chapter 25 urinary system.txt

• To eliminate waste products
• (Nitrogenous wastes, toxins, drugs)
• To maintain water and electrolyte balance
• To regulate blood pressure
• To control the level of red blood cells
• To activate vitamin D
• To control a constant level of pH

• Kidneys
• Ureters
• Urinary bladder
• urethra

• Located retroperitoneally
• Anchored against the dorsal body wall by a lot of adipose tissue
• At the level of T12-L3
• Attached to a ureter renal artery and vein and the nerves at the renal hilium
• Has an adrenal gland located at the top of each kidney

• The kidneys contain two layers: renal cortex and renal medulla
• The renal medulla contain few pyramids
• Renal pyramids lead to the minor calyx which leads to the major calyx
• Major calyces collect in the renal pelvis which leads to the ureter

• Nephrons are the functional units of the kidney where urine formation occur
• Each kidney has 1 million nephrons

• The renal artery leads to the interlobar artery to the articulate artery then to the interlobular artery
• The interlular artery leads to the afferent arteriole
• This in turns leads to a network of capillaries called glomerulus

• Glomerular capsule: receives filtrate from glomerulus
• Proximal convoluted tubule
• Descending loop of henle
• Ascending loop of henle
• Distal convoluted tuble

Filtration is the process of the fluid leaving the glomerulus into the glomerular capsule of the nephrons

• Three processes:
• Glomerular filtration:
• Movement of water ions urea glucose
• amino acids from the blood to the lumen of nephron
• Tubular reabsorption
• The movement of substances from the nephron into the blood (water ions glucose)
• Tubular secretion
• Moving substances from the blood into the nephron (hydrogen ions, toxin)

• A hollow distensible muscular organ
• Stores urine and forces it into the urethra
• Includes a triangular area called the trigone which has three openings
• Has four layers

• Mucousal layer
• Made of transitional epithelium

• Submucousal layer:
• connective tissue and elastic fibers
• Muscular layer
• Detrusor muscle (smooth muscle ) that is innervated by the parasympathetic nervous system
• Forms internal urethral sphincter that prevents the bladder from emptying
• Serous layer
• Parietal peritoneum and connective tissue