This document discusses the movements of the gastrointestinal tract. It begins by listing the learning objectives which are to describe the various types of GIT movements and specific mechanisms like mastication, deglutition, gastric emptying, and defecation. It then provides details on the two main types of movements - propulsive and mixing. Key points include descriptions of specific movements like mastication, deglutition, gastric emptying, peristalsis, and haustration. Causes, pathways, and disorders involving gastrointestinal motility are also summarized.
This document discusses gastric secretion and the physiology of stomach acid production. It covers the following key points:
1. The stomach lining contains various cell types that secrete substances like mucus, hydrochloric acid, and the enzyme pepsin. Parietal cells secrete hydrochloric acid through a mechanism involving hydrogen-potassium ATPase pumps.
2. Gastric acid secretion is regulated through neural and hormonal mechanisms in three phases: cephalic, gastric, and intestinal. The cephalic phase begins with eating cues, while the gastric phase responds to food in the stomach through gastrin and vagal stimulation.
3. Experiments like Pavlov's pouch and sham feeding helped
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
The document discusses the structure and function of the gastrointestinal tract, including the layers of the GI wall, innervation by the enteric and autonomic nervous systems, and hormonal control of GI functions. It covers topics like the roles of motility, digestion, secretion and absorption in the GI system. Key hormones that control GI processes like gastric acid secretion, pancreatic enzyme release and gallbladder contraction are also explained.
The document discusses the defecation reflexes in humans. There are two main reflexes - the intrinsic defecation reflex mediated by the enteric nervous system and the parasympathetic defecation reflex mediated by the autonomic nervous system. When feces enter the rectum, stretch receptors in the rectal wall are stimulated which initiate peristaltic waves to move feces towards the rectum and relax the internal anal sphincter through these reflex pathways. Voluntary control of the external anal sphincter allows defecation to occur at convenient times through maneuvers like the Valsalva maneuver.
The document discusses the anatomy and functions of the small intestine. It is divided into three parts - the duodenum, jejunum, and ileum. The small intestine contains villi and microvilli to increase surface area for absorption. Digestive enzymes in the intestinal juices and glands help break down nutrients into absorbable molecules. Peristaltic waves and segmentation contractions mix and propel food through the small intestine where most absorption occurs before entering the large intestine.
The document discusses acidification of urine and the kidney's role in maintaining acid-base balance.
1) The kidneys excrete acidic or alkaline urine to maintain blood pH within a narrow range of 6.8-7.8. When blood pH changes, the kidneys compensate by regulating urine pH.
2) The kidneys secrete hydrogen ions into the tubular fluid in exchange for sodium and bicarbonate ions to be reabsorbed into the blood. This maintains bicarbonate levels and helps buffer acids produced by metabolism.
3) When acidosis occurs, the body responds through intracellular and extracellular buffering, increased ventilation, and enhanced renal acid secretion and bicarbonate re
The pancreatic juice is a transparent, isotonic fluid secreted by the pancreas. It has both endocrine and exocrine functions. The exocrine secretions contain digestive enzymes like amylase, lipase, and proteases that aid in digestion. Bicarbonate ions secreted in pancreatic juice neutralize the acidic chime from the stomach and provide an optimal pH for the enzymes. The secretions occur in three phases regulated by both the autonomic nervous system and hormones like secretin and cholecystokinin. Secretin increases the secretion of bicarbonate-rich fluid while cholecystokinin stimulates enzyme secretion after eating. Disorders like pancreatitis and cystic fibrosis can impair pancreatic function and digestion.
The document discusses gastrointestinal physiology, including the general principles, anatomical layers, electrical activity, movements, and control systems of the gastrointestinal tract. Some key points include:
- The GI tract provides water, electrolytes, and nutrients through movement of food, secretion of juices, absorption, blood circulation, and control by local and hormonal systems.
- Electrical activity in the smooth muscle is regulated by slow waves and spike potentials that control rhythmic contractions for propulsion.
- The enteric nervous system controls motor and secretory functions through two plexuses and works with the sympathetic and parasympathetic nervous systems.
- Peristalsis, segmentation, and mixing movements propel and process contents through the different regions.
This document discusses gastric secretion and the physiology of stomach acid production. It covers the following key points:
1. The stomach lining contains various cell types that secrete substances like mucus, hydrochloric acid, and the enzyme pepsin. Parietal cells secrete hydrochloric acid through a mechanism involving hydrogen-potassium ATPase pumps.
2. Gastric acid secretion is regulated through neural and hormonal mechanisms in three phases: cephalic, gastric, and intestinal. The cephalic phase begins with eating cues, while the gastric phase responds to food in the stomach through gastrin and vagal stimulation.
3. Experiments like Pavlov's pouch and sham feeding helped
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
The document discusses the structure and function of the gastrointestinal tract, including the layers of the GI wall, innervation by the enteric and autonomic nervous systems, and hormonal control of GI functions. It covers topics like the roles of motility, digestion, secretion and absorption in the GI system. Key hormones that control GI processes like gastric acid secretion, pancreatic enzyme release and gallbladder contraction are also explained.
The document discusses the defecation reflexes in humans. There are two main reflexes - the intrinsic defecation reflex mediated by the enteric nervous system and the parasympathetic defecation reflex mediated by the autonomic nervous system. When feces enter the rectum, stretch receptors in the rectal wall are stimulated which initiate peristaltic waves to move feces towards the rectum and relax the internal anal sphincter through these reflex pathways. Voluntary control of the external anal sphincter allows defecation to occur at convenient times through maneuvers like the Valsalva maneuver.
The document discusses the anatomy and functions of the small intestine. It is divided into three parts - the duodenum, jejunum, and ileum. The small intestine contains villi and microvilli to increase surface area for absorption. Digestive enzymes in the intestinal juices and glands help break down nutrients into absorbable molecules. Peristaltic waves and segmentation contractions mix and propel food through the small intestine where most absorption occurs before entering the large intestine.
The document discusses acidification of urine and the kidney's role in maintaining acid-base balance.
1) The kidneys excrete acidic or alkaline urine to maintain blood pH within a narrow range of 6.8-7.8. When blood pH changes, the kidneys compensate by regulating urine pH.
2) The kidneys secrete hydrogen ions into the tubular fluid in exchange for sodium and bicarbonate ions to be reabsorbed into the blood. This maintains bicarbonate levels and helps buffer acids produced by metabolism.
