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Medical Science
How the Body Controls Blood Sugar
Insulin, glucagon, and the glucose set point
Related Worksheets
Your body keeps blood sugar in a safe range so every cell can get steady energy. After you eat, carbohydrates are digested into glucose, a sugar that enters the bloodstream. Too much or too little glucose can make the brain, muscles, and organs work poorly. The pancreas helps control this balance by releasing hormones at the right time.
Key Facts
- Healthy blood glucose is often about 70 to 140 mg/dL for many people, depending on timing and individual health.
- After a meal, blood glucose rises and the pancreas releases insulin.
- Insulin helps body cells take in glucose and helps the liver store glucose as glycogen.
- Between meals, blood glucose falls and the pancreas releases glucagon.
- Glucagon signals the liver to break down glycogen and release glucose into the blood.
- Blood sugar balance uses negative feedback: change is detected, hormones respond, and glucose moves back toward the normal range.
Vocabulary
- Glucose
- Glucose is a simple sugar that travels in the blood and provides energy for body cells.
- Insulin
- Insulin is a hormone from the pancreas that lowers blood glucose by helping cells take in glucose.
- Glucagon
- Glucagon is a hormone from the pancreas that raises blood glucose by signaling the liver to release stored glucose.
- Pancreas
- The pancreas is an organ near the stomach that releases hormones involved in blood sugar control.
- Glycogen
- Glycogen is the stored form of glucose found mainly in the liver and muscles.
Common Mistakes to Avoid
- Saying insulin turns glucose into energy immediately is wrong because insulin mainly helps glucose enter cells or be stored, while cells still use cellular respiration to release energy.
- Thinking glucagon and insulin do the same job is wrong because insulin lowers blood sugar and glucagon raises blood sugar.
- Assuming only the pancreas controls blood sugar is wrong because the liver, muscles, bloodstream, and body cells also play important roles.
- Treating one blood glucose number as always good or bad is wrong because the meaning depends on timing, such as before a meal, after a meal, or during illness.
Practice Questions
- 1 A student's blood glucose is 130 mg/dL one hour after lunch. If insulin helps lower it by 45 mg/dL, what is the new blood glucose level?
- 2 Between meals, a person's blood glucose drops from 90 mg/dL to 68 mg/dL. How many mg/dL did it drop, and which hormone should increase to help raise it?
- 3 Explain why the body needs both insulin and glucagon instead of using only one hormone to control blood sugar.