Introduction

• Each structure in the body carries out functions necessary for life.
• These functions can be grouped into 6 categories:
  1. Organization
  2. Metabolism
  3. Responsiveness
  4. Movement
  5. Development
  6. Reproduction

Organization

• For the body to function effectively there must be organization and separation.
• For example, blood will only flow if it is kept inside your circulatory system.
• The integumentary system, which includes the skin, hair, nails and exocrine glands, functions as a barrier. It separates our internal organs from potentially harmful toxins in the external environment.
• Organization can also be found at the microscopic level, with the cell membrane acting as a barrier between the intracellular environment separate from the extracellular environment.

Metabolism

• Metabolism is the process of consuming food and using it for energy and maintenance.
• It is made up of two types of reactions:
  • Anabolism
    • This is the process of combining small molecules into larger ones.
    • It requires energy.
    • The result of anabolism is usually referred to as a 'macromolecule'.
  • Catabolism
    • This is the process of breaking down large molecules into smaller ones.
    • It releases energy.
• adenosine triphosphate (ATP) is a chemical compound used by cells to store and release energy.
  • The cell uses anabolism to synthesize ATP, this stores energy
  • ATP molecules can then be moved to where they are needed
  • The cell then uses catabolism to break down the ATP and release energy

Responsiveness

• Responsiveness can be split into internal and external.
• Internal:
  • E.g. sweating in response to increased body temperature.
• External:
  • E.g. moving towards sources of food and water, or moving away from danger.

Movement

• Movement can be found at all the levels of organization:
  • Movement of water, carbon dioxide, and other molecules
  • Movement of cells (blood, for example) through the body
  • Movement of tissues, such as muscle contraction
  • Movement of organs, and organ systems, e.g. to move food through your digestive system
  • Movement of an entire organism, e.g. walking or running

Development

• Development encompasses changes in the body, such as:
  • Renewal
  • Differentiation
    • A cell changing from one type to another (usually a more specialized type)
  • Growth
    • An increase in the total number of cells
    • An increase in the size of existing cells
    • An increase in non-cellular molecules
      • For example, storing minerals in bones

Reproduction

• The creation of new organisms from their parents.