The Urinary System Overview

The Urinary System

• The urinary system comprises two kidneys, two ureters, one urinary bladder, and one urethra.
• Kidneys are composed of stroma (dense fibrous connective tissue) and parenchyma (uriniferous tubules).
• The stroma of the kidney is a dense fibrous capsule with reticular and collagenous fibers.
• The parenchyma is made of uriniferous tubules.
• Renal tissue is divided into an outer cortex and an inner medulla.
• The cortex appears brown red due to Malpighian renal corpuscles.
• The medulla is light grey and contains 18 medullary pyramids.
• Each kidney has up to 18 lobes, each lobe contains lobules.
• Lobules are demarcated by interlobular arteries.
• Uriniferous tubules consist of nephrons, which produce urine.
• Collecting tubules concentrate urine and carry it to calyces.
• Nephrons are the structural and functional units of the kidney, about 30-40mm long.
• Each kidney contains 1-1.5 million nephrons.
• Each nephron comprises a Malpighian renal corpuscle, two proximal convoluted tubules, two distal convoluted tubules, and a loop of Henle.
• Nephrons filter blood, and the collecting tubules concentrate urine, conveying it to the calyces.
• Malpighian (renal) corpuscles are rounded bodies primarily located in the cortex.
• Malpighian corpuscles consist of renal glomerulus and Bowman's capsule.
• The function of the Malpighian corpuscle is blood filtration.
• Renal glomerulus contains afferent and efferent arterioles, a bed of fenestrated blood capillaries (glomerulus), and mesangial cells.
• Bowman's capsule has an internal or visceral layer and an external or parietal layer, separated by Bowman's space.
• The proximal convoluted tubules are connected to the renal corpuscle and the loop of Henle, lined by simple cuboidal cells.
• They reabsorb sodium, chloride, phosphate, glucose, amino acids, plasma proteins, and certain drugs.
• Distal convoluted tubules are lined by simple cuboidal epithelium and shorter than proximal convoluted tubules.
• They reabsorb water by using antidiuretic hormone (ADH) and sodium using aldosterone hormone, excreting sodium and potassium using atrial natriuretic factor (ANF).
• The loop of Henle is a U-shaped tube that connects the proximal and distal convoluted tubules.
• It consists of a thick descending portion, a thin descending portion, a thin ascending portion and a thick ascending portion.
• Two types of loops of Henle exist: juxta-medullary and cortical.
• Collecting tubules collect urine from nephrons, conveying it to the ducts of Bellini.
• The urinary passages include minor and major calyces, renal pelvis, ureters, urinary bladder, and urethra.
• The wall of each passage consists of mucosa (transitional epithelium), muscularis (smooth muscle), and adventitia (areolar CT).
• The ureters and urethra exhibit specific histological structures.
• The urinary bladder comprises a transitional epithelium resting on a CT corium, smooth muscle layers, and adventitia.
• The urinary system regulates fluid and electrolyte balance, forms renin hormone for electrolyte balance and blood pressure regulation, secretes erythropoietin for blood cell development, and secretes medullin hormone for blood pressure control.

This quiz explores the anatomy and functions of the urinary system, covering components such as kidneys, ureters, and nephrons. Understand the structure of renal tissue and the processes involved in urine production. Test your knowledge on how these elements work together to maintain bodily functions.