Stomach 1

Question 1

name the two functional regions of the stomach (and their main parts)

Answer 1

proximal- fundus and proximal body

distal- distal body and antrum (pylorus)

Question 2

the proximal region (orad stomach) is responsible for what?

Answer 2

receiving ingested meal

Question 3

the distal region (caudad stomach) is responsible for what

Answer 3

contractions that mix food and propel it into duodenum

Question 4

what are the three functions of the stomach?

Answer 4

storage
mixing
emptying

Question 5

what occurs in the stomach during food storage

Answer 5

proximal stomach relaxes to accommodate ingested meal- via receptive relaxation
pressure slowly returns to basal level
stomach can hold up to 1.5 L w/ little change in pressure

Question 6

receptive relaxation (what is it, what mediates it, how is it abolished)

Answer 6

process by which the proximal stomach relaxes to accommodate ingested meal
mediated by vagovagal reflex
abolished by vagotomy

Question 7

the vagovagal reflex is initiated by what?

Answer 7

distention of the stomach

Question 8

what occurs in the stomach during mixing

Answer 8

presence of food causes distal stomach to increase contractions
this mixes food with gastric sections and reduces size of particles
food mixed into pasty consistency (chyme)

Question 9

what is chyme?

Answer 9

semifluid mass of partly digested food passed from the stomach to small intestine (made during mixing in stomach)

Question 10

what occurs in stomach during emptying

Answer 10

distal stomach contracts to propel food into duodenum

Question 11

peristaltic contractions originate where and proceed how?

Answer 11

originate in pacemaker region (midstomach)

proceed distally

Question 12

a peristaltic contractions move distally toward pylorus what happens to velocity and force of the contractions?

Answer 12

they both increase

Question 13

retropulsion (what is it)

Answer 13

process by which most of chime is propelled back into the stomach to be mixed
due to wave on contractions closing distal antrum and pyloric sphincter before chyme reaches there

Question 14

the wave of peristaltic contractions does what to distal antrum and pyloric sphincter

Answer 14

closes them before the chyme can reach there

causes retropulsion

Question 15

what occurs during fasting (contractions wise and how often)

Answer 15

contractions called migrating myoelectric complexes occur at 90 minute intervals

Question 16

migrating myoelectric complexes (what do they do)

Answer 16

occur every 90 minutes during fasting
clear the stomach of any residual food
cause hunger contractions if stomach has been empty for about 2 hours

Question 17

how are migrating myoelectric complexes abolished

Answer 17

eating

Question 18

hunger pangs (when do they start and how long do they last)

Answer 18

start 12-24 hours after last meal

continue for about 3-4 days before subsiding

Question 19

emptying of the stomach occurs when?

Answer 19

chyme decomposed into small enough pieces to fit through pyloric sphincter

Question 20

following a normal mixed meal emptying of the stomach may take about how long, and is dependent on what?

Answer 20

about 3 hours

depends on type of food ingested

Question 21

place the following in order of fastest to slowest in terms of emptying from the stomach:
protein-rich food
carbohydrate-rich food
fat-rich food

Answer 21

carbohydrate-rich food (fastest of these three) > protein-rich food > fat-rich food (slowest of these three)

Question 22

between liquids and solids which empty from the stomach fastest

Answer 22

liquids

Question 23

the rate of emptying has what type of relationship with the pressure in the proximal stomach (which increases slowing during digestive period)

Answer 23

inversely proportional

Question 24

gastric emptying is controlled mostly by what?

Answer 24

signals from duodenum

Question 25

gastric emptying is inhibited by what stimuli?

Answer 25

``` high [H+] fat or protein digestion products non-isotonic solutions increases distention of proximal stomach increase pressure in proximal small intestine ```

Question 26

gastric emptying prevents what? (in terms of the flow of chyme)

Answer 26

prevents flow of chyme from exceeding ability of intestine to handle it

Question 27

Gastroparesis (what is it, what does it produce, what causes it

Answer 27

impaired/ delayed emptying produces symptoms of fullness, loss of appetite, nausea, vomiting most common cause is diabetes

Question 28

increased gastric emptying can cause what?

Answer 28

``` diarrhea (b/c increased osmotic load in small intestine) duodenal ulcers (b/c stomach acid damages duodenum) ```

Question 29

dumping syndrome (what is it, when is it common)

Answer 29

occurs when lower end of small intestine fills too quickly with undigested food from the stomach common after surgery

Question 30

dumping syndrome (what are the phases, when do they occur, and what are the symptoms)

Answer 30

early phase- occurs either during/right after meal (nausea, vomiting, diarrhea) late phase- occurs 1-3 hours after meal (sweating, weakness, dizziness)

Question 31

the symptoms of dumping syndrome are due to what?

