routes of elimination
exhalation biotransformation (chemical transformation - liver) feces urine sweat
kidney and homeostasis
most important organ for this
filters blood
removes waste products
regulates concentration of ions
metabolite
what’s produced as a drug breaks down
importance of breakdown of molecules in drug development
safest drugs are eliminated easily and predictably
very hard to predict this without human testing
liver
venous blood flows to liver from intestine, access to all nutrients and toxins, excretes to bilary system and empries to small intestine
converts lipid soluble materials into polar compounds so kidney can excrete them
hepatocytes
liver cells that extract compounds from blood
have enzymes that help with conversion of lipids
bilary system
create/store bile and release to duodenum which helps with digestion and controlled release of bile
bile
fluid with waste products, cholesterol, and salts
bile salts
component that helps break down and absorb fats
nephrons
main functional subunit of kidney (fluid exchange)
process of urine conentration
step 1: glomerulus (filtration - permeable to fluid waste but not blood) (waterproof with some permeability)
step 2: tubules (reabsorption and secretion)
glomerular filtration
total renal plasma flow (RPF)=0.6L/min
oncotic pressure
osmotic pressure due to presence of proteins, not electrolytes like Na+ and Cl-)
hydrostatic pressure
combined with oncotic pressure - driving force for fluid movement in glomerulus
pressure drop in glomerulus
need to apply pressure so fluid can go through the membrane, so there is a pressure drop on either side
Glomerular filtration rate (GFR)
total volume of fluid that is filtered across the membranes in kidneys per unit time
directly proportional to hydrostatic pressure drop across membrane
approx 125mL/min
Resistance and GFR
GFR will be affected if there is resistance in arterioles
resistance goes up as diameter goes down, so if a blood vessel decreases in diameter by a factor of 2, the resistance increases by 16
