Accessory Structures of the Urinary System Urinary Day 4 Accessory Structures of the Urinary System

Ureters Urine flows from collecting ducts to minor calyces major calycesrenal pelvis Urine then drains into the ureters It then drains into the bladderurethra Beyond the minor calyces urine it not modified in volume or in composition

The body has 2 ureters(1 from each kidney) The ureters are retroperitoneal like the kidneys The ureters pass under the bladder causing compression of the ureters Prevents backflow when the bladder is full

Ureter Composition Inner wall layer is a mucous membrane Prevents the cells from coming in contact with urinepH of urine is very different of that of the cell The middle layer of the ureter is made up of smooth muscle Peristaltic contractions help move urine Hydrostatic pressure and gravity play a role

Urinary Bladder Hollow muscular organ behind pubic symphysis Freely movable organ held by folds of peritoneum When empty looks like deflated balloon When full looks like a pear, rises into abdominal cavity

Bladder Structure Base= trigone small triangular area Opening to urethra is at the apex of the trigone This is where the ureters drain into the bladder Transistional Epithelium= part of the mucous membrane that line the bladder Able to stretch for inflation/deflation

Three layers of smooth muscle compose the bladder Sphincters Opening to urethra=internal urethral sphincter Involuntary Smooth muscle below = external urethral sphincter Somewhat voluntary Skeletal muscle

Functions of bladder Micturition=the action of expelling urine Brought about by involuntary and voluntary nerve impulses capacity is 700-800 ml Stretch receptors send impulses at 200-400ml Lack of bladder control=incontinence Under 2 years of age, neurons to the urethral sphincter are not fully developed

Urethra Tube leading from the floor of the urinary bladder to the exterior of the body. In females – embedded into the front wall of the vagina Urethra discharges urine In males it passes vertically through the prostate Urethra also discharges semen from the body

Urine 1000-2000 ml per day eliminated per day Sterile/95% water/5% solutes See charts 25.2 for abnormal diagnosis Volume is influenced by blood pressure, blood concentration temperature diuretics mental state