5/24: Excretion: Ureters and Bladder

 Ureters Move Urine from the Kidneys to the Bladder

Urine drains from the renal pelvis of each kidney into the ureters. 

Thin tubes made of smooth muscle.

Contractions of the smooth muscle push urine down through the ureters and into the bladder

Urinary Bladder Is a Reservoir for Urine

Urine flows through the ureters into the urinary bladder.

The triangular base of the urinary bladder, the trigone, is defined by the two ureters that deliver the urine and the one urethra that drains the urine.

The wall of the bladder contains folds called rugae, and a layer of smooth muscle called the detrusor muscle.

The tiny wrinkles, known as rugae, allow it to stretch as it fills with urine.

 The detrusor relaxes to hold the urine, then contracts for urination. 

The adult bladder is full at about half a liter, or about two cups.

The triangular base of the urinary bladder, the trigone, is defined by the two ureters that deliver the urine and the one urethra that drains the urine.

In women, the bladder is located in front of the vagina and below the uterus.

In men, the bladder sits in front of the rectum and above the prostate gland.

Urine produced in the kidneys passes through the ureters, collects in the bladder, and is then excreted through the urethra

The urethra is narrow and about 4 cm long

 It extends from the bladder neck to the external urethral orifice in the vestibule of the vagina.

Four or five times as long as in females.

Male Urethra Is Divided into Three Sections

1. The prostatic urethra (the widest portion)

2. The membranous urethra (the narrowest portion)

3. The spongy urethra (the longest portion).