[3] GI Motility

Question 1

Function: Upper Esophageal Sphincter

Answer 1

Prevent reflux of food into the respiratory tree

Prevent too much air coming in when we breathe

Question 2

Why don’t we want too much air in our gut?

Answer 2

Prevent feeling full

Avoid increased abdominal pressure

Question 3

Function: Lower Esophageal Sphincter

Answer 3

Prevents reflux of food

Allows food to enter the stomach

Question 4

Which is more important for incontinence? Internal or External Anal Sphincter?

Answer 4

Internal: About 80%

Question 5

What controls electrical activity and coordinates it in the GI Tract?

Answer 5

Cells of Cajal

Question 6

Contraction uses about how much % of the energy of striated muscle?

Answer 6

1%

Question 7

What activates Myosin Light-Chain Kinase?

Answer 7

Ca2+ + Calmodulin

Question 8

2 Basic Types of Electrical Activity of GI Smooth Muscle

Answer 8

Slow Waves

Spike Potentials

Question 9

At what action potential will a spike be generated?

Answer 9

< - 40mV

Question 10

What stimulates spikes?

Answer 10

Stretch
Acetylcholine
Parasympathetics

Question 11

Types of GI Movements

Answer 11

Phasic

Tonic

Question 12

Define: Phasic GI Movement

Answer 12

Short, rhythmic, and promotes efficient mixing and transit of chyme

Question 13

Define: Tonic GI Movement

Answer 13

Long, sustained, serve to limit flow or provide reservoir

Question 14

What is responsible for Orad Contraction?

Answer 14

ACh and Tachykinins

Question 15

What is responsible for Caudad Contraction?

Answer 15

VIP and Nitric Oxide

Question 16

What do you call the rumblies in your tumsies?

Answer 16

Migratory Motor Complex

Question 17

What initiates the rumblies?

Answer 17

Motilin

Question 18

Phases of MMC

Answer 18

I: Quescence

II: Irregular contractions fail to propel luminal contents but contractive activity increases

III: 5-10 minutes, intense luminally occlusive contractions; pylorus fully open allowing clearance of indigestible residues

Question 19

Extrinsic Regulator of GI Motility

Answer 19

ANS
Parasympathetic: Vagus, Pelvic Nerves
Sympathetic: Thoracolumbar Portion of Spinal Cord

Question 20

Why are malignancies not common in the small bowel?

Answer 20

Food passes through it pretty quickly

Question 21

What produces primary peristalsis of the esophagus?

Answer 21

Swallowing

Question 22

What relaxes during swallowing?

Answer 22

Lower Esophageal Sphincter

Stomach

Question 23

Would you feel hungry or full if your stomach is not relaxing when you swallow?

Answer 23

Full

Question 24

What muscle is located in the UES

Answer 24

Cricopharyngeus

Question 25

Describe the Esophagus at Rest

Answer 25

Like a sausage, UES and LES with tonic contractions

Question 26

Control of UES and LES

Answer 26

UES: Nervous LES: Nervous + Hormonal

Question 27

UES Pressure Increased By

Answer 27

Respiration Distention Stress

Question 28

UES Pressure Decreased By

Answer 28

Sleep | Anesthesia

Question 29

Most common cause of Gastroesophageal Reflux

Answer 29

Transient LES Relaxation

Question 30

Function: Proximal Stomach

Answer 30

Storage

Question 31

Why does vagotomy cause patients to feel full faster?

Answer 31

The stretching phenomenon of the stomach is mediated by the Vagus

Question 32

Functional: Distal Stomach

Answer 32

Mixing and Propulsion of Food

Question 33

What part of the GIT has the most contractility?

Answer 33

Stomach: 3 Duodenum: 12 Ileum: 8-9 Colon: 6 Contractions / Minute

Question 34

Gastric Factors that Promote Emptying

Answer 34

Components of Gastric Content Time of Food Intake Gastrin

Question 35

Gastric Factors that Inhibit Emptying

Answer 35

High lipid High H+ ion Increased osmolality Tryptophan

Question 36

General Trend of Reflex Naming

Answer 36

If the distal part is the first part of the name, it would be inhibitory (Enterogastric Reflex: Inhibitory)

Question 37

[Enterogastric Reflex] Acids cause secretion of?

Answer 37

Secretin

Question 38

[Enterogastric Reflex] Fats cause secretion of?

Answer 38

GIP, CCK

Question 39

[Enterogastric Reflex] Amino Acids/Peptides cause secretion of?

Answer 39

Gastrin

Question 40

Define: Vomiting

Answer 40

Forceful expulsion contents of stomach and upper intestinal tract

Question 41

What coordinates Vomiting?

Answer 41

Vomiting Center in the Medulla

Question 42

At what phase of the MMC does 25% of the Gallbladder secrete bile?

Answer 42

Phase II

Question 43

What causes Gallbladder contraction?

Answer 43

ACh and CCK

Question 44

What causes Sphincter of Oddi relaxation?

Answer 44

CCK