monogastric stomach

Question 1

stomach

Answer 1

initiates digestion with low pH, enzymatic activity, and physical constrictions

Question 2

pyloric sphincter

Answer 2

smooth muscle valve enabling chyme entry into duodenum

Question 3

what are the three major interlinked control mechanisms of the GI tract

Answer 3

• hormonal (endocrine)
• paracrine
• neural

Question 4

CNS influence on the GI tract is ___

Answer 4

indirect via the ENS and GI endocrine systems

Question 5

the innervation of the GI tract consits of two interacting components:

Answer 5

• extrinsic (autonomic CNS)
• intrinsic (enteric nervous system)

Question 6

what type of innervation consists of the two subdivisions of the autonomic nervous system

Answer 6

extrinsic

Question 7

what are the two subdivision of the autonomic nervous system

Answer 7

parasympathetic and sympathetic

both have important sensory (afferent) component

Question 8

what type of nervous system can act independently of extrinsic neural innervation

Answer 8

the intrinsic - enteric nervous system

Question 9

what are the two systems of ganglia that the ENS is arranged into

Answer 9

submucosal and myenteric plexuses

Question 10

what is the major function of the GI tract

Answer 10

absorption

Question 11

the GI control systems operate to provide an ____ for absorption

Answer 11

optimal environment

Question 12

what are the two regulatory processes of the GI

Answer 12

motility and secretions

Question 13

what is the neural control of the GI

Answer 13

• extrinsic from CNS: autonomic nervous system (parasympathetic and sympathetic)
• intrinsic: enteric nervous system

Question 14

what is the chemical control of the GI

Answer 14

• endocrine secretions
• paracrine secretions
• neurocrine secretions

Question 15

what is the myogenic control of the GI

Answer 15

muscle contraction via interstitial cells of Cajal

Question 16

sympathetic innervation of the ENS is ____

Answer 16

postganglionic

mesenteric ganglia

Question 17

parasympathetic innervation of the ENS is ____

Answer 17

preganglionic

vagus nerve and pelvic nerves

Question 18

sympathetic innervation is inhibitory or stimulatory and what does it use

Answer 18

inhibitory and using peptide neurocrines

shuts off digestion

Question 19

parasympathetic innervation is inhibitory or stimulatory and uses what

Answer 19

stimulatory and uses cholinergic - acetylecholine neurotransmitter

Question 20

plexuses

Answer 20

places where nerves branch and rejoin

Question 21

ganglia

Answer 21

bunches of nerve cell bodies (soma)

Question 22

myenteric plexus

Answer 22

• ganglia between circular and longitudinal muscle
• extensive interneuronal connections

muscle contractions

Question 23

submucosal plexus

Answer 23

• ganglia in submucosal layer
• interneuronal connections limited within plexus

local action - local mucus secretions

Question 24

parasympathetic

Answer 24

• rest and digest
• blood pressure decrease, decreased energy usage, slower heart rate
• active digestion

Question 25

where do the parasympathetic neurons synapse with

Answer 25

ENS neurons

Question 26

sympathetic

Answer 26

* fight or flight * blood pressure increases, heart rate increases digestion slows down

Question 27

where do sympathetic neurons synapse

Answer 27

* some directly affect target cells * other synapse with ENS neurons

Question 28

is there a synapse between enteric neurons and target cells

Answer 28

no; axons end in varicosities

Question 29

what do varicosities release

Answer 29

neurocrine affecting nearby muscle and glandular cells

Question 30

what is afferent signaling

Answer 30

sensory signaling to CNS and ENS

Question 31

what is efferent signaling

Answer 31

motor signaling from the CNS & ENS

Question 32

monogastric stomach is primarily a ____ stomach

Answer 32

glandular stomach

Question 33

what are the glandular regions

Answer 33

* cardiac * fundic * pyloric

Question 34

where are pseudo stratified and stratified columnar epithelium in the GI

Answer 34

in ducts of secretory glands throughout

Question 35

where is stratified squamous epithelium in the GI

Answer 35

lips to cardiac stomach and anal canal

Question 36

where is simple columnar epithelium in the GI

Answer 36

glandular stomach on

Question 37

what is homogenizes and processes food function of the glandular stomach

Answer 37

* chemically via enzymes and acids secreted by the mucosa * mechanically via muscular churning of the stomach wall

Question 38

where does the epithelium change in the stomach

Answer 38

stratified squamous in the esophagus (nonglandular) to simple columnar (glandular)

Question 39

the stomach is lined by longitudinal folds called

Answer 39

rugae | disappear when stomach distends

Question 40

what do the mucus cells in epithelium secrete

Answer 40

protective gel layer: gastric mucosal barrier

Question 41

what are the two functions of the gastric mucosal barrier

Answer 41

* protect stomach lining from auto-digestion * protect stomach from abrasion with food

