Digestion and Excretion Chapter 12, Lesson 3

What 2 major processes is Lesson 3 about? DIGESTION EXCRETION

What is “digestion”? The process of breaking down food into molecules that cells can absorb and use.

What is “absorption”? The process in which broken down food is taken into the body’s cells

What analogy can you use to help you remember these 2 terms? If you spill salt on the kitchen counter you cannot clean it up with a sponge. BUT, if you Add water to the salt, you will BREAK IT DOWN INTO SMALLER PARTICLES (this is like digestion) Then you can TAKE THE BROKEN DOWN SALT (and water) INTO THE SPONGE (this is like absorption into the cells)

Animals have different structures for digestion that depend on: Their diet

Structures for feeding – ALL depend on the animals diet Teeth – type animal has depends on diet Baleen – for filter feeders like whales Specialized Mouthparts Long tubes for nectar (butterflies and moths) Crushing jaws for ripping plants & animals (ants, some beetles)

“How do animals obtain nutrients?” RC-p. 429 Animals obtain nutrients by processing and absorbing food during digestion.

Structures for Digestion-ALL depend on the animal’s diet Stomachs/Intestines – used to break down food in many animals Some animals have more than one chamber in their stomach if their diet consists of hard to digest things like grass (cows) Crop – a specialized structure in the digestive system where eaten material is stored. (birds and insects) Gizzard – In animals with no teeth, a muscular pouch similar to a stomach that is used to grind food (birds-also swallow rocks to help grind food in the gizzard)

Assignment for tomorrow: Complete the Key Concept Builder, p. 55&56 (both sides) for tomorrow.