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Human A&P BIO 304 · American River College ← Week 1 pre-work hub

BIO 304 · Human Anatomy & Physiology

Levels of Organization

Foundations of Anatomy & Physiology · Module 1

A reference sheet to accompany the Levels of Organization video. The body is built from atoms up to a whole organism. Each step adds a new property the parts alone do not have, what scientists call emergence.

How to use this sheet Toggle the toolbar above. Notes prints the full reference for review. Study prints as a fill-in-the-blank worksheet — print it, then write each definition while you watch the video or read your book. Quiz me is on-screen typing practice; type the term, click Reveal to check yourself.

Open spaced recall
By the end
  1. Name the six levels of structural organization, in order, from chemical to organism.
  2. Describe what new function or property emerges at each level.
  3. Identify the four primary tissue types and pair each with an organ system that depends on it.
OpenStax Figure 1.3: a pyramid showing biological organization from chemical (atoms bonding into water) at the top, down through cellular (smooth muscle cell), tissue (smooth muscle tissue), organ (bladder and urethra), organ system (urinary system), to organism (a woman drinking water) at the base.
Fig 1.3 · Levels of organization
OpenStax Figure 1.4: silhouettes showing the integumentary, skeletal, muscular, nervous, endocrine, and cardiovascular organ systems with their main organs labeled.
Fig 1.4 · Organ systems I
OpenStax Figure 1.5: silhouettes showing the lymphatic, respiratory, digestive, urinary, and reproductive organ systems with their main organs labeled.
Fig 1.5 · Organ systems II

Click any image to enlarge. Images: OpenStax Anatomy & Physiology 2e, CC BY 4.0.

The Six Levels

  • 1 · Chemicalatoms bond to form molecules · water, glucose, DNA
  • 2 · Cellularmolecules organize into the smallest living unit · one neuron, one red blood cell
  • 3 · Tissuea group of similar cells doing one job · cardiac muscle, epithelium
  • 4 · Organtwo or more tissue types in one structure with a specific function · heart, kidney
  • 5 · Organ Systemseveral organs working toward a shared function · cardiovascular, respiratory
  • 6 · Organismall eleven systems supporting one independent human

Four Primary Tissue Types

  • Epithelialcovers surfaces, lines cavities · skin, gut lining, glands
  • Connectivesupports, binds, transports · bone, blood, tendon, fat
  • Musclecontracts to produce force · skeletal, cardiac, smooth
  • Nervousconducts electrical signals · brain, spinal cord, peripheral nerves

The Eleven Organ Systems

  • Integumentaryskin, hair, nails · barrier & surface sensation
  • Skeletalbones, joints, cartilage · framework & movement
  • Muscularskeletal muscle, tendons · movement, posture, heat
  • Nervousbrain, spinal cord, nerves · rapid signaling & control
  • Endocrineglands & hormones · slow chemical signaling
  • Cardiovascularheart, vessels, blood · delivery & pickup
  • Lymphaticlymph vessels, nodes, spleen · fluid return & immune defense
  • Respiratoryairways & lungs · O₂ in, CO₂ out
  • DigestiveGI tract & accessory organs · break down food, absorb nutrients
  • Urinarykidneys, ureters, bladder · filter blood, balance fluid & electrolytes
  • Reproductivegonads & tracts · gametes, sex hormones, support of offspring
Dr. Sharilyn Rennie BIO 304 · Module 1 · Levels of Organization