Insulin and Beta Cells of the Pancreas

• What do the receptors on beta cells do?

  Detect a stimulus of a rise in blood glucose concentration.
• What do beta cells do to respond to a rise in blood glucose concentration?

  Secrete the hormone insulin directly into the blood plasma.
• What is insulin?

  A globular protein made of 51 amino acids.
• What do almost all cells have?

  Glycoprotein receptors that bind specifically to insulin.
• How does insulin cause blood glucose concentration to fall?

  It activates the enzymes that convert glucose to glycogen, increases the number of carrier proteins responsible for glucose transport, and changes the tertiary structure of the glucose carrier proteins allowing more glucose into cells be facilitated diffusion.
• How does negative feedback occur with insulin?


  After the blood glucose concentration is lowered, beta cells are caused to reduce their secretion of insulin.