URINARY SYSTEM I

Histology 2016-2017
Department of Anatomy &Histology: Dr.Rajaa Ali
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URINARY SYSTEM I
INTRODUCTION
• Urinary system consists of a pair of kidneys, a pair of ureters, urinary bladder and urethra.
• Kidneys are involved in the production of urine which is conveyed by the ureters to the urinary bladder, where it is stored for a short period and is voided through urethra during micturition.

KIDNEY
GENERAL FEATURES
? Each kidney is a large bean-shaped organ situated in the posterior abdominal wall behind the peritoneum.
? It measures 7.5 cm in length, 5 cm in breadth and 2.5 cm in thickness.
? Its medial concave border has hilum through which renal vessels and nerves pass.
? The chemical composition of urine refl ects the important functions performed by the kidney.
? It controls water and electrolyte balance in the body.
? Maintains acid base balance.
? Excretes many toxic metabolic waste products (nitrogen, urea and creatinine).
? Maintains blood pressure by renin-angiotensin-aldosterone mechanism.
? Stimulates RBC production in bone marrow through erythropoietin.

Coverings:
• Kidney is surrounded by a thin fi brous capsule which is adherent to the substance of the kidney.
• External to it there is condensation of fatty tissue forming perinephric pad of fat, which is surrounded by a fascial sheath
• called the renal fascia (fascia of Gerota).

MACROSCOPIC FEATURES
• A vertical section through the kidney reveals its gross internal features (Fig.):
• The hilum leads to a space called renal sinus, which contains, apart from branches of renal vessels and nerves, the pelvis of ureter and its subdivisions, namely, major calyces (2–3) and minor calyces (8–12).
• The substance of the kidney is divided into outer dark granular (reddish brown) zone, the cortex and an inner pale striated zone, the medulla.