February 22, 2024

Levels of structural organization and body systems

Our bodies are organized at many different levels. The levels of organization of living things, from smallest to largest, are

  1. Atoms, the smallest functional units of matter.
  2. Molecules, active chemicals.
  3. Organelles, specialized structures within a cell.
  4. Cells, the smallest living units.
  5. Tissues, a group of similar cells that work together.
  6. Organs, two or more tissue types working together.
  7. Organ systems, two or more organs working together.
  8. Organism, a single individual, including all of the above

The human body is divided into 11 interconnected organ systems. All organ systems work together, and many organs function in more than 1 organ system

  1. The Integumentary System: includes the skin & derived structures, it protects internal organs & helps maintain body temperature.
  2. The Skeletal System: includes the bones & joints, it provides support & protection to internal organs.
  3. The Muscular System: includes skeletal muscle and it provides movement.
  4. The Nervous System: includes the brain, spinal cord, and nerves. It provides regulation of body functions & sensory perception.
  5. The Endocrine System: includes hormone-producing cells & glands. It regulates homeostasis, growth & development.
  6. The Cardiovascular System: includes blood, heart, & blood vessels. It is responsible for delivery of oxygen & nutrients to the tissues.
  7. The Lymphatics & Immune System: includes lymphatic vessels & fluid. It is involved in the defense against infection.
  8. The Respiratory System: includes lungs & airways. It is involved in the absorption of oxygen & release of carbon dioxide.
  9. The Digestive System: includes organs of the gastrointestinal tract. It is responsible for the absorption of nutrients
  10. The Urinary System: includes the kidneys, ureters, and bladder. It is responsible for electrolyte balance & waste removal.
  11. The Reproductive System: includes the reproductive organs in males and females. It controls the biological process by which new individuals are produced

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