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lect 4 homeo uic
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| Term | Definition |
|---|---|
| Gills fresh water | have to be very thin to take in O2 but thend to lose alot of salt as a result to |
| passive diffusion | solute passing down conc. gradient |
| passive transport | channel diffusion |
| carrier mediated passive transport | facilitated diffusion |
| active transport | primary active transport against ecg, secondary active transport against ecg driven by ion movenment down gradient |
| K+ permeable membrane | passes K down conc gradient and creates an electrical gradient until chemical and electrical are at equ against eachother |
| ions of opposite charges | electrical gradient |
| fast diffusion | if both electrical and chemical are the same way |
| slow diffusion | if electrical and chemical are against eachother |
| electrochemical equilibrium | when electrical and chemical effects are equal and opposite |
| animal cells have a net __ charge inside cell | negative |
| animal cells have a __ sodium conc. | low |
| animal cells have a __ potassium conc. | high |
| easily diffusable substances through passive diffusion | gasses (co2, o2) hydrophobic molecules (benzene) small polar molecules (ethanol and h2o) |
| transporters carry | large polar molecules (glucose) |
| channels allow | charged molecules through ( H+, cl-, na+, k+, ca2+, amino acids) |
| cannot diffuse | large polar molecules and inorganic ions ( hydrophilic) |
| inorganic ions cross membranes via 4 functional groups of ion channels | voltage gated, stretch- or tension-gated, ligand-gated, phosphorylation gated |
| resting membrane potential is usually areound | -60 Mv |
| donnan equilibrium | relative cell permeability to each of the ions produces a complex equilibrium |
| Na+ | far from electrochemical equ. and tends to diffuse in. |
| K | is quite far from its ec equ and tends to diffuse out |
| Cl | is close to its ec equ (little net flow ) |
| more K leakage than Na conc. gradients away from equ and requires atp | Na K atpase pump |
| active transport | requires a carrier protein (transporter) to which solutes bind non-covalently -E required |
| Na K pump | is counter transporter--antiporter-- transporting two solutes in opposite directions |
| what mechanisms exist to transport hydrophilic sugars from a hummmingbirds intestinal lumen across epithelial membranes into its blood | transport glucose across 2 epithelial membranes (lumen of small intestine) |
| how is glucose transported across intestinal epithelia? | Na conc. gradient acts as an energy store to drive glucose transport -symport of 2 Na and 1 Glucose into molecule once gradient created (secondary active transport) |
| Primary active transport | ex Na k pump, draw energy from ATP directly, transporters are atpases |
| Secondary active transporters | such as Na glu cotransport draw energy from the ecg of Na established by atp by another transporter. |
| how is glucose then transported from epithelial cell cytoplasm to blood | by facilitated diffusion,- transporter protein that transports glu down its conc gradient, in form of passive diffusion |
| important tight jcts for glu transport | true |
| two forms of passive diffusion | channel diffusion, facilitated diffusion |
| how is blood plasma compositon maintained in fresh water fish | both Na and Cl are lost to pond water across gill epithelia -ions derived from food and two ion-pumping mechanisms help maintain blood compositon |
| two mechanisms for transport for fresh water fish | na uptake is driven into epithelia cells by channel diffusion through an ecg created by proton pump -na is actively transported into blood plasma by Na K pump ( primary active transport) |
| How is cl transported in | proton pump drives reaction towrd more HCO3 produced from Co2 which then countertransported for Cl from pond water- form of sec. active transport |
| Osmosis | pssive transport of water across a membrane - depends on # of dissolved entities per unit volume regardless of their ids |
| water moves from where its abundant to | where its less abundant |
| Phi | osmotic pressure |
| x | distance separating solutions |
| K | depends on temp and permeability |
| Rate of osmosis= | (K(phi1-phi2))/X |
| hyposmotic | lower osmotic pressure ( water wants to leave here) |
| hyperosmotic | higher osmotic pressure ( water wants to be here) |
| isoosmotic | same osmotic pressure (equilibrium) |
| a cell is _____ if it contains more impermeant solute than outside. The surrounding fluid is _____. This results in cell____. | -hyperosmotic -hypotonic -swells |
| Acell that starts out ____, has a lower impermeant solute concentration than the surrounding ______ solution. The cell ____. | hypoosmotic hypertonic shrinks |
| hypotonic | cell swells |
| hypertonic | cell shrinks |
| how does water move into animal cells | two routes: passive diffusion through lipid bilayer, passive transport through water channels called aquaporins |
| aquaporins | channels htat specifically permeable to H20. These channels greatly speed up rate of H20 transport across membranes |
| Saltwater fish | respond to drinking large amounts of water and excreting salt through kidneys |
| fresqhater fish blood plasma is ___ relative to pond water. Conswquently they take in a thrid of their body weight in water every day causing bloating. Much energy is expended in voiding this water. | hypertonic |
| blood cappillaries containt a ____ molecules that create a ____ environment | non-permeating hyperosmotic |
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