Lecture 30 - Monogastric Secretions (Oral, Gastric)

Question 1

what are the 4 functions of saliva

Answer 1

-moisten and lubricate bolus
-dilutes osmolarity of the ingested material
-digestion of carbs and fat
-anti-bacterial

Question 2

what kind of cells are contained in salivary glands

Answer 2

acinar cells

Question 3

what do acinar cells produce

Answer 3

proteins and antibacterial peptides

Question 4

parasympathetic fibers have what effect on acinar cells and myoepithelial cells

Answer 4

• increase production of acinar cells
• contraction of myoepithelial cells

Question 5

what do salivary ducts add

Answer 5

add an alkaline secretion

Question 6

what is the effect of secretin on salivary duct cell secretion

Answer 6

increases

Question 7

(lower/higher) pH in the duodenum increases secretin production

Answer 7

lower pH in the duodenum

Question 8

what kind of drugs dry up secretions from the mouth

Answer 8

anticholinergic drugs

Question 9

what toxin can make horses drool alot? by what mechanism?

Answer 9

toxin in mouldy red clover activates salivary muscarinic receptors

Question 10

esophageal stomach is lined by what kind of epithelium

Answer 10

stratified squamous epithelium

Question 11

is the esophageal stomach glandular or nonglandular

Answer 11

non glandular

Question 12

does the esophageal stomach produce mucus, acid or enzymes?

Answer 12

no

Question 13

is the cardiac stomach glandular

Answer 13

yes

Question 14

what does the cardiac stomach produce and its function

Answer 14

mucus and buffer –> adheres to cells to protect epithelium from proteolytic enzymes and acid

Question 15

is the fundic region of the stomach glandular or non glandular

Answer 15

glandular

Question 16

what does the fundic region of the stomach produce

Answer 16

produces acid, proteolytic enzymes, hormones, mucus

Question 17

which compartment of the stomach is generally the largest

Answer 17

fundic region of the stomach

Question 18

is the pyloric region of the stomach glandular or non glandular

Answer 18

glandular

Question 19

what does the pyloric stomach produce

Answer 19

produces mucus and buffer but not acid or proteolytic enzymes

Question 20

what cells live in the pyloric region of the stomach

Answer 20

enteroendocrine cells and G cells that produce gastrin

Question 21

what increases gastrin secretion from G cells in the pyloric stomach

Answer 21

high stomach distention and high stomach pH

Question 22

what are gastric pits lined with

Answer 22

lined with mucus secreting cells at the luminal surface

Question 23

what is the function of the mucus on the surface of gastric pits

Answer 23

forms a thick gel to protect stomach from acid and proteolytic enzymes

Question 24

where does each gastric pit lead into

Answer 24

leads into a gastric gland: very deep invagination in the submucosa

Question 25

function of chief cells

Answer 25

secrete proteolytic enzyme precursor pepsinogen into the stomach

Question 26

describe the activation of pepsinogen

Answer 26

pepsinogen is cleaved into pepsin by HCl

Question 27

what do chief cells also produce in neonates? what does it do>

Answer 27

also produces rennin in neonates, helps digest milk `

Question 28

effect of rennin on milk

Answer 28

converts liquid milk to semisolid for longer residence in the GI and better absorption

Question 29

what do parietal cells secrete? function?

Answer 29

acid to help hydrolytic breakdown of diet components and kills bacteria in ingesta

Question 30

how are parietal cell proton secretions increased

Answer 30

Hormonal and parasympathetic efferent innervation

Question 31

3 factors that activate mechanisms to increase proton secretions by parietal cells** (tAkE a DeEp BrEaTh:)

Answer 31

• histamine produced by ECL cells when gastric gland fluid pH is too high, histamine then diffuses to reach nearby parietal cells and binds to receptors on parietal cell (on basolateral side)
• hormone gastrin secreted into blood and reaches parietal cell on basolateral side
• increases in stomach distention and osmolarity which then increases vagal afferent to medulla and then vagal efferent stimulation of parietal cells increases (Ach working on muscarinic receptors)

Question 32

describe the anticipation of food on vagal efferents to parietal cells

Answer 32

sight/smell/chewing/ swallowing of food increases parasympathetic activity which directly increases parietal and chief cell acivity
- increase in parasympathetic activity also increases gastrin secretion by G cells which then increases parietal and pepsinogen secretions

Question 33

why are there multiple mechanisms in the control of acid secretion

Answer 33

ensure acid production by parietal cell can be increased on demand

Question 34

mucous cells secrete…

Answer 34

mucus!!!! (shocker i know)

Question 35

parietal cells secrete…

Answer 35

HCl

Question 36

chief cells secrete…

Answer 36

pepsinogen

Question 37

G cells secrete

Answer 37

gastrin

Question 38

ECL cells secrete

Answer 38

histamine

Question 39

how can epithelial cells lining the stomach get damaged

Answer 39

excessively low pH or other trauma

Question 40

how do epithelial cells lining the stomach respond to damage

Answer 40

produce prostaglandin (requires function of cyclooxygenase (COX)-1

Question 41

actions of prostaglandin

Answer 41

• reduce histamine and gastrin secretion by enteroendocrine cells (reduce acid secretion)
• increases mucus secretion by nearby epithelial cells
• increases blood flow to area: provides nutrients needed for rapid repair or replacement of damaged cells

Question 42

what are ulcers

Answer 42

erosions of the mucosal lining of the GI system

Question 43

clinical signs of GI ulceration

Answer 43

vomiting, anorexia, abdominal pain, weight loss

Question 44

what enzyme is expressed in arthritic joints

Answer 44

COX-2

Question 45

action of COX-2

Answer 45

catalyzes production of prostaglandins which are proinflammatory and activate nociceptors (pain) in affected region

Question 46

COX 2 inhibitors are…

Answer 46

NSAIDs: ex. aspirin, Ibuprofen

Question 47

COX 1 inhibitors

Answer 47

also NSAIDs :(

Question 48

function of NSAIDs on COX-1

Answer 48

prevents prostaglandin production by cells that are damaged within the digestive tract (decreases tissue homeostasis and increases risk of ulcer development)

Question 49

how can ulcers be treated

Answer 49

administer synthetic analogs of prostaglandins

Question 50

carprofen

Answer 50

major COX 2 inhibitor (good for arthritic ouchies) with minor effects on COX1 activity (allows digestive tract to keep producing prostaglandins

Question 51

what are other ways that ulcers can be treated

Answer 51

histamine receptor antagonists, muscarinic antagonists, proton pump inhibitors