3) When acidosis occurs, the body responds through intracellular and extracellular buffering, increased ventilation, and enhanced renal acid secretion and bicarbonate re
The pancreatic juice is a transparent, isotonic fluid secreted by the pancreas. It has both endocrine and exocrine functions. The exocrine secretions contain digestive enzymes like amylase, lipase, and proteases that aid in digestion. Bicarbonate ions secreted in pancreatic juice neutralize the acidic chime from the stomach and provide an optimal pH for the enzymes. The secretions occur in three phases regulated by both the autonomic nervous system and hormones like secretin and cholecystokinin. Secretin increases the secretion of bicarbonate-rich fluid while cholecystokinin stimulates enzyme secretion after eating. Disorders like pancreatitis and cystic fibrosis can impair pancreatic function and digestion.
The document discusses gastrointestinal physiology, including the general principles, anatomical layers, electrical activity, movements, and control systems of the gastrointestinal tract. Some key points include:
- The GI tract provides water, electrolytes, and nutrients through movement of food, secretion of juices, absorption, blood circulation, and control by local and hormonal systems.
- Electrical activity in the smooth muscle is regulated by slow waves and spike potentials that control rhythmic contractions for propulsion.
- The enteric nervous system controls motor and secretory functions through two plexuses and works with the sympathetic and parasympathetic nervous systems.
- Peristalsis, segmentation, and mixing movements propel and process contents through the different regions.
Functions,Secretion and Regulation of BileKaif Qureshi
Bile is produced by the liver and stored in the gallbladder. It aids in digestion by emulsifying fats in the small intestine. Bile is secreted from the liver into bile canaliculi and stored in the gallbladder. Upon eating, bile is discharged from the gallbladder through the bile duct into the duodenum where it helps to digest lipids. Bile salts are reabsorbed in the ileum through enterohepatic circulation and returned to the liver to be reused.
The document summarizes the key aspects of the endocrine system. It discusses the two main control systems - the nervous system and the endocrine system. It then focuses on the endocrine system, describing the endocrine glands and hormones. The mechanisms of hormone action and classifications of hormones are explained. Finally, it provides overviews of specific endocrine glands including the pituitary gland, thyroid gland, parathyroid glands, and adrenal glands.
The document discusses the movements of the small and large intestines. It begins by describing two types of movements in the small intestine - mixing (segmentation) contractions and propulsive (peristalsis) movements. Nervous and hormonal factors that control peristalsis are discussed, including gastroenteric reflexes and hormones like gastrin and CCK. The document then covers the ileocecal valve and sphincter, which prevent backflow and allow controlled emptying. Finally, it describes two types of movements in the large intestine - mixing (haustration) movements proximally and propulsive (mass) movements distally.
The small intestine has four layers and is divided into three regions: the duodenum, jejunum, and ileum. Its interior walls contain circular folds, villi, and microvilli that greatly increase its surface area for nutrient absorption. The small intestine secretes enzymes like enterokinase in the duodenum as well as hormones like gastrin, cholecystokinin, and secretin from endocrine cells in response to food constituents. These secretions aid in digestion and regulate secretions from other organs to maximize nutrient absorption in the small intestine.
The enteric nervous system (ENS) is composed of two plexuses - the myenteric plexus and submucosal plexus. The myenteric plexus controls gastrointestinal movements through motor neurons that innervate the outer longitudinal and inner circular muscle layers. The submucosal plexus controls local intestinal secretion, absorption, and submucosal muscle contraction through mainly excitatory neurons. Together the ENS can function independently of the autonomic nervous system to regulate peristalsis and secretory functions through a network of sensory neurons, interneurons, and motor neurons.
Nerve fibers can be classified in six different ways: by structure, distribution, origin, function, neurotransmitter secretion, and diameter/impulse conduction. By structure, they are myelinated or non-myelinated. By distribution, they are somatic or autonomic. By origin, they are cranial or spinal. By function, they are sensory or motor. By neurotransmitter, they are adrenergic or cholinergic. By diameter/impulse conduction, Erlanger and Gasser classified them as type A, B, or C fibers with different speeds and functions.
The document summarizes gastric motility and secretion. It discusses the main functions of the stomach including storage, preparing chyme, and absorption. It describes the different cell types in the stomach that secrete gastric juice components like HCl and pepsinogen. It also outlines the roles of gastric motility in serving as a reservoir, breaking down food, and emptying contents at a controlled rate. Key regulators of gastric emptying and secretion include hormones like CCK, gastrin, and secretin.
The document summarizes the movements of the small and large intestines. It describes two types of movements in the small intestine: segmentation movements and peristaltic movements. Segmentation movements involve localized contractions that divide the intestine into segments, while peristaltic movements propel contents forward in waves. The document also discusses two types of movements in the large intestine - haustral contractions and mass movements - and describes the reflex involved in defecation.
FUNCTIONAL ANATOMY
INTESTINAL VILLI AND GLANDS
PROPERTIES AND COMPOSITION OF SUCCUS ENTERICUS
FUNCTIONS OF SUCCUS ENTERICUS
FUNCTIONS OF SMALL INTESTINE
REGULATION OF SECRETION OF SUCCUS ENTERICUS
METHODS OF COLLECTION OF SUCCUS ENTERICUS
APPLIED PHYSIOLOGY
The human digestive system breaks down food through mechanical and enzymatic digestion. It is composed of the gastrointestinal tract (GIT) which has four layers and runs from the mouth to the anus. The GIT performs the functions of ingestion, propulsion, digestion, absorption, and elimination. Key components of the GIT include the mouth, esophagus, stomach, small intestine, liver, gallbladder and pancreas, each playing an important role in digestion.
The document discusses the physiology of the gastrointestinal system. It describes the main parts and functions of the GI tract, including digestion, absorption, and waste excretion. It explains the physiologic anatomy of the GI wall and discusses gastrointestinal smooth muscle and its electrical activity. Slow waves and spike potentials are described. Neural control of the GI system is also covered, including the enteric nervous system, autonomic nervous system, and various neurotransmitters.
Gastric secretion is produced by epithelial cells in the stomach's gastric glands. These cells include parietal cells, chief cells, mucus-secreting cells, and hormone-producing cells. Parietal cells secrete hydrochloric acid and intrinsic factor. Chief cells secrete pepsinogen, which is converted to the protease pepsin by hydrochloric acid. Mucus-secreting cells produce a bicarbonate-rich mucus that protects the stomach lining. Hormone-producing cells secrete gastrin, somatostatin, and histamine, which help regulate acid secretion.
