Chapter 48-The Digestive System

Question 1

4 phases of animal nutrition

Answer 1

1. Ingestion
2. Digestion-break down large molecules into smaller monomers
3. Absorption-absorb monomers, water, salts form digestive tract into body
4. Elimination-of undigested material

Question 2

Types of digestive systems

Answer 2

Intracellular-single celled organisms
Extracellular-within digestive cavity
-Gastrovascular cavity-cnidarians and flatworms, only one opening

Question 3

who has the most primitive complete digestive tract

Answer 3

-nematodes

Question 4

Order of general digestive characteristics

Answer 4

ingested food=stored or physical fragmentation

• chemical digestion next
• products pass through guts epithelial linging into the blood
• wastes excreted from anus

Question 5

Chemical digestion

Answer 5

digestion by a specific enzyme that cleaves a sspecific bond

Question 6

Physical Digestion

Answer 6

any digestion that does not involve specific enzymes

Question 7

Tubular tract of vertebrates consists of

Answer 7

• mouth and pharynx-ingestion
• esophagus-delivers food to stomach
• stomach-preliminary digestion
• small intestine-digestion and absorption
• large intestine-absorption of water and minerals
• cloaca or rectum-elimination

Question 8

Layers of gastrointestinal tract

Answer 8

• mucosa-innermost surface (lined with epithelium)
• submucosa-connective tissue
• muscularis-circular and longitudinal smooth muscle layers
• serosa-outermost

Question 9

Birds have what to break up food

Answer 9

two chambered stomach

-gizzard-muscular chamber that uses ingested pebbles to pulverize food

Question 10

Carnivores have what type of teeth

Answer 10

pointed teeth that lack flat grinding surfaces

Question 11

Herbivores have what type of teeth

Answer 11

large flat teeth suited for grinding cellulose walls

Question 12

Humans have what type of teeth

Answer 12

carnivore teeth up front and herbivore teeth in the back

Question 13

what is salivation controlled by

Answer 13

nervous system

Question 14

Epiglottis

Answer 14

closes off the respiratory tract, blocks off larynx

Question 15

Bolus

Answer 15

food from mouth ready to be swallowed

Question 16

peristalsis

Answer 16

rhythmic one direction waves on contraction that push the bolus through the esophagus to the stomach

Question 17

3 types of secretory cells in stomach

Answer 17

mucus-secreting cells-mucus protects stomach lining

• parietal cells-secrete HCL and intrinsic factor, makes stomach pH about 2
• chief cells-secrete pepsinogen which is converted to pepsin within stomach by HCL activity

Question 18

what type of digestion does stomach do

Answer 18

physical-low pH helps denature food proteins

-absorption of some water

Question 19

Chyme

Answer 19

mixture of partially digested food and gastric juice in stoach

Question 20

small intestine

Answer 20

very long

• digests chyme from stomach
• digestive enzymes and bicarbonate from pancreas secreted into here with bile form liver and galbladder

Question 21

small intestine consists of?

Answer 21

Duodenum-first section, most digestive enzymes enter, much digestion

• Jejunum-digestion in first part, absorption elsewhere
• Ileum-some absorption, form feces, many bactery

Question 22

epithelial wall of small intestine?

Answer 22

covered with villi, which are covered with microvilli

Question 23

Pancreas

Answer 23

exocrine and endocrine gland

-Exocrine function-pancreatic fluid with enzymes is secreted into the duodenum through pancreatic duct

Question 24

Pancreatic enzymes

Answer 24

trypsin and chymotrypsin-proteins into smaller polypeptides

• pancreateic amylase-polysaccharides into shorter sugars
• Lipase-fats into free fatty acids and monoglycerides
• bicarbonate neutralizes acidic chyme

Question 25

Liver

Answer 25

bodys largest internal organ

-secretes bile-involved with physical digestion of lipids

Question 26

Gallbladder

Answer 26

stores and concentrates bile from liver

Question 27

Absorption in small intestine

Answer 27

Jejunum

• amino acids and monosaccharides are transported through epithelial cells to blood
• fatty acids and monoglycerides diffuse into epithelial cells

Question 28

Large intestine

Answer 28

Much shorter than small intestine

• no digestion
• reabsorbs water, remaining electrolytes, vitamin k

Question 29

Feces composition

Answer 29

• 60-75% water

- 40-25% undigested material, salts, bacteria

Question 30

Ruminants

Answer 30

Four chambered stomach

-cellulose degrading microbes

Question 31

Rumination

Answer 31

Contents of stomach are regurgitated and chewed

Question 32

What regulates gastrointestinal activiteis

Answer 32

nervous and endocrine systems

Question 33

What does the nervous system do for digestion

Answer 33

stimulates salivary and gastric secretions in response to sight, smellm and consumption of food

Question 34

Liver

Answer 34

chemically modifies the substance absorbed from the digestive tract before they reach the rest of the body
–ex. alcohol

Question 35

Insulin

Answer 35

Liver regulated

-stimulates removal of excess blood glucose by liver and skeletal muscles (converted and stored as glycogen)

Question 36

Glycogenolysis

Answer 36

glucagon stimulates liver to break down glycogen to release glucose into blood

Question 37

Gluconeogenesis

Answer 37

liver converts other molecules into glucose if fasting continues

Question 38

Basal Metabolic Rate

Answer 38

Minimal amount of energy consumed under defined resting conditions

Question 39

Leptin

Answer 39

peptide hormone

• key to appetite control
• produced by adipose tissue in response to eating, receptor located in hypothalamus

Question 40

Essential nutrients

Answer 40

animals are unable to manufacture these for themselves

• vitamins (vitamin c)
• amino acids-9 required
• long chain unsaturated fatty acids
• minerals