Urinary System: Ureters

Ureters

• Ureters are tubes that transport urine from the kidneys to the urinary bladder.
• They are retroperitoneal, sitting directly against the posterior abdominal wall, covered by parietal peritoneum on their anterior surface.
• Each ureter originates at the renal pelvis as it exits the hilum of the kidney and terminates by entering the urinary bladder.
• The wall of the ureters has three layers: mucosa, muscularis, and adventitia.

Mucosa

• The mucosa is composed of transitional epithelium with an underlying lamina propria made of fibroelastic connective tissue.
• The mucosa is folded, which gives the ureters a star-shaped lumen, allowing them to stretch when they fill with urine.

Muscularis

• The muscularis consists of two smooth muscle layers: an inner longitudinal layer and an outer circular layer.

Adventitia

• The outer layer of the ureters is an adventitia composed of areolar connective tissue, anchoring the ureters to the posterior abdominal wall.

Urinary Bladder

• The urinary bladder is a muscular sac that stores urine until it is ready to be expelled from the body.
• It is located in the pelvic cavity directly posterior to the pubic symphysis, but can ascend slightly into the abdominal cavity when it is full.
• The urinary bladder has an apex that points anteriorly and a base that is directed posteriorly.
• The ureters enter the urinary bladder at its two posterolateral angles.
• The neck of the urinary bladder is located inferiorly and is where it drains urine into the urethra to be expelled from the body.
• Internally, there is a triangular region called the trigone, defined by the two ureteric openings in the superior corners and the urethral opening in the inferior corner.

Female Reproductive System

Components and Functions

• The female reproductive system is composed of the ovaries, uterine tubes, uterus, vagina, and vulva.
• The uterus can be divided into four main parts: fundus, body, isthmus, and cervix.

Vagina

• The vagina is a fibromuscular canal that connects the uterus to the external environment.
• It is located posterior to the urinary bladder and urethra and anterior to the rectum.
• The external opening of the vagina is called the vaginal orifice and is partially guarded by a vascularised, membranous structure called the hymen.

Vulva

• The vulva is the external genitalia of the female.

Urinary Bladder Walls

Mucosa

• The mucosa is composed of transitional epithelium with an underlying lamina propria.
• It is folded to form rugae, which increases the distensibility of the urinary bladder.
• The rugae flatten out when the bladder fills with urine.
• The mucosa lacks these folds in the area of the trigone.

Muscularis

• The muscularis consists of a smooth muscle called the detrusor muscle, arranged in three layers: an inner longitudinal layer, a middle circular layer, and an outer longitudinal layer.
• The addition of a third smooth muscle layer allows the urinary bladder to squeeze urine out when the detrusor muscle contracts during micturition.

Adventitia/Serosa

• The outer layer of the urinary bladder is mostly an adventitia composed of areolar connective tissue, as it lies outside of the peritoneal cavity.
• However, its superior surface is covered by parietal peritoneum, making the outer layer in this region a serosa composed of simple squamous epithelium with underlying areolar connective tissue.

Ureters

• Ureters are tubes that transport urine from the kidneys to the urinary bladder.
• They are retroperitoneal, sitting directly against the posterior abdominal wall, covered by parietal peritoneum on their anterior surface.
• Each ureter originates at the renal pelvis as it exits the hilum of the kidney and terminates by entering the urinary bladder.
• The wall of the ureters has three layers: mucosa, muscularis, and adventitia.

Mucosa

• The mucosa is composed of transitional epithelium with an underlying lamina propria made of fibroelastic connective tissue.
• The mucosa is folded, which gives the ureters a star-shaped lumen, allowing them to stretch when they fill with urine.

Muscularis

• The muscularis consists of two smooth muscle layers: an inner longitudinal layer and an outer circular layer.

Adventitia

• The outer layer of the ureters is an adventitia composed of areolar connective tissue, anchoring the ureters to the posterior abdominal wall.

Urinary Bladder

• The urinary bladder is a muscular sac that stores urine until it is ready to be expelled from the body.
• It is located in the pelvic cavity directly posterior to the pubic symphysis, but can ascend slightly into the abdominal cavity when it is full.
• The urinary bladder has an apex that points anteriorly and a base that is directed posteriorly.
• The ureters enter the urinary bladder at its two posterolateral angles.
• The neck of the urinary bladder is located inferiorly and is where it drains urine into the urethra to be expelled from the body.
• Internally, there is a triangular region called the trigone, defined by the two ureteric openings in the superior corners and the urethral opening in the inferior corner.

