This document summarizes key aspects of gastrointestinal motility including mastication, deglutition, and gastric and small intestinal motility. It discusses the muscles and reflexes involved in chewing food and swallowing. It describes the different phases of swallowing and disorders that can occur. Motility in the stomach is summarized, including the basal electrical rhythm, factors that initiate and regulate contractions, and types of gastric movements like receptive relaxation and mixing. Small intestinal motility includes discussions of migrating motor complexes, mixing and propulsive movements like peristalsis, and the regulation of these movements.
Movements in the GIT( the guyton and hall physiology)Maryam Fida
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
Gastrointestinal Hormones by Pandian M, Dept of Physiology DYPMCKOP, for MBBS...Pandian M
Classify GIT hormones
List the source and functions of different GI hormones
Explain the mechanism of action and regulation of secretion of different GI Hormones
Describe the role of GI hormones in regulation of GI functions
Explain the dysfunctions produced by alteration in secretion of GIT hormones
Receptor by Pandian M, Tutor, Dept of Physiology, DYPMCKOP, MH. This PPT for ...Pandian M
Introduction
SENSORY RECEPTORS
Structurally 3 types of receptors
Transducers
CLASSIFICATION OF RECEPTORS
A. Depending on the source of stimulus(Sherrington’s classification)
B. Depending upon type of stimulus
C. Clinical or anatomical classification of receptors
Production of receptor potential
Properties of receptors
Properties of receptor potential
Enteric nervous system - GIT physiology, EXTRINSIC AND INTRINSIC NERVE SUPPLY, Meissner's and myenteric's plexus.
local reflex, short reflex. Parasympathetic and sympathetic nerve supply of GIT. Functions of the plexuses.
Movements in the GIT( the guyton and hall physiology)Maryam Fida
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
Gastrointestinal Hormones by Pandian M, Dept of Physiology DYPMCKOP, for MBBS...Pandian M
Classify GIT hormones
List the source and functions of different GI hormones
Explain the mechanism of action and regulation of secretion of different GI Hormones
Describe the role of GI hormones in regulation of GI functions
Explain the dysfunctions produced by alteration in secretion of GIT hormones
Receptor by Pandian M, Tutor, Dept of Physiology, DYPMCKOP, MH. This PPT for ...Pandian M
Introduction
SENSORY RECEPTORS
Structurally 3 types of receptors
Transducers
CLASSIFICATION OF RECEPTORS
A. Depending on the source of stimulus(Sherrington’s classification)
B. Depending upon type of stimulus
C. Clinical or anatomical classification of receptors
Production of receptor potential
Properties of receptors
Properties of receptor potential
Enteric nervous system - GIT physiology, EXTRINSIC AND INTRINSIC NERVE SUPPLY, Meissner's and myenteric's plexus.
local reflex, short reflex. Parasympathetic and sympathetic nerve supply of GIT. Functions of the plexuses.
Dr Carlene Starck, Postdoctoral Research Fellow at Riddet Institute, New Zealand: http://www.kiwifruitsymposium.org/presentations/kiwifruit-and-digestive-comfort-in-vitro-and-in-vivo-supporting-evidence/
Presentation at the 1st International Symposium on Kiwifruit and Health.
Kiwifruit (Actinidia deliciosa) hosts a number of beneficial properties for gut health. In addition to its high fibre content, water holding capacity and levels of the vitamins C and E, its consumption has been reported to provide relief of symptoms of gastrointestinal discomfort.
Peptic ulcer disease, a journey through history, explaining how the peptic ulcer disease treatment has evolved through history. Pathogenesis, risk factors, surgical treatment and Medical treatment, H. pylori etiology and its eradication therapy.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
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Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
CDSCO and Phamacovigilance {Regulatory body in India}NEHA GUPTA
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Pharmacovigilance, on the other hand, is the science and activities related to the detection, assessment, understanding, and prevention of adverse effects or any other drug-related problems. The primary aim of pharmacovigilance is to ensure the safety and efficacy of medicines, thereby protecting public health.
In India, pharmacovigilance activities are monitored by the Pharmacovigilance Programme of India (PvPI), which works closely with CDSCO to collect, analyze, and act upon data regarding adverse drug reactions (ADRs). Together, they play a critical role in ensuring that the benefits of drugs outweigh their risks, maintaining high standards of patient safety, and promoting the rational use of medicines.
