Swallowing, Gastric Emptying, Intestinal Motility Flashcards Preview

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Flashcards in Swallowing, Gastric Emptying, Intestinal Motility Deck (29):
1

What are the three phases of swallowing? 

Describe each

1. Oral phase:  Voluntary

    -Bolus: tongue ► pharynx  

 

2. Pharyngeal phase: Involuntary

    -Initiated by response to pressure

      receptors in pharynx

    -Directs bolus into esophagus via                          

      relaxed upper esophageal sphincter (UES)

3. Esophageal phase: Involuntary

    -Bolus from UES via peristalsis through

     lower esophageal sphincter (LES) ► stomach  

2

What is Barrett's esophagus?  What is the cause?

A special type of GERD where columnar cells replace squamous cells in the mucosa of the esophagus.

 

Main cause is chronic acid exposure.

3

What is achalasia?

Failure of LES to relax, food in LES

4

What are diffuse esophageal spasms?

 

Uncoordinated esophageal contraction

5

What disease leads to Achalasia?

Chagas disease

6

What happens physiologically to cause achalasia?

nerve degeneration (enteric nervous system)

     - lack of NO synthase, VIP, etc

7

What is this called?  What can trigger episodes?

Diffuse esophageal spasms

Hot or cold foods.  Actual cause is not known

8

What is this called?

Achalasia

9

What is the Orad region of the stomach?  What does it do?

The fundus and proximal body.  

Recieves and stores food

10

What is the caudad region of the stomach? What does it do?

Distal body and antrum.  Mixes and propels food.

11

What sets the maximal frequency of gastric contractility?

Frequency of slow waves

12

What are the components of gastric mixing?

Propulsion

Grinding

Retropulsion

Trituration

13

How do hormones regulate the pyloric sphincter?

CCK, GIP, Secretin, Gastrin all constrict the pyloric sphincter.

14

What does neural regulation do to the pyloric sphincter.

Sympathetics --> Constriction

Parasympathetics --> constriction via acetylcholine

Relaxation via VIP

15

What is the postprandial period of segmentation?

Alternating contractions of circular smooth muscle.

16

What causes relaxation in front of the food bolus?

VIP and NO

17

What causes contraction behind the bolus?

ACh and Substance P

18

What does the migrating myoelectric complex do?  What are the three phases?

Moves undigested material from stomach to the colon.

1. Quiescence

2. small disorganized contractions

3. Strong propagating contractions

19

What hormone is the migrating myoelectric complex associated with?

Motilin (a small intestinal hormone)

20

What are the three primary types of colonic motility?

1. haustration

2. Long-duration contractions

3. Mass movements

21

Describe haustration movement

Short-duration contractions (~ 8 sec stationary pressure waves)

Circular m. mixing contractions (not propulsive)

22

Describe the long-duration contractions in the colon.

(~ 20-60 sec)

Taeniae coli

Mixing contractions, may propagate short distances in either direction

Antipropulsive movements in proximal colon: retain chyme

Goal: slow movement through colon for absorption

23

Describe the mass movements of the colon

High-amplitude propagating contractions (high intensity)

Sweep length of colon (cecum to rectum)

1-3/day (1-10/day)

High variability in colonic motility rates among individuals. (vs. small intestinal motility)

24

What is the long range reflex?

Gastric distension, gastrocolic reflex... stomach distention results in generalized increase in colonic motility.

25

What parasympathetics increase colonic motility, and where do they work?


Vagus n. via ENS:

Increased mixing contractions in proximal colon

 

vPelvic n.n. via ENS:

Increased contractions and propulsive movements in distal colon

26

What does distention of the rectum lead to?

Reflex relaxation of IAS, rectosphincteric reflex: VIP and NO

Refles constriction of EAS

27

What are the three events of defecation?

Voluntary relaxation of EAS

Contraction of abdominal m.m.

Relaxation of pelvic muscles

28

Identify

This course

29