excretion
removal of metabolic wastes produced in the body
aerobic respiration
leads to the production of carbon dioxide and water
deamination
of amino acids leads to produced of nitrogenous wastes such as urea and ammonia
elimination
removable of undigestible material, such as dietary fiber
lungs, liver, skin and kidneys
principal organs of excretory system
lungs
CO2 and water vapor diffuse from blood and are continually exhaled
skin
sweat glands here excrete water and dissolved salts (and a small quantity of urea)
liver
produces nitrogenous wastes, hemoglobin, and other chemicals for excretion
kidneys
urea is produced by the deamination of amino acids in the liver and diffuses into blood for ultimate excretion here
bile salts
excreted as bile and pass out with the feces
kidneys
function to maintain the osmolarity of the blood, excrete numerous waste products and toxic chemical, and conserve glucose, salt, and water
nephron
unit that composes the kidney
cortex, medulla, and renal pelvis
3 regions of kidney
glomerulus
contained by bowman's capsule
bowman's capsule
nephron consists of a bulb called
medulla
loops of henle and collecting duct run through which region of kidney
cortex
convoluted tubules and bowman's capsule run through which region of kidney
pelvis of kidney
concentrated urine in the collecting tubules flows into
urinary bladder
ureters coming from pelvis of kidney empty into
urethra
expels the urine
filtration, secretion, reabsorption
3 processes that lead to urine formation
filtration
passive process driven by hydrostatic pressure of the blood; blood pressure forces 20% of blood plasma entering the glomerulus through its capillary walls and into Bowman's capsule via diffusion; called filtrate; filtrate is isotonic with blood plasma
secretion
nephron secretes waste substances such as acids, ions, and other metabolites from the interstitial fluid into the filtrate by passive AND active transport; materials secreted from the peritubular capillaries into the nephron tubule
reabsorption
essential substances (glucose, salts, and amino acids) and water are reabsorbed from the filtrate and returned to blood; active process in proximal convoluted tubule; water passively follow solute; concentrated urine hypertonic to blood
proximal convoluted tubule
reabsorption occurs here
distal convoluted tubule
secretion occurs here
ascending loop of henle, collecting duct, descending loop of henle
primary sites that regulate water, sodium, and potassium loss in the nephron
descending loop of henle
very permeable to water but not to ions or urea
ascending loop of henle
impermeable to water but permeable to ions, allowing for passive diffusion of ions
cortex to inner medulla
tissue osmolarity increases from
counter-current-multiplier system
a system in which energy is used to create a concentration gradient
renal tubule
osmolarity of urine established here by the counter-current-multiplier system
hyperosmolar
counter-current system causes the interstitial space in the medulla of the kidney to be THIS with respect to the dilute filtrate flowing through the renal tubule
osmosis
water flows out of collecting ducts by:
ADH (vasopressin)
hormone that increases permeability of the collecting duct to water, allowing more water to be absorbed and more concentrated urine to be formed
aldosterone
steroid hormone that causes increased transport of sodium and potassium ions along the distal convoluted tubule and collecting duct, resulting in decreased secretion of sodium ions and increased excretion of potassium ions in the urine
antidiuretic hormone (ADH)
vasopressin; peptide hormone with same net effect of increased water reabsorption as aldosterone; directly affects water absorption by the distal convoluted tubule and collecting ducts, opening addition aquaporins to allow water to be reabsorbed more read
diuretics
drugs that increase urine producion
respiratory acid-base disorder
affect the blood acidity by causing changes in the PCO2
metabolic acid-base disorder
affect the blood acidity by causing changes in the HCO3-
cortex
region of kidey that has lowest solute concentration
reabsorption
in the nephron, amino acids enter the peritubular capillaries bia
proximal tubule
glucose reabsorption occurs here
hypertonic
urine is WHAT to the blood