Adv. biopharm. APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMSAkankshaAshtankar
MIP 201T & MPH 202T
ADVANCED BIOPHARMACEUTICS & PHARMACOKINETICS : UNIT 5
APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMS By - AKANKSHA ASHTANKAR
3. INTRODUCTION
Ingestion include 4
steps
Placing food in mouth
Mastication
Lubrication
Swallowing.
Thursday, June 18, 2020
4. MASTICATION
Chewing – food is cut &
grounded into smaller
pieces.
Achieved by
Movement of jaw
Action of teeth
Coordinated movements
of tongue & muscles of
oral cavity.
Thursday, June 18, 2020
6. Thursday, June 18, 2020
Food placed
in mouth
stretches jaw –
initiate stretch
reflex
contraction of
muscles of
mastication –
mouth closed
food comes in
contact with
buccal receptors –
inhibits
contraction & also
initiate
contraction of
Digastric & Lateral
Pterygoid muscles
open mouth
– cycle
continues
7. MUSCLES OF MASTICATION
Masseter – raises & protract
mandible & clenches teeth.
Temporalis – retract
mandible
Int & ext Pterygoids –
protrude & depress mandible
& opens mouth
Buccinator- prevents
accumulation of ffod between
teeth & cheek.
Thursday, June 18, 2020
8. FUNCTIONS OF MASTICATION
Breaking of food into smaller pieces.
Mixing of food with saliva
Swallowing & lubrication & softening of food
Stimulate olfactory receptors & taste
receptors & increase pleasure of eating &
stimulate gastric secretion.
Thursday, June 18, 2020
9. DEGLUTITION
Def – Passage of food from oral cavity to into
stomach.
Phases
Oral
Pharyngeal
Oesophageal
Thursday, June 18, 2020
10. ORAL
First stage
Voluntary
Bolus of food after
mastication put over
dorsum of tongue
Tongue forces back
into oropharynx
against hard palate.
Thursday, June 18, 2020
11. PHARYNGEAL
Second stage
Involuntary by
swallowing reflex
Receptors – around
opening of pharynx
over tonsillar pillars
Afferents – Trigeminal,
Glossopharyngeal &
Vagus nerve.
Thursday, June 18, 2020
12. PHARYNGEAL
Center – Deglutition center
– in medulla & lower pons
(in NTS & Nucleus
Ambiguus)
Efferent – through 5th, 9th,
10th & 12th
Effector organ –
pharyngeal musculature &
tongue (causes contraction)
Thursday, June 18, 2020
14. OESOPHAGEAL
Food pushed from upper
part of oesophagus to
stomach by oesophageal
peristalsis & helped by
greavity.
Thursday, June 18, 2020
15. APPLIED PHYSIOLOGY
Oesophagus –
fibromuscular tube
about 25 cm long
Seperated from pharynx
by UES (Upper
oesophageal sphincter
& stomach by LES
(Lower oesophageal
sphincter)
Thursday, June 18, 2020
16. OESOPHAGEAL PERISTALSIS
Primary – Initiated by swallowing &
coordinated by vagal fibers from swallowing
centers
As food enters oesophagus UES contracts prevents
regurgitation of food into mouth & propels food
down.
As reaches LES , it relaxes & allow food to enter
stomach.
Thursday, June 18, 2020
17. OESOPHAGEAL PERISTALSIS
Secondary – when primary peristalsis is not
able to pass food down, remaining food
stretches mechanical receptors & initiate
secondary peristalsis.
It is coordinated by intrinsic nervous system
of oesophagus.
Thursday, June 18, 2020
18. DISORDERS OF SWALLOWING
Abolition of deglutition
reflex – causes
regurgitation of food into
nose or aspiration into
larynx. Occurs in
IX & X nerve paralysis
When pharynx
anaesthetized with cocaine.
Aerophagia – unavoidable
swallowing of air.
Thursday, June 18, 2020
19. DISORDERS OF SWALLOWING
Dysphagia – Difficulty in swallowing.
Cardiac achalsia – neuromuscular disorder
of LES, failure of LES to relax & food
accumulate in lower oesophagus.
Gastroesophageal reflux disease.
Incompetence of LES, leads to reflux of acidic
gastric content into oesophagus.
Causes pain & irritation.
Thursday, June 18, 2020
20. Physiology of gastric motility
Gastric musculature
Three layers of smooth
muscle fibres:
Outer longitudinal layer,
Middle circular layer
Inner oblique layer.
