GI Tract Part 1

Question 1

what does the alimentary canal extend from

Answer 1

oral cavity to anus

Question 2

what are the 5 phases that breakdown of food occurs in

Answer 2

ingestion, fragmentation, digestion, absorption, elimination

Question 3

what phases of food breakdown occurs in the oral cavity

Answer 3

ingestion and fragmentation resulting in bolus formation

Question 4

what phases of food breakdown occurs in the stomach

Answer 4

fragmentation and initiates digestion

Question 5

what is peristalsis and what type of innervation is it

Answer 5

contractions of smooth muscle under autonomic control

Question 6

what do duodenum, pancreatic and biliary secretions do

Answer 6

emulsification of fat

Question 7

where does the primary absorption of nutrients occur

Answer 7

jejunum and ileum

Question 8

what phases of food breakdown occur in the colon

Answer 8

resorption of water and elimination of waste

Question 9

what is the gut

Answer 9

a muscular tube lined by mucus membrane

Question 10

what are the 4 distinct layers of the GI tract

Answer 10

mucosa, submucosa, muscularis externa and adventitia

Question 11

what are the 3 functions of the mucosa

Answer 11

protection, secretion and absorption

Question 12

what are. the 3 layers of the mucosa

Answer 12

epithelium, lamina propria and muscularis mucosae

Question 13

what are the functions of the epithelium in the mucosa

Answer 13

secretory and absorptive functions

Question 14

what is the lamina propria and what does it contain

Answer 14

underlying CT, contains lymphoid nodules, glands, blood vessels and lymphatics

Question 15

what is the muscularis mucosae

Answer 15

-thin layer of smooth muscle, boundary between mucosa and submucosa

Question 16

what is the submucosa

Answer 16

loose to dense irregular CT layer beneath muscularis mucosae

Question 17

what does the submucosa contain

Answer 17

larger blood vessels, nerves and lymphatics

Question 18

what are the 2 layers of the muscularis externa

Answer 18

inner circular layer and outer longitudinal smooth muscle layers

Question 19

describe how the muscle fibers of the inner circular layer and the outer longitudinal layer are oriented to each other

Answer 19

at right angles

Question 20

what does segmentation do

Answer 20

local contractions that result in mixing of food occurring proximally and distally

Question 21

what does peristalsis do

Answer 21

propels food distally only (aborally)

Question 22

what is the adventitia and what does it contain

Answer 22

outer loose CT layer, contains major nerves, vessels, and adipose tissue

Question 23

what is the adventitia referred to within the abdominal cavity

Answer 23

serosa or visceral peritoneum

Question 24

what is the adventitia continuous with

Answer 24

the supporting mesentary

Question 25

what is the adventitia lined with

Answer 25

simple squamous epithelium (mesothelium)

Question 26

what does the adventitia merge with in some areas

Answer 26

retroperitoneal tissue

Question 27

what is the result of parasympathetic stimulation in the gut

Answer 27

excitatory

Question 28

what is the result of sympathetic stimulation in the gut

Answer 28

inhibitory

Question 29

where do parasympathetic motor nerves synapse in the GI tract

Answer 29

with ganglia located within submucosa and muscularis externa

Question 30

what are clusters of parasympathetic ganglia within submucosa called

Answer 30

Meissner's plexus or submucosal plexus

Question 31

what are large clusters located between inner circular and outer longitudinal muscle layers called

Answer 31

myenteric or Auerbach's plexus

Question 32

describe the esophagus

Answer 32

short muscular tube lined by stratified squamous nonkeratinized epithelium

Question 33

in the upper third of the esophagus what is the muscularis externa composed of

Answer 33

voluntary skeletal muscle

Question 34

in the middle third of the esophagus what is the muscularis externa composed of

Answer 34

skeletal muscle and smooth muscle

Question 35

in the lower third of the esophagus what is the muscularis externa composed of

Answer 35

smooth muscle only

Question 36

what does the gastro-esophageal junction between the esophagus and the stomach contain

Answer 36

gastroesophageal sphincter

Question 37

what is pyrosis and what is its cause

Answer 37

heartburn, due to regurgitation of stomach acid into distal esophagus from cardia of stomach

