up the system

Parts Kidney - filters the blood Ureter – transports the waste material to the bladder Urinary Bladder – stores the waste products Urethra – releases waste products out of the body

Kidney Located next to the vertebral column. Top about even with the 12th thoracic vertebra and the bottom about even with the 3rd lumbar vertebra Reddish brown, bean shaped Adults about 13 cm long, 6 cm wide, and 3cm thick Located in a fibrous capsule

Function Maintain homeostasis by regulating the blood pH, volume, and composition Removes metabolic wastes from blood Are diluted with water and electrolytes to make urine Secretes erythropoietin – controls rate of red blood cell production Helps activate vitamin D Secretes renin, an enzyme that maintains blood volume and pressure

Structures Renal sinus – hollow chamber where blood vessels, nerves, lymphatic vessels and the ureter enter and leave Renal pelvis – superior end of the ureter expanded into a sac inside the renal sinus Renal medulla – inner region of the kidney composed of the renal pyramids Renal cortex – outer shell around medulla that dips into the medulla to create the renal columns Nephrons – the functional unit of the kidney about 1 million/kidney

To clean blood, you need blood Renal Artery Branches from the abdominal Aorta 15-30% of total cardiac out put is sent to the kidneys when you are at rest The renal artery branches into smaller and smaller vessels until it becomes the afferent arterioles that lead to the nephrons Renal Vein “Clean” blood travels through ever larger vessels to the renal vein Empties into the Inferior Vena Cava that leads to the heart

Okay, we got blood, now it is the nephron's turn Blood vessels become tangled into a glomerulus which is located in a glomerular capsule (AKA Bowman's capsule) Fluid in the blood is filtered into the capsule ( the proximal end of the renal tubule) Renal tubule becomes highly coiled then dips down into the Loop of Henle This is interlaced with capillaries Fluid is returned to the blood and electrolyte balances are fine tuned here The renal tubule climbs back up and empties into the collecting duct – we now have urine

We got urine... now what? The collecting ducts merge together and empty into a minor renal calyx which in return empties into a major calyx, which them empties into the renal pelvis, which empties into the ureter The ureter is a tube that leads to the urinary bladder Uses peristaltic waves to move the urine down its length

We made it to the bladder A hollow, distensible, muscular organ Stores urine and then forces out the urethra In the pelvic cavity, behind the symphysis pubis and under the parietal peritoneum A sphincter at the neck of the bladder hold urine in until the pressure inside is to a certain level Involuntary control External urethral sphincter – skeletal muscles – voluntary control

Micturition AKA urination How do we know to go? By the amount there 150 ml typically = urge to go 300 ml sensation of fullness, bladder contraction intensify 600 ml typically = pain Bladder signals spinal cord, which releases involuntary sphincter, you feel like you must go External urethral sphincter is released when you go to the restroom

Kidney Dialysis As shown in the diagram above, there are two separate circuits along which liquids flow. They are: 1. The blood-flow from the patient, into the dialyser, through the dialyser, then back to the patient, and 2. The flow of dialysate around its own circuit which includes the dialyser plus some other stages.