GIT MOTILITY

Question 1

IMPORTANCE OF MASTICATION

Answer 1

1. Breaking down the food molecule to increase surface area
2. Mixing of saliva and food
3. Grind food to fine particle (prevent mucosa damage)
4. break cellulose
5. Stimulate taste & smell receptor

Question 2

MECHANISM MASTICATION

Answer 2

1. Presence of bolus
   -Drop the jaw
2. Stretch the mastication muscle
   
   • Lower jaw contraction
   • Raise jaw
   • close mouth
3. Bolus compressed at the wall
   
   • jaw drops
   • Jaw contract

Question 3

STAGES OF DEGLUTITION

Answer 3

1. Oral stage (ORAL TO PHARYNX)
   
   • tongue elevated & backward
   • Bolus into the pharynx
2. Pharyngeal stage (PHARYNX TO ESOPHAGUS)
   
   • Soft palate move up (prevent food to nose)
   • Epiglottis move back (closing larynx)
   • Palatopharyngeal make opening
   • Upper esophageal sphincter relax (open)
   • wall contracts (FAST PERISTALSIS)
   • food to the esophagus
3. OESOPHAGEAL (ESOPHAGUS TO STOMACH)
   
   • Primary peristalsis (continuation of pharynx)
   • Secondary peristalsis (by esophagus)
   • Complete esophagus emptying into the stomach
   • LES relax (bolus pass thru)
   • rest (contract-prevent gastric reflux)

Question 4

ACHALASIA & GASTRO-ESOPHAGEAL REFLUX DISEASE

Answer 4

ACHALASIA
- Accumulation of food in the esophagus
- LES pressure HIGH
- Myenteric plexus destruction

GERD
- LES relax state (remains open)
- Gastric content reflux

Question 5

MOTOR FUNCTION OF STOMACH

Answer 5

1. STORAGE
   
   • Fundus & upper body expand to accumulate food
2. MIXING WAVES
   -Mix & grind
   
   • chyme produced
   • to pyloric
3. PERISTALTIC WAVE
   
   • Same direction as mixing wave
   • fluid chyme (push to pyloric)
   • solid chyme (push back to body)

Question 6

FACTORS & REGULATION OF GASTRIC EMPTYING

Answer 6

FACTORS
- Volume of gastric content high (emptying high)
- Consistency of gastric content (liquid faster)

REGULATION
1. GASTRIN (high emptying)
2. inhibit emptying
- CHOLECYSTOKININ
- SECRETIN
- GIP

Question 7

SMALL INTESTINE MOTILITY

Answer 7

1. SEGMENTATION
   
   • Small intestine wall distended by chyme
   • cause: concentric contraction
     : Divide the small intestine into smaller segments
   • ring at regular intervals & disappear
   • As 1 contraction relaxes another begin
2. PERISTALSIS
   
   • Increase after meal
   • Chyme enter duodenum
   • stomach distend and myenteric plexus conduction

Question 8

LARGE INTESTINE MOTILITY

Answer 8

1. HAUSTRAL CONTRACTION
   
   • Circular & longitudinal muscle contraction
   • cause bulge (expose more content to mucosa) INCREASE ABSORPTION
2. MASS MOVEMENT
   
   • Push content to the rectum

Question 9

DEFECATION REFLEX

Answer 9

1. Content in rectum
2. Rectal wall stretched
   
   • Intrinsic reflex initiate weak peristalsis
3. The pelvic nerve is stimulated
   
   • Stimuli sent to the spinal cord & large int
4. Strong peristaltic wave
   
   • rectum contracts
   • internal anal sphincter relax
5. pushed to anus
6. Pudendal nerve inhibited
   - external anal sphincter relax
7. contraction of abdominal muscle
   - feces defecated