Motility of the GI tract

Question 1

What is the landmark between the upper and lower GI tract?

Answer 1

The ligament of Treitz

Question 2

Which site in the GI tract is the primary site of absorption?

Answer 2

The small intestine

Question 3

Which nerve plexus is involved in peristalsis?

Answer 3

Myenteric nerve plexus

Question 4

Describe the nervous system control of peristalsis within the oesophagus (secondary wave)

Answer 4

facilitated by stretch. under control of vagus nerve and the myenteric plexus

Question 5

Why does the GI tract require sphincters?

Answer 5

To prevent the backwards movement of the GI tract

Question 6

The myenteric plexus is located in the ________ layer and controls ________ and contraction.

Answer 6

muscular, motility

Question 7

The submucosal plexus is located in the ___________ layer and controls glandular _________ and blood flow.

Answer 7

submucosal, secretions

Question 8

What is the term for the folds of the stomach that stretch to hold the contents of the stomach?

Answer 8

Ruggae

Question 9

Which phase of deglutition is the only voluntary one?

Answer 9

The oral phase (initiation of swallowing in the oral cavity)

Question 10

Signals from motor efferents from which cranial nerves promote muscular contractions within the pharyngeal phase of swallowing?

Answer 10

Trigeminal (V)
Glossopharyngeal (IV)
Vagal (X)

Question 11

What are the four layers of the GI tract?

Answer 11

1. Mucosa (innermost layer)
2. Submucosa
3. Muscularis externa
4. Serosa (outermost layer)

Question 12

This layer is the interface between the contents of the abdominal cavity and the GI tract

Answer 12

the epithelium (part of the mucosal layer)

Question 13

Which layer of the GI tract contains the GALT?

Answer 13

The lamina propria (part of the mucosal layer)

Question 14

This layer contains a thin layer of CT which is home to a multitude of bv’s and lymphatic vessels.
This is where we encounter the nerve plexus that is responsible for the secretion of substances

Answer 14

submucosal layer

Question 15

In which layer of the GI tract will the myenteric nerve plexus be found?

Answer 15

In the muscularis externa layer. The myenteric plexus is in between a layer of circular muscle and a layer of longitudinal muscle.

Question 16

this layer encompasses the GI tract. Responsible for protection, and also secretes substances to reduce friction between the GI tract and neighbouring structures.

Answer 16

The serosa

Question 17

What two features of the small intestine aid absorption of nutrients?

Answer 17

Microvilli in the brush border, and large surface area

Question 18

What reflex activates the myenteric plexus to promote peristalsis of the small intestine?

Answer 18

gastroenteric reflex (stimulated by either duodenal distention or changes to pH)

Question 19

What feature separates the ileum from the ascending colon?

Answer 19

the ileo-cecal valve

Question 20

What is the function of the ileo-cecal valve?

Answer 20

Prevents back flow of contents from ascending colon (the cecum) into the small intestine

Question 21

In the large intestine, mixing occurs mainly due to _______ __________.

Answer 21

haustral churning

Question 22

What are the two reflexes that initiate “mass movements” of bowel contents from the sigmoid colon to the rectum?

Answer 22

the gastro-colic and duodeno-colic relfexes (occur after meals, on stretching from the ANS)

Question 23

Movement of which muscle generates the pressure gradient needed to permit emesis?

Answer 23

the diaphragm

Question 24

Which hormones STIMULATE motility of the small intestine?

Answer 24

Gastrin, CCK, insulin, and motilin

Question 25

Which hormones have an INHIBITORY action on the motility of the small intestine?

Answer 25

Secretin, glucagon

Question 26

What anatomical structure controls the emptying of chyme from the ileum into the colon?

Answer 26

The ileocecal valve

Question 27

Absence of the migrating motor complex in the small intestine can lead to what?

Answer 27

Bacterial overgrowth of the small intestine

Question 28

what are the three phases of emesis?

Answer 28

Nausea, retching, and expulsive phase (emesis)

Question 29

what anatomical structure prevents the aspiration of vomit into the respiratory tract during emesis?

Answer 29

the epiglottis

Question 30

Where is the “vomiting” centre of the CNS?

Answer 30

In the brainstem- the medulla oblongata

Question 31

What detects blood bourne chemicals and innervates the central “vomiting centre?”

Answer 31

the chemoreceptor trigger zone

Question 32

Name the three main things that can trigger the emetic reflex

Answer 32

Vomiting centre in the medulla
Chemreceptor trigger zone (detects blood born chemicals)
Laryrinth/inner ear vestibular system