PHAR2210 Lecture Notes - Lecture 9: Ohm, Electrochemical Gradient, Lipid Bilayer
Document Summary
Ligand-gated ion channels ligand-binding to the ion channel regulates channel opening and ion conductance(flow of ions: voltage-gated ion channels change in the membrane potential (if threshold is met) or voltage gradient regulates channel opening and ion conductance. Second messenger-regulated ion channels: binding of the ligand to g protein-coupled receptor leads to second messenger generation second messenger regulates channel opening and ion conductance. Ions (charged moelculees) are unable to penetrate the cell membrane: as the cell membrane is a phospholipid bilayer, under resting conditions, cells maintain a negative internal potential of 30 to 80mv(inside is negative) Ion channels/pores open/close to regulate ion flow: depolarisation or hyperpolarisation of the cell membrane, play a critical role in neurotransmission, cardiac conduction, muscle contraction, secretion. Membrane potential: depends on the balance of positive and negative ions inside/outside: cl-: determine the potential, na+, k+,ca+2 determine the potential, more na outside than inside.
