Excretion and Osmoregulation Flashcards
What is excretion, and what is often excreted?
elimination from the body of metabolic waste products
CO2, H2O, nitrogen
CO2 is often released through gas exchange
What is osmoregulation, and what does it maintain?
regulation of water and ion balance within the body fluids
maintains concentration of body fluids
What is nitrogeneous waste, and what is it released as?
excess nitrogen released during deamination of amino acids to build protein
liberated as ammonia that is diluted, eliminated, or converted
What are ammonotelic organisms?
aquatic invertebrates releasing nitrogenous waste as ammonia
How do ammonotelic invertebrates excrete, and examples?
diffuses easily through fluids and tissues, and lost through body wall
sponges, cnidarians, xenacoelomorphs, and echinoderms lack excretory organs
What limits ammonotelic organisms?
limited to aquatic habitat and ammonia production
What do terrestric invertebrates convert nitrogenous waste to?
less toxic compounds like urea and uric acid
Pros and cons of terrestrial invertebrate nitrogenous conversion
energetically expensive
no dilution by water
can be stored within body
What are ureotelic animals?
amphibian, mammals, fish
What are uricotellic animals?
terrestrial invertebrates
Why is uric acid conversion beneficial?
uric acid is insoluble, and excreted as waste without water loss
What is osmoregulation tied to?
environment
What state are marine invertebrates in? (2)
isotonic
none are exactly isotonic, and must maintain regulation
What state are freshwater invertebrates?
hypertonic, and must prevent influx of water and loss of salts
What must terrestrial animals face?
water loss
What kind of body walls do aquatic animals have?
modified body wall to reduce permeability
WHat are osmoregulators?
maintain internal body fluid; freshwater
What are osmoconformers?
allows body fluid change in response to environment (mussels), but must osmoregulate to an extent
What are stenohalines?
restricted to a narrow range of salinity
What are euryhaline?
tolerate extensive variation of salinity
How are all hypotonic organisms similar (2)?
all tends to swell in a hypotonic environment, and excrete excess water
- cells are now in stress and swells, and must release solutes
How do terrestrial arthropods and gastropods prevent dessication?
exoskeleton
How do small creatures osmoregulate?
diffusion
What are water expulsion/ contractile vacuoles? (2)
freshwater sponges/protists method to excrete excess water
accumulates cytoplasmic water and expels it from the cell
What is nephridia?
ectodermally derived excretion organ
What is protonephridium, and how is it arranged (2)?
simplist nephridium
tubular arrangement opening to the outside via nephridiopores and terminating internally in closed unicellular units
cap cells (terminal) are folded into cups to create a nephridioduct, into the nephridiopore
What are flame bulbs?
protonephridia with cilia
What are solenocytes?
protonephridia with one or two flagella
What does cilia/ flagella do in a protonephridium (2)?
drives fluids down the duct to create low pressure
low pressure draws in fluids and waste
What are protonephridium common in>
acoelomates, blastocoelomates, some annelids
What is protonephridium important in?
important for osmoregulation than excretion
Flaw of protonephridium?
cannot handle large fluid volumes
What are metaniphridium?
open internally to the body fluid
What kind of metaniphridium do large coelomates have, and what kind do arthropods have?
many have multiple for larger coelomates
Arthropods have closed metanephridia
What is the structure of metaniphridium?
inner ends bare a nephrostome (ciliated funnel) with an elongated duct
What do metanephridium do?
takes in large amounts of body fluid through the open end and asborbs most of the reclaimable components
Why would metaniphridium be ineffective in non-coelomates?
ineffective for acoelomates and would drain quickly in blastocoelomates
What are coelomoducts?
tubular connections from the coelom extending to the outside via pores
What is the structure of coelomoducts? (2)
ciliated for release of gamete
fused with nephridia to produce nephromixia
What are protonephromixium?
when nephromixia and protonephridium share a common duct
What are metanephromixium and mixonephridium, and how do they differ?
when a coelomoduct is united with a metanephridium
depends on structural nature
Where does nephridia arise from?
nephridia arises from the outer body wall (mesoderm and ectoderm)
How do echinoderms and chaetognaths excrete? (3)
no discrete system
waste is eliminated across skin surface or gut lining
can use ameboid phagocytic cells
What are malpighian tubules?
- excretory organs that resemble modified nephridia
