Ch 25 Digestive System

Question 1

Mucosa

Answer 1

• Stratified squamous (in mouth, esophagus, and anus)

- Simple columnar in rest

Question 2

Simple columnar

Answer 2

• secretes enzymes and absorbs nutrients

- goblet cells secrete mucous onto cell surfaces

Question 3

Lamina propria

Answer 3

Thin layer of loose ct

Contains BV and lymphatic tissue

Question 4

Muscularis mucosae

Answer 4

Thin layer of smooth muscle causes folds to form in mucosal layer
Increases local movements increasing absorption

Question 5

Submucosa

Answer 5

Composed of areolar ct and meissner’s plexus

Question 6

Muscularis

Answer 6

Includes skeletal muscle, smooth muscle, and Auerbach’s plexus

Question 7

Skeletal muscle of muscularis

Answer 7

• In mouth, pharynx, upper esophagus and anus

- Control over swallowing and defecation

Question 8

Smooth muscle of muscularis

Answer 8

• Inner circular fibers and outer longitudinal fibers

- Mixes, crushes and propels food along peristalsis

Question 9

Auerbach’s plexus

Answer 9

Both parasympathetic and sympathetic innervation of circular and longitudinal smooth muscle layers

Question 10

Serosa (serous membrane)

Answer 10

• Covers all organs and walls of cavities not open to the outside of the body
• Secretes slippery fluid
• Consists of ct covered with simple squamous epithelium

Question 11

Peritoneum

Answer 11

• visceral layer covers organs

- parietal layer lines walls of body cavity

Question 12

Parts of peritoneum

Answer 12

Mesentery, mesocolon, lesser omentum, greater omentum

Question 13

Peritonitis

Answer 13

Trauma, rupture of GI tract, appendicitis, perforated ulcer

Question 14

Vestibule

Answer 14

Area between cheeks and teeth

Question 15

Enamel

Answer 15

• hardest substance in body

- calcium phosphate or carbonate

Question 16

Dentin

Answer 16

Calcified connective tissue

Question 17

Cementum

Answer 17

• bone-like

- periodontal ligament penetrates it

Question 18

Amylase

Answer 18

• begins starch digestion (pH 6.25-7) in mouth

- when bolus and enzyme hit the pH 2.5 gastric juices hydrolysis ceases

Question 19

Lingual lipase

Answer 19

• secreted by glands in tongue

- begins breakdown of triglycerides into fatty acids and glycerol

Question 20

Layers of GI tract

Answer 20

Mucosal, submucosal, muscularis, serosa

Question 21

Parts of stomach

Answer 21

Cardia, fundus, body, antrum, pylorus

Question 22

Pylorus

Answer 22

Starts to narrow as it approaches pyloric sphincter

Question 23

Gastrin hormone

Answer 23

• release more gastric juice
• increase gastric motility
• relax pyloric sphincter
• constrict esophageal sphincter preventing entry

Question 24

3 layers of stomach

Answer 24

Longitudinal, circular, and oblique

Question 25

Gentle mixing waves

Answer 25

- every 15 to 25 seconds | - mixes bonus with 2 qts/ day of gastric juice to turn it into chyme

Question 26

More vigorous waves

Answer 26

Travel from body of stomach to pyloric region

Question 27

Intense waves near pylorus

Answer 27

Opens and squirts 1-2 tsps into the duodenum with each wave

Question 28

HCl in protein digestion

Answer 28

- HCl denatures (unfolds) protein molecules - HCl transforms pepsinogen into pepsin that breaks peptide bonds btwn certain amino acids - kills most microbes in food

Question 29

Gastric lipase

Answer 29

- splits the triglycerides in milk fat | - most effective at pH 5 or 6 (infant stomach)

Question 30

Digestive enzymes in pancreas

Answer 30

Pancreatic amylase, trypsin, chymotrypsin, elastase, pancreatic lipase, and other proteases

Question 31

Trypsinogen

Answer 31

Activated by enterokinase (brush border enzyme) and by trypsin too

Question 32

Chymotripsinogen

Answer 32

Activated by trypsin

Question 33

Procarboxypeptidase

Answer 33

Activated by trypsin

Question 34

Proelastase

Answer 34

Activated by trypsin

Question 35

Anatomy of liver

Answer 35

- weighs 3 lbs - below diaphragm - 4 lobes; right lobe largest, caudate smallest

Question 36

Hepatic portal vein

Answer 36

Nutrient rich blood from stomach, spleen, and intestines

Question 37

Components of bile

Answer 37

- water and cholesterol - bile salts=Na+ and K+ salts of bile acids - bile pigments (bilirubin)

Question 38

Carbohydrate metabolism

Answer 38

- turn proteins into glucose - triglycerides into glucose - excess glucose into glycogen and store in liver - glycogen back into glucose as needed

Question 39

Lipid metabolism

Answer 39

- synthesize cholesterol - synthesize lipoproteins - HDL and LDL - stores some fat - breaks down some fatty acids

Question 40

Function of HDL and LDL

Answer 40

Used to transport fatty acids in bloodstream

Question 41

Deamination

Answer 41

Removes NH2 from amino acids so can use what is left as energy source

Question 42

Protein metabolism

Answer 42

- Deamination - converts resulting toxic ammonia into urea for excretion by the kidney - synthesizes plasma proteins - convert one amino acid into another

Question 43

Anatomy of small intestine

Answer 43

- 20 ft long, 1 in diameter | - Large surface area for majority of nutrient absorption

Question 44

3 parts of small intestine

Answer 44

Duodenum, jejunum, ileum

Question 45

Segmentation

Answer 45

Helps mix chyme with enzymes and breaks down the big chunks of chyme as small as it can

Question 46

Brush border enzymes

Answer 46

- maltase, sucrase, and lactase - act on disaccharides - produces monosaccharides

Question 47

Digestion of proteins in stomach

Answer 47

- HCl denatures or unfolds proteins | - pepsin turns proteins into peptides

Question 48

Digestion of proteins in pancreas

Answer 48

- digestive enzymes split peptide bonds between different amino acids - brush border enzymes split off amino acid at amino end of molecule or split dipeptides

Question 49

Digestion of lipids in small intestine

Answer 49

- emulsification by bile - pancreatic lipase splits into fatty acids and monoglyceride - no enzymes in brush border

Question 50

Absorption of water

Answer 50

- 9 liters of fluid dumped into GI tract each day - small intestine reabsorbs 8 liters - large intestine reabsorbs 90% of that last liter