Digestive System

Question 1

Layers of GI tract

Answer 1

1. Lumen: opening
2. Mucosa: epithelium, lamina propria, muscularis mucosae
3. Submucosa: glands
4. Muscularis: circular muscle, longitudinal muscle
5. Serosa: areolar connective tissue, epithelium

Question 2

Hard & Soft palate

Answer 2

• Hard palate: most of roof of mouth (bony)
• Soft palate: rest of mouth’s roof (muscular)

Question 3

Uvula

Answer 3

prevents swallowed food from entering nasal cavity

Question 4

Lingual frenulum

Answer 4

limits movement of tongue posterity

Question 4

Gingivae

Answer 4

cover tooth sockets & help anchor teeth

Question 5

Tongue

Answer 5

• forms floor of oral cavity w/ associated muscle
• skeletal muscle covered w/ mucous membrane
• chewing, swallowing, speech
• upper & lateral surfaces are covered w/ papillae, some contain taste buds

Question 6

Esophagus

Answer 6

• collapsible, muscular tube that lies posterior to trachea & connects pharynx to stomach

Question 7

Pharynx

Answer 7

• Funnel shaped tube that extends from internal vares to esophagus
• skeletal muscle lined w/ mucous membrane

Question 8

Stomach function

Answer 8

• mixes saliva, food, & gastric juice to form chyme
• serves as reservoir for food before release into small intestine
• secretes gastric juices, contains HCl, pepsin, intrinsic factor, & gastric lipase

Question 9

Surface mucous cell

Answer 9

secretes mucus

Question 10

Mucous neck cell

Answer 10

• secretes mucus
• absorption

Question 11

Parietal cell

Answer 11

• secretes hydrochloric acid: kills food microbes, denatures proteins, turns pepsinogen into pepsin)
• intrinsic factor (needed for vit. B12 absorption)

Question 12

Chief cell

Answer 12

• secretes pepsinogen (pepsin –> breaks down proteins into peptides) & gastric lipase

Question 13

G cell

Answer 13

secretes hormone gastrin: stimulates parietal cells to secrete HCl & chief cells to secrete pepsinogen, increases stomach motility, & relaxes pyloric sphincter

Question 14

Phases of digestion

Answer 14

• cephalic: sight, smell, taste, or though of food; stimulates gastric secretion & motility by activating parietal & G cells
• gastric: caused by stretching stomach & stimulating receptors; most gastric acid secretion happens during this stage
• intestinal: chyme arrives in small intestine; inhibit gastric secretion & emptying by release of secretin & cholecystokinin (CCK)

Question 15

Gastrin

Answer 15

• action: promotes secretion of gastric juice, increases gastric motility, relaxes pyloric sphincter
• stimulus: stomach distension, partially digested proteins, stomach chyme has high pH

Question 16

Secretin

Answer 16

• actions: stimulates secretion of pancreatic juice, inhibit secretion of gastric juice
• stimulus: acidic chyme enters small intestine; in duodenum

Question 17

Cholecystokinin

Answer 17

• action: inhibits gastric emptying, stimulates secretion of bile, induces satiety
• stimulus: partial amino acid digestion; fats enter small intestine

Question 18

Leptin

Answer 18

• action: regulation of fat storage; acts on hypothalamus to decrease appetite
• stimulus: insulin & higher fat body content; released by adipocytes

Question 19

Liver function

Answer 19

• stores glycogen & fat; plasma protein production; detoxification of blood; bile production
• energy storage: regulates blood sugar by removing glucose & storing it as glycogen & triglycerides; breakdown glycogen to increase blood sugar & make glucose from amino acids

Question 20

Gallbladder function

Answer 20

stores, concentrates, & releases bile

Question 21

Pancreas

Answer 21

produces enzymes that digest carbohydrates, proteins, fats, & nucleic acids; produces sodium bicarbonate which buffers stomach acid; empties contents into duodenum