Salinity and osmosis Flashcards
How is nitrogenous waste excreted in eukaryotes in aquatic organisms?
in the form of ammonia, which can be quickly carried away
what salinity is salt water?
35
What temperature does salt water freeze at?
-1.86 degreec C
what is an osmoconformer?
an organism in which the internal osmostic concentration is approximately isoosmotic with the surrounding seawater
what is an osmoregulator?
an organism which has to regulate the ionic and osmotic composition of their body fluids since they are often found in variable habitats, or migrate between habitats
Name a species that regulates its salt content for improved buoyancy and explain how
Aurelia/common jellyfish exchnage sulphate ions for less dense ammonia and potassium ions
Give a behavioural mechanism organisms may use to avoid exposure to extreme conditions
burrowing
How do cells maintain an isosmotic intracellular composition?
regulate amino acids by breaking down or synthesising proteins.
What is the main amino acid used in intracellular osmotic regulation?
glycine, and betaine or TMAO in higher organisms (e.g. cephalopods)
What is a disadvantage of intracellular osmotic regulation?
it changes the electrochemical environment around proteins, including enzymes
which amino acids are not used in osmotic regulation?
lysine and arginine, because they alter protein’s tertiary structure
What is a hypotonic regulator?
organisms that maintain a low internal ionic concentration, i.e. marine vertebrates, that regulate ionic composition but not necessarily their total osmotic concentration
How can organisms regulate their intracellular osmotic concentration without increasing their ionic levels?
by the accumulation of urea and TMAO
Give a disadvantage of the accumulation of urea
it destabilises protein structure by lowering the denaturation temperature
Give an advantage of using TMAO in addition to urea
the accumulation of TMAO may offset the negative effects of urea by stabilising proteins and increasing denature temperature
How do marine vertebrates actively regulate their ionic concentration?
they remove ions that diffuse through gills and secrete them out through specialised removal mechanisms, e.g. cloacal gland extracts salts and deposits them into the cloaca
What does it mean for a marine teleoist to be a true hypo-osmotic regulator
the composition of their body fluids are just a fraction of saltwater concentration
How do marine teleosts counteract osmotic water loss?
they drink sea water, which is removed of chloride ions by large specialised chloride cells in active transport, and is followed by the passive removal of sodium ions.
How do birds and reptile maintain an isosmotic internal concentration when they ingest a large amount of saltwater?
they have salt glands in their head which secrete hyperosmotic NaCl solution
How does the chinese swamp turtle uniquely reduce urinary water loss?
it excretes urea through specialised glands in its mouth
How can dolphins and whales ingest salt water without disrupting their isosmotic composition?
their kidneys form a concentrated urine of around 820mM Cl-.
Name the 3 basic processes that make up a tubular filtration system of metabolically active organisms?
filtration, selective reabsorption/secretion, excretion.
What is a protonephrial system?
tubules spread across the body. Beating cilia force interstitial fluid into the gut, where specialised cells with ionic channels and intermembrane pumps to reabsorb important ions in exchange for less useful CL- ions
What is a metanephridial system?
has an internal opening (nephrostome) with funnel structure, allowing body fluids to pass along a convoluted tubule system, where lining cilia move to generate a unidirectional flow.
What is the function of antennal/green glands in crustacea?
similar to kidneys - sac at top allows for diffusion of body fluids across wall of coelomosac, followed by labyrith to increase SA for selective reabsorption before nephridial canal.