Question 42

what do cardiac glands secrete

Answer 42

alkaline mucus

Question 43

what do gastric (fundic) glands secrete

Answer 43

mucus, HCL, and pepsinogen

Question 44

what do pyloric glands secrete

Answer 44

mucus/lysozyme and produce Gastrin

Question 45

where are the gastric (fundic) glands located

Answer 45

fundus/body

Question 46

what type of cells are in the neck of the gastric glands

Answer 46

mucous cells and stem cells

Question 47

what type of cells are in the body of the gastric glands

Answer 47

* mucous cells * chief cells * parietal cells * stem cells * enteroendocrine cells

Question 48

what do chief cells produce

Answer 48

pepsinogen

Question 49

what do parietal cells produce

Answer 49

HCl

Question 50

what do enteroendocrine cells produce

Answer 50

gastric hormones

Question 51

what do mucous cells produce

Answer 51

mucins

Question 52

what does the mucus blanket (gastric mucosal barrier) do

Answer 52

* traps bicarbonate ions (HCO3) * the alkalinity of which offsets the acids secreted by the gastric gland and keeps the pH immediately around the epithelium at 7.0

Question 53

enteroendocrine cells are ____

Answer 53

monohormonal

Question 54

enteroendocrine cells produce hormones that contents are released into the lamina propria and act ...

Answer 54

* locally * enter the bloodstream and affect target cells

Question 55

what are two important types of enteroendocrine cells and what do they produce

Answer 55

* G cells - gastrin (produce HCl - pro-digestion) * D cells - somatostatin (suppresses gastrin)

Question 56

where is gastrin produced | stomach region

Answer 56

distal stomach

Question 57

where is cholecystokinin (CCK) produced | GI region

Answer 57

duodenum to ileum

Question 58

where is gastric inhibitory polypeptide (GIP) produced | GI region

Answer 58

duodenum and upper jejunum

Question 59

parietal cells - cytoplasm, produce, and how are they stimulated

Answer 59

* eosinophilic cytoplasm * produce HCL * stimulated to produce HCL by enteroendocrine hormone gastrin

Question 60

chief cells - cytoplasm, produce

Answer 60

* basophilic cytoplasm * proenzyme pepsinogen

Question 61

when pepsinogen is released into the stomach it interacts with _ to form _

Answer 61

HCl; pepsin

Question 62

what nervous systems does the enterogastric reflex involve

Answer 62

CNS and ENS, endo/paracrine signals

Question 63

what type of fibers of the vagus nerve recieve stimuli in the duodenum

Answer 63

afferent

Question 64

what are the types of stimuli that the duodenum recieves | enterogastric reflex

Answer 64

pH, fat, osmolarity

Question 65

what do these stimuli block | enterogastric reflex

Answer 65

block Vagus-induced stomach emptying

Question 66

what is released from endocrine cells in the duodenum | enterogastric reflex

Answer 66

CCK (cholecystokinin) and secretin into the bloodstream

Question 67

what does CCK respond to

Answer 67

fat

Question 68

what does secretin respond to

Answer 68

low pH

Question 69

what do CCK and secretin do

Answer 69

suppress gastric emptying

Question 70

how are H+ ions secreted and generated

Answer 70

* secreted from parietal cells * generated from the dissociated of carbonic acid (H2CO3) * this leaves behind one bicarbonate ion (HCO3-) per H+

Question 71

the carbonic acid utilized in H+ generation is a product of

Answer 71

carbonic anhydrase; which combines H2O and CO2 | exists in high concentrations in gastric mucosa

Question 72

what happens in disease states where gastric secretions are not able to enter the intestine, or are lost via vomiting

Answer 72

blood pH can rise to dangerous levels

Question 73

during the cephalic phase of digestion (anticipation-prior to food entry) which nerve is stimulated

Answer 73

vagal cholinergic nerves (parasympathetic, stimulatory, Ach)

Question 74

what does acidification of the gastric antrum stimulate

Answer 74

the release of somatostatin from D cells

Question 75

what does somatostatin from D cells inhibit

Answer 75

gastrin release and thus acid secretion

Question 76

what does vagal Ach inhibit

Answer 76

somatostatin release

Question 77

pepsinogen is released as a __

Answer 77

proenzyme (zymogen) from chief cells by exocytosis

Question 78

what does hydrochloric acid do to pepsinogen molecules

Answer 78

reversibly acivates them

Question 79

what is pepsinogen cleaved into

Answer 79

pepsin

Question 80

proventriculus

Answer 80

* glandular * oxynticopeptic cells secrete both pepsinogen and HCL

Question 81

ventriculus (gizzard)

Answer 81

* nonglandular * grinding ingesta - grit