faal gastro erwin 07.ppt
TRANSCRIPT
FISIOLOGIGASTROINTESTINAL
IRAWAN YUSUFM.E.RACHMAN
BLOK XSISTEM GASTROINTESTINAL
Motto : The Anatomi-Physiology Of To-day Is The Medicine OfTo-morrow
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Tujuan Instruksional Khusus
Setelah kuliah ini mahasiswa akan dapat :
Mengetahui tujuan pencernaan Mengetahui proses-proses sistem gastrointestinal Mengetahui fungsi traktus gastrointestinal Mengetahui fungsi accesory Organs Mengetahui mekanisme sekresi sistem gastrointestinal Mengetahui regulasi sistem gastrointestinal . Mengetahui mekanisme gangguan pada sistem
gastrointestinal
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LEARNING CONCEPT
STRUCTURE
GI TRACT
ORAL CAVITYPHARYNXESOPHAGUSSTOMACHSMALL INTESTINELARGE INTESTINERECTUMANAL CANAL
ACCESSORYORGANS
TONGUETEETHSALIVARY GLANDSPANCREASLIVERGALL BLADDER
FUNCTION
INGESTION
DIGESTION
ABSORPTION
SECRETION
MOVEMENT
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FUNCTION
Breaking down food and supplying the body with the water, electrolytes, and nutrients to sustain life.
Before can be used, food must be:ingesteddigestedabsorbed
All of these processes involve coordinated movemen of muscle and secretion of various substances
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INGESTION
Placing food into the mouth Chewing the food into smaller pieces
(mastication) Moistening the food with salivary
secretions Swallowing the food (deglutition)
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DEGLUTITION (SWALLOWING)
Deglutition or swallowing consists of three phase: Oral (voluntary) phase. During this phase, the
tongue forms a bolus of food and forces it into the oropharynx by pushing up and back against the hard palate
Pharyngeal phase. This phase coordinated by a swallowing center in the medulla and lower pons
Esophageal phase. After reaching the esophagus, food is propelled into stomach by peristaltis
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Pharyngeal Phase This phase begins when the food reaches the
oropharynx and progresses as follows: The nasopharynx is closed by the soft palate,
preventing regurgitation of food in to nasal cavities
The palatopharyngeal folds are pulled medially, forming a passageway for the food to move into the pharynx
The glottis and vocal cords are closed and the epiglottis swing down over the larynx, guiding the food toward the esophagus
Respiration is inhibited for the duration of the pharyngeal phase (1-2 seconds)
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DIGESTION
Food is broken down into small particle by grinding action
Food is degraded by digestive enzymes into usable nutrient Starches are degraded by amylase into
monosaccharides Proteins are degraded by variety of enzymes
(pepsin, trypsin) into dipeptides and amino acids
Fats are degraded by lipases and esterases into monoglyserides and free fatty acids
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MOTILITY OF GI TRACT
The basic mechanisms of GI movement is peristaltis. Peristaltis is a coordinated pattern of smooth muscle contraction and relaxation
Peristaltis helps move food through the paharynx and esophagus and within the stomach. Peristaltis plays a minor role in propelling food through the intestine
During peristaltis, contraction of small section of proximal muscle is followed immediately by relaxation of the muscle just distal to it. The resulting wavelike motion.
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MOTILITY OF STOMACH
Intrinsic innervation directly responsible for peristaltis The myenteric plexus (Auerbach’s) is located between the
layers of the circular and longitudinal muscles of the stomach
The submucosal plexus (Meissner’s) is located between the layers of the circular muscle and mucosa on the luminal surface of the stomach
Extrinsic through autonomic nervous system: Sympathetic, via the celiac plexus (inhibits motility) Parasympathetic, via the vagus nerve (stimulates motility)
Innervation
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Electrical Activity and Regulation of Motility
The smooth muscle of GI tract has spontaneous rhytmic fluctuations (basic electrical rhytm; BER) which is initiated by the interstitial cells of Cajal
The rate of BER is 4/min in the stomach, 12/min in duodenum and fall to about 8/min in distal ileum
Spike potensials playing important role in BER Ionic basis of spike potentials is due to Ca2+ influx, and K+
efflux Many neurotransmitter and hormone affect the BER.
