Blood Glucose & Metabolic Adaption in Starvation

Regulation of Blood Glucose in the Body

Maintaining blood glucose levels within a normal range (70–110 mg/dL) is essential for homeostasis. The body regulates glucose levels through hormonal control, metabolic pathways, and organ-specific functions.

1. Hormonal Regulation of Blood Glucose

Several hormones control blood glucose by either increasing or decreasing its levels.

A. Hormones that Decrease Blood Glucose (Hypoglycemic Hormone)

🔹 Insulin (Secreted by β-cells of the pancreas)

• Promotes glucose uptake by cells (via GLUT4 in muscle & adipose tissue).

• Stimulates glycogenesis (storage of glucose as glycogen in liver & muscles).

• Inhibits gluconeogenesis and glycogenolysis.

• Enhances lipogenesis (conversion of glucose to fats).

📝 Effect: Lowers blood glucose levels after a meal (Postprandial state).

B. Hormones that Increase Blood Glucose (Hyperglycemic Hormones)

1️⃣ Glucagon (Secreted by α-cells of the pancreas)

• Stimulates glycogen breakdown (glycogenolysis) in the liver.

• Promotes gluconeogenesis (formation of glucose from non-carbohydrate sources).

2️⃣ Epinephrine (Adrenaline) (From adrenal medulla)

• Increases glycogenolysis in muscles and liver during stress.

• Inhibits insulin secretion.

3️⃣ Cortisol (From adrenal cortex)

• Enhances gluconeogenesis by breaking down proteins into amino acids.

• Reduces glucose uptake by tissues.

4️⃣ Growth Hormone (GH) (From anterior pituitary)

• Decreases glucose uptake by muscles and fat.

• Increases lipolysis and gluconeogenesis.

📝 Effect: Increases blood glucose levels during fasting, stress, or energy demand.

2. Metabolic Pathways Controlling Blood Glucose

3. Organ-Specific Role in Blood Glucose Regulation

4. Clinical Conditions Related to Blood Glucose Regulation

Summary