The enteric nervous system (ENS), also known as the intrinsic nervous system, is a complex network of neurons located in the lining of the gastrointestinal tract. It contains around 100-300 million neurons and is capable of independent functioning without input from the central nervous system. The ENS contains two main types of neurons - Dogiel type 1 and 2 - which serve motor and sensory functions respectively. Sensory neurons detect chemicals, pressure, and damage in the gut and initiate peristaltic and secretory reflexes through neurotransmitters like serotonin and acetylcholine. Motor neurons then coordinate contraction and relaxation of muscles and glands through various neurotransmitters to facilitate digestion and movement of contents through the gastrointestinal tract.
All about Neuromuscular junction...Structure,Steps involved,Drugs acting at neuromuscular junction , Clinical aspects (Myasthenia gravis and lambert eaton syndrome)
The document summarizes salivary secretion and regulation. It discusses that saliva is secreted by three major salivary glands and contains water, electrolytes, and enzymes. Salivary secretion is regulated by both the parasympathetic and sympathetic nervous systems. The functions of saliva include lubrication, taste perception, digestion of starch, and maintenance of oral health. Disorders of salivation can include hypo-salivation, hyper-salivation, and xerostomia.
The document summarizes the juxtaglomerular apparatus (JGA) and tubuloglomerular feedback mechanism. The JGA is located near the glomerulus and is formed by macula densa cells, extraglomerular mesangial cells, and juxtaglomerular cells. The primary function of the JGA is secretion of hormones like renin and prostaglandins. The tubuloglomerular feedback mechanism regulates glomerular filtration rate through detection of NaCl concentration by the macula densa cells, which signals the release of adenosine to constrict or dilate the afferent arteriole accordingly.
Anatomy of urinary bladder. surfaces, border of urinary bladder its relation , ligament support, peritoneal relation in male and females, pouches, blood supply of bladder, nerve supply of bladder, true and false ligament of urinary bladder,
2nd chapter of digestive system from Guyton & HallDrMisba
This document discusses the propulsion and mixing of food in the alimentary tract. It covers topics like the control of food intake by the hypothalamus, the mechanics of ingestion including mastication and swallowing, and the movements that propel and mix food through the small intestine like segmentation and peristalsis. The small intestine uses various movements controlled by the enteric nervous system to thoroughly mix foods with enzymes to aid absorption over a period of 3-5 hours.
The small intestine is responsible for the digestion and absorption of nutrients. It is made up of the duodenum, jejunum, and ileum. The small intestine contains finger-like villi covered in microvilli that increase surface area for absorption. Glands including crypts of Lieberkuhn and Brunner's glands secrete enzymes and mucus. Movement patterns in the small intestine include segmentation contractions that mix contents, peristalsis that propels contents aborally, and villi movements that enhance absorption. Disorders can impair digestion or absorption.
1) The document discusses the processes of mastication, deglutition, digestion in the stomach and small intestine. It describes the stages of swallowing and peristalsis that move food through the esophagus.
2) In the stomach, mixing waves macerate food and reduce it to chyme, which is periodically emptied into the duodenum. Enzymatic digestion of proteins, fats, and carbohydrates begins in the stomach.
3) The small intestine uses segmentations and migrating motility complexes to mix chyme, bring it in contact with the mucosa, and propel it forward for absorption over 3-5 hours.
The document discusses physiology of the gastrointestinal system. It covers the goals of physiology, characteristics of the GI wall, neural and hormonal control of the GI tract, reflexes, hormones like secretin and gastrin, movements in the GI tract, and the phases of digestion. It also describes specific processes like mastication, swallowing in oral, pharyngeal and esophageal phases, stomach functions of storage, mixing and emptying, and small intestine movements including mixing contractions.
Functions,Secretion and Regulation of BileKaif Qureshi
Bile is produced by the liver and stored in the gallbladder. It aids in digestion by emulsifying fats in the small intestine. Bile is secreted from the liver into bile canaliculi and stored in the gallbladder. Upon eating, bile is discharged from the gallbladder through the bile duct into the duodenum where it helps to digest lipids. Bile salts are reabsorbed in the ileum through enterohepatic circulation and returned to the liver to be reused.
The document summarizes the key aspects of the endocrine system. It discusses the two main control systems - the nervous system and the endocrine system. It then focuses on the endocrine system, describing the endocrine glands and hormones. The mechanisms of hormone action and classifications of hormones are explained. Finally, it provides overviews of specific endocrine glands including the pituitary gland, thyroid gland, parathyroid glands, and adrenal glands.
The document discusses the movements of the small and large intestines. It begins by describing two types of movements in the small intestine - mixing (segmentation) contractions and propulsive (peristalsis) movements. Nervous and hormonal factors that control peristalsis are discussed, including gastroenteric reflexes and hormones like gastrin and CCK. The document then covers the ileocecal valve and sphincter, which prevent backflow and allow controlled emptying. Finally, it describes two types of movements in the large intestine - mixing (haustration) movements proximally and propulsive (mass) movements distally.
The small intestine has four layers and is divided into three regions: the duodenum, jejunum, and ileum. Its interior walls contain circular folds, villi, and microvilli that greatly increase its surface area for nutrient absorption. The small intestine secretes enzymes like enterokinase in the duodenum as well as hormones like gastrin, cholecystokinin, and secretin from endocrine cells in response to food constituents. These secretions aid in digestion and regulate secretions from other organs to maximize nutrient absorption in the small intestine.
The enteric nervous system (ENS) is composed of two plexuses - the myenteric plexus and submucosal plexus. The myenteric plexus controls gastrointestinal movements through motor neurons that innervate the outer longitudinal and inner circular muscle layers. The submucosal plexus controls local intestinal secretion, absorption, and submucosal muscle contraction through mainly excitatory neurons. Together the ENS can function independently of the autonomic nervous system to regulate peristalsis and secretory functions through a network of sensory neurons, interneurons, and motor neurons.
Nerve fibers can be classified in six different ways: by structure, distribution, origin, function, neurotransmitter secretion, and diameter/impulse conduction. By structure, they are myelinated or non-myelinated. By distribution, they are somatic or autonomic. By origin, they are cranial or spinal. By function, they are sensory or motor. By neurotransmitter, they are adrenergic or cholinergic. By diameter/impulse conduction, Erlanger and Gasser classified them as type A, B, or C fibers with different speeds and functions.
