Digestive System

Question 1

Parietal Peritoneum

Answer 1

• somatic mesoderm along the body wall

Question 2

Visceral Peritoneum

Answer 2

splanchnic mesoderm surrounding the gut tube

Question 3

Dorsal Mesentery

Answer 3

double-layered parietal peritoneum that suspends gut tube from the dorsal aspect
(present in all vertebrates)

Question 4

Ventral mesentery

Answer 4

double-layered parietal peritoneum that supports the gut tube from the ventral aspect
(most degenerates in adult vertebrates)

Question 5

Omentum

Answer 5

double (or quadruple)- layered parietal peritoneum that connects parts of the digestive tract to each other (visceral peritoneum- visceral peritoneum)
* Derived from ventral or dorsal mesenteries

Question 6

Steps in Gut Tube Movement

Answer 6

1. Mastication
2. Propulsion and
   digestion
3. Absorption
4. Defecation
   * Segmentation:
   churning and mixing
   of material
   Segmentation
   * Peristalsis: forces
   material further along
   the lumen of the GI
   tract

Question 7

Stomach: 3 main regions

Answer 7

Cardia*: Glands secrete mucus
Fundus: Glands secrete mucus, HCl, and digestive enzymes
Pylorus: Glands secrete mucus that neutralizes food as it moves into
intestine
*Present in mammals only.

Question 8

Small Intestine Parts

Answer 8

3 parts (proximal to distal)*
Duodenum
* Shortest part
* Receives ducts for accessory
digestive organs
Jejunum
Ileum
*Not all tetrapods have all 3 parts, and these are best defined in
mammals.

Question 9

Large Intestine Parts

Answer 9

2 parts (proximal to distal)
Colon
Terminal portion (rectum if
anus is present)
Cloaca: Common terminal chamber for digestive and urogenital tracts
Anus: Short canal and opening for digestive tract only

Question 10

Accessory Organs

Answer 10

Liver
* FUNCTION is to remove toxic substances from the blood and
produce and deliver bile to intestine. Bile helps in the breakdown of
fats.
* Present in all vertebrates
* Typically a large organ
Gallbladder
* FUNCTION is to store and
deliver bile to intestine.
* Not present in all vertebrates
(which is not necessarily
related to diet)
Pancreas
* FUNCTION is to (1) produce and release pancreatic enzymes to
intestine for digestion and (2) release hormones (e.g., insulin),
which regulates blood sugar levels.
* Present in all vertebrates but is not always a discrete organ