Osmoregulation... Flashcards
Osmoregulation
The maintenance of salt (solute) and water balance in an organism
Osmosis
Special case of diffusion in which the molecules dissolve in water (“solute”) are not diffusing, but rather the water molecules (“Solvent”) diffuse across the cell membrane.
Solute
Molecules dissolved in water
Solvent
Water molecules (dissolves solute)
Isoosmotic
when two solutions have the same osmolarity
hyperosmotic
when one solution has a greater osmolarity than another (more solute)
hypoosmotic
when one solution has a more dilute solution than another
osmoconformer
are isoosmotic with surroundings (marine animals only)
Have no tendancy to gain or lose water
osmoregulator
must control its internal osmolarity (all freshwater & terrestrial animals)
i.e.
if it lives in a hyperosmotic environment it must take in water
if it loves in a hypooosmotic environment it must get rid of excess water
stenohaline
can tolerate only narrow changes in external osmolarity
i.e.
goldfish
Euryhaline
organism can tolerate large fluctuations in external osmolarity
i.e.
Tilapia
osmoregulatory adaptations
Gills ( excretion of salt ions & osmotic water loss)
Sharks maintain high internal solute concentrations (urea) which makes them hyperosmolar to sea water.
anhydrobiosis
ability to survive when water source dries up
Tardigrades
“Water Bears” anhydrobiosis animals can survive for 4-7 years in this dried up state.
Filtration
the excretory tubule collecs a filtrate from the blood. Blood preesure forces water & solutes across the selectively permeable membreane into the tubule.
Reabsorpiton
the transport of epithelium reclaims needed substances from the filtrate where they return to the body fluids
Secretion
other unwanted compounds (toxins, ions) are actively extracted from the body fluids & added to the filtrate for excretion
Excretion
the filtrate leaves the body as urine
Filtrate
water and solutes forced inside the excretory tubule by blood pressure.
urine
filtrate that was not reabsorbed into the body made up of water, solutes, toxins, and ions)
transporting epithelium
the key to re absorption & secretion
Solutes move selectively across the transporting epithelium to/from the blood to the lumen of the tubule
to go against concentration gradients specialized proteins move solute across the epithelium
Lumen
Inside of secretory cell in the secretory tubule where solutes move either accross the membrane to the lumen or accross the tubule to the blood
protonephridia
osmoregulation
metanephridia
osmoregulation & excretion
Malpighian tubules
osmoregulation & excretion of N2 wastes
*kidney (renal cortex)
jl;
*kidney (renal medulla)
daf
*kidney (renal arteries & veins
ad
ureter
modified fluid leaves the kidney and enters the ureter.
bladder
the fluid (urine) passes through the two ureters and empties into the urinary bladder
urethra
The bladder expands and fills with urine until by reflex action it contracts & expels the urine through he urethra
Nephron
The functional unit of the kidney. Contains the loop of Henle, juxtamedullary nephron and cortical nephron
cortical Nephron
resides entirely in the cortex; reduced loop of Henle (80% of all nephrons)
juxtamedullary nephron
dives dep into the medulla; enables mammals to produce urine that is hyperosmotic to body fluids.
*glomerulus
daf
*Bowman’s capsule
daf
proximal tubule
sals, especially NaCl, water and nutriens are absorbed primarily in the proximal tubule (right before the loop of Henle).
Loop of Henle
the descending portion is not very permeable to solutes, but permeable to water.
the ascending portion is permeable to solutes, but not much to water.
distal tubule
Right after loop of Henle. Plays key role in regulation of NaCl and K+ in body fluids by varying their absorption and secretion; also in pH regulaion
Collecting duct
plays role in how much NaCl is reclaimed in the filtrate by altering its acive transport. As it passes through the medulla more water is reabsorbed, concentrating the urine
