Metabolism

Metabolism refers to the set of all chemical reactions that occur within living organisms to sustain life. These reactions are responsible for converting food into energy, building and repairing cells, and eliminating waste products. Metabolism can be broadly categorized into two main processes: catabolism and anabolism.


Components of Metabolism

  1. Catabolism (Breakdown):
    • Involves breaking down large molecules, such as carbohydrates, fats, and proteins, into smaller units.
    • Releases energy, which is stored as ATP (adenosine triphosphate).
    • Example: The breakdown of glucose during cellular respiration.
  2. Anabolism (Building):
    • Involves synthesizing complex molecules from simpler ones.
    • Requires energy input, often in the form of ATP.
    • Example: The synthesis of proteins from amino acids.

Functions of Metabolism

  1. Energy Production:
    • Provides energy to power cellular processes such as muscle contraction, nerve function, and cell division.
  2. Building and Maintenance:
    • Produces building blocks for growth and repair, such as proteins, lipids, and nucleic acids.
  3. Waste Elimination:
    • Converts harmful byproducts of metabolism, such as ammonia, into less toxic substances for excretion.
  4. Regulation of Body Processes:
    • Maintains homeostasis by regulating enzyme activity, hormone levels, and nutrient availability.

Phases of Metabolism

  1. Energy Input (Food Intake):
    • Nutrients from food, such as carbohydrates, fats, and proteins, are absorbed and transported to cells.
  2. Energy Transformation:
  3. Energy Utilization:
    • Anabolic pathways use ATP to build and maintain cellular structures and perform physiological functions.

Metabolism and Energy

  • Basal Metabolic Rate (BMR):
    • The amount of energy expended by the body at rest to maintain basic functions such as breathing and circulation.
  • Thermic Effect of Food (TEF):
    • The energy required to digest, absorb, and process nutrients from food.
  • Activity Energy Expenditure:
    • Energy used during physical activity.

Regulation of Metabolism

Metabolism is tightly regulated by hormones and enzymes:

  1. Hormones:
    • Insulin: Promotes glucose uptake and anabolic processes.
    • Glucagon: Stimulates glucose release and catabolic processes.
    • Thyroid Hormones: Regulate overall metabolic rate.
  2. Enzymes:
    • Speed up chemical reactions and ensure efficiency and specificity in metabolic pathways.

Importance of Metabolism

  1. Energy Supply:
    • Supports vital functions like heartbeat, breathing, and cellular repair.
  2. Growth and Repair:
    • Enables tissue repair and growth in response to injury or stress.
  3. Adaption to Environment:
    • Helps organisms adapt to changes in food availability or environmental conditions.

In summary, metabolism encompasses all biochemical reactions in the body that sustain life. It involves the interplay of catabolism and anabolism to provide energy, build and maintain tissues, and regulate physiological processes.