9.3 Introducing Digestion
4 Main Steps:
1. Ingestion; taking in nutrient
2. Digestion; chemical + physical breakdown of complex food molecules to
smaller ones
3. Absorption; transfer of digested nutrients to blood
4. Egestion; removal of unnecessary nutrients
Gastrovascular Cavity - Simple sac-like digestive cavity with only one opening
through which food is taken and expelled
- Simple Animals have a digestive sac with a single opening, serves for both
entrance of food and exit of unneeded nutrients
- Some cavities are surrounded by tentacles that can capture prey
- Ex., Flatworms or Jellyfish
Process of Gastrovascular Cavity
- Food is taken intro gastrovascular cavity
- Broken down by chemicals released by this cavity
- Nutrients are absorbed by cells that line the cavity
- Digestion continues inside cells
- Nutrients diffuse from such cells to the rest of their body
Complex Animals (Complete Digestive Systems)
- 2 openings;
- 1 for intake
- 1 for waste elimination
- Digestive Tract for these organisms are organized into specialized regions
that enable breakdown and absorption of nutrients to go smoothly
- Ex., Earthworms - Foot ingested through mouth, travels through muscular pharynx and goes to
esophagus, gizzard is an organ that carries the physical breakdown of the food, and they go to the
intestine that breaks the nutrients into even smaller molecules, then the small molecules can be
absorbed into the bloodstream by the cells lining the intestinal system and any undigested waste
goes out of the body front he anus.
Structure of Human Digestive System
It is a Complete Digestive System
- The tract is much longer than the human body when stretched out (7 to 9 m)
4 Main Steps:
1. Ingestion; taking in nutrient
2. Digestion; chemical + physical breakdown of complex food molecules to
smaller ones
3. Absorption; transfer of digested nutrients to blood
4. Egestion; removal of unnecessary nutrients
Gastrovascular Cavity - Simple sac-like digestive cavity with only one opening
through which food is taken and expelled
- Simple Animals have a digestive sac with a single opening, serves for both
entrance of food and exit of unneeded nutrients
- Some cavities are surrounded by tentacles that can capture prey
- Ex., Flatworms or Jellyfish
Process of Gastrovascular Cavity
- Food is taken intro gastrovascular cavity
- Broken down by chemicals released by this cavity
- Nutrients are absorbed by cells that line the cavity
- Digestion continues inside cells
- Nutrients diffuse from such cells to the rest of their body
Complex Animals (Complete Digestive Systems)
- 2 openings;
- 1 for intake
- 1 for waste elimination
- Digestive Tract for these organisms are organized into specialized regions
that enable breakdown and absorption of nutrients to go smoothly
- Ex., Earthworms - Foot ingested through mouth, travels through muscular pharynx and goes to
esophagus, gizzard is an organ that carries the physical breakdown of the food, and they go to the
intestine that breaks the nutrients into even smaller molecules, then the small molecules can be
absorbed into the bloodstream by the cells lining the intestinal system and any undigested waste
goes out of the body front he anus.
Structure of Human Digestive System
It is a Complete Digestive System
- The tract is much longer than the human body when stretched out (7 to 9 m)