The document summarizes gastric motility and secretion. It discusses the main functions of the stomach including storage, preparing chyme, and absorption. It describes the different cell types in the stomach that secrete gastric juice components like HCl and pepsinogen. It also outlines the roles of gastric motility in serving as a reservoir, breaking down food, and emptying contents at a controlled rate. Key regulators of gastric emptying and secretion include hormones like CCK, gastrin, and secretin.
The document summarizes the movements of the small and large intestines. It describes two types of movements in the small intestine: segmentation movements and peristaltic movements. Segmentation movements involve localized contractions that divide the intestine into segments, while peristaltic movements propel contents forward in waves. The document also discusses two types of movements in the large intestine - haustral contractions and mass movements - and describes the reflex involved in defecation.
FUNCTIONAL ANATOMY
INTESTINAL VILLI AND GLANDS
PROPERTIES AND COMPOSITION OF SUCCUS ENTERICUS
FUNCTIONS OF SUCCUS ENTERICUS
FUNCTIONS OF SMALL INTESTINE
REGULATION OF SECRETION OF SUCCUS ENTERICUS
METHODS OF COLLECTION OF SUCCUS ENTERICUS
APPLIED PHYSIOLOGY
The human digestive system breaks down food through mechanical and enzymatic digestion. It is composed of the gastrointestinal tract (GIT) which has four layers and runs from the mouth to the anus. The GIT performs the functions of ingestion, propulsion, digestion, absorption, and elimination. Key components of the GIT include the mouth, esophagus, stomach, small intestine, liver, gallbladder and pancreas, each playing an important role in digestion.
The document discusses the physiology of the gastrointestinal system. It describes the main parts and functions of the GI tract, including digestion, absorption, and waste excretion. It explains the physiologic anatomy of the GI wall and discusses gastrointestinal smooth muscle and its electrical activity. Slow waves and spike potentials are described. Neural control of the GI system is also covered, including the enteric nervous system, autonomic nervous system, and various neurotransmitters.
Gastric secretion is produced by epithelial cells in the stomach's gastric glands. These cells include parietal cells, chief cells, mucus-secreting cells, and hormone-producing cells. Parietal cells secrete hydrochloric acid and intrinsic factor. Chief cells secrete pepsinogen, which is converted to the protease pepsin by hydrochloric acid. Mucus-secreting cells produce a bicarbonate-rich mucus that protects the stomach lining. Hormone-producing cells secrete gastrin, somatostatin, and histamine, which help regulate acid secretion.
The enteric nervous system (ENS), also known as the intrinsic nervous system, is a complex network of neurons located in the lining of the gastrointestinal tract. It contains around 100-300 million neurons and is capable of independent functioning without input from the central nervous system. The ENS contains two main types of neurons - Dogiel type 1 and 2 - which serve motor and sensory functions respectively. Sensory neurons detect chemicals, pressure, and damage in the gut and initiate peristaltic and secretory reflexes through neurotransmitters like serotonin and acetylcholine. Motor neurons then coordinate contraction and relaxation of muscles and glands through various neurotransmitters to facilitate digestion and movement of contents through the gastrointestinal tract.
All about Neuromuscular junction...Structure,Steps involved,Drugs acting at neuromuscular junction , Clinical aspects (Myasthenia gravis and lambert eaton syndrome)
The document summarizes salivary secretion and regulation. It discusses that saliva is secreted by three major salivary glands and contains water, electrolytes, and enzymes. Salivary secretion is regulated by both the parasympathetic and sympathetic nervous systems. The functions of saliva include lubrication, taste perception, digestion of starch, and maintenance of oral health. Disorders of salivation can include hypo-salivation, hyper-salivation, and xerostomia.
The document summarizes the juxtaglomerular apparatus (JGA) and tubuloglomerular feedback mechanism. The JGA is located near the glomerulus and is formed by macula densa cells, extraglomerular mesangial cells, and juxtaglomerular cells. The primary function of the JGA is secretion of hormones like renin and prostaglandins. The tubuloglomerular feedback mechanism regulates glomerular filtration rate through detection of NaCl concentration by the macula densa cells, which signals the release of adenosine to constrict or dilate the afferent arteriole accordingly.
Anatomy of urinary bladder. surfaces, border of urinary bladder its relation , ligament support, peritoneal relation in male and females, pouches, blood supply of bladder, nerve supply of bladder, true and false ligament of urinary bladder,
2nd chapter of digestive system from Guyton & HallDrMisba
This document discusses the propulsion and mixing of food in the alimentary tract. It covers topics like the control of food intake by the hypothalamus, the mechanics of ingestion including mastication and swallowing, and the movements that propel and mix food through the small intestine like segmentation and peristalsis. The small intestine uses various movements controlled by the enteric nervous system to thoroughly mix foods with enzymes to aid absorption over a period of 3-5 hours.
The small intestine is responsible for the digestion and absorption of nutrients. It is made up of the duodenum, jejunum, and ileum. The small intestine contains finger-like villi covered in microvilli that increase surface area for absorption. Glands including crypts of Lieberkuhn and Brunner's glands secrete enzymes and mucus. Movement patterns in the small intestine include segmentation contractions that mix contents, peristalsis that propels contents aborally, and villi movements that enhance absorption. Disorders can impair digestion or absorption.
1) The document discusses the processes of mastication, deglutition, digestion in the stomach and small intestine. It describes the stages of swallowing and peristalsis that move food through the esophagus.
2) In the stomach, mixing waves macerate food and reduce it to chyme, which is periodically emptied into the duodenum. Enzymatic digestion of proteins, fats, and carbohydrates begins in the stomach.
3) The small intestine uses segmentations and migrating motility complexes to mix chyme, bring it in contact with the mucosa, and propel it forward for absorption over 3-5 hours.
The document discusses physiology of the gastrointestinal system. It covers the goals of physiology, characteristics of the GI wall, neural and hormonal control of the GI tract, reflexes, hormones like secretin and gastrin, movements in the GI tract, and the phases of digestion. It also describes specific processes like mastication, swallowing in oral, pharyngeal and esophageal phases, stomach functions of storage, mixing and emptying, and small intestine movements including mixing contractions.
- Chewing food exposes it to enzymes and secretions, prevents damage to the GIT, and makes food easier to pass through the digestive tract.
