Urinary System Components Kidneys paired structures functional unit that filters the blood push filtrate into ureter Ureters one for each kidney passively fill urinary bladder Urinary bladder Urethra passes filtrate from bladder to outside body Anatomy Joke of the Day Functions Fluid filtration Functions Fluid filtration Regulate blood volume Functions Fluid filtration Regulate blood Maintains salt water volume balance Functions Fluid filtration Regulate blood Maintains salt water Maintains acid base volume balance balance Functions Fluid filtration Regulate blood Maintains salt water Maintains acid base volume balance balance Gluconeogenesis Functions Fluid filtration Regulate blood Maintains salt water Maintains acid base volume balance balance Gluconeogenesis Renin production Functions Fluid filtration Regulate blood volume Maintains salt water Maintains acid base balance balance Gluconeogenesis Renin production Erythropoietin production Functions Fluid filtration Regulate blood volume Maintains salt water Maintains acid base balance balance Gluconeogenesis Renin production Erythropoietin production Activates vitamin D Kidney Structure Capsule outside covering of kidney Cortex outer portion Medulla inner portion deep to cortex Pelvis flattened collection area at the hilum area and is continuous with ureter Pyramids structures that appear to have stripes running through them that are actually collecting ducts will ultimately run to ureter Columns between pyramids inward extensions of the cortex Major calyces where renal pyramids first empty Minor calyces Supportive Layers Renal capsule part of supportive anchoring system Adipose capsule surrounds renal capsule rich in fat fat cushions and protects kidneys insulates because all this blood is passing through kidneys Renal fascia anchor kidneys in place against rear abdominal walls Nephron structural and functional unit of kidney more than 2 million of these in body Glomerulus combo of 2 things blood capillaries and tubule system Renal tubule Glomerular Bowman s capsule immediately surrounds Proximal convoluted tubule Loop of Henle Distal convoluted tubule Collecting ducts Renal corpuscle basically just another name for glomerulus and Bowman s capsule Types of nephrons Cortical mostly in cortex 85 of nephrons Juxtamedullary descend deeply into medulla 15 the deeper loop of henle descends into medulla the more concentrated the urine will be Nephron Vasculature Afferent arteriole going toward glomerulus Efferent arteriole going away from glomerulus Glomerulus Peritubular capillaries extra capillaries assoc with convoluted tubules branch off efferent arterioles will absorb solutes and water and return back to circulatory sytem 99 gets reabsorbed Vasa recta Juxtaglomerular Apparatus JG Modification where distal convoluted tubule runs against afferent arteriole Filtration Membrane Fenestrated epithelium Podocytes Basement membrane Filtration Pressure Glomerular hydrostatic pressure BP Colloid osmotic pressure of intracapsular space protien not allowed out Colloid osmotic pressure of glomerular blood Capsular hydrostatic pressure Filtration Regulation Other Factors Prostaglandins function in opp to neural and hormonal vasodilators Nitric oxide vasodilator release counteracts vasoconstriction Adenosine vasoconstrictor in kidney vasodilator everywhere else in body Endothelin vasoconstrictor Action by Region Urine Production Countercurrent Mechanism Countercurrent Multiplier Fluids in PCT osmotically equal to plasma Descending limb freely permeable to water and impermeable to solutes Ascending limb impermeable to water but selectively permeable to solutes Collecting ducts permeable to urea Renal Gradient Countercurrent Exchanger Vasa recta maintain osmotic gradient of kidney which allows for kidney function to occur in absence of gradient then no reabsorption occurs are freely permeable to water and salt Urine Formation Concentration of urine dependent on ADH secretion Low ADH produces a dilute urine ADH production increases water reabsorption from collecting duct and DCT Urinary Bladder Micturition Micturition Micturition Urine accumulates Stretch receptors activated Voiding reflexes under conscious control Parasympathetic stimulation contracts bladder and relaxes internal and external sphincters Anatomy Joke of the Day