Lecture 4: A &P of digestive system pt 2

Question 1

cephalic phase of the stomach

Answer 1

• smell or thought of food causes parasympathetic stimulation of vagus nerve, which innervates the stomach
• in response cell in stomach release mucus, HCl, pepsinogen, ghrelin, and gastrin.

Question 2

gastric phase of the stomach

Answer 2

• begins w arrival of food in stomach
• more gastrin is released into the blood, which leads to protein digestion, mixing wave contractions, and stimulates gastric motility
• gastric lipase digests fats
• protein called intrinsic factor binds to b12 for b12 absorption

Question 3

function of HCl in stomach

Answer 3

• acidic environment necessary for cells that secrete pepsinogen
• kills most food pathogens
• denatures proteins for further breakdown
• inactivates food enzymes as well as salivary amylase
• breaks down plant cell walls and meat connective tissue

Question 4

rate of gastric emptying: increased volume of food

Answer 4

increased rate (activation of stretch receptors and increased pressure)

Question 5

rate of gastric emptying: increased osmality

Answer 5

lowered rate (osmosis has to happen first)

Question 6

rate of gastric emptying: increased nutrient density

Answer 6

lowered rate

Question 7

rate of gastric emptying: increased food particle size

Answer 7

lowered rate (heavier particles collect in lower part of stomach and have to be broken down)

Question 8

rate of gastric emptying: increased food viscosity

Answer 8

lowered rate (soluble fiber means more water has to be drawn in)

Question 9

dietary fibers

Answer 9

• carbohydrate polymers with ten or more units that can’t be digested by humans
• bacteria in colon breaks it down into SCFAs
• reduces risk of colon cancer

Question 10

insoluble fiber

Answer 10

• found in plant skins, main component of plant cell wall
• swells in water
• reduce transit time in GI tract because it gives bulk to stool and helps with constipation

Question 11

soluble fiber

Answer 11

• inner fleshy part of fruits and endosperm of grains and seeds
• thickens in water, increases viscosity
• slows gastric emptying, increases satiety
• binds to bile for elimination, reduces level of circulating cholesterol
• slows glucose absorption rate and increases insulin sensitivity, aids diabetics

Question 12

ulcer

Answer 12

when stomach acid damages lining of digestive tract.

-causes: specific bacteria, anti-inflammatory pain medications like aspirin

Question 13

intestinal phase

Answer 13

• begins when chyme first enters the duodenum

- controls emptying and secretions in GI tract

Question 14

reactions to distention of duodenum

Answer 14

• inhibits gastrin production
• inhibits gastric contractions
• stimulates contraction of pyloric sphincter (prevents further discharge of chyme into small intestine till it’s good and ready)

Question 15

intestinal phase secretions

Answer 15

alkaline mucus, cholecystokinin (CKK), gastric inhibitory peptide (GIP), and secretin

Question 16

alkaline mucus

Answer 16

-triggered by parasympathetic vagal stimulation

Question 17

CKK

Answer 17

• cholecystokinin
• triggered by proteins and fat in chyme
• constricts pyloric sphincter which inhibits gastric emptying (which makes you feel fuller)
• stimulates pancreatic enzyme secretion, increases bile synthesis in liver, and stimulates gallbladder contractions to release bile

Question 18

GIP

Answer 18

• gastric inhibitory peptide
• triggered by carbs in chyme
• stimulates release of insulin from pancreas
• promotes growth and survival of beta cell
• stimulates adipogenesis (formation of fat cells from stem cells)

Question 19

secretin

Answer 19

• triggered by decreased pH
• stimulates release of pancreatic buffers (pancreatic amylase and lipase)
• protects duodenum from acidic chyme
• increases mucus secretion in duodenum
• neutralizes pH in duodenum

Question 20

4 pancreatic enzymes

Answer 20

• pancreatic alpha-amylase: breaks down carbs and starches
• proteases: breaks down proteins to amino acids
• pancreatic lipase: breaks down lipids to fatty acids
• nucleases: breaks down RNA or DNA

Question 21

3 parts of the small intestine and functions

Answer 21

• duodenum (secretions and hormones to further aid in digestion of chyme)
• jejunum (chemical digestion and nutrient absorption)
• ileum (absorbs bile acids, fluid, and vit B-12)

Question 22

mesentary

Answer 22

a membrane that attaches the intestine to the abdominal wall and holds it in place
-highly vascularized and depot for fat

Question 23

large intestine/colon

Answer 23

• final absorption: water, vitamins and electrolytes from chyme
• comes after small intestine; forms and propels feces towards rectum for elimination
• colonic bacteria produce vit K and biotin, help to digest fiber and breast milk, help immune system and brain health

Question 24

dysfunctions of large intestine

Answer 24

diarrhea, constipation, hemorrhoids (swollen veins in rectum and anus), and diverticulosis (pockets develop in large intestine cause of weakness of muscle walls)