The document discusses the gastrointestinal tract and motility. It begins with defining the GI tract and its parts. It then discusses GI motility including peristalsis and segmentation contractions that move food through the digestive system. It details the layers of the stomach and small intestine walls and their roles in digestion. It concludes with describing motility and movement of food through the specific parts of the GI tract.

2. Presenter #01
Muhammad Moaz Ashraf
Reg. No : ZO220172032

3. What is Gastrointestinal Tract?????
 It begins at the mouth and ends at the anus.
 The digestive tract includes
 Esophagus (or food tube)
 Stomach
 Small intestine/bowel
 Colon or large intestine/bowel.

4. What is GI Tract Motility?????
 Gastrointestinal (GI) motility is defined by the movements of the digestive
system, and the transit of the contents within it.
 Gut motility is the term given to the stretching and contractions of the
muscles in the gastrointestinal (GI) tract.
 The synchronized contraction of these muscles is called peristalsis.
 These movements enable food to progress along the digestive tract while, at
the same time, ensuring the absorption of the important nutrients.

6. After food is swallowed, it is moved down the esophagus by
peristalsis. The muscles in the stomach, small intestine, and large
intestine continue the process.

7. What increases gastric motility?
 Gastric motility is controlled by a very complex set of neural and
hormonal signals.
 A large battery of hormones have been shown to influence gastric
motility -
for example, both gastrin and cholecystokinin act to relax the proximal
stomach and enhance contractions in the distal stomach.

8. What is Peristalsis????
 Peristalsis is a distinctive pattern of smooth muscle contractions that propels
foodstuffs distally through the esophagus and intestines.
 It was first described by Bayliss and Starling in 1899 as a type of motility in
which there is contraction above and relaxation below a segment being
stimulated.

9. Segmentation contractions (or movements)
 It is a type of intestinal motility.
 Unlike peristalsis, which predominates in the esophagus, segmentation
contractions occur in the large intestine and small intestine, while
predominating in the latter.

10.  While peristalsis involves one-way motion in the caudal direction, segmentation
contractions move chyme in both directions, which allows greater mixing with
the secretions of the intestines.
 Segmentation involves contractions of the circular muscles in the digestive
tract, while peristalsis involves rhythmic contractions of the longitudinal
muscles in the gastrointestinal tract.
 Unlike peristalsis, segmentation actually can slow progression of chyme
through the system.

12. Four layers of the Gastrointestinal Tract
 The GI tract contains four layers: the innermost layer
is the mucosa, underneath this is the submucosa, followed
by the muscularis propria and finally, the outermost layer -
the adventitia.
 The structure of these layers varies, in different regions of
the digestive system, depending on their function.

13. Mucosa
 A lining epithelium, including glandular tissue, an underlying layer
of loose connective tissue called the lamina propria, which
provides vascular support for the epithelium, and often contains
mucosal glands.
 Products of digestion pass into these capillaries. Lymphoid follicles,
and plasma cells are also often found here.
 Finally, a thin double layer of smooth muscle is often present - the
muscularis mucosa for local movement of the mucosa.

15.  Outermost layer of loose
connective tissue - covered by the
visceral peritoneum.
 Contains blood vessels,
lymphatics and nerves.
 Adventia layer (or serosa)

16.  The esophagus propels food from the mouth to the stomach.
Solid food is gradually broken down by powerful muscle contractions
in the lower end of the stomach.
This muscular activity produces small food particles suitable to enter
the small bowel, where processes of nutrient absorption begin.
Esophagus

17.  The esophagus commonly known as
the food pipe is
an organ in vertebrates through
which food passes, aided by peristaltic
contractions, from the pharynx to
the stomach.
 The esophagus contains four layers,
the mucosa, submucosa, muscularis,
and tunica adventitia.

18. What foods increase GIT motility?
High fiber foods which includes:
 Fruits such as apples, berries, figs, and oranges.
 Vegetables such as broccoli, cauliflower, cabbage, and green
beans.
 Whole grain cereals.
 Nuts and seeds.
 Beans and lentils.

20. Movement In Esophagus
 After food is chewed into a bolus, it is swallowed and moved through the esophagus.
 Smooth muscles contract behind the bolus to prevent it from being squeezed back
into the mouth.
 Then rhythmic, unidirectional waves of contractions work to rapidly force the food
into the stomach.
 The migrating motor complex (MMC) helps trigger peristaltic waves.
 This process works in one direction only and its sole esophageal function is to move
food from the mouth into the stomach (the MMC also functions to clear out
remaining food in the stomach to the small bowel, and remaining particles in the
small bowel into the colon).

21. In the esophagus, two types of peristalsis occur:
 First, there is a primary peristaltic wave, which occurs when the bolus
enters the esophagus during swallowing.
 The primary peristaltic wave forces the bolus down the esophagus and
into the stomach in a wave lasting about 8–9 seconds.
 The wave travels down to the stomach even if the bolus of food descends
at a greater rate than the wave itself, and continues even if for some
reason the bolus gets stuck further up the esophagus.

22.  In the event that the bolus gets stuck or moves slower than the primary peristaltic
wave, stretch receptors in the esophageal lining are stimulated and a local reflex
response causes a secondary peristaltic wave around the bolus, forcing it further
down the esophagus, and these secondary waves continue indefinitely until the bolus
enters the stomach.
 The process of peristalsis is controlled by the medulla oblongata.
 During vomiting, the propulsion of food up the esophagus and out the mouth comes
from contraction of the abdominal muscles; peristalsis does not reverse in the
esophagus.

23. Layers of Stomach Wall
Layers of the stomach wall, among others, include serosa, muscularis,
submucosa, mucosa.
The three layers of smooth muscle consist of the outer longitudinal, the
middle circular, and the inner oblique muscles.
Construction of these muscles helps mix and break the contents into a
suspension of nutrients called chyme and propels it into the duodenum.

24. Small intestine
 Once food is processed and digested by the stomach, the milky chyme is
squeezed through the pyloric sphincter into the small intestine.
 Once past the stomach, a typical peristaltic wave only lasts for a few seconds,
travelling at only a few centimeters per second.
 Its primary purpose is to mix the chyme in the intestine rather than to move it
forward in the intestine.

25.  Through this process of mixing, continued digestion and
absorption of nutrients, the chyme gradually works its way through
the small intestine to the large intestine.
 In contrast to peristalsis, segmentation contractions result in that
mixing without pushing materials further down the digestive tract.

26. Large intestine
 Although the large intestine has peristalsis of the type that the small intestine
uses, it is not the primary propulsion.
 Instead, general contractions called mass movements occur one to three times
per day in the large intestine, propelling the chyme toward the rectum.