movements in GIT 1. Propulsive Movements -------- Peristalsis 2. Mixing Movements Moves food forward along GIT at an appropriate rate for digestion and absorption A contractile ring appears around the gut and then moves forward Stimulation at any point in the gut can cause a contractile ring to appear in the circular muscle, and this ring then spreads along the gut tube Directional movement toward Anus Can occur in either direction but normally occurs towards anus Requires active myenteric plexus Stimulus for intestinal peristalsis Distention of the gut Irritation Parasympathetic nervous signals Peristalsis is absent: Congenital absence of myenteric plexus Atropine (paralyzes cholinergic nerve endings) Peristalsis also occurs in Bile ducts Glandular ducts Ureters Many other smooth muscle tubes of the body Law of the Gut or Peristaltic Reflex or Myenteric reflex: Peristaltic reflex plus anal direction of movement of peristalsis is called "law of the gut” Contractile ring normally begins on orad side of distended segment The gut sometimes relaxes several centimeters downstream toward the anus, called "receptive relaxation," thus allowing food to be propelled easily anally

1. Movements in the GIT
source: The Guyton and Hall Physiology
Maryam Fida (o-1827)

2. Movements in the GIT
1. Propulsive Movements -------- Peristalsis
2. Mixing Movements

3. Propulsive movements or Peristalsis
Moves food forward along GIT at an
appropriate rate for digestion and absorption
• A contractile ring appears around the gut and
then moves forward
• Stimulation at any point in the gut can cause a
contractile ring to appear in the circular muscle,
and this ring then spreads along the gut tube
• Directional movement toward Anus
• Can occur in either direction but normally occurs
towards anus
• Requires active myenteric plexus
Stimulus for intestinal peristalsis
• Distention of the gut
• Irritation
• Parasympathetic nervous signals
Peristalsis is absent:
1. Congenital absence of myenteric plexus
2. Atropine (paralyzes cholinergic nerve
endings)
• Peristalsis also occurs in
• Bile ducts
• Glandular ducts
• Ureters
• Many other smooth muscle tubes of the body
Law of the Gut or Peristaltic Reflex or Myenteric
reflex:
• Peristaltic reflex plus anal direction of movement
of peristalsis is called "law of the gut”
• Contractile ring normally begins on orad side
of distended segment
• The gut sometimes relaxes several
centimeters downstream toward the anus,
called "receptive relaxation," thus allowing
food to be propelled easily anally

5. Mixing movements
• Keeps intestinal contents thoroughly mixed
at all times .
TYPES:
1. Peristaltic contractions
causing mixing
Occurs when forward
progression is blocked by
sphincter. Peristaltic wave can
then only churn the contents,
rather than propelling them
2. Local intermittent
constrictive contractions
Occurs every few
centimeters in gut wall.
These constrictions
usually last only 5-30
seconds; then new
constrictions occur at
other points, "chopping"
& "shearing" the
contents first here and
then there

6. What is Hunger and Appetite
• Hunger:
“ The amount of food that a person ingests is
determined by intrinsic desire for food is called
HUNGER.
 Appetite:
“ The type of food that a person
preferentially seeks is determined by Appetite”

7. It is the mechanical processing of food and
made it ready to swallow
Mastication (chewing)
Breaking Mixing é
saliva
Grinding
Softening

8. Mastication ( chewing )
1. Incisors (front teeth): cutting action with a
force of 55 pounds
2. Molars ( post teeth ): grinding action with
force 200 pounds
• Muscles of chewing are innervated by
motor branch of trigeminal( 5th cranial
nerve )
• Controlled by nuclei in the brain stem &
reticular area, areas of hypothalamus,
amygdala
• Chewing reflex
• Presence of food bolus in mouth  initiates reflex
inhibition of muscles of mastication  drooping
lower jaw  stretch of jaw muscle  rebound
contraction  jaw raised up  closure of teeth 
compression of bolus again………….
• FUNCTIONS:
* Chewing is important for digestion of fruits and raw
vegetables –
• Breakage of indigestible cellulose surrounding fruits
& vegetables
• Increase Surface Area of chewed food  digestible
particles
* Digestive enzymes act only on the surfaces of food
particles
* Rate of digestion increased
* Prevents excoriation of the gastrointestinal tract

9. Deglutition
(Swallowing)
Phases
1. Preparatory phase
2. Oral phase (buccal or voluntary ) bolus is forced into the oropharynx
3. Pharyngeal phase ( involuntary ) controlled by the medulla and lower pons
4. Oesophageal phase ( involuntary )controlled by the medulla and lower pons

