Physiology 63: Propulsion And Mixing Of Food In The Gi Tract

Front 1

Muscles of chewing are innervated by ..

Back 1

motor branch fo CN V

Front 2

How does our jaw drop while chewing?

Back 2

reflex inhibition of muscle of mastication

Front 3

Why is chewing important?

Back 3

create more surface area on the food to the enzymes can degrade it; also so we dont choke

Front 4

3 stages of swallowing

Back 4

voluntary, pharyngeal, esophageal

Front 5

Voluntary stage of swallowing

Back 5

push food to the back of the mouth

Front 6

Pharyngeal stage of swallowing

Back 6

soft palate closes passage to nose. pharynx comes closer together. vocal cords tighten/epiglottis closes. upper esophageal sphincter relaxes. pharyngeal muscles swallow

Front 7

Pharyngeal stage of swallowing involves what nerves?

Back 7

sensory: trigeminal, glossopharyngeal. motor: glossopharyngeal and vagus, also CN 12

Front 8

What happens during the esophageal stage of swallowing?

Back 8

peristalsis

Front 9

What is primary peristalsis?

Back 9

continued peristalsis when food enters after pharyngeal stage of swallowing

Front 10

What is secondary peristalsis?

Back 10

if primary peristalsis doesn't get the food into the stomach, intrinsic nervous innervation starts new peristalsis to move it more

Front 11

What type of muscle is in the esophagus?

Back 11

upper 1/3 = skeletal (CN 9 and 10). lower 2/3 = smooth (CN10)

Front 12

What happens if the vagus nerve to esophagus is cut?

Back 12

myenteric plexus will take over after a few days

Front 13

What is achalasia?

Back 13

lower esophageal sphincter does not open as food approaches

Front 14

In obese patients with high intra-abdominal pressure, why do they not always get gastric reflux?

Back 14

there is an additional valve-like closure at the end of the esophagus that provide more closure when there is extra pressure in the abdominal cavity. otherwise we would get GERD every time we coughed

Front 15

Stomach peristalsis begins in what part?

Back 15

starts in body and moves to antrum and gets stronger

Front 16

How does retropulsion occur in the stomach?

Back 16

persistalsis towards pyloric muscle, but pyloric muscle closes and food goes back up. important for mixing purposes

Front 17

What happens when the stomach is empty for more than several hours?

Back 17

hunger contractions

Front 18

What is the pyloric pump?

Back 18

strong antral contractions to move chyme into the duodenum

Front 19

To enter the duodenum, the food moves through the ...

Back 19

pyloric sphincter

Front 20

2 Gastric factors that promote emptying

Back 20

distension (food volume) + gastrin secretion (increases pyloric pump)

Front 21

5 factors (non-hormonal) in the duodenum that inhibit gastric emptying

Back 21

duodenum distension, irritation, chyme acidity, chyme osmolality, already digested chyme

Front 22

Hormonal factors from the duodenum that inhibit gastric emptying

Back 22

CCK, Secretin, GIP

Front 23

Segment contractions in the small intestine have what function?

Back 23

mixing/chopping chyme

Front 24

Frequency of segmentation in the small intestine is controlled by ...

Back 24

slow wave frequency

Front 25

Hormonal factors that INCREASE peristalsis in the small intestine

Back 25

CCK, Gastrin, insulin, motilin, serotonin

Front 26

Hormonal factors that DECREASE peristalsis in the small intestine

Back 26

secretin, glucagon

Front 27

What is the peristaltic rush?

Back 27

during intestinal irritation or diarrhea to quickly move large amounts of chyme down the Gi tract

Front 28

What are haustrations?

Back 28

out-pouchings of the unstimulated areas of the intestines while other parts are contracting

Front 29

Why would a patient with an inflamed appendix not have regular bowel movements?

Back 29

if the cecum (where the appendix is attached) is irritated, it prevents ileum peristalsis and closes the ileo-cecal sphincter

Front 30

Function of haustrations in the colon

Back 30

mixing

Front 31

What are mass movements in the colon?

Back 31

propulsive movements

Front 32

What causes mass movements in the colon?

Back 32

stomach/duodenum distension, irritation, extrinsic autonomics

Front 33

External anal sphincter innervation

Back 33

pudendal nerve (skeletal muscle, voluntary)

Front 34

Why does peritonitis cause decreased intestinal motility?

Back 34

peritonitis inhibits excitatory enteric nerves