Thursday, June 18, 2020
21. Physiology of gastric motility
As per gastric
contractions
Stomach shows 2
regions
Oral region
Caudal region.
Thursday, June 18, 2020
22. Motor functions of stomach
Done by the gastric motility are:
Storage of food,
Mixing of food and
Slow emptying of food.
Thursday, June 18, 2020
23. Initiation of gastric motility
Basal electrical rhythm.
Represents a wave of depolarization of
smooth muscle cells from the circular
muscles of the fundus of stomach
To the pyloric sphincter.
Thursday, June 18, 2020
24. Basal electrical rhythm.
Initiated by the
pacemaker cells located
near the fundus on the
greater curvature of the
stomach.
Thursday, June 18, 2020
25. Basal electrical rhythm.
Gastric slow waves
consist of an upstroke
and an plateau phase.
3–4 waves/min
upstroke is due to flow
of Na+ and Ca2+ into
the cell
Plateau is dependent on
the flow of Ca2+ into
the cell
Thursday, June 18, 2020
26. Factors affecting contractility
Thursday, June 18, 2020
Initiate contraction.
Gastrin,
Histamine,
Nicotine,
Barium and K+
Inhibit contraction.
Enterogastrone,
Epinephrine,
Norepinephrine,
Atropine and Ca2+.
27. Types of gastric motility.
Motility of empty stomach
Migrating motor complex
Hunger contractions
Gastric motility related to meal
Receptive relaxation
Mixing peristaltic waves
Gastric emptying.
Thursday, June 18, 2020
28. Motility of empty stomach
Migrating motor complex
Hunger contractions
Thursday, June 18, 2020
29. Migrating motor complex
Peristaltic wave that
begins in the oesophagus
and travels through the
entire gastrointestinal
tract (migratory motor
activity) during
interdigestive period
Thursday, June 18, 2020
31. Migrating motor complex
Rate -- regular rate (5
cm/min)
Frequency - every 60–
90 min during the
interdigestive period
Motilin
Food entry
Thursday, June 18, 2020
32. Hunger contractions
Mild peristaltic
contractions
MMC – responsible
When become strong
fuse to form tetanic
contraction lasting for
2–3 min
Thursday, June 18, 2020
33. Gastric motility related to
meal
Receptive relaxation
Mixing peristaltic waves
Gastric emptying.
Thursday, June 18, 2020
34. Receptive relaxation
Food stimulates the
stretch receptors of
oral region produces
relaxation
vagovagal reflex
Cholecystokinin, VIP
or NO
Vagotomy abolishes
receptive relaxation
Thursday, June 18, 2020
35. Mixing peristaltic waves
Food in the caudal region
(distal body and antral
part) of stomach
increases the contractile
activity
Peristalsis +Retropulsion
food mixed with stomach
acid & enzymes and
forms -- chyme
Thursday, June 18, 2020
36. Initiation and production of
peristalsis
Co-ordinated pattern of smooth muscle contraction and
relaxation where wave of relaxation precedes wave of
contraction.
Rhythm determined by the BER
The number of spikes fired in a
Slow wave determines the force of each peristaltic contraction
Thursday, June 18, 2020
37. Mixing mechanism of peristalsis and
retropulsion
Peristaltic contractions
begins in stomach &
deepens near pylorus.
It strikes against the closed
pyloric sphincter with a
force & forced back into the
body of stomach.
Thursday, June 18, 2020
38. Mixing mechanism of peristalsis and
retropulsion
The backward movement of
the food is called Retropulsion.
The forward and backward
movements (caused by forceful
propulsion and retropulsion)
converting it into a semiliquid
paste called chyme.
Thursday, June 18, 2020
39. Gastric emptying.
A progressive wave of forceful
contraction of antrum, pylorus
(pyloric sphincter) and
proximal duodenum, all the
three function as a unit.
It occurs when chyme
decomposed to much smaller
units.
Thursday, June 18, 2020
48. DURING INTERDGESTIVE PERIOD
Migrating motor
complexes.
Peristaltic waves
Begins at oesophagus.
Remove remaining food
(Interdigestive
Housekeepers)
49. Migrating Motor Complexes.
RATE- Regular 5 cm/min every 60-90 min.
Close correlation between BER & MMC.
Associated with increase in gastric secretion, bile
flow & pancreatic secretion.
Abolished immediately with entry of food.
51. Mixing movements
Responsible for mixing of chyme with digestive
juices ( intestine, bile, Pancreatic)
Includes
Segmental contractions.