- Swallowing involves both voluntary and involuntary stages, beginning with chewing and the oral phase and completing with the automatic pharyngeal and esophageal phases. During swallowing, the larynx is raised and the epiglottis and vocal cords cover the airway to prevent choking.
- Swallowing is coordinated by the medulla, which stops respiration briefly during the pharyngeal stage to prevent suffocation. Peristalsis then moves the food through the esophagus and into the stomach within 5-8 seconds.
- Chewing food exposes it to more surface area for digestion and prevents irritation of the gastrointestinal tract. Swallowing involves both voluntary and involuntary stages, moving food from the mouth to the stomach.
- The pharyngeal stage of swallowing is involuntary and coordinated by the medulla, stopping respiration temporarily to prevent choking. Peristaltic movements in the esophagus are controlled by both the brainstem and enteric nervous system.
- In the stomach, mixing waves and pyloric pumping propel food into the small intestine while hormones regulate emptying. Segmentation and peristalsis in the intestine are controlled by enteric reflexes to continue digestion and absorption.
This document describes the process of ingestion, digestion and absorption of food by the gastrointestinal system. It discusses the roles of the mouth, esophagus, stomach, small intestine and colon. The mouth chews and swallows food which is propelled through the esophagus to the stomach. The stomach stores, mixes and slowly empties food chunks (chyme) to the small intestine where nutrients are absorbed. The colon absorbs water from waste and stores feces until defecation. Regulatory mechanisms such as hormones and nerves coordinate movement and emptying between organs.
The third phase of swallowing involves involuntary movement of food through the esophagus to the stomach. The cricopharyngeal sphincter relaxes and peristalsis pushes the food down through the esophagus, aided by gravity. The lower esophageal sphincter then relaxes to allow the food to enter the stomach. Primary peristalsis is a continuation of the pharyngeal swallow and moves food through the esophagus in 8-10 seconds, while secondary peristalsis occurs if food is not fully cleared from the esophagus. The lower esophageal sphincter helps prevent reflux of stomach contents into the esophagus.
1. Swallowing involves three phases - oral, pharyngeal, and esophageal. The pharyngeal phase is involuntary and involves closing the nasal cavity, elevating the larynx, and propelling the food bolus into the esophagus.
2. During the pharyngeal phase, respiration is inhibited by the swallowing center in the medulla to prevent food from entering the airways.
3. The esophageal phase involves peristaltic movements that are controlled by the upper and lower esophageal sphincters to propel the food bolus into the stomach. Disorders can occur if these phases are disrupted.
This document discusses the process of deglutition (swallowing). It begins with an introduction describing that swallowing involves coordinated activity of the oral cavity, pharynx, larynx, and esophagus muscles. It is partly under voluntary and partly under reflexive control. The document then covers the components, phases (oral, pharyngeal, esophageal), muscles involved, theories of swallowing, and neural control of deglutition. Key points include that swallowing has oral preparatory and oral phases under voluntary control and a pharyngeal phase that is reflexive, propelling the bolus into the esophagus for involuntary transport.
The stomach is a J-shaped organ located in the upper abdomen between the esophagus and small intestine. It has four regions - cardia, fundus, corpus, and pyloric part. The stomach stores and breaks down food through secretion of acids and enzymes. Motility mixes foods and empties contents into the small intestine. Diseases include peptic ulcers, gastritis, and stomach cancer.
Mastication (chewing) involves cutting food with the incisors and grinding with the molars, powered by strong jaw muscles. Chewing is mostly controlled by reflexes where dropping the jaw allows food to be re-compressed and the process repeats. Thorough chewing increases the food's surface area for efficient digestion. Swallowing has three stages - voluntary oral movement into the pharynx, involuntary passage through the pharynx and esophagus by peristalsis waves to the stomach in 5-8 seconds. The lower esophageal sphincter regulates food entry into the stomach.
The digestive system breaks down food into nutrients that can be absorbed and used by cells in the body. It consists of a digestive tract made up of the oral cavity, esophagus, stomach, and small and large intestines. Accessory organs that help digestion include salivary glands, liver, gallbladder and pancreas. Food is ingested, mechanically and chemically broken down, absorbed, and waste is eliminated in a complex multi-step process involving both the digestive tract and accessory organs.
This document summarizes the processes of mastication, swallowing, and digestion in the stomach. It discusses:
1) The roles of different teeth in chewing and the muscles that power jaw movement.
2) The reflexive nature of chewing that involves dropping and raising the jaw.
3) The voluntary and involuntary stages of swallowing, including the roles of the soft palate, epiglottis, and esophageal sphincters.
4) The peristaltic movement of food through the esophagus and into the stomach, aided by relaxation of the stomach and duodenum.
5) The functions and mechanics of the stomach in accommodating, mixing, and slowly emptying
The document discusses digestion in the mouth and swallowing. It describes the processes of mastication, saliva secretion and function, and the three stages of swallowing - voluntary, pharyngeal, and esophageal. Mastication involves chewing by the teeth and mixing with saliva. Saliva contains enzymes and ions that begin digestion and lubricate food into a bolus. The pharyngeal stage of swallowing is a reflex initiated by receptors in the throat and controlled by the brainstem swallowing center.
The document provides an overview of gastrointestinal physiology. It describes the main components and layers of the gastrointestinal tract, from the mouth to the anus. It then discusses the four main functions of the digestive system: motility, secretion, digestion, and absorption. Specific sections cover the salivary glands, swallowing process, stomach functions and secretions, pancreatic secretions, liver and biliary system, gastrointestinal hormones, and the histology and innervation of the gastrointestinal tract.
The document provides an overview of gastrointestinal physiology. It describes the main components and layers of the gastrointestinal tract, from the mouth to the anus. It then discusses the four main functions of the digestive system: motility, secretion, digestion, and absorption. Specific sections cover the salivary glands, swallowing process, stomach functions and secretions, pancreatic secretions, liver and biliary system, gastrointestinal hormones, and the histology and innervation of the gastrointestinal tract.
This document summarizes the stages and mechanisms of swallowing and digestion. It describes the voluntary and pharyngeal stages of swallowing, including the soft palate closing the nasal cavity and epiglottis protecting the larynx. In the esophageal stage, food moves through peristalsis into the stomach for storage, mixing, and emptying into the small intestine through the pyloric pump. The small intestine further breaks down food through peristalsis and absorption. The ileocecal valve regulates emptying into the large intestine, where haustral contractions and mass movements slowly propel waste for absorption and storage until defecation.
