Anatomy Bones and Muscles · MU Pleven

69. Urinary system -- general review and growth.

Introduces the urinary system's role in producing, storing and eliminating urine, then describes the kidneys, ureters and bladder. Development is traced through three stages: the pronephros, mesonephros and metanephros, with the nephrotomes, pronephric duct, Wolffian duct and ureteric bud explained in order. Covers how the collecting system and functional nephrons arise from the metanephric blastema.

Inside: 4 sections · 3 labelled pictures · 10 flashcards · 2 min

Topic 68 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 4 sections, about 257 words (2 min of reading), with 10 flashcards.

In this note

  1. Introduction
  2. URINARY SYSTEM
  3. Organs :
  4. Development :

URINARY SYSTEM

  • Also known as the renal system is responsible for producing, storing and eliminating urine from the body.

Organs :

  1. Kidneys
  • the primary organs
  • filters waste products and excess substances from the blood to produce wine.
  1. Ureters :
  • Narrow tubes carry urine from the kidneys to the bladder.
  1. Bladder :
  • Hollow, muscular organ located in the pelvis that stores wine until its ready to be expelled from the body.

Development :

  • From intermediate mesoderm .
  • Begins at the 4th week.
  • There are 3 stages :

1. Pronephrons

  • The pronephrons emerges around the 4th week of development.
  • It begins in the cervical region of the embryo.
  • Segmented divisions of intermediate mesoderm form tubules called nephrotomes.
  • These nephrotomes join to create the pronephric duct, which extends from the cervical region to the cloaca (distal end) of the embryo.

2. Mesonephrons :

“late in 4th week”

  • The mesonephrons develops inferiorly to the pronephrons.
  • They have mesonephric tubules, which are associated with capillaries.
  • So they can perform filtration.
  • The tubules drain into the mesonephric duct (Wolffian duct).
  • opens into the cloaca.

3. Metanephrons

  • The metanephros forms the definitive kidney.
  • It appears around the 5th week of development and becomes functional around the 12th week.
  • The ureteric bud from the mesonephric duct makes contact with a caudal region of intermediate mesoderm called the metanephric blastema.
  • Collectively, these blastema form the metanephric system, which has two components:
  • Collecting system: Derived from the ureteric bud, it includes the ureter, renal pelvis, major and minor calyces, and collecting tubules.
  • Functional nephrons: These nephrons are responsible for urine production and filtration.

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