4.2 Urinary System of Man

The urinary system is the body system responsible for removing nitrogenous wastes, regulating water and electrolyte balance, and maintaining the pH and volume of body fluids. It consists of the kidneys, ureters, urinary bladder, and urethra.

Definition

Urinary System: The excretory system (urinary system) consists of kidneys, ureters, urinary bladder, and a tubular urethra. It removes various salts and nitrogenous wastes, maintains normal concentrations of water and electrolytes, regulates pH and volume of body fluids, and controls red blood cell production and blood pressure.

Main Idea

• Removes nitrogenous wastes and salts
• Maintains water and electrolyte balance
• Regulates pH and volume of body fluids
• Controls red blood cell production
• Controls blood pressure

Core Concept

• Kidneys = filter blood; produce urine
• Ureters = transport urine to bladder
• Urinary bladder = stores urine
• Urethra = carries urine out of body
• Kidneys = located between T12 and L3
• Ureter = 25 cm long; begins as renal pelvis
• Urinary bladder = hollow, distensible muscular organ
• Urethra = tube from bladder to outside

Detailed Explanation

Organs of the Urinary System

• Kidneys
• Ureters
• Urinary bladder
• Urethra

Location of the Kidneys

• The kidneys lie on either side of the vertebral column.
• They are located between the twelfth thoracic and third lumbar vertebrae.

Ureters

• Each ureter is a tubular organ about 25 cm long.
• It begins as the funnel-shaped renal pelvis.
• It extends downward parallel to the vertebral column to join the urinary bladder.
• It transports urine from the kidney to the urinary bladder.

Urinary Bladder

• The urinary bladder is a hollow and distensible muscular organ.
• It is located within the pelvic cavity.
• It serves as a urine reservoir.

Urethra

- The urethra is a tube that carries urine from the urinary bladder to the outside of the body.

Summary Table of Urinary System Organs

Intermediate Level

Organs of the Urinary System

Functions of the Urinary System

Ureters

Urinary Bladder

Urethra

Formula / Mathematical Form

Not applicable to this topic.

Solved Example

Not applicable to this topic (descriptive topic).

Important Points

• 1. Urinary system consists of kidneys, ureters, urinary bladder, and urethra.
• 2. Kidneys lie between T12 and L3.
• 3. Ureters are 25 cm long.
• 4. Ureters begin as renal pelvis.
• 5. Ureters transport urine to bladder.
• 6. Urinary bladder is hollow and distensible.
• 7. Urinary bladder is in the pelvic cavity.
• 8. Urinary bladder stores urine.
• 9. Urethra carries urine out of body.
• 10. Urinary system removes salts and nitrogenous wastes.
• 11. Urinary system maintains water and electrolyte balance.
• 12. Urinary system regulates pH and volume of body fluids.
• 13. Urinary system controls red blood cell production.
• 14. Urinary system controls blood pressure.
• 15. Right kidney is slightly lower than left.

Remember

• - Urinary system = kidneys, ureters, bladder, urethra
• - Kidneys = filter blood; produce urine
• - Ureters = 25 cm long; transport urine
• - Urinary bladder = stores urine
• - Urethra = carries urine out of body
• - **Kidneys** = between T12 and L3
• - Ureters = begin as renal pelvis
• - Urinary bladder = in pelvic cavity
• - Urethra = female shorter; male longer

Common Mistakes

• 1. Confusing ureter and urethra — Ureter carries urine to bladder; urethra carries urine out of body.
• 2. Mixing up the location of kidneys — Between T12 and L3.
• 3. Thinking the bladder is in the abdominal cavity — It is in the pelvic cavity.
• 4. Forgetting the length of ureters — 25 cm.
• 5. Confusing the functions — Kidneys filter; ureters transport; bladder stores; urethra carries out.
• 6. Thinking the right kidney is higher — The right kidney is slightly lower than the left.
• 7. Forgetting the role of urinary system in blood pressure — It controls blood pressure.
• 8. Mixing up the functions of the urinary system — Excretion, water balance, electrolyte balance, pH regulation, volume regulation, RBC production, blood pressure.
• 9. Thinking the urethra is the same in males and females — Female urethra is shorter.
• 10. Believing the urinary system only removes waste — It also regulates water, electrolytes, pH, and blood pressure.

Quick Revision

The urinary system consists of kidneys, ureters, urinary bladder, and a tubular urethra. The kidneys lie on either side of the vertebral column between the twelfth thoracic and third lumbar vertebrae. Each ureter is a tubular organ about 25 cm long, which begins as the funnel-shaped renal pelvis. It transports urine from the kidney to the urinary bladder. The urinary bladder is a hollow and distensible muscular organ located within the pelvic cavity. It serves as a urine reservoir. The urethra is a tube that carries urine from the urinary bladder to the outside of the body. The urinary system removes various salts and nitrogenous wastes, maintains normal concentrations of water and electrolytes, regulates pH and volume of body fluids, and controls red blood cell production and blood pressure.

60-Second Revision

• Urinary system = kidneys, ureters, bladder, urethra
• Kidneys = filter blood; produce urine
• Ureters = 25 cm long; transport urine
• Urinary bladder = stores urine
• Urethra = carries urine out of body
• Kidneys = between T12 and L3
• Ureters = begin as renal pelvis
• Urinary bladder = in pelvic cavity
• Urethra = female shorter; male longer
• Warning: Ureter carries urine to bladder; urethra carries urine out of body

NEXT TOPIC

• Chapter:
• 4. Urinary System of Man

• Topic:
• 4.2.1 STRUCTURE OF KIDNEY

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