This document discusses the movement and motility of the gastrointestinal tract (GIT). It describes the different regions of the GIT including the oral cavity, esophagus, stomach, small intestine and large intestine. It explains that peristalsis is the wave of smooth muscle contractions that propels food through the GIT. The document also discusses the two main types of GIT movements - propulsion movements which move food along, and mixing movements which ensure thorough mixing and grinding of food.
Deglutition dyp by Pandian M, Tutor, Dept of Physiology, DYPMCKOP,MHPandian M
This document summarizes the process of deglutition (swallowing) which involves three stages - oral, pharyngeal, and esophageal.
The oral stage is voluntary and involves tongue movements that propel the food bolus from the mouth into the pharynx. The pharyngeal stage is involuntary and involves coordinated movements that push the bolus into the esophagus while preventing entry into the larynx, nasal cavity or mouth. The esophageal stage is also involuntary and involves peristaltic contractions that propel the bolus through the esophagus and into the stomach. Key components and reflex pathways involved in coordinated swallowing are described. Common disorders of swallowing like dysphagia and gastro
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2. Learning Objectives
At the end of this session, the students would be able to:
• List the types of GIT Movements
• Explain mechanism of Mastication & Function
• List the phase of deglutition and explain the mechanism of
deglutition. Explain Achalasia
• List the motor functions of the stomach
• Explain the mechanism of gastric emptying and its regulation
• Describe the types of movements of small intestine and large
intestine
• Explain the mechanism of defecation
• Explain the common gastrointestinal motility disorders
3. Movements of GIT
• Function of Myenteric plexus but alters by extrinsic nervous system
• Mainly Two types of Movements
– Propulsive movement: push chyme toward aboral end
– Mixing Movements: chopping of chyme and mixing chyme with
digestive juices and secretion as well as also facilitate absorption.
• Main movements in GIT are
– Mastication
– Swallowing
– Esophageal Peristalsis
– Gastric Emptying
– Peristalsis
– Haustration
– Defecation reflex
4. Propulsive movements
• Mainly function of myenteric plexus
• Oral to anal, inherent feature of unitary smooth muscle, also called
peristalsis, some degree of mixing as well.
• Characterized by constricting ring on oral side of food bolus and dilating
ring toward anal side
• occur in any part of small intestine and move at a velocity of 0.2-2cm/sec.
They usually dies off after travel this distance.
• new peristalsis state and move a chyme in forward direction, thus several
peristaltic waves occur one after the other and push the small intestine
contents at the distal end of the small intestine
• slow movement of peristalsis waves usually 3-5hours are required for
passage of chyme from pyrolysis to the ileocecal valve.
• segmental and peristalsis movements occurs simultaneously.
5. Mixing movements
• Also called as segmentation movements, controlled by the Myenteric
plexuses
• Allow the chopping of chyme & mixing of enzymes with chyme and
appropriate absorption
• localized constrictor rings appear simultaneously at multiple segments [1-
2 cm] of GIT followed by dilatation of constrictor segment.
• Next few seconds dilated parts constricts and constrictor part dilates.
• Contraction of segment last for 5-6sec, they occur through out the
digestive period
• This type of movements continues
• Such movements are predominant in stomach, duodenum, jejunum, and
ileum.
6. Mastication
• Initially Voluntary later converts as involuntary
• Presence of a bolus of food in the mouth at first initiates reflex
inhibition of the muscles of mastication,
• Drop of lower jaw which initiates a stretch reflex of the jaw muscles-
results in rebound contraction.
• Rebound contraction automatically raises the jaw to cause closure
of the teeth and compresses the bolus again against the linings of
the mouth and inhibits the jaw muscles once again,
• Allowing the jaw to drop and rebound another time; this is repeated
again and again.
7. Mastication Reflex
Presence of a
bolus of food
in the mouth
Voluntary closure
of the teeth & jaw
increases pressure in
mouth compresses the
bolus again against the
linings of the mouth
reflex inhibition of the
muscles of mastication
Drop of lower jaw which
initiates a stretch reflex
causes reflex contraction of
the jaw muscles
reflex contraction of the jaw
muscles to cause closure of the
teeth and compresses the bolus
again
Drop of lower jaw
again
8. Deglutition [Swallowing]
• Refers to passage of bolus from the esophagus to stomach.
• Pharynx complexed the process [being common passage for
respiration & food passage].
• Divided into 3 stages:
1. Oral Phase (voluntary)
2. Pharyngeal phase (involuntary)
3. Esophageal phase (involuntary)
• Initiated voluntarily, sequentially programmed reflex
• Swallowing center located in the medulla
• Receptors in the pharyngeal wall
9. Deglutition reflex
• Receptors: Pressure receptors on the pharyngeal wall,
especially on the tonsillar pillars
• Afferents: V, IX, X cranial nerves
• Center: Medulla oblongata (deglutition centre)
• Efferent: V, IX, X , XII nerves
• Effectors: Muscles of tongue, pharynx, larynx
10. Oral phase
• Begins with contractions of the tongue
and striated muscles of mastication-
forms bolus
• Bolus positioned in the middle of the
tongue and squeezed or rolled
posteriorly into the pharynx by pressure
of the tongue upward and backward
against the palate- trigger the
pharyngeal phase.
• The oral preparatory phase-processing
of the bolus to render it swallowable.
• The oral propulsive phase - propelling of
food into the oropharynx.
11. Pharyngeal phase
• Shortest phase of deglutition, but is the
most complex.
• Involuntary and totally reflexive,
• Lasts approximately 1-2 second
• Involves the receptor areas around the
opening of the pharynx, especially on the
tonsillar pillars,
• Impulses from these pass via from cranial
nerves V, IX (glossopharyngeal) , X (vagus)
and XII [hypoglossal] to the brain stem to
initiate a series of automatic pharyngeal
muscle contractions .
12. a) Elevation of the soft palate: closes posterior nasal
openings, thus preventing food reflux into the nasal
cavities.
b) Elevation of the larynx against the epiglottis: closes
the superior laryngeal orifice (glottis), thus preventing
food entrance into the trachea.
c) Approximation of the vocal cords: This also closes
the glottis, but its role is much more important than that
of the epiglottis.
d) Temporary apnea: stoppage of breathing for few
seconds which also prevents food entrance into the
trachea.
