Urinary System
General Functions
Regulation of: Ion concentrations in blood (K+, Na+, Ca2+, Cl-), H+ (protons) in blood - pH of blood, acidity should be around 7.4, and volume of blood by regulating water volume (MAJOR FUNCTION)
Excretion of: environmental toxins and wastes (mostly nitrogen), foreign substances (MAJOR FUNCTION)
Kidney: regulation/excretion, Ureter & Urethra : passageway, Urinary Bladder: storage
Filtration: occurs in glomerulus, blood is pushed through into capsular space to be filtered. The liquid that is pushed through is filtrate.
Resorption: substances are moved from kidney tubules to blood capillaries (peritubular)
Secretion: opposite of resorption, substances are moved from blood capillaries (peritubular) to kidney tubules
Kidney Anatomy
External Structures
Fibrous Capsule: dense connective tissue on surface of kidney, maintains shape and forms barrier
Renal Hilum: cleft on kidney where vessels, ureter and nerves enter and exit
Internal Divisions
Cortical Structures: renal corpuscles in renal cortex
Medullary Structures: pyramid shaped collection of tubules in renal medulla
Minor/ Major Calices: major calices are branching extensions from the renal pelvis, which then divide into the minor calices, they collect urine to drain into renal pelvis (which then flows into the ureter then bladder for storage)
Renal Pelvis: flat funneled shape tube that is the superior expansion of the ureter
Nephron Structure
Nephron: structural and functional unit of the kidney, composed of renal corpuscle and kidney tubule
Filtrate Flow through Kidney
Renal Corpuscle (filters in glomerulus) --> Renal Tubule (proximal convoluted tubule --> Nephron Loop --> Distal Convoluted Tubule) --> Collecting Duct --> Minor/Major Calices --> Ureter --> Urinary Bladder --> Urethra --> External Urethral Orifice
Renal Corpuscle: where filtration occurs, contains - Glomerulus - network of capillaries
Renal Tubule: Proximal convoluted tubule: part of the tubule that is twisted, and near glomerulus in renal cortex. Nephron Loop: part of tubule that drops down into renal medulla and comes back up to renal cortex. Distal convoluted tubule: part of tubule that is twisted in renal cortex, farther from glomerulus, before collecting duct.
Cortical Nephron: more common nephron ~ 85%, mostly in renal cortex, loop dips a little into renal medulla.
Juxtamedullary Nephron: Glomerulus is closer to renal medulla, loop is very long in renal medulla ( makes it possible to concentrate urine, or take water out)
Collecting Duct: structure after nephron, water can be reabsorbed here (under the influence of antidiuretic/ vasopressin hormone)
Urinary Tract
Ureters: tubes that transport urine from kidneys to bladder, continuation of the renal pelvis, retroperitoneal
Urinary Bladder: muscular sac that stores urine, has detrusor muscle to squeeze urine out through urethra
Urethra: passageway of urine from bladder to orifice, longer in males vs. females.