Digestive System

Question 1

extracellular digestion

Answer 1

obtaining nutrients from food within the lumen of the alimentary canal

Question 2

enteric NS

Answer 2

• 100 million neurons that are present in the walls of the GI system
• trigger peristalsis
• heavily regulated by the autonomic NS
• high parasympathetic activity to encourage peristalsis and exocrine secretion, hence lethargy after meals

Question 3

basic path of food

Answer 3

oral cavity
pharynx
esophagus
stomach
small intestine
large intestine
rectum

enzymes and lubricaron provided by salivary glands, pancreas, liver, gallbladder

Question 4

how many salivary glands in mouth?

Answer 4

3

Question 5

which branch of NS triggers salivation?

Answer 5

parasympathetic

Question 6

enzymes of the mouth

Answer 6

salivary amylase and lipase

• hydrolyzing starch into smaller sugars (maltose and dextrins)
• catalyzes hydrolysis of lipids

Question 7

3 parts of pharynx

Answer 7

nasopharynx, oropharynx, laryngopharynx

food prevented from entering the larynx during swallowing by the epiglottis

Question 8

comp of sections of the esophagus

Answer 8

top~> skeletal, somatic
mid~> mix
bottom~> smooth, autonomic

Question 9

which two sphincters must the bolus pass through in the esophagus?

Answer 9

upper and lower esophageal sphincters

Question 10

passage of bolus through stomach

Answer 10

esophagus
fundus
body
antrum
pylorus
pyloric sphincter
duodenum

Question 11

gastric glands respond to signals from…

Answer 11

vagus nerve

Question 12

gastric glands cell types

Answer 12

• mucous: bicarb rich mucus to protect walls from stomach acid
• chief cells: pepsinogen, proteolytic enzyme
• parietal cells: HCl, intrinsic factor which is glycoprotein involved in proper absorption of B12

Question 13

pyloric glands of stomach

Answer 13

G-cells: gastrin, which signal to parietal cells to produce more HCl and induces more stomach contractions

Question 14

food leaves stomach through…

Answer 14

pyloric sphincter and enters the duodenum

Question 15

entrance of chyme into duodenum causes the release of…

Answer 15

brush-border enzymes

disaccharidases (maltase, isomaltase, lactase, and sucrase) and peptidases (including dipeptidase)

Question 16

enzymes of duodenum

Answer 16

• disaccharidases
• peptidases
• enteropeptidases ~> activation of other digestive enzymes from the accessory organs of digestion, trypsinogen to trypsin
• secretin ~> reduce HCl secretion from parietal, inc bicarb secretion, slow motility
• CCK ~> stimulates release of both bile and pancreatic juices (neutralize acidic chyme and emulsify fats into micelles)

Question 17

acinar cells

Answer 17

exocrine cells that produce pancreatic juices

Question 18

pancreatic juices

Answer 18

• bicarb rich, alkaline
• digestive enzymes
• pancreatic amylase ~> polysaccharide into disaccharide
• trypsinogen, chymotrypsinogen, & carboxypeptidases A and B ~> protein digestion after being activated out of zymogen form
• lipase

Question 19

how are pancreatic juices transferred to the duodenum?

Answer 19

• via duct system
• empty into the duodenum via major and minor duodenal papillae

Question 20

bile ducts

Answer 20

liver structure that connects the liver with the gallbladder and small intestine

can be stored in gallbladder or secreted into duodenum

Question 21

liver receives all blood draining from the abdominal portion of the digestive tract through…

Answer 21

• hepatic portal vein
• processed by liver before draining into IVC on its way to the right side of the heart

Question 22

liver and glucose processing

Answer 22

• glycogen storage
• glycogenolysis, gluconeogenesis

Question 23

liver and fat processing

Answer 23

• triacylglycerol formation
• lipoproteins (fat mobilization)

Question 24

liver and detox

Answer 24

• exogenous and endogenous compounds
• ammonia into urea
• metabolizes alcohol and meds

Question 25

bile…

Answer 25

- produced by liver - bile salts, pigments, cholesterol - amphipathic, emulsify fat - bilirubin

Question 26

bilirubin

Answer 26

- byproduct of hemoglobin breakdown - travel to liver for conjugation (attach to protein) and secreted into bile - excess bile and subsequent jaundice is a sign of liver damage

Question 27

liver and protein production

Answer 27

- albumin: maintains plasma oncotic pressure and serves as drug and hormone carrier - clotting factors

Question 28

gallbladder and bile

Answer 28

stores and concentrates it CCK release cause contraction and gallbladder pushes bile into biliary tree, the duct system merges w pancreatic duct before emptying into duodenum

Question 29

pancreatitis

Answer 29

cholesterol and bilirubin stone formation stones get stuck in biliary tree get caught before entering duodenum

Question 30

jejunum and ileum are lined w…

Answer 30

villi ~> capillary bed in the middle for absorption of water soluble nutrients; lacteal, takes up fats for transport into lymphatic system microvilli

Question 31

small intestine simple sugar absorption

Answer 31

- 2° AT and diffusion into epithelial cells - move across the membrane into intestinal capillaries - blood constantly passing carrying carb and aa away - concentration gradient, blood less concentrated - all of these molecules then enter the liver via hepatic portal circulation

Question 32

fats and the small intestine

Answer 32

- short chain FA diffuse into capillaries bc they are nonpolar - large fats, glycerol, and cholesterol move into cell and become triglycerides and esterified cholesterol ~> packaged into chylomicrons ~> enter lymphatic circulation via lacteals ~> enter venous circulation at the thoracic duct in base of neck which empties into left subclavian vein

Question 33

fat soluble vitamin absorption

Answer 33

- ADEK into chylomicrons - straight into lymphatic circulation

Question 34

water soluble vitamin absorption

Answer 34

- BC - taken up across endothelial cells of small intestine and straight into plasma

Question 35

small intestine water absorption

Answer 35

transcellularly and paracellularly

Question 36

cecum

Answer 36

- large intestine - accepts fluid exiting the small intestine via ileocecal valve and is site of attachment of the appendix

Question 37

colon

Answer 37

- large intestine - ascending, transverse, descending, and sigmoid - absorb water and salts - forms feces

Question 38

external vs internal anal sphincter

Answer 38

somatic vs autonomous