Oral and Gastric Biochemistry Flashcards Preview

GI/Nutrition > Oral and Gastric Biochemistry > Flashcards

Flashcards in Oral and Gastric Biochemistry Deck (24)
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1
Q

What are the components of saliva? (3)

A

Salivary gland secretions
Microorganism products
Soluble food products

2
Q

How much saliva is produced per day?

A

One liter

3
Q

What is the purpose of saliva? (6)

A

Lubrication
Aids in digestion/enzymatic cleavage
Growth factors for epithelium
Neutralization of bacterial acids (bicarbonate)
Taste mediation
Defense against microbes

4
Q

What is the innervation of the parotid, submaxillary/submanidbular and sublingual glands?

A

Parotid glands – CN IX
Submaxillary/submandibular – CN VII
Sublingual – CN VII

5
Q

What are the primary secretions of the salivary glands? (3)

A

Ptyalin (alpha-Amylase)
Mucus
ECF

6
Q

What types of ion balancing are the salivary glands responsible for? (4)

A

Na+ active absorption
Cl- passive absorption
K+ active secretion
HCO3 secretion

7
Q

What specific salivary substances are responsible for bacterial defense?

A

Lysozyme
Peroxidase
Lactoferrin
IgA
Defensins
Mucins

8
Q

Mechansims of lysozyme and what does it target?

A

Beta 1-4 Linkage Cleavage
NAM and NAG in peptidoglycan (gram positive walls)
NAG residues in fungal wall

9
Q

Mechanism of peroxidase, lactoferrin, mucins

A

Peroxidase – Bromide and iodine

Lactoferrin – Iron sequestration

Mucins
Lubricants, antimicrobial, found throughout the GI tract
Highly O-glycosylated specific glycoproteins targeting Ser/Thr

10
Q

What viruses are associated with saliva?

What conditions can be associated with xerostomia?

What other pathology should you be concerned with

A

HSV, HHVs, EBV, Mumps, Rabies, HIV

Cystic fibrosis
Sjorgen’s syndrome

Cancer of glands

11
Q

What are the cell types of the gastric crypts?

A

Superficial epithelial cells
Mucous neck cells
Stem cell
Parietal cells
Chief cell
Endocrine cells

12
Q

What are the phases of gastric secretion?

A

Cephalic phase
Gastric phase
Intestinal Phase

13
Q

Which molecules are released by the vagus nerve release?
What do they affect?

A

ACh - Stimulates Parietal Cell, ECL cell; Inhibits D cell

Gastric releasing peptide - Stimulates G cell

14
Q

What does the D cell secrete?

What affects its secretion?

What does it affect?

A

Somatostatin

Stimulated by HCl, Inhibited by ACh

Inhibits G cell, ECL cell, parietal cell

15
Q

What do G cells release?
What affects its secretion?
What does its secretion affect?

A

Gastrin

Stimulated by GRP, Inhibited by somatostatin

Stimulates D cell, ECL, cell, Parietal cell

16
Q

What do ECL cells secrete?

What affects its secretion?

What does its secretion affect?

A

Histamine

Stimulation by ACh, D cell somatostatin inhibition

Parietal cell HCl

17
Q

What happens to the pH level of the stomach during a meal and digestion?

A

Food essentially buffers the acid and increases the pH
Emptying of stomach decreases pH and increased acid secretion
As stomach digestion ends, somatostatin reduces acid secretion, stabilizing the pH

18
Q

What is released for fat digestion and from where?

A

Lingual lipase – Salivary glands
Gastric lipase – Chief cells

19
Q

What is released for carbohydrase digestion?
Where?
Mechanism?

A

Amylase (Ptyalin) – Salivary glands

Cleaves Alpha 1,4 in glucose

20
Q

What is released for protein digestion?
From where?
How they are activated and why is it necessary?
What do they target?

A

Pepsinogens – Chief Cells
Activated by HCl or activated Pepsin
Cleavage required to expose active site
Pepsin cleaves hydrophobic proteins

21
Q

Where is stomach mucous from?
What is it composed of?
What is its function?

A

From mucous cells
Composed of Mucins, Phospholipids, Electrolytes, Water
Lubricates, Protects using bicarbonate and mucins

22
Q

What is motor function of the stomach while storing food?
Which reflex is important?

A

Food in concentric circles stretching the stomach
Vasovagal reflex results in relaxation of wall

23
Q

What motor function occurs in stomach during mixing and propulsion?
How does this affect digestion?
Where does the food move to?
How much is released at this time?

A

Mixing waves from peristalsis breaks non-covalent bonds of food
Allows access for protein based denaturation
Pylorus muscle contraction pushes food to mid stomach
Only a few millimeters of food released as chyme

24
Q

How does emptying occur in the stomach?

What is regulation of this at the stomach and duodenal levels?

A

Intense peristaltic contractions in stomach anthrum begin mid-stomach and propagate down
Progressively contractions start higher up in stomach wall

Stomach level
Stretching of stomach wall stimulates myenteric reflex to increase pylorus pump
Gastrin also induces pylorus pump

Duodenal
Nerves in response to wall distension, mucosal irritation and chime acidity
Signals sent through ENS, extrinsic nerves and vagus nerves together inhibit stomach contractions and increase tone of pyloric sphincter