Chapter 10 Urinary System Abdominal cavity and lower pelvic cavity Bladder is made of epithelial cells What are the functions of the urinary system Excretion of metabolic wastes urinary system removes toxins in form of urine Maintenance of water salt balance Maintenance of acid base balance Secretion of enzyme renin and hormone erythropoietin EPO Reabsorb filtered nutrients and synthesize vitamin D What are the 3 regions of the kidney Renal cortex an outer granulated layer Renal medulla cone shaped tissue masses called renal pyramids Renal pelvis central cavity that is continuous with the ureter Nephrons Microscopic functional unit of the kidney that produces urine 1 million per kidney Anatomy of a nephron Glomerulus a knot of capillaries inside the glomerular capsule where pores produce a blood filtrate are tight fine because it exerts pressure and helps in filtration force It is forced out to the collecting ducts Proximal convoluted tubule epithelial layer with a brush border of microvilli to allow reabsorption of filtrate components Loop of nephron U shaped structure that has a descending limb to allow water to leave and an ascending limb that pushes out salt Distal convoluted tubule made of epithelial cells rich in mitochondria and thus is important for movement of molecules from the blood to the tubule tubular secretion Collecting ducts several nephrons share a collecting duct which serve to carry urine to the renal pelvis Glomerular capillaries are tight fine because it exerts high pressure and helps in filtration force It is forced out to the collecting capsule cup What are the 3 processes in the formation of urine 1 Glomerular filtration Water and small molecules move from the glomerulus to the glomerular capsule while large molecules and formed elements remain in the glomerular blood 1 Tubular reabsorption 2 Tubular secretion Many molecules and ions are reabsorbed from the nephron into the blood Is a second way to remove substances such as drugs H and creatinine from the blood 1 2 How does a nephron form urine How do the kidneys maintain homeostasis Excrete wastes Urea creatinine and uric acid Water salt balance of blood Helps regulate blood volume and pressure Acid base balance of blood Helps regulate pH Assistance to other systems Endocrine cardiovascular skeletal muscular nervous and digestive How is blood volume and pressure maintained by the kidneys Reabsorption of salt increases the blood volume Renin enzyme produced by kidney promotes release of Aldosterone hormone that augments excretion of K and reabsorption of Na Atrial natriuretic hormone ANH is secreted by the heart when blood volume increases and inhibits the secretion of aldosterone which promotes the excretion of Na How is blood volume and pressure maintained by the kidneys Establishment of solute gradient a greater concentration is towards the inner medulla Reabsorption of water due to the solute gradient water leaves the descending limb of the loop of the nephron then antidiuretic hormone ADH from the pituitary plays a role in water reabsorption at the collecting duct What role does alcohol play in this process Alcohol inhibits ADH secretion and thus increases the amount of urine and dehydration Kidney function disorders Diabetes hypertension and inherited conditions are the most common cause of renal disease and failure such as Urethritis localized infection of the urethra Cystitis infection in the bladder Pyelonephritis infection of the kidneys Kidney stones hard granules formed in the renal pelvis due to UTIs enlarged prostate pH imbalances or intake of too much calcium Uremia high levels of urea and other waste substances in the blood that cause a serious condition when water and salts are retained due to extensive nephron damage How can kidney failure be treated needed Hemodialysis uses an artificial kidney machine to subtract and add substances to the blood as Continuous ambulatory peritoneal dialysis CAPD uses the peritoneal membrane to filter the blood and allows a person to go about their normal life without interruption Kidney replacement single kidney transplant with a high success rate
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