Pendular movements.
52. SEGMENTAL CONTRACTIONS.
Features
Most common, regular….Rhythmic
segmental contractions
Small segment contract & adjoining
segment relaxes.
Alternate contracted & relaxed
segment, so ring like appearance.
Function
Slow down transit time & increase
contact time with absorption.
Propels the chyme slowly towards
the colon.
53. SEGMENTAL CONTRACTIONS. (cont…)
Rate & duration.
12 times/ min ( duodenum)
8 times / min (ileum)
Types (2 types)
Eccentric ( lesser than 2 cm in length)
Concentric (longer than 2cm in length)
Control
Initiation
Occur only when slow waves (BER) produces spikes or action
potential.
Frequency
Directly related to frequency of slow waves & controlled by
pacemaker cells.
Strength
Proportional to frequency of spikes generated by slow waves.
54. PENDULAR MOVEMENTS.
Small constrictive waves sweep forward &
backward or upward & downward in
pendular fashion.
55. Propulsive movements
Involved in pushing the
chyme towards the aboral
end.
These include
Peristaltic contractions
Peristaltic rush.
56. PERISTALTIC CONTRACTIONS
Features.
Wave of contraction
preceded by wave of
relaxation.
Highly coordinated,
involve contraction of
segment behind bolus &
relaxation in front.
Consists of deep circular
ring @ 0.5 to 2 cm/sec.
Chyme move @ 1cm/min.
so 3-4 hrs from pylorus to
iliocecal valve.
57. Law of intestine.
Starling (1901)
Polarity of intestine, Polar conduction of intestine,
Electrical activity of intestine, Law of gut, Theory
of receptive relaxation.
“Peristaltic contraction travels from point of
stimulation in both direction but contraction
in oral direction disappears & persists in
aboral direction.”
58. PERISTALTIC CONTRACTIONS
Functions
Propel food.
Digestion & absorption.
Control
Initiation
Stimulus –
distention.(myentric
reflex).
Rate – 2-2.5 cm/sec.
Local stretch
Releases SEROTONIN
Activate sensory neurons
Stimulate myentric plexus
Activity travels in either
direction to release
Ach & sub P —Circular
constriction.
NO & VIP, ATP – Receptive
relaxation.
60. PERISTALTIC RUSH.
Very powerful peristaltic contractions
When intestinal mucosa irritated
Partly initiated by extrinsic nervous system & partly by
myentric reflex.
Begins in duodenum through entire length up to iliocecal
valve.
Relieve small intestine irritant or extensive distention.
E.g. ---Diarrhoea.
61. Movements of villi.
Features
Consists of alternate shortening & elongation of
villi by contraction & relaxation of muscles.
Initiation.
Local nervous reflexes.
Villikinin.– hormone from small intestine mucosa.
62. Movements of villi.
Functions
Help in emptying
lymph from central
lacteal into the
lymphatic system.
Increases surface area
so absorption
63. MOTILITY REFLEXES.
Gastroileal reflex.
Distention of stomach by food.
Reflex stimulation of vagus.
Relaxation of iliocecal sphincter
Intestinointesinal reflex.
Over distention of one segment
Relaxation of smooth muscle of rest of
intestine.
65. PARALYTIC ILEUS.
Adynamic ileus.
Pathophysiology –
intestinal motility
markedly decreased
leads to retention of
contents
Irregular distension of
small intestine by
pockets of gas & fluids.
Causes ---
Direct inhibition of
smooth muscle of small
intestine due to handling
of intestine. e.g.
Intraabdominal
operations & trauma.
Reflex inhibition due to
increased discharge of
noradrenergic fibres in
splanchnic nerves.
Thursday, June 18, 2020
66. INTESTINAL OBSTRUCTION.
Causes –
Due to tumors,
strictures and fibrotic
bands in abdomen.
Features –
Intestinal colic – severe pain
due to peristaltic rush.
Distension of small intestine
due to increased
intraluminal pressure.
Local ischemia.
Sweating , hypotension &
severe vomiting due to
stimulation of visceral afferent
nerves.
When obstruction in upper
part of small intestine—
antiperistaltic reflux causes
intestinal juices to flow into
stomach.
When obstruction in upper
part of small intestine— vomit
become more basic than
acidic.
Thursday, June 18, 2020
67. LARGE INTESTINE MOTILITY.
Slow wave activity.
Coordinated by BER Or Slow wave
activity (SWA)
Frequency of SWA gradually increase
down the LI.