Acetylcholine increases BER and Epinephrine decrease BER
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Basic Electrical Activity (BER) of Gastrointestinal Sooth Muscle
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Migrating Motor Complex
Modification of motor activity during fasting between periods of digestion
Each cycle of this activity starts with quiescent period (phase I), continues with period of irregular activity (phase II), and ends with a burst of regular activity (phase III)
MMCs migrate at a rate of about 5 cm/min, with interval of 90 minutes
The function of MMC is to clear the stomach and small intestine luminal contents in preparation of the next meal
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Migrating Motor Complexes
Meal
90 minute
III
IIIStomach
DistalIleum
Propagatianrate 5cm/min
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MASTICATIONFunction of Mastication
Breaks food into smaller pieces, which: Makes it easier for the food to be swallowed Breaks off the undigestible cellulose
coatings of fruits and vegetables Making easier for food to be digested by
digestive enzymes
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MASTICATIONFunction of Mastication
Mixes the food with salivary gland secretions, which: Initiates the process of starch digestion by
salivary amylase Initiates the process of lipid digestion by
lingual lipase Lubricates and softens the bolus of food,
making it easier to swallow
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MASTICATIONFunction of Mastication
Brings food into contact with taste receptors and release odors that stimulate the olfactory receptors
The sensations generated by these receptors increase the pleasure of eating and initiate gastric secretions
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MASTICATIONMastication Reflex
Although mastication is a voluntary act, it is coordinated by reflex centers in he brain stem that facilitate the opening and closing of the jaw When the mouth opens, stretch receptors in the
jaw muscle initiate a refkex contraction of the masseter, medial pterygoid, and temporal muscle, causing mouth to close
When the mouth closes, food comes into contact with buccal receptors eliciting a reflex contraction of digastric and lateral pterygoid muscles, causing the mouth to open
When the jaw drops, the stretch reflex causes the entire cycle to be repeated
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Esophageal Phase Sphincters involved in esophageal peristaltis:
The upper esophageal sphincter (striated muscle) The lower esophageal sphincter (smooth muscle)
Types of esophageal peristaltis: Primary esophageal peristaltis is initiated by
swallowing Secondary peristaltis is initiated by the presence
of food within the esophagus Coordination of esophageal peristaltis:
Primary esophageal peristaltis is coordinated by vagal fibers
Secondary esophageal peristaltis is coordinated by the intrinsic nervous system
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Swallowing Mechanism and Regulation
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Disorders of Swallowing
Esophageal reflux, may occur if the intragastric pressure rise high enough to force the lower esophageal sphincter open During pregnancy Reflux of stomach acid causes esophageal pain
Belching (eructation), following a heavy meal or ingestion of large amount of gas (e.g., from carbonated beverages)
Achalasia, is a neuromuscular disorder of the lower two-thirds of the esophageal that leads to absence of peristaltis and failure of the lower esophageal sphincter to relax
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MOTILITY OF STOMACH
The three functional parts of the stomach are the fundus, corpus, and antrum
Gastric contents are isolated from other parts of the GI tract by the lower esophageal sphincter proximally and by the pylorus distally
The antrum and pylorus are anatomically continous and respond to nervous control as a unit
Functional components
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MOTILITY OF STOMACH
Each muscle layer forms a functional syncytium and therefore acts as a unit
In the fundus, where the layers are relatively thin, strength of contraction is weak; in the antrum, where the muscle layers are thick, strength of contraction is strong
The stomach and duodenum are divided by a thickened muscle layer called the pyloric sphincter
Musculature
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MOTILITY OF STOMACH
Intrinsic innervation directly responsible for peristaltis The myenteric plexus (Auerbach’s) is located between the
layers of the circular and longitudinal muscles of the stomach
The submucosal plexus (Meissner’s) is located between the layers of the circular muscle and mucosa on the luminal surface of the stomach
Extrinsic through autonomic nervous system: Sympathetic, via the celiac plexus (inhibits motility) Parasympathetic, via the vagus nerve (stimulates motility)
Innervation
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Function of Motility
Storage. When food enters the stomach, the upper region - primarily fundus - enlarges to accommodate the food by receptive relaxation
Mixing. Combination of peristaltis and retropulsion mixes the food with acid and enzymes. When the food is mixed into pasty consistency, it is called chyme
