Ion + Water Regulation and Nitrogenous Waste in Animals Flashcards
Osmosis
the diffusion of water DOWN its concentration gradient through a semipermeable membrane
- water’s CG is inversely proportional to the concentration of solutes in the water
Osmolarity
the total solute concentration in a solution
Osmotic Pressure
the pressure exerted on a membrane to equalize the solute concentration on either side of the membrane
- influenced by solute concentration
- directly proportional to the # of solute molecules
- NOT dependent on the size of solute molecules
Hypotonic
extracellular fluid has lower osmolarity (lower solute concentration) than the cell cytoplasm, and water enters the cell
- extracellular water has higher water than in the cell
- water follows its CG + enters the cell
- cell expands and may burst
Hypertonic
extracellular fluid has higher osmolarity (more solute concentration) than the cell cytoplasm, and water exists the cell
- cell cytoplasm has more water
- cell will shrink + shrivel
Isotonic
the extracellular fluid and cell cytoplasm have the same osmolarity
- if they match, there is no NET movement of water
- water will still move in and out of the cell
Osmoregulating
maintaining an internal cellular environment with specific salt + water concentration in their tissues INDEPENDENT of the external environment
- the internal cellular environment could either be HYPO/HPER to the external environment
- depending on the external environment (salt water, fresh water, terrestrial)
- MOST FISH
Osmoconforming
maintaining an internal cellular environment that is ISOTONIC to the external environment (NO NET MOVEMENT)
- the specific ions and dissolved solutes inside the cells are quite different that that of the external as necessary for cellular function
- animals have a narrow range of salinity they can survive in
- MARINE INVERTEBRATES
Cartilaginous Fish
ISOTONIC with sea water, but do not have the same ion composition as the water
- maintain osmotic balance by storing large concentrations of urea
OSMOREGULATION: Movement of Ions
ions can move through a cell membrane through:
1. facilitated diffusion
2. Active transport
Facilitated Diffusion
requires protein-based channels for moving solute
Active Transport
requires energy in the form of ATP conversion, carrier proteins, or pumps to move ions against the CG
OSMOREGULATION: Freshwater Fish
gain water and lose ions to the freshwater environment
- most actively transport ions back to their cells from the external environment
OSMOREGULATION: Saltwater Fish
lose water and gain ions from the saltwater environment
- most actively pump ions out of their cells back into the external environment
OSMOREGULATION: Salt/Fresh Water Migrating Fish
FRESHWATER: take up water since the EE is hypotonic (fish do not drink much water)
- instead, they pass dilutes urine and achieve electrolyte balance by active transport of salts through gills
SALTWATER: fish drink sea water and excrete excess salts in their gills and urine (hypertonic environment)
Nitrogenous Waste Mechanisms
- Ammonia
- Urea
- Uric Acid
Ammonia
FISH + organisms in AQUATIC environments; excrete nitrogenous waste directly as ammonia
- formation of ammonia requires ATP and large quantities of water to dilute it out of a biological system
Urea
TERRESTRIAL organisms
- less water necessary to dilute ammonia
- MAMMALS detoxify ammonia by converting it to relatively nontoxic urea
- made in the liver and extracted in urine
- requires more ATP, but less water loss
Uric Acid
BIRDS, REPTILES, TERRESTRIAL ARTHROPODS
- convert ammonia into uric acid or guanine
- insoluble in water
- forms a white paste powder
- LEAST water loss of any mechanisms
- requires more ATP as it is a more complex conversion
Excretory System
mediates nitrogenous waste removal and players roles in osmoregulation; different types include:
- Vacuoles
- Flame Cells
- Malpighian Tubules
- Kidneys
Contractile Vacuoles
used in some unicellular eukaryotic microorganisms (EX: amoeba)
- cellular waste and excess water are excreted by EXOCYTOSIS
- a contractile vacuole emerges with the cell membrane to expel waste into the environment
Flame Cells
cells with a cluster of cilia that propel waste matter down tubes
+ drawn water from the interstitial fluid, allowing for filtration
- metabolites are recovered by reabsorption
- maintain osmotic balance
Flame Cells + Duct System
used in flatworms + Planaria; two tubules connected to a highly branched duct system
- FC propel waste down the tubes and out of the body through excretory pores on the body surface
Nephridia
used in earthworms + Annelids
- one pair of nephridia is present in each body segment
- similar to flame cells (have a tubules with CILIA)
- have a system for tubular reabsorption by a capillary network before excretion