Pharyngeal phase of swallowing
13.
14. Events in Pharyngeal Phase
• Soft palate closes the posterior nares, to prevent reflux of food into
the nasal cavities.
• Tonsillar muscle [palatopharyngeal folds] approximate and make a slit
to prevent passage of big bolus in to posterior pharynx.
• Vocal cords strongly approximated, and larynx is pulled upwards &
anterior by the neck muscles- cause the epiglottis to swing backwards
– Closes the trachea to prevent entry of food into trachea.
– Enlarges relaxes and open upper esophageal sphincter
[pharyngoesophageal sphincter]
• Pharynx begins primary peristaltic wave in the superior part and
spreads downward, propels the bolus into the esophagus.
15. Events in Esophageal Phase
• Primary peristalsis:
– Continuation of the peristaltic wave begins
in the pharynx
– Passes from the pharynx to the stomach in
about 8 to 10 seconds.
– Gravity facilitate movement of food during
upright position
• Secondary peristaltic waves
– Caused due to distention of the esophagus
by the retained food [initiated by myenteric
plexus and partly by reflexes]
• Receptive relaxation of stomach due to wave of
relaxation initiated by myenteric inhibitory
neurons [VIP], precedes the esophageal
peristaltic wave approaching the stomach
16. Disorders of swallowing
• Paralysis of muscle of swallowing or muscle dystrophy- disrupt the
ingestion of food- e.g. Myasthenia gravis
• Drug [Anesthetics] induced inhibition of swallowing reflex- may
results in to aspiration of vomitus- cause asphyxia [Fatal some time]
• Achalasia –
– neurological failure within myenteric plexus-prevent relaxation of
lower esophageal sphincter results in to dysphasia.
– Bolus remain in esophagus casing local distention
17. Motor Function of Stomach
• Storage: large quantities of food until the food can be
processed in the stomach, duodenum, and lower intestinal
tract
• Mixing: food with gastric secretions until it forms a semifluid
mixture called chyme
• Emptying of the chyme: from the stomach into the small
intestine at a rate suitable for proper digestion and
absorption by the small intestine.
18. Stomach
• 3 divisions [fundus, body and antrum with differences in motility], but
divided into two regions,
• Orad region:
– thin walled region, comprises of fundus and the proximal portion of
the body
– Generate much weak contractions and mainly mixing movement
• Caudad region:
– thick walled, contains the distal portion of the body and the antrum
– Generate much stronger contractions than the orad region. Mix the
food and propel into the small intestine.
• Innervation of the stomach includes vagus nerve and sympathetic fibers
originating in the celiac ganglion
20. Storage Function
• Entry of food bolus in stomach results stretch, Activate a "vasovagal
reflex” afferent and efferent of the reflex are carried in the vagus nerve
• Sensory impulse of distention of the stomach sent to the CNS via vagus.
• CNS then sends motor signals to the smooth muscle of the orad
stomach release VIP from these postganglionic vagal nerve.
• Reduces the tone in the muscular wall of the body of the stomach
and causing it to relax. [Receptive relaxation]
• Wall bulges progressively outward, accommodating greater and greater
quantities of food up to a limit, called accommodative relaxation
• Completely relaxed stomach can store up to 0.8 to 1.5 liters of food.
21. Mixing and Propulsion function
• Distention of stomach, initiated by the slow wave
of gut wall -produce a weak peristaltic constrictor
waves, called mixing movement
• Begins in the mid to upper portions of stomach
wall move toward the antrum about 3-4/ seconds.
• As the constrictor waves progress from the body
of the stomach into the antrum, becomes more
intense,
• Digs deeply into the food contents in the antrum
and mix the gastric contents with juice
• These contractions periodically expelled a few
milliliters of antral contents into the duodenum
22. • Most of the antral contents are squeezed back
toward the body of the stomach for further mixing
and further reduction of particle size, called
"retropulsion,”
• Process continues until the food broken down in
very small size and mixing complete.
• Vagus, gastrin and motilin increase the frequency of
action potentials and the force of gastric
contractions.
• Sympathetic stimulation secretin and GIP,CCK
decrease the frequency of action potentials and the
force of contractions.
Mixing and Propulsion function
23. Hunger Contractions
• Refer to special type of intense rhythmical
peristaltic contractions occurs in the body of the
stomach.
• Lasts for 2 to 3 minutes, often fuse to cause a
continuing tetanic contraction
• Most intense in young, healthy people or
during hypoglycemia
• Hunger contraction associated with pain is
called hunger pangs.
• Begin 12 to 24 hours after the last ingestion of
food or 3 to 4 days after starvation, and
gradually weaken in succeeding days.
24. Gastric Emptying
• Propulsion of gastric content into duodenum -Gastric emptying
• Intense mixing movement as tight ring like constrictions begin in mid
stomach and spreading through the caudad stomach called strong
peristaltic contraction
• Each contraction create 50 to 70 cm of water pressure in stomach,
six times as powerful as the usual mixing type of peristaltic waves.
• Higher gastric pressure due intense contraction wave, several
millimeter gastric chyme is propelled in to duodenum by each strong
peristaltic contraction under normal pressure- Cause stomach
emptying.
• As emptying progresses, constrictions rings begin farther and farther
up the body of the stomach, gradually pinching off the food in the
body of the stomach and adding to the chyme in the antrum.
26. Regulation of Gastric Emptying
• Control mechanism is mainly Neural and Hormonal, influencing
stomach and duodenal mechanisms
• Stomach Mechanisms : Weaker regulation, promotes emptying
– Volume of food- increase volume food elicit local myenteric reflexes in
the wall that greatly increase activity
– Vagal stimulation- more release of Ach – more force of contraction
– Gastrin: increases antral contraction but increases constriction of
pyloric sphincter – though stimulate force of contraction but decreases
gastric emptying
– Sympathetic postganglionic fibers stimulation decreases gastric
emptying
27. • Duodenal factors: powerful control,
inhibit emptying
• Enterogastric Reflex: Over Distention
of duodenum- inhibit gastric emptying
by reducing gastric peristaltic
contraction and increase pyloric
pump tone.
• More acidic Chyme- inhibit
• Hyperosmotic or hypo-osmotic chyme
– inhibit [maintain fluid balance]
• Protein and fat excess in Chyme –
slows down the gastric emptying
Regulation of Gastric Emptying
28. • Hormonal mechanism:
• cholecystokinin (CCK) released from “I” cells of the mucosa of
the jejunum in response to fatty substances in the chyme. This
hormone acts as an inhibitor to block increased stomach motility
caused by gastrin.
