A&p.2.digestive.2

Front 1

what do exocrine gland cells in the stomach do?

Back 1

secretions from gastric juice

Front 2

what are the three types of exocrine gland cells in the stomach?

Back 2

1. mucous neck cells
2. parietal cells
3. chief cells

Front 3

what do mucous neck cells do?

Back 3

line the pit, protection, and secretes mucous

Front 4

what 4 things do parietal cells in the stomach do?

Back 4

1. give us HCl (acid)
2. intrinsic factors
3. transport H+ into the stomach lumen
4. transport Cl- into stomach lumen

Front 5

how is parietal cells and intrinsic factor?

Back 5

help us absorb vitamin B12

Front 6

what happens when pareital cells transport H+ into the stomach lumen?

Back 6

-H+ generated from CO2 and H2O via carbonic annhydrase
-H+ actively transported via H+/K+ pump into lumen

Front 7

what are the 4 functions of increased HCl in stomach?

Back 7

1. denatures protein
2. enzyme inactivation
3. kills most microorganisms
4. activated pepsinogen to pepsin

Front 8

what is an alkaline tide?

Back 8

when bicarbonate ions (HCO3-) dump into blood and cause local increase in pH

Front 9

what do chief cells do?

Back 9

secrete pepsinogen and acid activation

Front 10

what is the positive feedback of chief cells?

Back 10

pepsin activation of pepsinogen

Front 11

what is the function of chief cells?

Back 11

protein digestion- breaking up peptide bonds and leaves fragments of smaller peptide chains

Front 12

what are 2 types of enteroendocrine cells?

Back 12

1. G cells
2. D cells

Front 13

where are G cells and what do they secrete?

Back 13

in lowest portion of stomach; secretes gastrin

Front 14

what are 2 functions of the hormone gastrin?

Back 14

1. stimulates secretion by parietal and cheif cells
2. stimulate gastric wall contractions by acting on muscularis externa

Front 15

what do D cells secrete?

Back 15

somatostatin

Front 16

how is somatostatin released?

Back 16

continuously released adjacent to G cells and goes through blood through the sympathetic nerve to inhibit gastrin release

Front 17

when is the only time you want gastrin release?

Back 17

during digestion

Front 18

what overrides D cells?

Back 18

hormonal and neural stimuli

Front 19

what do D cells protect us from?

Back 19

early gastric release

Front 20

where is the cardia region?

Back 20

at the top where esophagus reaches stomach

Front 21

what 2 compnents make up the cardia region?

Back 21

1. gastric pits (GP) lines with simple columnar epithelium
2. cardia glands (CG) make mucous secretion

Front 22

what 2 compnents make up the body of fundic region?

Back 22

1. cheif cells
2. parietal cells

Front 23

what happens in the pyloric region?

Back 23

open pyloric sphincter to release into small intestine

Front 24

what 2 types of secretions are involves in pyloric region?

Back 24

1. mucous secretion line for acidity
2. enteroendocrine secretions

Front 25

what two hormones are involved in enteroendocrine secretions?

Back 25

1. gastrin
2. somatostatin

Front 26

how does the ANS and SNS affect somatostatin release?

Back 26

-ANS controls release
-SNS turns down- stops release so G cells can release gastrin

Front 27

what are the three phases of the stomach digestive processes?

Back 27

1. cephalic phase
2. gastric phase
3. intestinal phase

Front 28

what happens during the cephalic stage?

Back 28

-occurs before the bolus enters stomach
-inputs activate olfactory and taste bud receptors

Front 29

what happens once olfactory and taste bud receptors are activated during the cephalic stage?

Back 29

they're relayed to the hypothalamus to the vagus nerve and they stimulate neurons in the medulla oblagata

Front 30

what 3 things occur once neurons in the oblagata are stimulated?

Back 30

1. motor impulses via vagus nerves to parasympathetic enteric ganglia
2. stimulate stomach glands
3. enhance secretory activity

Front 31

briefly explain the process of the cephalic stage through flowchart

Back 31

CNS-> Vagus nerve-> submucosal plexus-> stimulates: mucous (neck) cells, parietal, chief, and G cells

Front 32

what 5 things happen during the gastric phase?

Back 32

1. bolus enters the stomach
2. acid and enzymes process the ingested material
3. chemical stimuli and local neural and hormonal mechanisms provides release of gastric juice
4. churning and mixing of material
5. results in chyme

Front 33

what is the chemical stimuli of the gastric phase?

Back 33

- increase activity of chief and parietal cells
- increase pH, more alkine, activate G cells

Front 34

what 2 things happen once gastric juice is release in the gastric phase?

Back 34

1. protein digestion begins
2. lingual lipase (secreted from saliva) begins lipid digestion

Front 35

what do local neural mechanisms activate during the gastric phase?

