BRS Cell Phys - 1 Flashcards
have a glycerol backbone which is the hydrophobic head and two fatty acid tails which are hydrophobic.
phospholipids
can cross cell membranes because they can dissolve in the hydrophobic lipid bilayer
lipid soluble substances
cannot dissolve in the lipid of the membranem but may cross through water filled channels, pores, or may be transported by carriers
water soluble substances
Na+, Cl-, glucose, H2O
anchored to and imbedded in the cell membrane through hydrophobic interactions
integral (intrinsic) proteins
ion channels / transport proteins / receptors / GTP binding proteins
loosely attached to cell membrane by electrostatic interactions
NOT imbedded in the cell membrane
NOT covalently bound to cell membrane components
peripheral (extrinsic) proteins
the attachments between cells
tight junctions (zona occludens)
“tight” (impermeable) tight junctions are found in the
distal renal tubule
“leaky” (permeable) tight junctions are found in the
renal proximal tubule and gallbladder
attachments between cells that permit intercellular communication
-permit current flow and electrical coupling between myocardial cells
gap junctions
only form of transport that is not carrier mediated
occurs down an electrochemical gradient (downhill)
- passive
simple diffusion
carrier mediated transport includes
facilitated diffusion and primary and secondary active transport
characteristics of carrier mediated transport
saturation
stereospecificity
competition
occurs DOWN an elcetrochemical gradient
passive diffusion
carrier mediated
facilitated diffusion
glucose transport in muscle and adipose cells is “downhill” is carrier mediated , and is inhibited by sugars such as galactose: therefore it is categorized as
facilitated diffusion
in diabetes mellitus, glucose uptake by muscle and adipose cells is impaired because the carriers for facilitated diffusion of glucose require
insulin
