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58 Cards in this Set
- Front
- Back
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________ is a medium in which chemical reactions necessary for life are performed
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water
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Which solutes do intracellular and extracellular fluids contain?
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Na+, K+ and Mg+ ions
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What does solute concentration determine and what does it affect?
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determines the pH, osmotic pressure and the availability of chemical reactants, all of which affect metabolic processes.
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What is osmoregulation?
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an homeostatic process that regulates solute concentrations and balances the gain and loss of water in the body
aka: solute (ion) concentration of a solution |
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What does osmoregulation regulate?
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the water and solute composition of extracellular (internal) fluids which effect the exchange of water and solutes with the cells
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How is osmoregulation achieved?
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by controlling movement of solutes (ions) between internal fluids and the external envrionment
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What does iso-osmotic mean?
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same osmolarity, the movement osfwater is equal in both directions
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What is the direction of flow of solutes?
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solutes move from regions of higher concentration to regions of lower concentration
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How does water diffuse? from which type of solution to which?
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from hypo-osmotic (dilute) to a hyper-osmotic solution
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What is hypo-osmotic?
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solution with lower concentration
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What is hyper-osmotic?
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solution with higher concentration
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Will a cell in a hypo-osmotic solution swell or shrink compared to the intracellular fluid?
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swell
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Will a cell in a hyper-osmotic solution swell or shrink compared to the intracellular fluid?
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shrink
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What is an osmoregulatory challenge faced by marine organisms?
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lower internal solute concentration than environment. therefore they lose water by osmosis and gain salts as a consequence of drinking seawater
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What is an osmoregulatory challenge faced by freshwater organisms?
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higher internal solute concentrations than environment. Therefore they gain water by osmosis and lose salts by diffusion
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What is an osmoregulatory challenge face by terrestrial organisms?
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lose body water through desiccation (evaporation)
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Name two strategies for osmotic regulation
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1) osmoconformers
2) osmoregulators |
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What is an osmoconformer?
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-body fluids are iso-osmotic with external environment.
-regulation of particular ions often occurs. -all line in marine habitats -marine invertebrates; hagfish, sharks |
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What is an osmoregulator?
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-controls the osmolarity of their body fluids independent of the osmolarity of the environment
-requires energy -different than environment -all freshwater and terrestrial animals, some marine animals |
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What does stenohaline mean?
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when animals cannot tolerate substantial changes in external osmolarity
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What is an Euryhaline animal?
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can survive large fluctuations in external osmolarity. can be either osmoregulators or osmoconformers.
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Give two examples of euryhaline animals
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1) Diadromous
2) Estuarine and inter-tidal animals |
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What are Diadromous animals?
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fish that migrate between freshwater and ocean during different phases of life.
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What is the difference between sea and freshwater diadromous animals
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sea: hypo-osmotic regulators
fresh: hyper-osmotic regulators |
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What are Estuarine and inter-tidal animals?
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exposed to lower salinity at low tide and high salinity at high tide twice daily
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Name two types of osmoregulators
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hypo-osmotic regulators
hyper-osmotic regulators |
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Define an hypo-osmotic regulator
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osmolarity of their body fluids lower than that of their hyper-osmotic environment
-face dehydration -respond by actively taking in water and ions -marine bony fishes and air-breathing marine vertebrates |
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Define hyper-osmotic regulators
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osmolarity of their fluids higher than the hypo-osmotic environment
-face problem of water gain and water loss -respond by discharging excess water and retaining ions -freshwater fishes, amphibians, freshwater invertebrates |
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What are some mechanisms of obtaining water in animals
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-absorb it from the environment via osmosis
-drinking -eating foods -as a by-product of cellular respiration (metabolic water) |
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What are most marine invertebrates?
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osmoconformers (body fluid=seawater)
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What are marine vertebrates? Why?
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hypo-osmotic regulators because ocean is saltier than their body fluids so they los water from their body by osmosis. They need to take in more water than is lost
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What happens (through osmoregulation) in marine bony fish?
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osmotic water loss through gills
-compensate by drinking seawater -excretion of excess salts through gills -produce very small amounts of urine |
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What do most chondrichthyans have that is different from other marine bony fish?
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internal osmolarity
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chondrichthyans have a much ________salt concentration than the sea water but their solute osmolarity is __________, preventing______
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lower; the same; water loss
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chondrichthyans tissues contain __________concentrations of urea which ____________the solute concentration of their fluid
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high; increases
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Urea is _________and trimethylamine oxide (TMAO) ________ proteins from damage from urea and ________the osmolarity
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toxic; protects; increases
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What are chondrichthyans also considered functionally?
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osmoconforming ion regulators
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Do chondrichthyans drink seawater?
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no
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how does sea water enter the chondrichthyans body?
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by osmosis and consumed in food
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In chondrichthyans, excess salt is excreted by _______ and by specialized _______
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kidneys; rectal gland
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What do marine birds and reptiles use to actively transport salt from the blood to outside?
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nasal salt glands
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What is a transport epithelium comprised of?
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one or more layers of specialized epithelial cells that regulate solute movements
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What does counter-current circulation maintain?
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the concentration gradient favouring the movement salts from the blood to the lumen of the gland
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In freshwater environments, animals have _________ solute concentrations in their body fluids than marine animals
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lower
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What kind of osmotic regulators are freshwater animals?
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hyper-osmotic regulators (opposite os marine animals)
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How do freshwater animals gain water and why? How do they compensate for this?
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gain water by osmosis and lose salts by diffusion because their body fluids are saltier than fresh water.
compensate by drinking very little water |
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How do freshwater animals obtain salts? How do they uptake it?
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obtain salts in food consumed; actively uptake salts across gills
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What is a serious challenge for many terrestrial environments?
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threat of desiccation
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In terrestrial environments, what adaptations reduce the risk of dehydrations?
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body coverings
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What happens to animals, that temporarily live in wetlands, when they water supply dries up?
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thy enter a dormant state
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What does anhydrobiosis?
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life without ater
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What is so special about tardigrades and midge larvae?
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>85% water by weight when active, but dehyrdrate to ~2% when inactive and dormant
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What is a tardigrade?
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water bear
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What do dessicated individuals possess large amounts of that prevent formation of crystals that cause cell damage?
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the sugar trehalose
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In frogs, what does freezing do?
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increases the osmolarity outside the cell ad causes cell dehydration
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Reduction of cell volume causes compressive stress on what?
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compressive stress on the cell membrane which can collapse
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What does intracellular cryoprotectant go ?? (glusoce)
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reduces the freezing point of the cell
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Shrinking prevention by accumulating large quantities extracellular cyroprotectant (glucose) which ______the osmolarity of the cell and ________water efflux
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increases; reduces
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