PHYSIOL 1 Lecture Notes - Lecture 3: Transcellular Transport, Lipid Bilayer, Facilitated Diffusion
Document Summary
Gated channels: chemically gated channels, voltage gated channels, mechanically gated channels. If a molecule is lipid soluble, it can cross through membrane: if not lipophobic, needs receptor or transporter. Channels can be selectively open specific molecule comes into contact with channel and cause gate to open or close but fluid from icf or ecf wont go through. Lipophilic exterior to allow protein to imbed into phospholipid bilayer. Middle: hydrophilic to allow peptide/amine based molecules to flow through and not get blocked by lipids. Uniport carriers: allows one molecule to pass through (simple/facilitated diffusion) Facilitated diffusion brings glucose into cell down [gradient] using a glut transporter. Cell has high [glucose] outside than inside & diffuses until equilibrium. Maltose (2 glucose) = competitive inhibitor that binds to glut but doesn"t get carried across membrane & blocks receptor from glucose. When transport rate levels out there will be no more transfer of molecule. Apical (mucosal) membrane vs basolateral (serosal) membrane.
