An illustrated quick reference guide to how animals nourish their bodies and power their cells.
Processes essential for the survival of living organisms collectively called life processes:
Food travels through a continuous long tube called the alimentary canal:
The inner lining of stomach secretes three crucial fluids:
The longest part of the digestive tract, receiving secretions from 3 sources:
Thousands of tiny finger-like projections on the inner lining. Villi vastly increase the surface area for efficient absorption of digested nutrients into blood vessels.
Partially chew grass and swallow to a chamber called the Rumen. It is later brought back to the mouth as cud for slow chewing (Rumination).
Birds have no teeth! They rely on a strong muscular organ called the Gizzard containing ingested grit (small stones) to crush food.
Inhaling oxygen-rich air & exhaling carbon dioxide.
Breaking down food inside cells to release energy.
Exchange occurs in balloon-like sacs called alveoli, rich with blood vessels.
| Gas | Inhaled Air | Exhaled Air |
|---|---|---|
| Oxygen (O2) | ~21% | ~16-17% |
| Carbon Dioxide (CO2) | ~0.04% | ~4-5% |
Gills absorb dissolved oxygen directly from water passing through them.
Tadpoles use gills. Adult frogs use lungs on land and moist skin in water.
Breathe completely through their thin, moist skin for direct gas exchange.
Dr. William Beaumont discovered digestion by performing experiments through a shotgun wound in patient Alexis St. Martin's stomach that never fully closed!
An autoimmune condition where eating gluten (wheat protein) damages the small intestine's villi, making it hard to absorb vital nutrients.
Ancient breathing techniques such as Pranayama and Tummo breathing are practiced globally to improve lung health, balance, and focus.
Curiosity Textbook • Grade 7 Science • Illustrated Quick Study Guide