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28 Cards in this Set
- Front
- Back
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What are the major contributions of osmolality of plasma again?
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sodium, glucose, and urea
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Ionic composition of sodium and potassium in and out of a cell.
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high K-inside
high Na-outside |
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capillary barrier is permeable to ___ and not to ____.
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permeable to electrolytes
but not to proteins |
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osmolality of Interstitail fluid and plasma...
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is about the same
treat as one compartment |
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both facilitated diffusion and primary and secondary active transport need?
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proteins to help!
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Both types of carrier-mediated transport exhibit 3 properties, which are...
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1. specificity
2. competition 3. saturation |
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In facilitate diffusion: transport porteins __ the movemnt of molecules across the plasma membrane : two types, __ and ___.
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speed!
channels and carriers |
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channel proteins
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provide pores that allow a specific molecule or ion to cross the membrane:
lined with hypdrophillic aas. and hydrophobic aas face the ouside of the channel |
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channel gating is control by what type of regulation?
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allosteric:
voltage, phosphorylation, binding of ligand, membrane stretch |
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channel
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usually consist of large protein complexes with multiple transmembrane a-helices
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K+ channels are____
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tetramers...only has one complex
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actylchoine receptor
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ligand-gated 5 identical subunits form the channel
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Cl- channels
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from the CLC family are dimers with an intracellular pore in each subunit
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aquaporin water channels
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tetramers with intracellular channel in each subunit
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channel specificity
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"selectivity"--only specific for substrate
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In channels what determines the rate of the ions moving through?
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the concentratino gradient
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Patch clamping
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used to study ion channel activity: use a micropipet to capture a fragment of membrane
voltage is imposed and a current is carried by ions flowing through membrane |
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The increment in current between open and closed states reflects the ____ trhough one channel
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rate of ion flux
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Ion channels can be ___ by voltage, membrane tension, ligands, and phosphorylation.
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gated
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In the ion channels, substrates ONLY move ___ their concentration gradients
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DOWN
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TTX
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tetrodotoxin: inhibitor for Na+ channels
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Ion channels show ___-at high substrate concentrations
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saturation
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Ion channels have a ____ dependence over physiological range [S]vs flux
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linear
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apamin and bungarotoxin
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apaimin (bee venom) K+ channels
bugarotoxin (snake) nAChR |
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Carrier proteins are ___ than ion channels...they under go a ____ tha translocates the solute-binding site across the membrane.
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slower
subtle change in shape |
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Michaelis-Menten kinetics
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Flux (rate of reaction)=
Vmax[S]/(Km+[S]) Vmax is max rate at saturation, s is substrate concentration, Km is michaelis constant (substrate concentration required for .5 maximal flux) |
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The carrier for glucose is very specific how do we know?
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looking at rate of flux vs concentration....D isomer is more efficient where as L is not and is also linear
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What type of carrier does the bicarbonate within the RBC use to get out? and in in the lungs?
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the anion exchanger with the input of Cl-
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