Back 35

1. activation of myenteric plexus (chemical and stretch receptors
2. activates submucosal plexus- chemical stimulation/stretch

Front 36

what is the myenteric plexus and what does it activate during the gastric phase?

Back 36

chemical and stretch receptors; it activates muscularis externa and we get churning

Front 37

what two type of responses are involved in the intestinal phase?

Back 37

1. hormonal
2. neural

Front 38

what 2 things happen dring the neural response of the intestinal phase?

Back 38

1. distension of duedenum and chemical triggers
2. enterogastric reflex

Front 39

what do the chemical triggers during distension of the duodenum involve?

Back 39

squeezing of chyme into intestine and acid comes in, low pH around 2, and undigested lipids, peptides, and carbs

Front 40

what 3 things does the enterogastric reflex do?

Back 40

-inhibit vagal nuclei in medulla
-inhibit local reflexes
-activate sympathetic fibers

Front 41

what happens once sympathetic fibers are activated?

Back 41

puts us into flight fright stage, digestive system slows, slows pyloris phincter which controls the rate of chyme entering

Front 42

what is the stomach result of the enterogastric reflex?

Back 42

-gastric activity declined

Front 43

what is the intestinal result of the enterogastric reflex?

Back 43

-protection and time to begin digestion

Front 44

what happens during the hormonal response?

Back 44

enterogastrones are triggered by arrival of chyme; everytime chyme comes in there in a decrease in pH

Front 45

what three hormons are involved in the hormonal response of the intestinal phase?

Back 45

1. cholecystokinin (CCK)
2. gastric inhibitory peptide (GIP)
3. secretin

Front 46

what is cholecystokinin (CCK)?

Back 46

lipids; inhibits stomach contraction which controls sphincter (slows pyloric release)

Front 47

what causes stomach contractions to be inhibited by CCK?

Back 47

by gallbladder contraction and pancreatic enzyme release

Front 48

what is gastric inhibitory peptide (GIP)?

Back 48

lipids, CHO; inhibitys gastric secretions and contractions by stimulating insulin release

Front 49

what does secretin do?

Back 49

lowers pH; inhibits parietal and chief cell activity by stimulating productions of bicarbonate ions (pancrease) and secretion of bile (liver)

Front 50

where does the small intestine extend?

Back 50

from the pyloric sphincter to ileocecal valve

Front 51

what are the 3 divisions of the small intestine?

Back 51

1. duodenum
2. jejunum
3. ileum

Front 52

where is the duodenum?

Back 52

retroperitoneal (behind the peritoneal); curves around the pancreas

Front 53

what is the duodenum's major job?

Back 53

-mixing tank (chyme comes in)
-pancreatic and bile released in here
-short (10 inches)

Front 54

what happens in the jejunum?

Back 54

chemical digestion and absorption (nutrient); reenters peritoneal cavity

Front 55

what is the ileum?

Back 55

-controls flow of chyme
-longest segment; ends at ileocecal valve

Front 56

what are the plicae circulares of the small intestine?

Back 56

permanent fold of mucosa and submucosa

Front 57

what is the villi in the small intestine?

Back 57

-projections of absorptive epithelial layer
-large in duodenum and gradually narrow and shorten
-absorptive columnar epithelial cells

Front 58

what does the core of the villi contain?

Back 58

capillary bed and lacteal for absorption

Front 59

what is a lacteal?

Back 59

lymph vessels; lipid absorption, muscularis mucosa- "milks the lacteals"-->gets fluid mocing

Front 60

what is the microvilli of the small intestine?

Back 60

projections of absorptive epithelial cells that release brush border enzymes for digestion completion

Front 61

what role does the muscularis externa contractions play in the small intestine?

Back 61

segmentation: absorption efficiency

Front 62

what four types of cells are in the epithelium of the small intestine?

Back 62

1. goblet cells
2. intestinal glands
3. paneth
4. enteroendocrine

Front 63

what do the goblet cells do?

Back 63

secrete mucus

Front 64

what do the intestinal glands of the small intestine epithelium do?

Back 64

-Crypts of Lieberkuhn: decrease as following the length of the large intestine; secrete intestinal juice

Front 65

what do paneth cells do?

Back 65

-secrete lysozyme and perform phagocytosis
-clear, yellow fluid- water and mucous, slightly alkaline

Front 66

what are the three cells involved in enteroendocrine cells?

Back 66

1. S cells
2. CCK cells
3. K cells

Front 67

what do S cells do?

Back 67

secrete secretin; activates pancrease to produce more gallbladder secretions

Front 68

what do CCK cells do?

Back 68

increase gallbladder contraction, increase pancreatic contraction

Front 69

what do K cells do?

Back 69

initiate release of insulin from pancreas

Front 70

what two factors make up the lamina propria?

