Urinary System Study Guide PDF

Urinary System Study Guide Structures of Urinary System: - Kidneys: filter blood and convert filtrate into urine - Ureters: transport urine from kidneys to urinary bladder - Urinary bladder: stores up to 1 liter of urine - Urethra: eliminates urine Functions of the Urinary System: - Elimination of m...

Urinary System Study Guide Structures of Urinary System: - Kidneys: filter blood and convert filtrate into urine - Ureters: transport urine from kidneys to urinary bladder - Urinary bladder: stores up to 1 liter of urine - Urethra: eliminates urine Functions of the Urinary System: - Elimination of metabolic wastes - Regulation of ion levels - Regulation of acid-base balance - Regulation of blood pressure Elimination of biologically active molecules Location of Kidneys: - Left kidney: between T12 and L3 vertebrae - Right kidney: 2 centimeters inferior to left kidney Tissue Layers Surrounding the Kidneys: - Fibrous capsule: maintains kidney’s shape and protects it from trauma and pathogens - Perinephric fat: cushions and supports kidney - Renal fascia: anchors kidney to surrounding structures Paranephric fat: cushions and anchors kidney Regions and Components of the Kidney: - Renal cortex: outermost region Renal columns: project into medulla and subdivide it into renal pyramids Renal pyramids: striped structures within the medulla - Medulla: inner portion Corticomedullary junction: where cortex meets medulla - Renal papilla: located at inner part of renal pyramids - Minor calyx: funnels urine from renal papilla - Major calyx: collects urine from minor calyces - Renal pelvis: collects urine from major calyces - Ureter: carries urine from renal pelvis to bladder Autonomic Innervation of the Kidney: - Sympathetic nerves: innervate blood vessels of the kidney, regulate blood flow and urine production - Parasympathetic nerves: play a role in regulating renal blood pressure and fluid balance Renal Corpuscle and its Components: - Renal corpuscle is located in the renal cortex and consists of the glomerulus and glomerular capsule - Glomerulus: network of capillary loops where blood is filtered - Glomerular capsule: receives filtrate from glomerulus, has a visceral and parietal layer Components of a Renal Tubule: - Proximal convoluted tubule (PCT): first region of the tubule, reabsorbs majority of water and solutes - Nephron loop: consists of descending and ascending limbs, establishes salt concentration gradient - Distal convoluted tubule (DCT): final region of the tubule, regulates reabsorption and secretion Types of Nephrons: - Cortical nephrons: located near top edge of cortex, have a short loop - Juxtamedullary nephrons: located near cortex-medulla junction, have a long loop Collecting Tubules and Ducts: - Collecting tubules: numerous in each kidney, project towards renal papilla - Collecting ducts: empty into papillary ducts in the renal papilla Principal Cells and Intercalated Cells: - Principal cells: have receptors for aldosterone and antidiuretic hormone, regulate reabsorption of ions and water Intercalated cells: help regulate urine and blood pH 1 Juxtaglomerular Apparatus: - Located where DCT makes contact with afferent arteriole - Involved in regulating filtration formation and systemic blood pressure - Granular cells synthesize, store, and release renin - Macula densa cells detect changes in NaCl concentration and signal granular cells to release renin Blood Supply to the Kidneys: - Renal artery divides into segmental arteries, then interlobar arteries, arcuate arteries, and interlobular arteries - Afferent arterioles supply blood to glomeruli, efferent arterioles carry blood away from glomeruli - Blood leaves kidney through cortical radiate veins, arcuate veins, interlobar veins, and renal vein Filtrate, Tubular Fluid, and Urine: - Filtrate is formed by filtering blood in the glomerulus - Tubular fluid is formed by exchange of gases and nutrients in the tubules - Urine is the final product that leaves the collecting duct Steps of Urine Formation: 1. Glomerular filtration: movement of substances from blood in glomerulus into capsular space 2. Tubular reabsorption: movement of substances from tubular fluid back into blood 3. Tubular secretion: movement of substances from blood into tubular fluid Countercurrent Multiplier: - Involves nephron loop - Establishes salt concentration gradient in the interstitial fluid - Important for regulating urine concentration Contribution of Urea Cycling to Concentration Gradient: - Urea is recycled between collecting tubules and nephron loops - Makes up one-half of the solutes in interstitial fluid concentration gradient Conscious Control over Micturition: - Starts from the cerebral cortex through the pudendal nerve - Causes relaxation of external urethral sphincter - Facilitated by voluntary contraction of abdominal and expiratory muscles Characteristics of Urine: - Composition: 95% water, 5% solutes including salts, nitrogenous wastes, hormones, and drugs - Volume: 1-2 L per day, varies based on fluid intake and other factors - pH, specific gravity, color, turbidity, and smell vary based on individual health and diet 2