Jethro - hydra vs human digestion

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Assignment "Jethro"
Human and Hydra digestive systems compared.

Type all answers on a separate paper and attach it behind this sheet.

Questions marked with a ** are optional, but must be answered if you want to get an "A" on the assignment. If you satisfactorily answer all the other questions, you will get a B+.
Many of the answers will be given during lecture. For extra helps, see the textbooks and/or:

http://kidshealth.org/kid/htbw/digestive_system.html (basic, but helpful)
http://www.dummies.com/how-to/content/running-through-the-human-digestive-system.html (a bit more detailed - quite good!)
http://yucky.discovery.com/flash/body/pg000126.html (cutesy, but good facts)
http://www.enchantedlearning.com/subjects/anatomy/digestive/

1. What are the three things that any digestive system must do?
2. What do the jaws, tongue and teeth do to aid the human digestive process?
3. Does a hydra have any structures that serve the same function as the human mouth? Explain.
4. **In the human digestive system, what is amylase, and what function does it serve?
5. What does the esophagus do in the human digestive system?
6. **What is peristalsis? Define and describe.
7. A hydra has no esophagus. What structures in the hydra carry out a similar function and how?
   
8. The human stomach contains strong acid; but it is NOT strong enough to dissolve the food. What IS the primary purpose of this acid?
9. How does the human stomach protect itself against being damaged by its own acid?
10. **What happens to the stomach acid when food passes into the duodenum?
    
11. What nutrients are broken down and absorbed in the human stomach?
12. What is the chemical that breaks down proteins
    
13. What are some of the most important differences between the human stomach and the gastro-vascular cavity of the hydra?
14. What are the main things that happen in the small intestine? (What materials are broken down?)
15. **What are villae?
16. How long is the long intestine? Why is it so long?
17. **Think about the previous question. What does the answer to that question suggest about a possible problem with the hydra's digestive system?
18. **What are villae, and how are they important to digestion? (I'll be especially happy if you use the concept of surface area in your answer.)
19. What happens in the large intestine? (What gets absorbed?)
20. **What part do bacteria in the large intestine play in digestion? Be specific?
    
21. What's a key difference between how a hydra and a human get rid of post-digestion waste?
22. Label the human digestive tract below. Label the mouth, esophagus, stomach, liver, small intestine, large intestine, rectum and anus. (**Label the gall bladder, pancreas and appendix.)
23. Label the hydra on the next page. Label the mouth, gastro-vascular cavity, and tentacles. (**show where the nematocysts are.)
    
24. Explain how the liver aids digestion.
    
25. Can you eat a new meal while still digesting a previous meal? Can a hydra? Explain your answer fully.