• Secretin is released mainly from “S” cells of the duodenal mucosa in
response to gastric acid passed from the stomach through the
pylorus.
• gastric inhibitory peptide [GIP] is released from the upper small
intestine in response mainly to fat in the chyme, has weak effect of
decreasing gastrointestinal motility.
Regulation of Gastric Emptying
29. Movement of small intestine
• Small intestine comprises of three parts: Duodenum -5%, Jejunum-
40%, Ileum-55%
• Major function- digestion and absorption, propulsion and mixing
movement
• Movement is due to muscular externa – longitudinal and circular
muscle
• Types of Movements
1. Peristalsis (Propulsive)
2. Segmentation contraction (Mixing)
3. Tonic contractions
4. Movements caused by muscularis mucosa and muscle fibers of
villi
30. Segmentation Movements
• Also called as mixing movements
• Ring like contractions , appear at regular
intervals along the gut, then disappear
and then replaced by another set of ring
contractions in the segments between the
previous contractions.
• Determined by slow electrical waves of
BER
• Normally 12/min at duodenum & jejunum,
weakens as moves down (9/min at ileum)
• If excitatory activity of enteric nervous
system is blocked by atropine
contractions become too weak.
31. Functions of segmentation contraction
• Helps in progressive mixing of chyme
with intestinal secretions, ensure
completion of digestion.
• Slow contractions permits longer
contact of the chyme with mucosal
surface and permits absorption
• Influenced with ANS and Hormonal
control
• CCK, Motilin, Gastrin, Ach,
serotonin- increase the motility
• Secretin and glucagon inhibit the
motility
32. Tonic contractions
• Slow and sustained contraction of large segments of
intestine, relatively for prolonged period so isolates one
segment of the intestine with other.
Function same as segmentation.
33. Peristaltic rushes
• Intense peristaltic waves not seen normally ,
• Observed during
– intestinal obstructions,
– intense irritation of mucosa or
– severe cases of infectious diarrhea.
Function : being powerful strong peristalsis, traveling long
distances, sweeps the contents of ileum into colon and
relieves ileum of irritative chyme & excessive distension
34. Migrating Motor Complex
• A propulsive movement initiated during interdigestive phase or
fasting
• begins in the stomach and moves undigested material from the
stomach and small intestine into the colon.
• Movement terminated at the distal ileum and begins a new one in the
stomach.
• Repeats every 90–120 minutes
• High circulating levels of motilin [hormone of the small intestine]
known to cause this movement.
• Function: sweeps the GIT tract having left over undigested food and
prevents the backflow of bacteria from the colon into the ileum
35. Movements of Large intestine
• Function of Proximal half of colon is absorption and distal
half storage & excretion of fecal matter
• Most slow movement,
• Migratory Motor Complex is absent
• Main types of Movements
– Segmentation contraction (Haustrations)
– Mass action contraction or mass peristalsis (unique to colon)
– Defecation
36. Haustration
• Similar to segmentation movements
• Comprises of large circular constrictions with simultaneous contraction
of longitudinal muscle of the colon, cause the unstimulated portion of
the large intestine to bulge outward into baglike sacs called
haustrations.
• Each haustration reaches peak intensity in about 30 seconds and then
disappears during the next 60 seconds.
• Function:
– Facilitate absorption of water converts chyme in to semi solid
– Provide a minor amount of forward propulsion of the colonic
contents.
37. Mass Peristalsis
• Modified type of peristalsis
• Simultaneous contraction of the smooth muscle over the large areas,
occurs twice a day.
• A ring of constriction appears at distended portion extend to 20 or
more centimeters of colon, travels down to colon, sweeping the
descending colon, pushing the feces into rectum.
• Function- moves material from one portion of the colon to other.
• Also move the material into rectum, rectal distension in turn initiates
defecation reflex.
38. Defecation reflex
• Stimulus- distension of the rectum with feces, following a mass
peristalsis.
• Normally defecation is a spinal level reflex, but to some extent
voluntarily can be controlled.
• Reflex consists of development of peristaltic waves in the sigmoid
colon & rectum pushing the feces into anus, increased pressure in
anus, relaxation of internal anal sphincter.
Steps of defecation
• Mass movement
• Filling of rectum
• Desire of defecation
• Stimulate intrinsic myenteric reflex
39. Defecation reflex
• External sphincter: skeletal muscle, voluntary control
• Internal sphincter: ring of smooth muscle, involuntary control
• distension of the rectum with feces, following a mass peristalsis –
caused by myenteric reflex ,
• Mass peristalsis in the terminal colon fills the rectum and causes a
reflex relaxation of the internal anal sphincter and a reflex contraction of
the external anal sphincter.
• Voluntary relaxation of the external sphincter accompanied with
propulsive contraction of the distal colon complete defecation.
• Conscious desire control the anal sphincter by exciting or inhibiting
pudendal nerve- results in defecation
40. Defecation reflex
• In adults habits & cultural factors play
a large role in determining when
defecation occurs.
• By voluntary efforts help reflex in
emptying of distended rectum. Such
as
• Violent expiratory efforts with glottis
closed ,
• Raises intra abdominal pressure,
41. Hirschspurng's disease or megacolon
• Rare congenital disorder, caused by absence of nerve
cells [Ganglion cells deficiency in the myentric plexus]
in the rectum and/or colon.
• Severe constipation, bowel movements may occur only
once a week or so, leads to accumulation of large
quantities of fecal matter,
• Colon may distend to a diameter of 3-4 inches.
42. Irritable bowel syndrome
• Group of symptoms that occur together.
• Symptoms include
• abdominal pain or cramping, bloating, gas,
• Altered bowel movement patterns such as diarrhea or constipation
Abdominal or stomach cramping and pain that are relieved with
bowel movements
• Number of theory to describe pathophysiology proposed
• Result from a combination of abnormal gastrointestinal tract
movements, a disruption in the communication between the brain
and the gastrointestinal tract movements
43. Disorders of motility of large intestine
Constipation:
• Infrequent bowel movements (less than 3 per
week), passage of hard stools, and sometimes
difficulty in passing stool.
Diarrhea:
• An excessive number of high amplitude
propagating contractions. Symptoms are frequent,
loose or watery stools