Digestive 2

Question 1

What adaptation to (most) Osteichthyes have to increase surface area for digestion & absorption?

Answer 1

Pyloric ceca, at junction of stomach and duodenum

Question 2

Describe ruminants’ stomach

Answer 2

Digastric - 2 main chambers:
Rumen - initial storage & foregut fermentation (helps break down cellulose to simpler carbs, fatty acids, amino acids, peptides)
Abomasum - reached after regurgitation & rechewing, used for chemical & mechanical digestion like a monogastric stomach (+ helps recover some bacteria & nutrients)

Question 3

What are the component(s) of the hindgut?

Answer 3

Caecum, large intestine

Question 4

What happens to material digested in the caecum?

Answer 4

Either re-enters ileum for absorption, or excreted as semi-solid feces and reconsumed (because small intestine has the absorptive surface, so want to go through there)

Question 5

Who has a spiral valve?

Answer 5

non-teleost fishes (Chondrichthyes, Sarcopterygii, non-teleost Actinopterygii)

Question 6

Describe rugae & their function

Answer 6

Folds in stomach, allow expansion without distension

Question 7

Function of taste sense in buccal cavity

Answer 7

Assess food quality

Question 8

Define monogastric stomach

Answer 8

Stomach is 1 connected chamber

Question 9

What comprises the midgut?

Answer 9

small intestine

Question 10

What is the structure of the caecum?

Answer 10

Blind-end chamber at small/large intestine junction, with high surface area

Question 11

Functions of stomach

Answer 11

• food storage
• glandular secretions (HCl, enzymes) for chemical digestion
• mechanical digestion

Question 12

What kind of stomach do most animals have? Who are the exceptions?

Answer 12

Most: monogastric
Archosaurs: proventriculus & gizzard
Ruminants: digastric
Agnathans: none

Question 13

What is the function of the small intestine, and how is it adapted for this?

Answer 13

Chemical digestion (esp anterior) - bacteria to help (esp w/cellulose) & provide nutrients; secretions + from pancreas, bile; longer if lower quality food

Absorption (esp posterior) - thin epithelium is easy to cross; v. high SA by plicae -> villi -> microvilli (brush border)

Question 14

Function of the large intestine

Answer 14

• consolidates undigested material
• prepares for defecation
• specifically reabsorbs remaining water, even without nutrient uptake creating an osmolar gradient

Question 15

Function of esophagus

Answer 15

• transport food to stomach

- keep water out of stomach

Question 16

Secretions found in buccal cavity? (content & where they are made)

Answer 16

• mucus, digestive enzymes, toxins/anticoagulants/analgesics

- from salivary glands

Question 17

Describe the stomach in archosaurs

Answer 17

2 chambers:
Proventriculus - glandular stomach
Gizzard - grinding stomach (may contain rocks or sand)

Question 18

What comprises the foregut?

Answer 18

Esophagus, stomach (+ crop, if present)

Question 19

What are pyloric ceca & who has them?

Answer 19

Pouch at junction of small intestine & stomach for DIGESTION & ABSORPTION, NOT fermentation; in most osteichthyes

Question 20

Function of the caecum & how it accomplishes it

Answer 20

• cellulose digestion

- lots of bacteria to do hindgut fermentation; lots of surface area

Question 21

What are the two functions of the buccal cavity?

Answer 21

Breathing, eating (structure is a compromise)

Question 22

What adaptation do non-teleost fishes (Chondrichthyes, Sarcopterygii, non-teleost Actinopterygii) have to increase small intestine surface area?

Answer 22

Spiral valve

Question 23

Who is the large intestine particularly important in?

Answer 23

Species in dry environments that must conserve water - large intestine is specialized for water reabsorption

Question 24

Function of crop

Answer 24

• store food for controlled digestion or regurgitation

- may secrete crop milk (nutrient-rich, for young)