AISYA BINTI BACHOTAN 60204 AHMAD SHAHIR (Gastrointestinal motility …
AISYA BINTI BACHOTAN 60204
gastrointestinal tract divided into 5 parts:
=the mouth, esophagus, stomach, small intestine, and large intestine (colon)
GI Motitility In the Mouth and Esophagus
-reflex that is initiated when a bolus of food-receptors in the oropharynx
-peristalsis occur in the walls of the esophagus
-bolus pushed by the tongue into the oropharynx
GI Motitility In the Stomach
=20% of the contractions in the stomach are peristaltic waves
80% of the contraction in the stomach are peristaltic waves
GI Motitility In the Small Intestine
Segmental contractions occur for short distances only along the small intestine
peristaltic waves occur to cause the chyme to move along the small intestine
segmental contractions and peristaltic waves
Local reflexes are the most important regulators of contractions in the small intestine
ileocecal sphincter remains contracted most of the time.
When the cecum is full, increased constriction of the sphincter prevents chyme from entering
GI Motitility In the Large Intestine
mass movements (strong peristaltic contractions in the circular muscles)
-Mass movement is responsible for the sudden distension of the rectum that triggers defecation.
Mass movements are stimulated by irritation or distention of the colon, local reflexes in the enteric plexus, and intense parasympathetic stimulation
defecation reflex removes undigested feces from the body
Peristaltic contractions in the rectum push material toward the anus
At the same time, the external anal sphincter is consciously relaxed if the situation is appropriate
The smooth muscle of the internal anal sphincter relaxes
-Defecation can be added by conscious abdominal contractions and foced expiratory movements against a closed glottis (Valsalva maneuver)
-It is a spinal reflex triggered by distension of the rectum
-Stress can increase intestinal motility and cause psychosomatic diarrhea or constipation
Regulation of GI Motility
Reflexes that originate inside the digestive system (called the enteric nervous system or short reflexes )
Gastrointestinal (GI) Peptides
Secretin: hormone secreted by endocrine cell
Motilin: stimulate migrating motor complex
Cholecystokinin (CCK) : promote intestinal motility
Glucagon-Like Peptide : it slow gastric emptying
Reflexes that originate outside the digestive system (called long reflexes)
TYPES OF MOTILITY
SLOW PROPULSIVE MOVEMENT .
2.PRESSURE AT TE PYLORIC END OF SMALL INTESTINE IS GREATER THAN AT THE DISTAL END.
1.MAJOR CONTRACTILE ACTIVITY OF THE SMALL INTESTINE
MIXING MOVEMENT INVOLVING CONTRACTION O CIRCULAR SMOOTH MUSCLE
MIxING OF STOMACH CONTENT
2.THE MORE FLUID PART OF THE CHYME IS PUSHED TOWARD THE PYLORIC REGION , WHEREAS THE MORE SOLID CENTER OF THE CHYME SQUEEZES PAST THE PERISTALTIC CONSTRICTION BACK TOWARD THE BODY OF THE STOMACH.
3.ADDITIONAL MIXING WAVES MOVE IN THE SAME DIRECTION AND IN THE SAME WAY AS THE EARLIER WAVES THAT REACH THE PYLORIC REGION
1.MIXING WAVES INIATIATED IN THE BODYOF THE BODY OF THE BODY OF THE STOMACH PROGRESS TOWARD THE PYLORIC REGION.
4.THE MORE FLUID PART OF THE CHYME IS PUSHED TOWARD HE PYLORIC REGION .
5.MOST OF THE FLUID CHYME IS SQUEEZED THROUGHTHE PYLORIC OPENING INTO THE DUODENUM AND SOME OF FLUID CHYME IS FORCED BACK TOWARD THE BODY OF THE STOMACH FOR FURTHER MIXING.
1.FOOD INTER THE STOMACH , THE RUGAE FLATTEN , AND THE STOMACH VOLUME INCREASE.
2.FUNDUS AND UPPER PORTION OF BODY RELAx KNOWN AS RECEPTIVE RELAxATION