Emptying. When the chyme is broken down into small enough particles, it is propelled through the pyloric sphincter into intestine
Gastric motility serves three basic function
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Function of Motility
Initiated as apart of the peristaltic process causing swallowing and esophageal motility or in response to food entering the stomach
Strecth receptors in the upper portion of stomach detect the presence of food and initiate a vago-vagal reflex producing relaxation
This process regulate by postganglionic fibers within the enteric nervous system release a noncholinergic nonadrenergic transmitter, may be ATP or VIP
Receptive relaxation
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Function of Motility
Produced by periodic change in BER originate in a pace maker within longitudinal muscle
BER or slow wave occur at a rate of approximately 3-4/min and velocity is 1 cm/sec at the corpus and increase to 3-4 cm/sec in the antrum
Ca2+ play an important role in BER, and the force of peristaltis contractions is regulated by gastrin and acetylcholine
Peristaltis
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Function of Motility
Is the back and forth movement of the chyme caused by the forceful propulsion of food against the closed pyloric sphincter
The forward and backward movement of the chyme (caused by peristaltis and retropulsion) breaks the chyme into smaller and smaller pieces and mixes it with the gastric secretions present within stomach
Retropulsion
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Function of Motility
Each time the chime pushed against the pyloric sphincter, a small amount (2-7 ml) may escape into duodenum
The amount of chyme passing the pylorus depends on the size of the particles
Liquids empty much faster than solids. The rate of liquids emptying is proportional to pressure within the upper portion of stomach, which increase slowly during the digestive period
Gastric emptying
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Function Disorder of Motility
Initiation The vomiting center. Directly activated by afferent fibers
or by irritation due to injury or increases in intracranial pressure
Chemoreceptor trigger zone. Activated by afferent nerves originating within the GI tract or by circulating emetic agents
Mechanical sequence of vomiting Begins with deep inspirasion followed by the closing of
the glottis Intestine propels chyme into upper region of stomach Increase in abdominal pressure forces the chyme into
esophagus and out of the mouth
Vomiting or emesis
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Vomiting Reflex
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INTESTINAL MOTILITY
Contractile activity of the smooth muscle lining the small intestine serve two functions: Mixing the chyme with digestive enzymes and bile to
facilitate digestion and absorption Propelling the chyme from the duodenum to the colon
It usually takes about 2-4 hours for the chyme to move from one end of the small intestine to the other
Contractile activity
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INTESTINAL MOTILITY
Segmentation is the most common type of intestinal contraction
Peristaltic contractions is not considered to be an important component of intestinal transit
MMC spreads over the intestine during interdigestive period
Types of movements
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INTESTINAL MOTILITY
During segmentation, about 2 cm of the intestinal wall contracts, forcing the chyme throughout the digestive period
When the muscle relaxes, the chyme returns to the area from which it was displaced
This back-and-forth movement enables the chyme to become mixes with digestive enzymes and to make contact with the absorptive surface of the intestinal mucosa
Segmentation occur about 12 times/min in the duodenum and 8 times/min in the ileum. The contraction last for 5-6 seconds
Segmentation contractions
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INTESTINAL MOTILITY
Segmentation occur only if the slow waves produce spikes potentials which is controlled by pacemaker cells within the wall of the intestine and is not infuenced by neural activity or circulating hormones
The frequency of segmentation is directly related to the frequency of the slow wave
The strength of segmentation is proportional to the frequency of the spike potentials generated by slow wave
Slow wave amplitude is increased by gastrin, CCK, motilin, and insulin; and decreased by secretin and glucagon
Regulation of intestinal motility
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FUNGSI SEKRESI SALURAN CERNA
IRAWAN YUSUFM.E.RACHMAN
BLOK XSISTEM GASTROINTESTINAL
Motto : The Anatomi-Physiology Of To-day Is The Medicine OfTo-morrow
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INTRODUCTION
Throughout the gastrointestinal tract secretory glands serve two primary function; To produce digestive enzymes; To provide mucus for lubrication and
protection Most digestive secretions are formed
only in response to the presence of food in the gastrointestinal tract
The types of enzyme and its component are varied according to the types of food present.
