osmosis
the net movement of water from higher water concentration to lower
solutes
dissolved molecules (AAs, sugars, electrolytes)
semipermeable membranes
let some but not all through
aquaporins
channels in the lipid bilayer that facilitate diffusion of water molecules
osmotic pressure
drives water diffusion, cause by difference in concentrations
- the tendency of water to move from one solution into another by osmosis
osmoregulation
regulation of water and solute conc. levels to control osmotic pressure
osmoconformers
keep internal osmotic pressure equal to external enviro (reduces mov’t and energy)
ex. marine animals retain lots of urea to match the external conc.
osmoregulators
organisms who maintain different internal enviro from external.
osmoregulator examples in animals
gills - chloride cells: counter ingestion and diffusion of excess electrolytes - pump Cl out into water, and Na out. In freshwater - pump Na in
sharks and rays - rectal gland: secrete excess salt
marine birds - nasal salt glands excrete salt
shrimp - hypo+hypertonic enviro
paramecia - contractile vacuole (exocytosis)
dehydration of prey
= capture
nitrogenous waste
byproduct/breakdown of proteins and nucleic acids
ammonia
mammals - urea: less toxic
birds and reptiles - uric acid
human nitrogenous waste process
1) filtration into excretory tubules
2) reabsorption (key ions and solutes)
3) secretion of toxic compounds and excess ions
excretory organs in organisms
flatworm - protonephridia : secretory organs
segmented worm - metanephridia
insects, terrestrial arthropods - malpighian tubes (secrete uric acid)
vertebrates/mammals - filter blood through kidneys
kidneys
1) glomerulus
2) renal tubules
3) collecting ducts
4) ureter
5) bladder/cloaca
nephron = functional unit of kidney
(glomerulus, capsule, renal tubes)
deuterostomes
hemichordates
echinoderms
chordates: cephalochordates, tunicates, vertebrates
hemichordates
seafloor wormlike animals
1) mouth w/ proboscis - elongate protuberance connected to
2) digestive tract by pharynx w/
3) pharyngeal slits - separated by stiff rods of protein
4) dorsal hollow nerve cord
acorn worms - burry in marine sediments
pterobranchs - attach to seafloor and use tentacle to filter feed
echinoderms
seastars, sea urchins, sea cucumbers, sand dollars (7000 species)
1) radially symmetric adult
- bilaterally symmetric larvae
- pentaradial symmetric adults
2) calcium carbonate endoskeleton
3) water vascular system:bulk transport of oxygen and nutrients
- hydrostatic skeleton
4) tube feet: small projections from water vascular system that facilitate locomotion, sensory perception, food capture, and gas exchange
sea cucumber self defense: self evisceration – can regrow intestines
chordate characteristics
1) pharynx w/ pharyngeal gill slits
2) dorsal hollow nerve cord that runs the length of the body, comprised of projections from neurons
- develops from neural tube
3) notochord - stiff, supportive, flexible rod of collagen, runs length of the body
- vertebral column eventually replaces notochord
4) muscular post-anal tail-
chordates
1) cephalochordates
2) urochordates (tunicates)
3) vertebrates
cephalochordates
lancelets or amphioxus
urochordates (tunicates)
sea squirts and tunicates
vertebrates (craniates)
chondrichthyes
osteichthyes
amphibians
sauropsids
vertebrate characteristics
1) veterbrae - series of hard segments that runs along the main axis of the body, creating the jointed skeleton
2) cranium - protects well developed brain
3) pair of eyes, distinctive mouth, internal skeleton
4) coelom in which organs are suspended - closed circulatory system
5) jaws
6) paired fins
hagfish and lamprey