Excretory System

icer215's version from 2016-08-19 23:00


Question Answer
Homeostasisregulation/stabilization of internal environment such as blood pressure, osmoregulation, pH, and soluble nitrogenous waste.
Blood pressure controlLow blood pressure and High blood pressure
Low blood pressureis raised by hormonal control (such as aldosterone or ADH) causing reabsorption of water or Na+
High blood pressure is lowered by provoking the release of those hormones
OsmoregulationNa+ and Cl– ions (blood plasma) mainly determine blood osmolarity. Low blood osmolarity aldosterone releases kidney reabsorbs Na+ (K+ ions are excreted). Other ions such as calcium and phosphate are regulated by PTH (parathyroid hormone).
pH regulationBicarbonate buffer system: blood and extracellular fluid. CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-.
Reabsorption of HCO3-(bicarbonate ion) more basic
Removal of HCO3-(by urinating it out) more acidic. H+ secretions gets rid of acidity
Phosphate buffer systeminside the cells
Soluble nitrogenouswaste removal
Urineconcentrated urea in water with some salt
Ureaharmless form of toxic ammonia (nitrogenous waste)
Amino acidsammonia urea pee out
Kidneylocated right below the ribs (includes nephron which will be discussed in details in later lessons). It remove liquid waste from blood as urine, keep balance between salts and other substances in blood, produce erythropoietin that aids the formation of RBCs


Question Answer
Uretersnarrow tube down the kidney that carry urine by tightening and relaxing the ureter muscle walls. Small amount of urine are emptied into the bladder every 10-15 seconds. An infection in kidney may occur if urine backs up
Bladderhollow triangular shape organ that is located in the lower abdomen area. Ligaments that are attached to other organs and pelvic bones hold bladder in place. It stores urine by expanding and empties by flattening the bladder wall (through urethrae).
Sphincter musclescircular shape muscles that keep urine from leaking by tightening around the opening of the bladder.
Nerves in the bladderalert a person when it is time to urinate (empty the bladder)
Urethraa tube that urine passes out the body. The brain signals the bladder muscles to tighten squeezes urine out the bladder sphincter muscles relax let the urine exit the bladder through urethra
KidneyRenal Hilus, Renal capsule,Renal cortex, Renal medulla, Renal pelvis, Renal artery, Renal vein, Interlobular artery, Interlobular vein, & Collecting duct
Renal Hilusarea where the ureter leaves kidney and the other structures including blood vessels, lymphatic vessels, and nerves enter/leave the kidney.
Renal capsulesmooth fibrous membrane that surrounds and protects the kidney (maintains the shape as well)
Renal cortexouter part of the kidney
Renal medullainner part of the kidney
Renal pelvisarea which receives the urine drained from the kidney nephrons (via collecting ducts) and then papillary ducts


Question Answer
Renal arterydelivers oxygenated blood to the kidney
Renal veinreceives deoxygenated blood from the peritubular veins within the kidney
Interlobular arterydelivers oxygenated blood at high pressure to the glomerular capillaries
Interlobular veinreceives deoxygenated blood at lower pressure that it drains away from the glomerular filtration units and from the loops of Henie
Collecting ductabove the kidney nephron, absorption of water
NephronGlomerulus, Tubule, & Loop of Henle
Nephronremove excess water, wastes, and other substances from blood & return substances (ions) when needed
Glomerulusblood vessel or capillary (looks like ball of yarn) that filters blood & keep normal proteins and cells in bloodstream and allows wastes, excess fluid and other substances to pass
Blood pressure within glomerulusis very high due to difference in diameter between the large afferent arteriole and the narrower efferent arteriole
Tubulewastes, extra fluid and other recyclable substances like sodium and potassium filtered out from the glomerulus pass through
Proximal convoluted tubule (PCT )highly coiled region that is the site of early reabsorption of water, ions, glucose, and amino acid & nitrogenous wastes are secreted


Question Answer
Distal convoluted tubule (DCT )site of the secretion of any extra wastes
Loop of Henledescending segment is the site of water reabsorption (osmosis) & ascending segment is site of ion reabsorption (active transport)
Glomerular filtrationpowered by hydrostatic pressure. Nutrients are reabsorbed and urea are filtered out (small amounts)
Secretion and reabsorptions of solutesProximal convoluted tubules reabsorb nutrients and most of the ions & urea are filtered as urine (actively excreted NH4+/creatinine/organic acids).
Loop of Henle reabsorbswater and salt using countercurrent mechanism
Distal convolutedtubules selectively reabsorb or secret nutrients/ions based on hormonal control
Collecting duct reabsorbswater to concentrated urine when ADH is released (hormonal control)


Question Answer
Acidic bloodsecret H+
Basic bloodfilter out HCO3-
Concentration of urineDistal convoluted tubes carry urine becomes more concentrated in collecting duct high concentration in the loop of Henle reabsorption of water in the collecting duct occurs
Countercurrent multipliercreates an osmotic gradient down the loop of Henle used by collecting duct to concentrate urine
NaCl pumpdrives ascending loop to allow urine to be concentrated in the collecting duct
Countercurrentis when descending limb filters water out and become impermeable to salt and ascending limb filters salt out and become impermeable to water
Urea recyclingurea at the bottom of the collecting duct leaks out into the interstitial fluid and back into the filtrate high osmolarity at the bottom of the loop of Henle
Excretory Storage and EliminationCollecting ducts drain urine into the ureter ureters drain into the bladder bladder stores urine (epithelium structure allows storage of large amount of urine) urine filters out through the urethra (exiting the body)