Answer 31

too much fluid in intestine and hypoglycemia

Question 32

based on secretory function what are the two regions of the stomach

Answer 32

oxyntic gland mucosa (located in proximal stomach) | pyloric gland mucosa (located in distal stomach)

Question 33

oxyntic gland mucosa (located where and secretes what)

Answer 33

``` located in proximal stomach secretes: acid pepsinogen intrinsic factor mucus ```

Question 34

pyloric gland mucosa (located where and secretes what)

Answer 34

``` located in distal stomach secretes: mostly gastrin some mucus some pepsinogen ```

Question 35

in the oxyntic gland the surface mucous cells extend into what?

Answer 35

duct opening

Question 36

in the oxyntic gland the mucous neck cells (what do they secrete and what do they serve as)

Answer 36

secrete mucus | serve as stem cells

Question 37

in the oxyntic gland the stem cells proliferate and differentiate into what?

Answer 37

surface mucous cells parietal cells chief cells endocrine cells

Question 38

in the oxyntic gland the parietal cells secrete what?

Answer 38

acid | intrinsic factor

Question 39

in the oxyntic gland the endocrine cells secrete what?

Answer 39

products that regulate gastric function

Question 40

in the oxyntic gland the chief (peptic) cells secrete what?

Answer 40

pepsinogen

Question 41

what are the 4 components of gastric juice that have physiological function

Answer 41

HCl Pepsin Mucus Intrinsic Factor

Question 42

what begins digestion of dietary protein?

Answer 42

HCl

Question 43

lack of or reduction in acid production leads to what? (in terms of the stomach and upper small intestine)

Answer 43

infections of the stomach and small intestine

Question 44

what kills most bacteria that enter the stomach

Answer 44

HCl

Question 45

pepsin is stored and secreted as what?

Answer 45

inactive precursor pepsinogen

Question 46

pepsinogen is converted to pepsin by what?

Answer 46

``` gastric acid (HCl) pepsin ```

Question 47

what begins digestion of proteins by splitting interior peptide bonds in proteins

Answer 47

pepsin

Question 48

what causes greatest increase in secretion of pepsin

Answer 48

vagal stimulation

Question 49

the mucus of the stomach serves what purpose?

Answer 49

serves as a protective coating for stomach and lubricant and barrier between cells and ingested material two forms: soluble and insoluble

Question 50

the soluble for of mucus in the stomach is secreted from where, does what, and is present when?

Answer 50

secreted from mucus neck cells after stimulation by vagus nerve mixes with other secretions of glands and lubricates chyme not present in resting stomach

Question 51

the insoluble/visible form of mucus in the stomach is secreted from where, as what, and what does it do?

Answer 51

secreted by surface mucus/goblet cells secreted as gel forming unstirred layer over mucosa traps dead cells from mucosa and forms protective coat

Question 52

insoluble/visible form of mucus is secreted when?

Answer 52

by resting stomach | in response to chemical or physical irritation

Question 53

what maintains the pH at the surface of the stomach nearly neutral

Answer 53

HCO3- trapped in the insoluble layer

Question 54

what happens to insoluble mucus on contact with acid?

Answer 54

precipitates into clumps and passes into duodenum with chyme

Question 55

insoluble mucus with alkaline secretions make up part of what barrier?

Answer 55

gastric mucosal barrier that prevents damage to mucosa by gastric contents

Question 56

intrinsic factor (what is it, what secretes it, what does it do)

Answer 56

glycoprotien secreted by parietal cells of gastric mucosa binds vitamin B12

Question 57

where is vitamin B12 absorbed and what is required of the absorption to occur?

Answer 57

absorption occurs in ileum | intrinsic factor is required of the absorption

Question 58

the absence of intrinsic factor results in what?

Answer 58

pernicious anemia

Question 59

total gastrectomy patients require what?

Answer 59

injections of vitamin B12

Question 60

parietal cells secrete what into the lumen of the stomach and what into the bloodstream

Answer 60

HCl into lumen of stomach | HCO3- into the bloodstream

Question 61

the H+ secrete into the lumen across the cell membrane is in exchange for what and by what?

Answer 61

K+ in a 1:1 ratio by H+/K+ ATPase

Question 62

where does the bicarbonate in the parietal cells come from?

Answer 62

CO2 generated by cell metabolism and then carbonic anhydrase

Question 63

Cl- enters the parietal cell how and is secreted into the lumen how?

Answer 63

enters cell in exchange for HCO3- | secreted in to lumen through channel

Question 64

alkaline tide (what creates it, where does it occur, and when)

Answer 64

HCO3- creates it in venous blood of actively secreting stomach by raising pH

Question 65

chronic vomiting can lead to what?

Answer 65

hypokalemia

Question 66

K+ concentration is what in the gastric juice compared to the plasma

Answer 66

always zΩhigher concentration in gastric juice than plasma

Question 67

ionic composition of gastric juice changes with what?

Answer 67

rate of secretion

Question 68

at low (basal) rates of secretion what is the ionic composition of gastric juice

Answer 68

primarily NaCl from nonparietal secretions

Question 69

at high (stimulated) rates of secretion what is the ionic composition of gastric juice

Answer 69

primarily HCl from parietal secretion