Female Reproductive System

Components and Functions

• The female reproductive system is composed of the ovaries, uterine tubes, uterus, vagina, and vulva.
• The uterus can be divided into four main parts: fundus, body, isthmus, and cervix.

Vagina

• The vagina is a fibromuscular canal that connects the uterus to the external environment.
• It is located posterior to the urinary bladder and urethra and anterior to the rectum.
• The external opening of the vagina is called the vaginal orifice and is partially guarded by a vascularised, membranous structure called the hymen.

Vulva

• The vulva is the external genitalia of the female.

Urinary Bladder Walls

Mucosa

• The mucosa is composed of transitional epithelium with an underlying lamina propria.
• It is folded to form rugae, which increases the distensibility of the urinary bladder.
• The rugae flatten out when the bladder fills with urine.
• The mucosa lacks these folds in the area of the trigone.

Muscularis

• The muscularis consists of a smooth muscle called the detrusor muscle, arranged in three layers: an inner longitudinal layer, a middle circular layer, and an outer longitudinal layer.
• The addition of a third smooth muscle layer allows the urinary bladder to squeeze urine out when the detrusor muscle contracts during micturition.

Adventitia/Serosa

• The outer layer of the urinary bladder is mostly an adventitia composed of areolar connective tissue, as it lies outside of the peritoneal cavity.
• However, its superior surface is covered by parietal peritoneum, making the outer layer in this region a serosa composed of simple squamous epithelium with underlying areolar connective tissue.

Ureters

• The ureters are tubes that transport urine from the kidneys to the urinary bladder.
• They are retroperitoneal, sitting directly against the posterior abdominal wall, and are only covered by parietal peritoneum on their anterior surface.
• Each ureter originates at the renal pelvis as it exits the hilum of the kidney and terminates by entering the urinary bladder.
• The wall of the ureters has three layers: an inner mucosa, a middle muscularis, and an outer serosa or adventitia.

Layers of the Ureters

• Mucosa: composed of transitional epithelium with an underlying lamina propria made of fibroelastic connective tissue, allowing the ureters to stretch when they fill with urine.
• The mucosa is folded, giving the ureters a star-shaped lumen that can increase in size when the ureters are stretched.
• Muscularis: consists of two smooth muscle layers - an inner longitudinal layer and an outer circular layer, opposite to the arrangement in the GI tract.
• Adventitia: composed of areolar connective tissue, anchoring the ureters to the posterior abdominal wall.

Urinary Bladder

• The urinary bladder is a muscular sac that stores urine until it is ready to be expelled from the body.
• It is located in the pelvic cavity, directly posterior to the pubic symphysis, but can ascend slightly into the abdominal cavity when it is full.
• The urinary bladder has an apex that points anteriorly and a base that is directed posteriorly.
• The ureters enter the urinary bladder at its two posterolateral angles.
• The neck of the urinary bladder is located inferiorly and is where it drains urine into the urethra to be expelled from the body.

Anatomical Relations of the Urinary Bladder

• In males, the urinary bladder sits directly anterior to the rectum and superior to the prostate gland.
• In females, the urinary bladder sits anteroinferior to the uterus and directly anterior to the vagina.

Features of the Urinary Bladder

• The trigone is a triangular region on the posteroinferior aspect of the urinary bladder, defined by the two ureteric openings in the superior corners and the urethral opening in the inferior corner.
• The trigone is smooth, unlike the rest of the internal surface which has mucosal folds called rugae.

Female Reproductive System

• The female reproductive system is composed of the ovaries, uterine tubes, uterus, vagina, and vulva.
• The ovaries are the female primary sex organs or gonads.
• The uterine tubes, uterus, and vagina are collectively referred to as the female reproductive tract.

Components and Functions of the Female Reproductive System

• Ovaries: produce eggs and hormones.
• Uterine tubes: transport eggs from the ovaries to the uterus.
• Uterus: nurtures a fertilized egg during pregnancy.
• Vagina: allows for the passage of a fetus during childbirth and serves as a conduit for menstrual flow.
• Vulva: protects the opening of the vagina and surrounding tissues.

Learn about the location, function, gross anatomy, and histology of the ureters, a part of the urinary tract system. Understand the structure and composition of the ureter walls.