 beta cells (Î² cells) are a type of cell in the pancreas located in the islets of langerhans. they make up 65-80% of the cells in the islets. ==function== the primary function of a beta cell is to store and release insulin. insulin is a hormone that brings about effects which reduce blood glucose concentration. beta cells can respond quickly to spikes in blood glucose concentrations by secreting some of their stored insulin while simultaneously producing more. ===control of insulin secretion=== voltage gated calcium ion channels and atp-sensitive potassium ion channels are embedded in the cell surface membrane of beta cells. these atp-sensitive potassium ion channels are normally open and the calcium ion channels are normally closed. potassium ions diffuse out of the cell, down their concentration gradient, making the inside of the cell more negative with respect to the outside (as potassium ions carry a positive charge). at rest, this creates a potential difference across the cell surface membrane of -70mv. when the glucose concentration outside the cell is high, glucose molecules move into the cell by facilitated diffusion, down its concentration gradient through the glut2 transporter. since beta cells use glucokinase to catalyze the first step of glycolysis, metabolism only occurs around physiological blood glucose levels and above. metabolism of the glucose produces atp, which increases the atp to adp ratio. the atp-sensitive potassium ion channels close when this ratio rises. this means that potassium ions can no longer diffuse out of the cell. as a result, the potential difference across the membrane becomes more positive (as potassium ions accumu
Peptide_hormone_secreting_cells