Digestive System

Question 1

digestive tract

Answer 1

• hollow passage from the mouth to the anus/cloacal opening

Question 2

division of digestive tract (3)

Answer 2

• buccal cavity
• pharynx
• alimentary canal

Question 3

alimentary canal (4)

Answer 3

• esophagus
• stomach
• small intestine
• large intestine

Question 4

how does food truly enter the body

Answer 4

• it must be absorbed: pass through an epithelial cell or pass between two epithelial cells

Question 5

digestive system: main functions

Answer 5

• digestion

- absoprtion

Question 6

digestion

Answer 6

• breaking down of food into molecules that can be absorbed

Question 7

absorption

Answer 7

• uptake of molecules through the epithelium of the digestive tract into the blood or lymph

Question 8

general process of the digestive system (8)

Answer 8

• ingestion
• food storage
• mechanical digestion
• chemical digestion
• microbial digestion
• absorption
• water reabsorption
• defecation

Question 9

general diets (6)

Answer 9

• other animals (carnivore)
• plants (herbivore)
• combination of everything (omnivore)
• dead organic material
• blood
• nectar

Question 10

quality of food

Answer 10

• the relative difficulty of digesting the food and the amount of energy released when the food is digested

Question 11

higher quality foods (2)

Answer 11

• release of a relatively large amount of energy

- requirement of relatively little time or energy for digestion

Question 12

rank the quality of these foods: whole fish, leaves, blood

Answer 12

1. blood
2. fish
3. leaves

Question 13

what are the characteristics of an organism that eats high quality food (2)

Answer 13

• small or no stomach

- small intestine does not require much surface area

Question 14

buccal cavity (4)

Answer 14

site of ingestion, feeding, and swallowing:

- tongue, chemoreceptors, salivary glands, saliva

Question 15

buccal cavity: tongue

Answer 15

• aids to propel food through the pharynx and into the alimentary canal during swallowing

Question 16

buccal cavity: chemoreceptors (taste buds) (2)

Answer 16

• signal to brain to start digestion

- detect quality of food

Question 17

buccal cavity: salivary glands/saliva (3)

Answer 17

• mucus (lubrication, protect/buffer lumen lining)
• digestive enzymes
• toxins

Question 18

pharynx (3)

Answer 18

• posterior to the buccal cavity
• many tetrapods lose slits during development, but are retained in fish
• many tetrapods have structure to prevent foods from entering larynx (epiglottis)

Question 19

alimentary canal: esophagus

Answer 19

• muscular tube that transports food from pharynx to the stomach

Question 20

aves: esophagus (2)

Answer 20

• contains crop used to store large amounts of food to be digested at a later time or regurgitated to feed their young
• lining of crop can produce nutritious substance (crop milk) that is regurgitated to feed young

Question 21

alimentary canal: stomach (3)

Answer 21

• stores meal
• mechanically churns food to physically break it down into smaller pieces
• gastric glands secrete mucus, enzymes, and acid for chemical digestion

Question 22

stomach: why is mechanical digestion necessary?

Answer 22

• increases SA to allow chemical digestion to be more efficient and accessible to enzymes

Question 23

rugae

Answer 23

• folds in the stomach that can unfold to increase stomach volume for storage of food

Question 24

mono-gastric stomach (2)

Answer 24

• single chamber stomach

- mechanical digestion generally due to muscular action

Question 25

aves: stomach (3)

Answer 25

- two chambered stomach: gizzard and proventriculus - proventriculus: produces acid and enzymes for chemical digestion - gizzard: specialized grinding stomach, may contain sand or small stones

Question 26

alimentary canal: small intestines (2)

Answer 26

- main site of chemical digestion of proteins, fats and carbohydrates - major site of nutrient absorption

Question 27

alimentary canal: anterior of SI (3)

Answer 27

- duodenum - contains glands that produce alkaline secretions - liver and pancreas produce secretions (bile, enzymes) into the duodenum

Question 28

bile

Answer 28

- acts as an emulsifier: breaks globules of fat into smaller droplets, increasing SA for enzymes to act

Question 29

what to the glands within the SI produce (2)

Answer 29

- enzymes | - mucus

Question 30

what general structural features of the SI help to increase the total amount of nutrients absorbed (4)

Answer 30

- large surface area - thin epithelium - vascularization - specializations that increase length of time spent in small intestine

Question 31

how does the SI increase SA (2)

Answer 31

- plicae: circular folds in internal surface that are covered in microvilli; do not unfold (permanent) - microvilli: tiny projections of the cell membrane

Question 32

how many layers thicks is the epithelium of the SI

Answer 32

- one cell thick

Question 33

small intestine: pyloric caeca (3)

Answer 33

- located at junction of stomach and duodenum - sites of chemical digestion and nutrient absorption (not fermentation) - internal surface contain villi and microvilli, increasing SA for nutrient absorption

Question 34

small intestine: spiral valve (2)

Answer 34

- chrondrichthyes and sarcopterygii - increases SA for digestion and absorption and slows passage of food through the intestine, increasing time available for digestion

Question 35

how do vertebrates without spiral valves prolong digestion (2)

Answer 35

- small intestine length is greatly increased | - helps slow passage of food and increases SA

Question 36

alimentary canal: microbial digestion (2)

Answer 36

- symbiotic microorganisms can digest some foods that vertebrate cannot produce enzymes for (cellulose; fermentation) - some microorganisms produce vitamins as well

Question 37

intestines: colic caecum (3)

Answer 37

- present at the junction between small and large intestines - many aves have 2 colic caeca - blind-ending chamber specialized for fermentation: contains enlarged SA and many microorganisms that digest cellulose

Question 38

how do vertebrates that digest cellulose using fermentation in the caecum obtain nutrients from digested cellulose?

Answer 38

- release fecal pellets and eat them again to absorb cellulose nutrients

Question 39

alimentary canal: large intestine (2)

Answer 39

- consolidates undigested material into feces for defecation - water reabsorption from indigested material to avoid dehydration: from digestive glands, enzymes, mucus and other secretions

Question 40

which large intestine would be larger: terrestrial tetrapods or freshwater tetrapods

Answer 40

- terrestrial tetrapods: conserving and retaining H2O is more important

Question 41

coelom (2)

Answer 41

- created in space between splanchnic and somatic hypomere layers - gives rise to major body cavities of adult body

Question 42

peritoneum (3)

Answer 42

- continuous sheet of tissue/serous membrane that secretes lubricating fluid - reduces friction to protect organs - lines the pleuroperitoneal cavity/peritoneal cavity