Upper GI biochem

Question 1

What is saliva?

Answer 1

mixture of salivary gland secretions, microorganism products and soluble food products in the mouth

Question 2

What are the main functions of saliva?

Answer 2

lubrication, digestion of food/enzymatic activity, growth factor prod. for epithelial cells, neutralizes bacterial acids, mediates taste sensations, defense again bacteria

Question 3

What are the 3 major salivary glands?

Answer 3

parotid
submaxilary
sublingual

Question 4

What are the 2 innervations of the salivary glands?

Answer 4

glossopharyngeal and facial nn.

Question 5

What is contained the the primary secretion in the salivary glands?

Answer 5

ptyalin (alpha amylase)
mucus
extracellular fluid
lingual lipse

Question 6

What ions are secreted into the saliva?

Answer 6

potassium & bicarb

Question 7

What ions are absorbed from the saliva?

Answer 7

sodium and chloride

Question 8

What does lysozyme do?

Answer 8

kills gram postive but not gram negative bacteria (cleaves beta 1,4 linkages of sugars in cell wall)

Question 9

Function of peroxidase?

Answer 9

kills bacteria by producing reactive bromide and iodine

Question 10

Function of lactoferrin?

Answer 10

binds iron and prevents bacterial and some fungal growth

Question 11

Function of IgA?

Answer 11

recognizes and binds bacteria to induce immune reactions

Question 12

Function of defensins?

Answer 12

antimicrobial polypeptides that form pore complexes on microbial cell membranes

Question 13

Function of mucins?

Answer 13

modulate adhesion of baceria to oral tissues including teeth (antimicrobial), also lubricates
contains Oglycostylated specific glycoproteins

Question 14

What does bicarb in the saliva do?

Answer 14

neutralizes bacterial produced acids (esp gram negative)

Question 15

Which virusses are carried in the saliva?

Answer 15

herpes, HSV, EBV, mumps, rabies, HIV

Question 16

How does CF causes xerostomia?

Answer 16

mutant chloride transports to plasma

Question 17

How does Sjoegren’s syndrome cause xerostomia?

Answer 17

autoantibodies to salivary gland proteins

Question 18

How much saliva is produced per day?

Answer 18

I liter

Question 19

Where are endocrine like cells located in the gastric gland?

Answer 19

base

Question 20

What are the 3 phases of gastric secretion?

Answer 20

cephalic-via vagus, PNS excites pepsin and acid prod.
gastric-local nervous secretory reflexes, vagal reflexes, gastrin-histamine stimulation
intestinal-nervous &hormonal mechanism

Question 21

What two transmitters does the vagus nerve release? what is their effect?

Answer 21

ACh-stimulated secretion of parietal cell HCl and ECL histamine
Gastric releasing peptide-stimulated secretino of G cell gastrin

Question 22

What do D cells secrete? what inhibits/stimulates its release? effect?

Answer 22

somatostatin-stimulated by HCl, inhibited by nerve cell ACh

-inhibits secretin of G celll gastrin, ECL histamine, parietal HCl

Question 23

What do G cells secrete? What inhibits/stimulates its release? effect?

Answer 23

gastrin-stimulated by nerve cell GRP, inhibited by somatostatin
-stimulates secretion of D cell somatostatin, ECL histamine, Parietal cell HCl

Question 24

What do ECL cells secrete? what inhibits/stimulates its release? effect?

Answer 24

Histamine-stimulated by nerve Ach, inhibited by D cell somatostatin
-stimulates scretion of parietal cell HCl

Question 25

What do parietal cells secrete? what inhibits/stimulates this release? effect?

Answer 25

HCl-stimulated by nerve ACh, ECL cell histamine, G cell gastrin, inhibited by D cell somatostatin

Question 26

Approximately how long after a meal does food buffer the pH of the stomach?

Answer 26

2hrs

Question 27

Do oral cavity enzymes work in the stomach?

Answer 27

no, they are inactivated by the decrease in pH

Question 28

What cell type secretes intrinsic factor?

Answer 28

parietal cells

Question 29

What enzymes do fat digetion here?

Answer 29

lingual lipase | gastric lipase

Question 30

What enzymes break down carbs here?

Answer 30

alpha amylase

Question 31

What does protein digestion here?

Answer 31

pepsinogen (once converted to pepsin) | cleaves before hydrophobic AAs

Question 32

What converts pepsinogen to pepsin?

Answer 32

HCl or Pepsin

Question 33

What makes up gastric mucous?

Answer 33

mucins, phosphipids, electrolytes, water

Question 34

What does gastric mucous do?

Answer 34

lube, protect (w/bicarb and mucins)

Question 35

What are the key motor functions of the stomach?

Answer 35

storage mixing and propulsion emptying

Question 36

What regulates stomach emptying?

Answer 36

in stomach-stretching stimulates myenteric reflex& gastrin stimulate pylorus pum in duodenum-uses enteric nervous system, exrinsic & vagus nerves in parallel to inhibit stomach contractions and increase pyloric sphincter tone

Question 37

Which endocrine cells are located in the body of hte stomach?

Answer 37

ECL

Question 38

Which endocrine cells are located in the antrum of the stomach?

Answer 38

D & G cells