GI 03 And 04: Saliva + Cephalic

Question 1

Cephalic phase

Answer 1

The GI is activated in readiness for meal (stimuli are cognitive; include idea of food, smelling food, seeing food, or hearing the sounds of food). These trigger responses in GI system even without ingestion of food

Question 2

Oral phase

Answer 2

Food is actually in the mouth now -manny responses are same as in cephalic phase, however - you’re just getting additional activation of GI because of taste buds and mechanical receptors in mouth and upper pharynx

Question 3

Area of brain associated with cephalic phase

Answer 3

Lower pons and upper medulla (brain stem)

Question 4

General function of PSNS on GI function

Answer 4

Activation

Question 5

General function of SNS action on GI

Answer 5

Inactivation

Question 6

Percent of gastric secretion which occurs as a result of cephalic preparation

Answer 6

33%

Question 7

Effect of SNS on saliva

Answer 7

Leads to increased mucosal secretion —> this increased mucus in saliva makes it more viscous, but SNS also makes there be less volume overall

Question 8

Enzymes present in saliva that begin digestion

Answer 8

Salivary amylase; lingual lipase

Question 9

What is absorbed by the mouth

Answer 9

Nothing except some drugs and alcohol

Question 10

Extrinsic salivary glands means the glands are

Answer 10

Outside the mouth itself

Question 11

Intrinsic salivary glands means the salivary glands are located -_____

Answer 11

Inside the mouth

Question 12

3 extrinsic salivary glands

Answer 12

Parotid, submandibular, sublingual

Question 13

Do extrinsic or intrinsic salivary glands account for the majority of saliva

Answer 13

Extrinsic

Question 14

Parotid salivary glands

Answer 14

Generate a serous (watery) saliva that has a lot of electrolytes and enzymes

Question 15

Sublingual salivary glands

Answer 15

Mucosal salivary glands that produce mucin glycoprotein that leads to high viscosity of saliva and helps with the lubrication of food

Question 16

Submandibular salivary glands

Answer 16

Mixed salivary glands that produce saliva with both serous and mucosal properties

Question 17

Composition and formation of saliva

Also include what is primary saliva and what is secondary saliva

Answer 17

Saliva begins in acinus where cells work to produce primary saliva that has similar tonicity to plasma. This saliva then passes through intercalated and striated ducts that have ductal cells, that eventually generate the final (secondary) saliva.
The primary saliva is squirted in after myoepithelial cells contract

Question 18

Tonicity of primary vs secondary saliva

Answer 18

Isotonic; hypotonic

Question 19

Inorganic components of saliva

Answer 19

Electrolytes (including fluoride) and water

Question 20

Organic components of saliva

Answer 20

Salivary alpha amylase (starts starch digestion)
Lingual lipase (starts lipid digestion
Glycoproteins (mucin forms mucous when hydrated)
Lysozyme (antibacterial)
Opiates (so eating bread is not painful)

Question 21

How does saliva become hypotonic

Answer 21

Ductal cells have many transporters that bring Na out, Cl out, bicarb in, and K out. H is exchanged across a few different of these electrolytes. 
N/H exchanger
Cl/HCO3 exchanger
K/H exchanger
On basalateral side NKA keeps this going

More NaCl is absorbed than we secrete so there is net absorption (hypotonic product)

Question 22

Are ductal cells permeable to water

Answer 22

No

Question 23

Phases of swallowing

Answer 23

Oral phase (voluntary) 
Pharyngeal phase (involuntary)
Esophageal phase (involuntary)

Question 24

How does food move through the esophagus

Answer 24

It rides a peristaltic wave

Question 25

Role of upper esophageal sphincter

Answer 25

Protect airway from swallowed material

Question 26

Role of lower esophageal sphincter

Answer 26

Protect esophagus and airway from swallowed material and acidic contents of the stomach

Question 27

Where would you see the diaphragm in a diagram of swallowing

Answer 27

A peak around 20mN/Sq inch

Question 28

Epithelium present in esophagus

Answer 28

Should be simple squamous

If you see columnar this is a sign of GERD / back flow and called Barrett’s esophagus (puts patient at risk of cancer)