9/min – iliocecal valve to 16/min at
sigmoid colon.
68. LARGE INTESTINE MOVEMENTS.
Functions
Absorption of water & electrolyte from chyme
(Proximal)
Storage of faecal matter.(Distal)
Contractile activity serves 2 main functions
Increase efficacy for absorption
Promotes excretion of faecal matter.
69. TYPES
Haustral shuttling.
Similar to segmental contractions
Circular muscle contractions– circular
rings
Longitudinal muscles contractions –
portion between rings bulge in bag like
sacs …… Haustrations.
Disappears within 60 sec.
Functions –
Mixing
Propulsion.
oPeristalsis
Progressive contractions preceded by receptive wave of
relaxation.
Take up to 42 hrs to travels up to colons.
70. TYPES
Mass movements.
Special types of peristaltic contractions in colon only.
3-4 times a day after a meals.
Contraction of the smooth muscle over a large area distal to the
constriction.
Force faecal matter into rectum initiate defecation reflex.
Can be initiated by
Gastro colic reflex
Intense stimulation of parasympathetic nerves.
Over distention of segment of colon.
73. DEFAECATION REFLEX.
Act of defaecation
Involves both – voluntary & reflex activity.
Reflex contraction of distal colon & rectum –
propel faecal matter in anal canal.
Reflex relaxation of internal anal sphincter.
Reflex relaxation with voluntary control of Ext
anal sphincter & voluntary contraction of
abdominal muscles.
74. EVENTS ASSOCIATED
Distention of rectum.—
Usually rectum is empty as
frequency of contractions is
greater in rectum than in
sigmoid colon leads to
retrograde movements of
fecal materials.
Gastrocolic reflex pushes
faeces into rectum
increases intrarectal
pressure passively.
75. Defaecation reflexes.
Intrinsic reflex.
Mediated by intrinsic nerve plexus.
Distension of rectum initiate afferents through myentric
plexus. --- Initiate peristalsis in descending colon, sigmoid
colon, rectum –-- Increase intra-rectal pressure. ---
Relaxation of internal anal sphincter.
Thursday, June 18, 2020
76. Spinal cord reflex.
Distension of rectum by faeces – afferent through pelvic
nerves to sacral part of spinal cord –-- reflex parasympathetic
discharge & pelvic splanchnic nerves to cause --- intense
peristaltic contractions --- rectal pressure above 55 mm Hg.
Relaxation of internal & external anal sphincter.
Thursday, June 18, 2020
77. EVENTS ASSOCIATED
Role of voluntary control on defaecation.
When defeacation is Not allowed --- voluntary
control maintains contraction of external anal
sphincter by pudendal nerves – internal sphincter
also closes --- rectum relaxes to accommodate
more faecal matter.
78. EVENTS ASSOCIATED
Role of voluntary control on defaecation.
When defeacation is allowed. --- external
sphincter relaxed voluntarily --- intra abdominal
pressure raised by Valsalva manoeuvre. --- smooth
muscle of distal colon & rectum contract forcefully
& propel faecal matter outside.
79. EVENTS ASSOCIATED
Role of voluntary control on defaecation.
Voluntary initiation of defaecation. --- before pressure
reached that relaxes both sphincters (less than 55mmhg &
more than 18mm Hg) ---by voluntary relaxing external
sphincter & contracting abdominal muscles.
80. APPLIED
Defaecation in Infants. – automatic emptying of
lower bowel without voluntary control.
Individuals with spinal cord transactions. ---
initially retention of faeces occurs --- later reflex
returns quickly --- as rectal pressure reaches 55
mm Hg reflex evacuation occurs automatically.
81. Role of dietary fibres.
Increases bulk of
faeces & play a role in
distending rectum.
Thursday, June 18, 2020
83. APPLIED
Hirschsprung’s disease –
Aganglionic mega colon -
-- congenital absence of
Auerbach’s plexus in wall of
rectosigmoid region.
Blockage of peristalsis & mass
contractions
Leads to dilatation of colon.
Treatment --- cutting
Aganglionic portion of pelvic-
rectal junction & anastomosing
cut ends.
Thursday, June 18, 2020
84. APPLIED
Constipation.---
Failure of voiding of faeces --- due to infrequent mass
movements in colon – faeces remain in colon for longer
time – becomes hard & dry due to fluid absorption.
Due to irregular bowel habits.
Thursday, June 18, 2020