Ianowski - theme 3 and 4 Flashcards
Osmoregulatory organs:
External surfaces (gills/skin), salt glands, gut, kidneys
What are kidneys called in insects? worms?
Insect - protonephrones
Worms - metanephrones, malphigian tubules
Gills:
Involved in ion transport and waste excretion. In teleost (bony) fish, they play a major role in osmoregulation. Gills are great for osmoreg because they have lots of contact between water and blood.
Skin:
Used when you can’t have gills :(
In frogs and stuff
Marine osmoregulators:
Water leaks out, ions leak in. Need to drink a lot of water and pump ions out. Pee out ions.
mOsm of osmoregulators:
300 mOsm.
Freshwater osmoregulators:
Water leaks in, ions leak out. Don’t drink water, pee lots of water.
Transporting epithelia:
Cells specialized for ion transport. Necessary for osmoregulation. Highly conserved across animal groups.
The story of transporting epithelia: marine fish
Fish loses water.
Chloride cells bring in chloride. Interior of cell becomes more positive than sewater, so they draw Na+ and K+ out of the blood and to the outside. *** this is so hard
Salmon alternate between hypo- and hyper-osmoregulation.
Acclimatization regulation and anticipatory mechanisms.
Going to salt: Cortisol triggers growth of seawater chloride transport epithelium and increases Na/K ATPase.
Going to fresh: prolactin triggers growth of freshwater chloride transport epithelium, reversing the direction of ion transport.
Salt glands, in birds and reptiles.
Cry out 0.9M NaCl solution from 0.45M sea water - keep half of seawater intake. NaCl is actively transported from blood into secretory tubules through secretory cells. Blood flows in opposite direction of salt solution.
Endocrine regulation of salt glands:
In high blood osmolarity…
PNS, corticosterone (from adrenal glands), ANP (from heart) stimulates salt gland. Kidney is shut down to conserve water.
The process of filtering through kidneys: beginning at proximal end
Filtration: small molecules and ions are nonselectively exchanged between blood/fluid and inside of tubule.
Reabsorption: nutrient molecules, ions, and water are actively transported out of the tubule.
Secretion: excess ions and toxins are pushed back into the tubule.
Release: pee
Where does osmolarity of pee vs blood change?
Collecting duct: equal osm
Proximal tubule: minor changes
Distal tubule: major changes
Storage bladder: no change
Primary urine:
Collecting duct urine that hasn’t been modified. Formed by ultrafiltration or active secretion.
Ultrafiltration:
Exchange between blood and primary urine. Solutes travel into the urine by blood pressure but plasma is blocked by a filter.
Active secretion:
Used by organisms with open circulatory systems because blood pressure can’t drive this. Active transport of ions creates concentration gradients for water and other stuff (sugars, AAs) to get into the primary urine.
Malphigian tubules of blood-drinking Rhodnius prolixus:
Blood is 50% plasma - need to get rid of this. Plasma is hyposmotic so it brings water and . Produces hyposmotic urine.
***
Insect excretory system:
h
What can get through membranes?
Non polar is good. If polar, must be small and uncharged. Too big or too charged can’t get through.
Aquaporin:
Passive transport of water.
K+ voltage-gated channel:
Under normal charge, K+ can’t move. With a charge difference, K+ is passively transported.
Primary active transport: follow (p)
Carrier protein is phosphorylated to make it active. It does its conformation changey magic to transport ions. Returns to inactive form when dephosphorylated.
Na/K pump:
Cytosol-facing: high affinity for Na.
Outside-facing: conformational change lowers affinity for Na and raises affinity for K.
Symport:
A passively travels and brings B against B’s gradient.
Antiport:
A actively travels and B can sneak the opposite direction with its gradient.
