BIOL 3510 1st Edition Lecture 11 Outline of Last Lecture I Membrane Structure Continued II Membrane Transport III Permeability and Impermeability IV Three Types of Active Transport Outline of Current Lecture I Ion Channels II Patch clamp Recording III Action Potentials IV Mechanically gated Channels Current Lecture Ion channels allow the passage of molecules via passive transport but they are not open pores 1 Selective particular channels allow for the passage of specific ions 2 Often gated channels open and close in response to a stimulus Membrane potential is the accumulation of electric charge across a membrane The membrane potential of a resting animal cell is negative K leak channels K flows out of the cell down its conc gradient K flows into the cells down its voltage gradient Equilibrium gives a slightly negative charge Patch clamp recording detects ion flow across a small area of membrane Also indicates that ion channels randomly switch between open and closed conformations Under various conditions one slate open or closed is favored over the other Three main types of gated ion channels voltage gated ligand gated and mechanically gated These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Voltage and ligand gated ion channels for example could be neuron action potentials An action potential is the propogation of an electrical signal change in membrane potential within a neuron An action potential is triggered by a depolarization of a neuron s membrane Voltage gated Na channels open and close in response to changes in membrane potential Depolarization is when a membrane potential moves towards a positive value Voltage gated Na channels have three conformations Diffusion of Na ions propagates the action potential along the axon After the Na ions rush in 1 Voltage gated K ion channels also open 2 Exit of K ions returns the membrane potential to its resting state 3 Na K pumps return the ion gradient to normal Electrical signals are converted to chemical signals and vice versa at synapses Chemical signals neurotransmitters Action potentials open Ca2 channels prompting release of neurotransmitters into the synapse Neurotransmitter binding opens transmitter gated ion channels initiating membrane depolarization They can be excitatory or inhibitory They combine interpret and record signals An example of mechanically gated ion channels are the ion channels in the inner ear Vibrations linked stereocilia move and ion channels open
View Full Document
Unlocking...