Question 38

what are the regions of the stomach

Answer 38

cardia, fundus, and pylorus

Question 39

what is the cardia surrounded by

Answer 39

smooth muscle cardiac sphincter

Question 40

what does the cardiac sphincter contain

Answer 40

mucus secreting glands

Question 41

what is another name for the cardiac sphincter

Answer 41

gastroesophageal sphincter

Question 42

what is the fundus and what does it secrete

Answer 42

glandular portion of stomach; secretes acid, pepsin and some mucus

Question 43

what is another name for the body of the stomach

Answer 43

corpus

Question 44

what does the pylorus contain

Answer 44

primarily mucus and gastrin secreting glands

Question 45

what is the pyloric sphincter made of and what does it control

Answer 45

made of smooth muscle and controls the outflow from stomach into duodenum

Question 46

what happens in peptic/gastric ulcer

Answer 46

loss of stomach/duodenal epithelium/mucosa

Question 47

where does damage extend to in an ulcer

Answer 47

below level of basement membrane which results in bleeding

Question 48

where does damage extend to in erosion

Answer 48

partial loss of epithelium which does not result in bleeding

Question 49

how are peptic/gastric ulcers treated

Answer 49

with antacids

Question 50

what are ulcers frequently associated with

Answer 50

chronic infection with helicobacter pylori

Question 51

what does helicobacter pylori produce

Answer 51

urease which increases gastric pH which increases acid production

Question 52

how are ulcers associated with helicobacter pylori treated

Answer 52

with triple therapy- 2 long term antibiotics and proton pump inhibitor

Question 53

how does food undergo mechanical breakdown in the stomach

Answer 53

via muscular activity

Question 54

how does food undergo chemical breakdown in the stomach

Answer 54

via gastric secretions to form chyme

Question 55

what is the third layer of the muscularis externa in the stomach called

Answer 55

inner oblique

Question 56

what is absorbed in the stomach

Answer 56

little absorption occurs except water, alcohol and some drugs such as aspirin

Question 57

what are the prominent longitudinal folds in the stomach lining called

Answer 57

rugae

Question 58

what does the mucosa in the glandular body of the stomach contain

Answer 58

gastric pits

Question 59

what do gastric pits form the entrance to

Answer 59

gastric glands

Question 60

describe gastric glands

Answer 60

straight, tubular glands

Question 61

what does gastric juice contain

Answer 61

HCl, pepsinogen, gastrin, rennin, lipase

Question 62

what is pepsinogen and what does it do

Answer 62

inactive precursor of pepsin that hydrolyzes protein

Question 63

what is pepsinogen converted to pepsin by

Answer 63

action of HCl

Question 64

what is the mucosa of the stomach protected by

Answer 64

thick layer of mucus

Question 65

what are the 5 types of cells in gastric glands

Answer 65

mucus secreting cells, surface mucus cells, mucus neck cells, acid secreting cells, pepsin secreting cells

Question 66

where are mucus secreting cells found

Answer 66

cover luminal surface and upper third of pit

Question 67

what do surface mucus cells secrete and where are they located

Answer 67

secrete thick, insoluble mucus and bicarbonate ions; located on surface

Question 68

what do mucus neck cells secrete and where are they located

Answer 68

secrete soluble mucus, located in upper third of pit, at neck of gastric gland

Question 69

what is another name for acid secreting cells

Answer 69

parietal cells

Question 70

what do acid secreting cells do

Answer 70

secrete HCl and intrinsic factor

Question 71

what is intrinsic factor necessary for

Answer 71

absorption of Vitamin B12 from ileum

Question 72

where are acid secreting cells most numerous and what color do they stain

Answer 72

in middle third of gland and stain pink to purple

Question 73

what is another name for pepsin secreting cells

Answer 73

chief cells

Question 74

what do pepsin secreting cells secrete and where are they located

Answer 74

secrete inactive pepsinogen and located at the base of gland (bottom third)

Question 75

what color do pepsin secreting cells stain and why

Answer 75

purple due to large numbers of ribosomes

Question 76

what color do mucus secreting cells stain on H and E

Answer 76

clear

Question 77

how often are mucus secreting cells renewed

Answer 77

3-7 days

Question 78

how often are parietal and chief cells replaced

Answer 78

every year

Question 79

what are parietal and chief cells controlled by

Answer 79

autonomic nervous system and hormones from endocrine cells in region of pylorus

Question 80

what does APUD cells stand for

Answer 80

amine precursor uptake and decarboxylation

Question 81

what are enteroendocrine cells

Answer 81

paracrine cells

Question 82

what do enteroendocrine cells do

Answer 82

secrete variety of peptide hormones such as gastrin and secretin in response to local factors - control GI motility and gastric secretion

Question 83

what secretes gastrin and what does it do

Answer 83

secreted by G cells, stimulates secretion of HCl and pepsin

Question 84

what secretes somatostatin and what does it do

Answer 84

secreted by D cells and inhibits secretion of gastrin

Question 85

what secretes secretin and what does it do

Answer 85

secreted by S cells and inhibits gastric secretion and stimulates smooth muscle contraction

Question 86

where are undifferentiated stem cells located

Answer 86

in the neck of gland

Question 87

what is the main function of the small intestine

Answer 87

primary site of absorption and digestion

Question 88

what are the relative lengths of small intestine

Answer 88

ileum> jejunum> duodenum

Question 89

what are plica circulares and where are they located

Answer 89

valve like folds/rings in the mucosa and submucosa throughout the small intestine

Question 90

what is the function of plica circulares

Answer 90

increase surface area and contain submucosal core

Question 91

what is the mucosal surface made up of and what is its core

Answer 91

made of villi that have a core of lamina propria

Question 92

what are between the villi

Answer 92

crypts of lieberkuhn

Question 93

what is coeliac disease and what happens

Answer 93

gluten enteropathy that causes villus blunting and atrophy resulting in malabsorption and weight loss

Question 94

what is the epithelium supported by and what does it contain

Answer 94

supported by connective tissue lamina propria, containing capillaries and lymphatics for absorption of nutrients

Question 95

what are intestinal villi lined by

Answer 95

simple columnar epithelium

Question 96

what are mucosal cells of the small intestine called

Answer 96

enterocytes

Question 97

what is the brush border

Answer 97

apical/luminal surface highly folded, modified into microvilli

Question 98

what is the function of the brush border

Answer 98

increased surface area for absorption coated with protected glycocalyx of disaccharides

Question 99

what is the site of membrane digestion at the brush border

Answer 99

glycocalyx of disaccharides