Ch 47 Animal Nutrition

Question 1

The digestive system has many specialized organs for:

Answer 1

• feeding
• digestion
• absorption
• egestion

Question 2

Structures for mechanical digestion

Answer 2

Digestive tract

Question 3

Produce digestive chemicals

Answer 3

Glands

Question 4

– Feeding, mechanical and enzymatic digestion of carbohydrates

Answer 4

Mouth

Question 5

– secrete saliva (enzyme salivary amylase digests starch)

Answer 5

Three pairs of salivary glands

Question 6

– carry food to stomach by peristalsis

Answer 6

Pharynx and esophagus

Question 7

• waves of muscular contraction
• pushes food along digestive tract with smooth muscles
• like movement with a hydrostatic skeleton

Answer 7

Peristalsis

Question 8

– mechanical digestion by vigorous churning

– enzyme pepsin in gastric juice digests proteins

Answer 8

Stomach

Question 9

– folds in stomach wall

– expand as stomach fills with food

Answer 9

Rugae

Question 10

Gastric glands secrete

Answer 10

– hydrochloric acid
– pepsinogen (precursor of pepsin)
– pepsin

Question 11

Partially breaks down protein

Answer 11

Pepsin

Question 12

• site of most chemical digestion and nutrient absorption.

Answer 12

Small Intestine

Question 13

– partly digested food of small intestine

Answer 13

Chyme

Question 14

Upper small intestine
– location of most enzymatic digestion
– produces and receives digestive enzymes from liver & pancreas

Answer 14

Duodenum

Question 15

Finger like projections
– to increase absorption surface
– S.I. is 17ft long, but area almost 3000 sq ft

Answer 15

Villi

Question 16

Cell mebrane projections

Answer 16

Microvilli

Question 17

Transports amino acids and glucose to liver

Answer 17

Hepatic portal vein

Question 18

Produces bile

– which emulsifies fats

Answer 18

Liver

Question 19

Releases enzymes

– digest protein, lipids, carbohydrate, RNA, DNA

Answer 19

Pancreas

Question 20

– digest polypeptides to dipeptides

Answer 20

Trypsin and chymotrypsin

Question 21

– degrades fats

Answer 21

Pancreatic lipase

Question 22

– digests complex carbohydrates

Answer 22

Pancreatic amylase

Question 23

• Polysaccharides: such as starch but not cellulose
– digested to disaccharide maltose by salivary and pancreatic amylases
• Maltase produced by small intestine
– splits maltose into glucose (main product of
carbohydrate digestion)

Answer 23

Carbohydrate Digestion

Question 24

• Proteins are split
– by pepsin in stomach into smaller polypeptides
– by proteolytic enzymes in pancreatic juice
* including trypsin and chymotrypsin
* break a variety of peptide bonds
• Dipeptidases

Answer 24

Protein Digestion

Question 25

• Lipids are emulsified by bile salts
– emulsify: break large masses into smaller droplets
– increases surfaces for digestion
• Ingested as triacylglycerols (basic fat molecule)
– hydrolyzed by pancreatic lipase
– into fatty acids and monoacylglycerols in duodenum
– digestion is often incomplete and triacylglycerols may be absorbed without modification

Answer 25

Lipid Digestion

Question 26

• Different from most other nutrients
• Fatty acids and monoacylglycerols
– enter epithelial cells in intestinal lining
– are reassembled into triacylglycerols (fat molecules)
– then packaged into chylomicron droplets
• Chylomicrons (fat transport units in circulatory system)
– also contain cholesterol and phospholipids
– are covered by a protein coat
• Lymphatic system
– transports chylomicrons to blood circulation

Answer 26

Lipid Absorption

Question 27

– cecum, colon, rectum, anus
– water and sodium absorbed from remaining chyme
– incubates many bacteria feeding on undigested food
• examples: E. coli, but anaerobic bacteria more prevalent
• produce vitamin K, certain B vitamins, CO2 methane
– eliminates (not excretes) undigested wastes

Answer 27

Large intestine

Question 28

• Fed amino acids and glucose through the hepatic portal vein; fats after retrieval from lymphatic system
• Contains a network of tiny blood sinuses
• like a sponge of specialized capillaries
• nutrients, toxins, and wastes are removed from blood
• Plays a central role in the biochemical conversions of organic molecules

Answer 28

Liver & Metabolism

Question 29

Building up

Answer 29

Anabolism

Question 30

Breaking apart

Answer 30

Catabolism

Question 31

– released by duodenum

– split small peptides into amino acids

Answer 31

Dipeptidases