Back 70

1. MALT
2. Brunner's glands (duodenal glands)

Front 71

what are 3 components of MALT in the lamina propria of the small intestine?

Back 71

1. solitary lymphatic nodules
2. aggregated lymphatic follicles also in ileum: Peyer's patches; increase as we near large intestine
3. submucosa only in duodenum

Front 72

what are brunner's glands?

Back 72

duodenal glands that have alkine mucus only to neutralize chyme

Front 73

where is the last part of digestion always done?

Back 73

at the lining

Front 74

what 3 things contribute to digestion in small intestine?

Back 74

1. brush border enzymes
2. digestion takes place at cell surface
3. sloughing of cells releases enzymes

Front 75

where are the brush border enzymes of the small intestine?

Back 75

inserted in plasma membrane of microvilli

Front 76

what are 3 types of brush border enzymes?

Back 76

1. 4 CHO digesting enzymes
2. Protein digesting enzymes
3. Nucleotide enzymes

Front 77

what are the 4 CHO digesting enzymes?

Back 77

dextrinase, maltase, sucrase, lactase

Front 78

what are protein digesting enzymes?

Back 78

peptidases (aminopeptidase and dipeptidase)

Front 79

what are nucleotide enzymes?

Back 79

nucleosidases and phosphatases

Front 80

what are the 2 types of mechanical digestion?

Back 80

1. segmentation
2. peristalsis

Front 81

what is segmentation?

Back 81

-circular muscles only; stimulus is distention to segment
-localized mixing contractions

Front 82

where are the localized mixing contractions most rapid? progressively slower?

Back 82

rapid- in duodenum where chyme comes in starting digestion
slow- ileum

Front 83

what is peristalsis?

Back 83

-begins after absorption success-less distension
-migrating motility complex= slow
-chyme remains in small intestine ~3-5 hours

Front 84

what are the six chemicals involved in chemical digestion within the small intestine?

Back 84

1. CHO's
2. Monosaccharides
3. proteins
4. amino acids
5. lipids
6. nucleic acids

Front 85

what is involved in CHO's?

Back 85

-pancreatic amylase
-a-dextrinase
-sucrase, lactase, and maltase

Front 86

what is pancreatic amylase?

Back 86

-glycogen and starches, mostly disaccharides
-acts on starches not already broken down into maltose, maltotriose, and a-dextrins

Front 87

what is a-dextrinase?

Back 87

-brush border enzyme
-clips off glucoses one at a time from a-dextrins; left over from pancreatic digestion

Front 88

what is sucrase, lactase, and maltase?

Back 88

brush border enzymes that digest disaccharides into monosaccharides

Front 89

what happens to monosaccharides during chemical digestion?

Back 89

they are absorbed by facilitated diffusion and cotransport mechanism

Front 90

what are proteins?

Back 90

-enzymes in pancreatic juice
-continue to breakdown proteins into peptides
-Peptidases (brush border enzymes): aminopeptidase and dipeptidase

Front 91

what are the 4 enzymes in pancreatic juice?

Back 91

1. trypsin
2. chymotrypsin
3. carboxypeptidase
4. elastase

Front 92

what is the most abundant lipid?

Back 92

triglyceride

Front 93

what are 3 compnents of lipids?

Back 93

1. bile
2. lipases
3. micelles

Front 94

what is bile?

Back 94

-salts of bile acids (Na+, K+)
-emulsification of large lipid globules

Front 95

what does emulsification of large lipid globules do?

Back 95

-amphiphatic
-breaks into smaller droplets (surround the fat)
-increases surface area for enzymatic action

Front 96

what are pancreatic lipases?

Back 96

-split triglycerides and phospholipids
-interact with bile salts in chyme
-form micelles

Front 97

what happens to micelles?

Back 97

they're absorbed and surrounded by bile; free, fatty acids and trigly. and monogly.

Front 98

what are the four different types of nucleic acids?

Back 98

1. ribonuclease (pancreas)
2. deoxyribonuclease (pancrease)
3. nucleosideases and phosphatases
4. pentoses, phosphates, nitrogenous bases absorbed by active transport

Front 99

what does ribonuclease digest?

Back 99

RNA in the pancreas

Front 100

what does deoxyribonuclease digest?

Back 100

DNA in the pancrease

Front 101

what are nucleosidases and phosphatases?

Back 101

brush border enzymes that digest nucleotides into pentoses, phospates and nitrogrnous bases

Front 102

what do ribonuclease and deoxyribonuclease breakdown to?

Back 102

phosphatases

Front 103

what is the smallest of DNA and RNA breakdown?

Back 103

nitrogenous bases

Front 104

how are pentoses, phosphates, nitrogenous bases absorbed?

Back 104

active transport