Question

1. the image shows two different types of stimuli (1 and 2), but doesnt explain what the stimuli is that causes blood sugar to rise or lower. based on clues in the graphic, what are the two stimuli?

diagram elements: pancreas, liver, stimulus: blood glucose level rises, stimulus: blood glucose level falls, beta cells in pancreas release insulin into the blood, alpha cells in pancreas release glucagon, liver takes up glucose and stores it as glycogen, liver breaks down glycogen and releases glucose, homeostasis (glucose levels 90mg/100ml) set point, blood glucose level declines, blood glucose level rises

Explanation:

• Stimulus 1: The graphic shows that when blood glucose level rises (stimulus 1), beta cells in the pancreas release insulin. Insulin makes the liver take up glucose and store it as glycogen, and also makes other cells (like the muscle cells shown) take up glucose, which causes blood glucose level to decline back toward the set point (90 mg/100 mL) for homeostasis. Common causes for blood glucose to rise could be eating a meal (digestion and absorption of carbohydrates into the bloodstream), or other factors that increase glucose availability in the blood.
• Stimulus 2: When blood glucose level falls (stimulus 2), alpha cells in the pancreas release glucagon. Glucagon makes the liver break down glycogen (stored glucose) into glucose and release it into the bloodstream, which causes blood glucose level to rise back toward the set point. Common causes for blood glucose to fall could be fasting (not eating for a period, so glucose isn't being added from digestion), or increased metabolic demand (like exercise) that uses up blood glucose faster than it's being replenished.

Answer:

• Stimulus 1 (blood glucose level rises): Likely caused by events like eating a meal (digestion/absorption of carbs into blood), or other processes that increase blood glucose (e.g., stress - induced release of glucose - raising hormones in some cases, though the graphic focuses on the pancreatic - liver response). The body’s response is insulin release to lower glucose.
• Stimulus 2 (blood glucose level falls): Likely caused by events like fasting (no new glucose from food), or increased glucose use (e.g., exercise). The body’s response is glucagon release to raise glucose.