1. 1Prof .Dr. Rashid Mahmood
Movements of small & large intestine
A 35 year old female was operated for acute appendicitis. She was
advised not to take anything by mouth till further advice by the
surgeon. Six hours after surgery she inquired the doctor on duty that
whether she can now start taking orally or not. The doctor examined
her bowl sounds. He could not listen the bowl sounds and advised
her to wait for another few hours.
•What is the name of this condition?
•Why does the motility of intestine decrease after abdominal
surgery?
•How the condition can be relieved if the movements of small
intestine do not recur in more than 10 hours?
2. 2Prof .Dr. Rashid Mahmood
Objectives
Goal /Aim
• By the end of this session the student should be able to describe the
mechanism, types and functions of the motility of small and large
intestine.
Specific objectives
By the end of this session the student should be able to
• Enlist the types of movements of small and large intestine
• Define the factors that control motility of small and large intestine
• Describe how chyme is transported from pylorus to anus
• Distinguish between Segmentation and Haustrations
• Explain Function and Feedback control of Ileocecal valve and
Ileocecal sphincter
3. 3Prof .Dr. Rashid Mahmood
Lesson contents
• Movements of Small Intestine
• Mixing (Segmentation Contractions)
• Progression of segmentation contractions
• Peristalsis (Propulsive Movements)
• Movements of Muscularis Mucosa
• Contraction of villi
• Control of Peristalsis of Small Intestine
• Ileocecal valve and Ileocecal sphincter
• Function
• Feedback control
• Emptying at Ileocecal valve
• Movements of Colon
• Mixing Movements (Haustrations)
• Propulsive Movements (Mass Movements)
7. 7Prof .Dr. Rashid Mahmood
Mixing Contractions
(Segmentation Contractions)
• Stimulus: Stretching
• Receptors: Nerve endings of enteric nervous system
• Response: localized concentric contractions
Spaced at intervals
Fraction of a minute
“Chop” 2-3 times per minute
Maximum frequency= 12/minute
Frequency depends on frequency of Electrical slow waves
• Integration area: Myenteric nerve plexus + extrinsic
control
• Propulsive effect
9. 9Prof .Dr. Rashid Mahmood
Propulsive Movements
• Peristalsis
• Any part
• Towards Anus
• Velocity: 0.5-2 cm/minute
• Net movement: 1 cm/min
• 3-5 hours from pylorus to ileocecal valve
• Function:
– Progression
– Spread of chyme along mucosa
• Peristaltic Rush
– Irritation
– Diarrhea
10. 10Prof .Dr. Rashid Mahmood
Assessment Question 1
• List the different types of movements in
small Intestine.
11. 11Prof .Dr. Rashid Mahmood
Control of Peristalsis of Small
Intestine
1. Nervous Factors
2. Hormonal Factors
12. 12Prof .Dr. Rashid Mahmood
Control of Peristalsis of Small Intestine
Nervous Factors
1. Entry of meal in duodenum
• Stretch
1. Gastroenteric reflex
• Distension of stomach
• Myenteric plexus
– Blocked at ileocecal valve till another food
→ Gastroileal reflex
1. Movements of Muscularis Mucosa and
Contraction of villi are controlled by
submucosal plexus
13. 13Prof .Dr. Rashid Mahmood
Control of Peristalsis of Small Intestine
Hormonal Factors
↑ motility
• Gastrin
• CCK
• Insulin
• Motilin
• Serotonin
↓ motility
• Secretin
• Glucagon
14. 14Prof .Dr. Rashid Mahmood
Assessment Question 2
• Fill in the blanks;
• Law of gut= ___________ + _________
16. 16Prof .Dr. Rashid Mahmood
Ileocecal valve and
Ileocecal sphincter
• Function
– Prevent backflow
– Controlled passage
– ↑ time for reabsorption in ileum
• 1500-2000 ml of chyme /day into cecum
• Feedback control
– Reflexes from ileum
– Myenteric plexus + autonomic nerves
– Inflamed appendix
27. 27Prof .Dr. Rashid Mahmood
Propulsive Movements
(Mass Movements)
• For many minutes
• 1-3 times/day
–Especially for about 15 minutes
during the 1st
hour after
breakfast
Defecation
28. 28Prof .Dr. Rashid Mahmood
Assessment Question 4
• Distinguish between Segmentation and
Haustrations
29. 29Prof .Dr. Rashid Mahmood
Summary
• Movements of Small Intestine are of TWO Types: Mixing (Segmentation)
Contractions and Propulsive (Peristalsis)
• Nervous Factors that Control of Peristalsis of Small Intestine include
Gastroenteric reflex, Gastroileal reflex & some other reflexes
• These reflexes are controlled by Myenteric plexus, and also by Autonomic
nervous system
• Hormones that increase the motility of Small Intestine include Gastrin
and CCK, while Secretin decreases the motility of Small Intestine
• Ileocecal valve prevents backflow of chyme from cecum to ileum
• Ileocecal sphincter allows controlled emptying at Ileocecal valve
• Feedback control of Ileocecal sphincter is by Reflexes from ileum, stomach
and cecum
• Movements of Colon are also of TWO types: Mixing Movements
(Haustrations), and Propulsive Movements (Mass Movements)
30. 30Prof .Dr. Rashid Mahmood
Learning Resources
1. Guyton and Hall (Text book of physiology), 13th
Edition
2. Ganong (Text book of physiology), 24th Edition
3. Berne & Levy Principles of Physiology (Koeppen
BM), 6th Edition
4. Human Physiology Stuart Ira Fox, 13th Edition
5. Human Physiology : from cells to system Lauralee
Sherwood, 9th Edition
6. Internet
31. 31Prof .Dr. Rashid Mahmood
Next topic
• Pancreatic secretion: Regulation & phases
• Prior knowledge required for next lecture
– Physiological Anatomy of Pancreas
– Composition of Pancreatic secretions
– Hormones of GIT
– Autonomic control of GIT
Notas do Editor
Paralytic Ileus (Adynamic Ileus)
When the intestines are traumatized, there is a direct inhibition of smooth muscle. It is due in part to activation of opioid receptors. When the peritoneum is irritated, reflex inhibition occurs due to increased discharge of noradrenergic fibers in the splanchnic nerves.
By passing a tube the nose down to the small intestine and aspirating the fluid and gas until peristalsis returns.
1. Mixing (Segmentation Contractions)
2. Propulsive (Peristalsis)
3. Movements of Muscularis Mucosa
4. Contraction of villi
Myenteric Reflex (Peristaltic reflex) = anal direction of movement of peristalsis
According to Bayliss and Starling: “If cerebral reflexes be excluded, excitation at any point of the gut excites contraction above, inhibition below. This is the Law of the Intestine
Myenteric Reflex (Peristaltic reflex) = anal direction of movement of peristalsis
instead of (=) , (+) should be written in the note of assessment 2.
Pressure (Distension ) at terminal Ileum
Chemical irritation of terminal Ileum
Gastrin
Gastro-ileal reflex
Segmentation are mixing contractions of small intestine
Fraction of a minute
“Chop” 2-3 times per minute
Maximum frequency= 12/minute
Haustrations are mixing contractions of large intestine
Large circular constrictions
Fecal matter slowly mixed , rolled over & propelled
< 2 minutes