Carbohydrate Metabolism

Carbohydrate Metabolism

In this slide set, we look at carbohydrate metabolism, specifically how blood glucose and storage convert into ATP, the energy-generating systems.

Learning Objectives

• Cellular respiration and cellular metabolism

• Utilization of carbohydrates by the body

Hierarchy of Glucose Metabolism

• Carbohydrates are metabolized for immediate energy needs.

• Immediate energy is required during high cognitive activity and intense physical activity.

• Carbohydrate Sources for Energy:

  • Blood Glucose: First short-term energy source

  • Glycogen: Second line, created when glucose levels exceed current energy needs.

Breakdown of Glycogen

• Glycogen breakdown is called glycogenolysis.

• Glycogen stored in liver (35%) and muscles (rest).

• Liver can release glucose; muscles can only use it for their ATP needs.

Gluconeogenesis

• When liver glycogen is depleted, the liver can create glucose from non-carbohydrate sources (proteins and glycerol).

• Proteins: Amino acids converted into glucose

• Glycerol: Backbones of triglycerides can create glucose.

Metabolism of Glucose

• Chemical reaction of glucose (C6H12O6) with oxygen (O2) produces:

  • Carbon dioxide (waste product)

  • Water (waste product)

  • ATP (energy currency)

Conditions of Glucose Oxidation

• Anaerobic Conditions: No oxygen present

  • Occurs in cytosol (breaks glucose to pyruvate, generates lactic acid)

• Aerobic Conditions: Oxygen present

  • Occurs in mitochondria (fully breaks down glucose)

Metabolism Without Carbohydrates

• Low carbohydrate diets can be clinically prescribed (e.g., for epilepsy).

• The body adapts by breaking down adipose tissue to liberate fatty acids for energy.

  • Ketone Bodies: These are produced from fat breakdown and can be used for energy.

• Long-term effects: Brain fog during adaptation, potential ketosis or ketoacidosis in diabetic patients.