Urinary System
The urinary system consists of the paired kidneys of & ureters & the unpaired bladder & urethra. This system contributes to the maintenance of homeostasis by producing urine, the kidneys also regulate the fluid & electrolyte balance of the body and are the site of production of the hormones renin and erythropoietin.
· Kidney
o Structure:
Each kidney has a concave medial border (hilum) where nerve, blood & lymph vessels enter and exist of ureter. The kidney can be divided into an outer cortex and inner medulla.
o Nephrons
Each kidney is composed of 1-4 million nephrons, each nephrone consist of dilated portion (renal corpuscles), proximal convoluted tubule, thick & thin limbs of Henle s loop and distal convoluted tubule, the collecting tubule of ducts.
The urine produced by nephron and conduct it to the renal pelvis, the nephrone and collecting duct into which it empties constitute a uriniferous tubules, which can be considered the functional unit of the kidney.
o Renal Corpuscle (glomerulus):
Each renal corpuscle consist of tuft of capillaries, it surrounded by a double-walled epithelial capsule called Bowman s capsule.
The internal layer (visceral), external layers forms the outer limit (parietal) between the 2 layers found spaces called urinary spaces.
Parietal layer consist of simple squamous epithelium. Visceral layer is greatly modified, the cells of this internal layer called podocytes have cell body from which arise several primary processes each process gives rise to numerous secondary processes called pedicles, that embrace the capillaries of the glomerulus.
Pedicles conduct with the capillary by spaces about 25 nm wide the filtration sites.
o Proximal convoluted tubules:
This tubule is longer than the distal and is therefore more frequently seen near corpuscles, in the cortical labyrinth, the tubules are lined with simple cuboidal or columnar epithelium, the cell apex has abundant microvilli which form a brush border with narrow lumen.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .