Ureter, Urinary Bladder & Urethra (Structures & Walls) - Urinary System Anatomy

Summary

In this detailed exploration of the urinary system, the video covers the anatomy and functions of the ureter, urinary bladder, and urethra in both males and females. It delves into the roles of these organs in urine transport and storage, explaining the structure of the ureter, its three main parts, and the muscular contractions that help move urine. The urinary bladder's capacity and structural layers are examined, alongside the unique features of the male and female urethra, highlighting their differences and roles in urinary function. This video provides an in-depth understanding of the entire urinary system, offering insights into its complex anatomy.

Takeaways

• 😀 The urinary system consists of the kidneys, ureters, urinary bladder, and urethra, all working together to handle urine.
• 😀 The ureter is a muscular tube that transports urine from the kidneys to the urinary bladder through peristalsis, not simply a passive tube.
• 😀 There are three parts of the ureter: the abdominal part, pelvic part, and intramural part, each with a specific location and function.
• 😀 The ureter has three constrictions: at the junction between the renal pelvis, at the linea terminalis, and at the point where it enters the urinary bladder.
• 😀 The layers of the ureter wall include the tunica mucosa (with transitional epithelium), tunica muscularis (which changes in the lower third of the ureter), and tunica adventitia.
• 😀 The urinary bladder stores urine and has a capacity ranging from 250–500 mL, with different positions based on whether it's full or empty.
• 😀 The bladder has a trigone area formed by the two ureteric orifices and the internal urethral orifice, and this area does not have the same mucosal layer as the rest of the bladder.
• 😀 The urinary bladder's histological layers include the tunica mucosa (with umbrella cells), tela submucosa, tunica muscularis (with three muscle layers), and tunica adventitia/serosa.
• 😀 The male urethra is about 15–22 cm long, with three sections: prostatic, membranous, and spongy urethra, and it passes through the penis.
• 😀 The female urethra is shorter (2.5–4 cm) and wider than the male urethra, and is prone to urinary leakage due to its size and position.

Q & A

What is the primary function of the ureter?

The primary function of the ureter is to transport urine from the kidneys to the urinary bladder through peristaltic movements, not just act as a passive tube.

How does the flow of urine in the ureter differ from continuous flow?

Urine flow in the ureter is not continuous; it occurs in waves due to peristaltic contractions, similar to how the intestines move content through muscle contractions.

What are the three parts of the ureter?

The three parts of the ureter are the abdominal part (from the renal pelvis to the pelvic inlet), the pelvic part (from the pelvic inlet to the bladder), and the intramural part (inside the bladder wall).

What are the three main narrowings (constrictions) of the ureter?

The three main narrowings of the ureter are: 1) the junction between the renal pelvis and the ureter, 2) the terminal line of the pelvis (Linea Terminalis), and 3) when the ureter enters the wall of the urinary bladder.

What is the structure of the ureter's wall?

The ureter's wall has several layers: the innermost layer is the tunica mucosa with transitional epithelium, followed by the tela submucosa with loose connective tissue, then the tunica muscularis with muscle fibers for peristalsis, and the outermost layer is the tunica adventitia for protection.

How does the muscle layer of the ureter differ in its upper and lower thirds?

In the upper two-thirds of the ureter, there are two muscle layers: inner longitudinal and outer circular fibers. In the lower third, three muscle layers are present: inner longitudinal, middle circular, and outer longitudinal fibers, resembling the structure of the urinary bladder.

What is the role of the internal urethral sphincter in the male urethra?

The internal urethral sphincter is made up of smooth muscle fibers and helps control the flow of urine from the bladder into the urethra. It is located at the junction between the urinary bladder and the urethra.

How does the female urethra differ from the male urethra in terms of length and diameter?

The female urethra is much shorter than the male urethra, measuring around 2.5 to 4 centimeters in length and 8 to 12 millimeters in diameter. In contrast, the male urethra is longer (15 to 22 cm) but narrower.

What is the significance of the triangular shape formed by the ureteric orifices and the internal urethral orifice in the bladder?

The triangular shape formed by the two ureteric orifices and the internal urethral orifice in the bladder is called the trigone of the bladder. It is an area where the mucous layer fuses with the muscular layer, making it a stable region that is less likely to form folds.

What is the difference between tunica adventitia and tunica serosa in the urinary bladder?

Tunica adventitia consists of dense fibrous connective tissue and is found on the surface of the urinary bladder that does not face the peritoneum. Tunica serosa, on the other hand, is a serous coat that covers the portion of the bladder that faces the peritoneum.