Digestive System

Question 1

What are the main elements of a digestive tract?

Answer 1

Mouth, pharynx, esophagus, stomach, and intestines. As well as accessory organs like tongue, teeth, salivary glands, pancreas and liver

Question 2

What is the evolution of the vertebrate mouth?

Answer 2

Cilia-mucus filter feeding to muscular pump suspension feeding to jaws for predatory feeding

Question 3

What are teeth derived from?

Answer 3

Bony dermal armor of placoderms

Question 4

Are salivary glands found in fish?

Answer 4

No

Question 5

What are the four layers of the gut wall?

Answer 5

• Serosa - connective tissue and mesenatery
• Muscularis externa - two layers of smooth muscle
• Submucosa - connective tissue, autonomic nerves
• Mucosa - epithelial lining, smooth muscle fibres, connective tissue

Question 6

What does the Caeca strategy for increased surface area mean?

Answer 6

Extensions of the gut

Question 7

Spiral valve increased surface area strategy?

Answer 7

Auger-shaped structure in the intestinal tract of chondrichthyans and lungfishes. Forces food through a spiral route, increasing path length.

Question 8

Foldings increased surface area strategy?

Answer 8

Coils of the canal, folds, villi and microvilli on the internal surface