Chapter 36 Flashcards
(43 cards)
what are the 3 properties of body fluids?
osmotic pressure, ionic composition, and volume
osmotic pressure
measure of the total concentration of solutes
what is the direction of water flow by osmosis?
regions of high concentration to regions of low concentration
ionic composition
principal solutes are Na+, K+ and Cl-
volume
volumes of water are coming and going all the time
urine
fluid that is excreted into the outside environment
nephrons
microscopically tiny tubules in a vertebrate kidney
what fluid does the kidney tubule start with?
blood plasma
what fluid does the kidney tubule end with?
urine
kidney
organ composed of tubular structures that produces an aqueous solution for excretion
what is the U/P ratio?
ratio of composition of urine to composition of plasma
what happens when U/P is less than 1?
kidneys are making the plasma become more concentrated
what happens when U/P is greater than 1?
kidneys are making plasma become more dilute
extrarenal salt excretion
other organs may be able to excrete ions at high total concentrations
salt glands
excrete highly concentrated salt solutions, seen in birds and non-avian reptiles that live near/in oceans and deserts
nitrogenous wastes
nitrogen containing toxic wastes
what is the simplest nitrogenous waste to produce?
ammonia
what is the problem with ammonia?
it is highly toxic, concentration must be kept low in the body fluids
ammonotelic
animals that excrete nitrogen principally as ammonia
why can the fish and other water-breathing animals excrete nitrogen?
they can lose it rapidly into their aquatic environment
what is the disadvantage of producing less toxic nitrogenous waste?
requires ATP and thus has a metabolic cost
what is the advantage of producing less toxic nitrogenous waste?
do not need to be excreted immediately
urea
a form of waste nitrogen that is very soluble and relatively low in toxicity
ureotelic
animals that excrete waste nitrogen principally as urea
