osmoregulation and excretion Flashcards
osmoregulation
regulates solute concentrations and balances the gain and loss of water
what does excretion do?
gets rid of nitrogenous metabolites and other waste products
osmosis
movement of water across a selective permeable membrane
osmolarity
the solute concentration of a solution, determines the movement of water across a selectively permeable membrane
osmoconformers
found only in some marine animals.
are isoosmotic with surroundings.
do not regulate osmolarity.
can be stenohaline (narrow) or euryhaline (wide) in tolerance.
osmoregulators
expend energy to control water uptake in a hypoosmotic environment and loss in a hyperosmotic environment
explain how marine bony fish are hypoosmotic to seawater
they lose water by osmosis and gain salt by diffusion and from food. they balance water loss by drinking seawater and excreting salts.
what is anhydrobiosis?
some aquatic invertebrates lose almost all their body water and survive in a dormant state.
explain how freshwater animals are hypoosmotic to their environment
they constantly take in water by osmosis.
they loose salts by diffusion and maintain water balance by excreting large amounts of dilute urine.
salts lost by diffusion are replaced in foods and uptake across gills
what are some adaptions of the kangaroo rat to conserve water?
concentrate urine
dry feces
produce uric acid instead of urea
transport epithelia
are specialized epithelial cells that regulate solute movement. essential components of osmotic regulation and metabolic waste disposal. Arranged in complex tubular networks.
how do seabirds eliminate excess salt from their bodies?
salt glands which remove excess sodium chloride from the blood
Ammonia in terms of nitrogenous waste
toxic needs lots of water. Common in aquatic species
urea
the liver in mammals converts ammonia to less toxic urea. the circulatory system carries urea to kidneys where it is excreted. less water to excrete than ammonia nut energetically expensive to convert
uric acid
excreted by insects, snails and reptiles. largely insoluble in water, can be secreted as a paste with little waterloss. more energetically expensive than urea
filtration
pressure-filtering of body fluids
reabsorption
reclaiming valuable solutes
secretion
adding toxins and other solutes from the body fluids to the filtrate
excretion
removing the filtrate from the system
protonephridia
network of tubules in flame cells/planaria
metanephridia
network of tubules in earthworms. similar to nephrons
malpighian tubules
network of tubules in insects
nephrons
network of tubules in humans. the functional unit of the kidney
Protonephridium
a network of dead-end tubules connected to external openings. The smallest branches of the network are capped by a cellular unit called a flame bulb. Excrete a dilute fluid and function is osmoreuglation
Metanephridia
Each segment of an earthworm has a pair of open-ended metanephridia. Both excretory and osmoregulatory functions. Consists of tubules that collect coelomic fluid and produce dilute urine for excretion.
Malpighian tubules
in insects and arthropods. remove nitrogenous wastes from hemolymph and function is osmoregulation. MT open into digestive tract. Insects produce a dry waste matter, highly efficient in water conservation.
kidneys
excretory organs of vertebrates, function in both osmoregulation and excretion. principle site of water balance and salt regulation
what is the kidney blood supply
supplied by a renal artery and drained by a renal vein
how does urine exit the kidney?
through a duct called the ureter, both ureters drain into the bladder and urine is expelled through the uretha
the nephron
the functional unit of the vertebrate kidney consists of a single long tubule and a ball of capillaries called the glomerulus
bowmans capsule
surrounds and receives filtrate from the glomerulus capillaries
how does filtration occur ?
as blood pressure forces fluid from the blood in the glomerulus to lumen of the bowmans capsule
is filtration of small molecules selective
no
what does the filtrate contain?
salts, glucose, amino acids, vitamins, nitrogenous wastes and other small molecules
what is the pathway of the filtrate ?
proximal tubule> loop of henle> distal tubule
Vasa rectA
capillaries that serve as the loop of henle
how do the vasa recta and loop of henle function?
as a counter current system
how does the kidney conserve water?
producing urine that is much more concentrated than bodily fluids
what happens in the proximal tubule?
Reabsorption of ions, water and nutrients. Molecules are transported actively and passively from the filtrate into the interstitial fluid and then capillaries. Some toxic materials are secreted into the . The filtrate volume decreases
What happens in the descending limb of the loop of henle
Reabsorption of water continues through channels formed by aquaporin proteins. Movement is driven by the high osmolarity of the interstitial fluid, which is hyperosmotic to the filtrate. The filtrate becomes increasingly concentrated
What happens in the ascending loop of henle?
salt but not water is able to diffuse from the tubule into the interstitial fluid. the filtrate becomes increasingly dilute
dital tubule
regulates the k+ and NaCl concentrations of body fluids
collecting duct
carries filtrate through the medulla to the renal pelvis. water is lost as well as some salt and urea and the filtrate becomes more concentrated.
is urine hyperosmotic to body fluids
yes
How much filtrate to human kidneys produce per day
180 L
what is reabsorbed?
99% of water and nearly all sugars, vitamins and amino acids