10. 1. Preparatory phase
• starts as soon as liquids are taken into the oral cavity
or after the bolus has been masticated.
• The liquid or bolus is position on the dorsum of the
tongue, with the oral cavity sealed by the lip and the
tongue.
• The positioning of a liquid on the dorsum of the
tongue before transporting it to the final swallow-
preparatory position may be facilitated through
suction created by moving the tongue posteriorly

11. Oral phase
• These combined movements make a
smooth path for the bolus as it is
pushed from the oral cavity by the
peristaltic-Iike action of the tongue.
• Solid food is actually pushed by the
tongue, whereas fluids flow ahead of
the lingual contractions.
• During this phase, the oral cavity
maintains an anterior and lateral seal,
and is stabilized by the muscles of
mastication.
• introduced by the withdrawal of the soft
palate from its rest position against the
root of the tongue, where it is held by
the tensor palati muscles.
• In this phase the soft palate moves
upward and the tongue drops
downward and backward.
• At the same time, the larynx and hyoid
move upward.
• The elevation of the hyoid may actually
be initiated as the bolus is positioned in
the swallow-preparatory phase.
• When a large bolus is to be swallowed,
most or all of it is moved into the
preparatory position and is then neatly
sectioned by the tongue in consecutive
swallows until the oral cavity is empty.

12. The pharyngeal phase:
contraction of the constrictor muscles of the pharynx occurs accompanied by
receptive relaxation of the upper esophageal sphincter.
• This phase begins as the bolus passes from the tongue through the fauces.
• The pharyngeal tube is raised and the nasopharynx sealed by closure of the
soft palate against the posterior pharyngeal wall.
• Entire pharyngeal stage < 6 sec
• Initiated as a reflex

13. 3. Pharyngeal phase
• Palatopharygeal folds approximate 
forming sagital slit  food pass to post
pharynx
• Vocal cords of larynx approximate The
hyoid and the base of the tongue move
forward
• These movements + prevention of the
ligament pulling epiglottis upwards 
epiglotis swing backwards  cover
opening of larynx
• Sealing passage of food into nose &
trachea
• Most essential is tight approximation of
vocal cords
• Finally, there is an abrupt elevation
of the larynx as the bolus reaches the
laryngo-pharynx and, this is then
followed by opening of the
oesophageal sphincter.
• Food moves from post pharynx
upper oesophagus
• b/w swallow pharyngeoesophageal
sphincter remains closed  no air
into oesophagus during respiration
• Whole pharygeal ms contraction 
propulsion of food

14. The oesophageal phase:
• It is involuntary, passage of food to the
stomach
• is rapid in the upper part & slow in the
lower end
Two types of peristalsis:
1. Primary peristalsis: continuation of
pharyngeal peristalsis
2. Sec peristalsis: develops if primary
peristalsis fail to propel food
completely into the stomach due to
local myenteric reflex or stimulation of
vagal afferents medulla( deglutition
center) glossopharyngeal ,& vagal
efferents
• Peristalsis:
• Produced by a series of localized
reflexes in response to distention
of wall by bolus.
• Wave-like muscular contractions:
• Circular smooth muscle contract
behind, relaxes in front of the
bolus.
• Followed by longitudinal
contraction (shortening) of
smooth muscle.
• Rate of 2-4 cm/sec.
• After food passes into stomach,
LES constricts.

15.  Motility of Esophagus
 The esophagus prevents air from entering
the GI tract through the function of the
upper esophageal sphincter.
 The esophagus prevents GI contents from
re-entering the esophagus from the
stomach through the function of the lower
esophageal sphincter.
 The contraction that sweeps down the
esophagus is the result of intrinsic and
extrinsic stimuli.
 Achalasia is a condition in which the lower
esophageal sphincter does not open,
causing food to accumulate in the
esophagus.
Lower Esophageal Sphincter
(Gastroesophageal Sphincter):
• NARROW LOWER END OF
ESOPHAGUS
• Normally tonically constricted
• “Receptive relaxation “ appears
ahead of peristalsis
• Protects lower end of esophagus by
preventing reflux of acidic stomach
contents
• Valve like closure of distal end of
esophagus is protective

16. Receptor
Afferent
Center
Efferents
Nervous pathways
around the pharyngeal opening
V, IX, X
deglutition center
V, IX, X, XI, XII