GI Lecture 46 & 47

Question 1

Cephalic phase

Answer 1

• activation of the GI tract in readiness for the meal
• thinking about food
• 10% stimulation

Question 2

Preparation to receive/digest food

Answer 2

• increased salivary secretion
• increased gastric secretion
• increased pancreatic secretion
• Gall bladder Contractoin
• Relaxation of Oddi’s sphincter

Question 3

Oral phase

Answer 3

• Same responses as cephalic phase

- Additional activation of GI from sensory of taste buds and mechanical receptors in mouth and upper pharynx

Question 4

Chewing

Answer 4

• digestion begins here

- no absorption in mouth

Question 5

Xerostomia

Answer 5

• dry mouth
• impaired salivary secretion
• lower pH as a result
• tooth decay, esophageal erosions, difficulty swallowing

Question 6

Chewing Muscles

Answer 6

• Temporalis
• Masseters
• Lateral Pterygoids
• Medial Pterygoids

Question 7

What innervates the chewing muscles?

Answer 7

Mandibular division (branch 3) of Trigeminal Nerve

Question 8

Secretions from the GI tract are from? (3)

Answer 8

• glands associated with tract (salivary glands, pancreas, liver)
• glands formed by gut wall
• intestinal mucosa itself

Question 9

Secretaogogues

Answer 9

any substance that stimulates secretion

Question 10

What are the major salivary glands? (3)

Answer 10

• Parotid
• Submandibular
• Sublingual

Question 11

What type of secretions are from the parotid glands?

Answer 11

Serous (water, electrolytes, enzymes)

Question 12

What type of secretions are from sublingual glands?

Answer 12

Mucous (mucin glycoprotein)

Question 13

What type of secretions are from submandibular glands?

Answer 13

Mixed (both)

Question 14

Acini

Answer 14

units of secretion via salivary gland

Question 15

Path of Saliva

Answer 15

Acinar cells produce initial saliva, which passes through intercalated duct, then striated duct
-out through the excretory duct and finally into the main collecting duct

Question 16

Myoepithelial cells

Answer 16

• contract to expel saliva in forward direction (contain actin & myosin fibers)
• present in the acini and intercalated ducts

Question 17

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Answer 17

Adenoma?

Question 18

Functions of Saliva

Answer 18

• Lubrication of ingested food with mucus
• Protection via dilution/buffering of ingested food, neutralization during vomiting, and contains lysozyme to maintain health oral tissue
• initial digestion

Question 19

Major Components of Saliva

Answer 19

Na, K, Ca, Mg, and Cl

-sometimes Fluoride too

Question 20

Major Organic Constituents of Saliva

Answer 20

• Salivary amylase (initiates starch digestion)
• Lingual Lipase (lipid digestion)
• Glycoprotein (mucin upon hydration)
• Lysozyme (attacks material wall)
• Kallikrein (converts plasma protein into bradykinin vasodilate

Question 21

How is human saliva hypotonic?

Answer 21

higher K & HCO3

lower Na & Cl

Question 22

Three types of transporters

Answer 22

• Na-H exchanger
• Cl-HCO3 exchanger
• H-K exchanger

Question 23

How is salivary secretion controlled?

Answer 23

• Neural

- primarily parasympathetic (IP3, Ca)

Question 24

Pharyngeal phase

Answer 24

• soft palate pulled upward
• palatopharyngeal fold moves inward
• epiglottis covers larynx
• UES relaxes to receive food bolus
• pharynx contracts

Question 25

Esophageal phase

Answer 25

• propels food & sphincters protect airway from swallowed material
• primary peristaltic comtraction propels food
• followed by secondary peristaltic waves to clear esophagus
• LES opens and stomach relaxes (receptive relaxation)

Question 26

What is the mucosa covered by?

Answer 26

• stratified squamous epithelium

- only in esophagus and anal sphincters

Question 27

What is metaplasia?

Answer 27

• squamous cells transitioning to columnar epithelium

- due to GERD

Question 28

What is Barret’s disease?

Answer 28

squamous transitioning to intestinal cells

Question 29

GERD acronym stand for?

Answer 29

Gastroesophageal reflux disease

Question 30

What is a hiatal hernia?

Answer 30

• Upper portion of stomach protruding into the chest cavity through esophageal hiatus
• same symptoms as GERD

Question 31

What is Achalasia?

Answer 31

• Smooth muscle of esophagus does not have normal peristalsis and LES does not relax normally
• damage to nerve plexus
• common symptoms include: dysphagia, regurgitation, and chest pain

Question 32

Vomiting

Answer 32

• reverse peristalsis of small intestine
• relaxed pyloric sphincter
• forced inspiration against a closed glottis
• decrease intra-thoracic pressure and increase intra-abdominal pressure
• retching
• salivation increases