Urinary System Anatomy

Urinary System Anatomy The urinary system consists of: Kidney The kidneys are shaped like red beans Kidney Function for: 1. Regulates the volume of water (fluid) in the body 2. Excretion of metabolic waste products (urea, uric acid and creatinine) 3. Regulation of blood volume and pressure. 4. Regulate osmotic balance and ion balance 5. Regulates the acid-base balance of body fluids 6. Hormonal Function and Metabolism 7. Regulation of vitamin D synthesis Microscopic Structure of the Kidney 1. Nephron Each nephron consists of Bowman's capsule that surrounds the glomerular capillary tuft, the proximal tubule, the loop of Henle, and the distal tubule, which empties into the collecting duct. 2.Renal Corpusculu The renal corpuscle consists of Bowman's capsule and the glomerular capillary tuft. 3.Juxtaglomerular apparatus The Juxtaglomerular cells of the afferent arteriole wall contain secretory granules that are thought to secrete renin. 4.Renin-angiotensin system The release of renin from the kidneys will result in the conversion of angiotensinogen into angiotensin. In the kidneys three main processes occur, namely: 1. Glomerular filtration: when blood flows through the glomerulus, protein-free plasma filtration occurs through the glomerular capillaries into the Bowman's capsule. 2. Tubular reabsorption In this process, substances that are still needed by the body will be selectively reabsorbed by substances that have been filtered. 3. Tubular secretion, the process of reabsorption and secretion takes place both through active and passive transport mechanisms which refer to the selective movement of substances from the peritubular blood capillaries into the tubular lumen. Ureter The ureters transport urine from the renal pelvis to the bladder. The flow of urine is caused by peristaltic contractions of the muscle walls of the ureters, approximately 1-5 peristaltic waves are formed every minute depending on the formation of urine. Bladder The two functions of the bladder are: 1) As a storage place for urine before it leaves the body 2) The function of the bladder is to push urine out of the body with the help of the urethra Urethra The urethra is a thin-walled, muscular tube that functions to drain urine from the bladder and remove it from the body. The length in women is 1.5 inches and in men about 8 inches. The opening of the urethra exiting the body is calledurinary meatus. Micturition Micturition is the emptying of the bladder after it has filled with urine. The flow of urine from the kidneys to the bladder via the ureters is relatively continuous about 500 mL. The capacity of the bladder to expand is due to three factors, namely: 1. First, the bladder wall contains many folds, similar to the abdomen. 2. Second, the bladder lining is transitional epithelium, which can stretch. 3. Third, the smooth muscle walls of the bladder, except the trigone, also stretch to accommodate fluid. Urine characteristics 1. Fresh color and transparency, namely dark yellow. 2. The smell of fresh urine is slightly aromatic but if left to stand it develops a smellammonia bacteria. 3. Urine pH is usually slightly acidic. The pH is around 6 but changes in body metabolism or diet can cause pH variations from around 4.5-8.0. The composition of urine consists of:: 1. Urine consists of about 95% water. 2. Nitrogen waste from protein metabolism, urea acid, ammonia and creatinine. 3) Electrolytes sodium, calcium, NH3, bicarbonate, phosphate and sulfate. 3. Pigment (bilirubinAndurobilin). 4. Toxins and hormones