ch 10 Flashcards
main organs of excretory
- kidneys
- ureters
- bladder
- urethra
main functions of excretory: 4
- excretion of metabolic wastes
- nitrogenous wastes (ammonia: highly toxic and converted to urea in liver, urea, uric acid) - maintenance of water-salt balance
- maintain appropriate levels of K+. HCO2- (bicarbonate), and Ca2+ in the blood - maintenance of acid-base balance
- kidneys monitor and help keep blood pH at 7.4 by excreting H+ ions and reabsorbing HCO2- as needed - secretion of hormones
- kidneys help endocrine in hormone secretion (secrete CALCITRIOL (active form of vitamin D: promotes Ca++ absorption from digestive tract) and ERYTHROPOIETIN (stimulates red blood cell production + is released in response to either increase oxygen demand/reduce oxygen-carrying capacity of blood)
3 regions of kidneys
- cortex (outer layer)
- medulla (inner layer, beneath cortex, consists of renal pyramids: cone-shaped tissue masses)
- renal pelvis (hollow chamber where collecting ducts join and empty into ureter)
define nephrons
microscopic tube-like functional filtration units of kidneys (approx 1 million per kidney)
- each has its own blood supply provided by 2 capillary regions
- role: filter wastes while retaining/reabsorbing water and other vital materials
3 main parts of nephrons anatomy
- filter (glomerulus, afferent/efferent arterioles)
- tubules (proximal convoluted tubule, loop of henle, distal convoluted tubule)
- duct (collecting duct)
3 main parts of nephrons anatomy: THE FILTER: glomerulus
knot of capillaries inside bowman’s capsule
- walls: filtration device, impermeable to proteins, other large molecs, and red blood cells (they remain in blood)
- waste of metabolism (water, small molecs, ions, urea) pass through walls and into nephron to eventually be excreted like blood in urine
- filtered fluid = filtrate (not yet urine)
3 main parts of nephrons anatomy: THE FILTER: afferent arteriole
carries blood TO glomerulus
3 main parts of nephrons anatomy: THE FILTER: efferent arteriole
- carries blood AWAY from glomerulus
- connects to the peritubular capillary network
3 main parts of nephrons anatomy: THE TUBULES: proximal convoluted tubule
narrow region of nephron after the bowman’s capsule, found in renal cortex
- joins bowman’s capsule to loop of henle
- main function: water + solutes reabsorption
- involves both active and passive transport mechanisms
3 main parts of nephrons anatomy: THE TUBULES: loop of henle
- as the tube narrows, a U-turn making a loop in the tubule
- consists of a descending limb (allows water to leave filtrate/reabsorbed) and an ascending limb where ions (Na+, Cl-, K+) leave filtrate (reabsorbed into bloodstream)
- found in renal medulla
- animals in desert have adapted to their environment: have extremely long loops of henle (longer path: more surface area to reabsorb more water)
- must reabsorb most of water from filtrate
3 main parts of nephrons anatomy: THE TUBULES: distal (convoluted) tubule
last convoluted tubule following loop of henle
- function: reabsorption of water + solutes
- found in renal cortex
3 main parts of nephrons anatomy: THE DUCT: collecting duct
water conservation device (reabsorbing water from filtrate)
- filtrate = now urine
- area where urine is collected in kidney
- dis. conv. tubules of several nephrons enter on collecting duct
- many collecting duct in each kidney
- carries urine to renal pelvis
- found in renal medulla
general process + movement of urine
- kidneys produce urine
- ureters transport urine
- urinary bladder stores urine
- urethra passes urine to outside
