Intro to GI II/ Mouth and Esophagus

Question 1

Phase 1 of the migrating motor reflex is what?

Answer 1

A quiescent period which occurs before the MMC with no spike periods or contractions.

Question 2

What occurs in Phase II of the migrating motor reflex?

Answer 2

Phase II corresponds to an increase in irregular action potentials which can initiate contractions.

Question 3

What occurs during Phase III of the migrating motor reflex?

Answer 3

Here, a peak of electrical activity occurs with regular spike potentials and contractions. This then will lead back to the phase I quiescent period.

Question 4

What are the key stimulates to GI contractions?

Answer 4

Mechanical stretch and PNS/ENS neurotransmitter Acetylcholine.

Question 5

What are some key inhibiting factors that act on the GI?

Answer 5

Nitric Oxide
VIP
and
Norepinephrine.

Question 6

Which two sections of the GI tract are controlled by striated voluntary muscle?

Answer 6

Upper esophageal sphincter along with the upper 1/3 of esophagus.

And the external anal sphincter.

Question 7

Which two hormones are largely involved in relaxing the sphincter smooth muscle?

Answer 7

NO and VIP

Question 8

The pyloric sphincter can be found between what structures and what action does it have?

Answer 8

Found between the stomach and the duodenum regulating gastric emptying.

Question 9

The ileocecal sphincter is found between what structures and what action does it have?

Answer 9

Found between the ileum and cecum.

Question 10

What causes the ileocecal sphincter to close or open?

Answer 10

Ileum distension relaxes the sphincter

Ascending colon distention causes contraction.

Question 11

Serious/watery salivary excretions contain what enzyme?

Answer 11

Alpha amylase.

Question 12

Mucous salivary excretions contain what substance?

Answer 12

Water, electrolytes, phospholipids, and mucin.

Question 13

What function does salivary Mucin have?

Answer 13

Glycosylated protein with multiple functions in lubrication and protection of the epithelial surfaces of the mouth.

Question 14

Ninety percent of saliva is produced by what three glands?

Answer 14

Parotid gland
Submandibular gland
Sublingual salivary glands.

Question 15

Which salivary gland produces only watery saliva?

Answer 15

The parotid Gland

Question 16

Which salivary gland produces only mucus?

Answer 16

Minor glands.

Question 17

Which salivary glands secrete both watery and mucal saliva?

Answer 17

Submandibular and sublingual glands.

Question 18

How is water initially moved into a salivary gland?

Answer 18

Acetylcholine activates an apical membrane muscarinic chloride ion channel leading to chloride secretion followed by water and sodium diffusion.

Question 19

When saliva initially enters the duct it is …. to its environment, as it travels from the duct to the mouth it becomes … to its environment.

Answer 19

Begins as isotonic.
Through the removal of sodium and chloride ions and the additio of HCO3 and K+ it becomes hypotonic.

Furthermore, the ducts are impermeable to water.

Question 20

What is the primary stimulus for saliva secretion?

Answer 20

Acetylcholine is the primary stimulus through muscarinic receptors and subsequent calcium signaling pathways.

Question 21

What are some of the secondary stimulus for saliva secretion?

Answer 21

Substance P
Norepinephrine
And acetylcholine.

Question 22

What effect does norepinephrine have on the salivary glands?

Answer 22

Stimulates secretion of fluid and enzymes initially BUT:

Decreases blood flow to salivary glands causing net reduction in secretion.