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GENERAL PRINCIPLES Functions of gastrointestinal secretions
Transport Digestion Protection Absorption
The type of secretory glands Mucus gland or mucus cells (Goblet cells) Pits; invagination of surface lining epithelial Tubular glands (stomach and upper duodenum) Complex glands (Salivary glands, pancreas and
liver) Basic mechanism of secretion by glandular cells
Secretion of organic substances Water and electrolyte secretion
Basic regulatory mechanism of glandular cells
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Daily Secretion of Gastrointestinal Fluid
Fluid Daily volume (ml) pH
Saliva 1000 6.0 – 7.0 Gastric secretion 1500 1.0 – 3.5Pancreatic secretion 1000 8.0 – 8.3 Bile 1000 7.8Small intestinal secretion 1800 7.5 – 8.0 Brunner’s gland secretion 200 8.0 – 8.9 Large intestinal secretion 200 7.5 – 8.0
Total 6700
Guyton, AC; 2000blueberry
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PENGATURAN FUNGSI SEKRESI
Kontak dengan makanan dan saraf enterik
Pengaruh susunan saraf otonom Pengaruh hormonal
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SALIVA
Ludah 95% terutama terdiri atas air, elektrolit, dan sedikit protein
Osmolalitasnya rendah Konsentrasi ion K tinggi Mengandung bahan organik -
amilase, lipase, dan faktor pertumbuhan
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Saliva Function
Protection the mouth by: Cooling hot food Diluting gastric acid or bile regurgitated
into the mouth Washing food away from the teeth Antibacterial and antiviral effects (IgA and
peroxidase) Aids speech by facilitating movement of
the lips and tongue Digestion of glucose by amylase (ptyalin)
and fat by lingual lipase Lubrication; for easier swallowing, moisten
the mouth
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Parameter Kolinergik -adrenegik -adrenergik
Volume banyak sedikit sedikitViskositas rendah rendah tinggiProtein rendah tinggi tinggiMusin rendah rendah sangat tinggi
Karakteristik ludah yang dihasilkan oleh perangsangan kolinergik dan adrenergik
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Control of Salivary Secretion
Autonomic Nervous System Parasympathetic cause secretion of
watery fluid, high electrolyte but low in protein
Increases secretion of amylase with large volumes of fluid
Sympathetic cause secretion of small volume of fluid containing high mucin
Stimulates small volume of saliva rich in amylase, bicarbonate and K+
Salivary reflexes. Thought, aroma, or taste cause salivary reflexes
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MUKUS
Melekat kuat pada makanan/partikel lainnya, menutupi permukaan dinding sal cerna
resistensi rendah ----> pergerakan makanan menjadi mudah terjadi
Resisten thd enzim pencernaan Buffer asam atau alkali Mengandung ion bikarbonat untuk
netralisir asam
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ESOFAGUS
Sepanjang esofagus umumnya kelenjarnya bersifat mukoid untuk fungsi lubrikasi (agar mudah menelan) dan proteksi (mencegah ekskoriasi mukosa akibat makanan atau asam lambung
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Gastric Secretory Cells
Gastric secretory cells are located on the surface of the stomach and in glands that are buried within the mucosa consits of: Oxyntic glands are located in the fundus and
corpus. They contain three types of secretory cells: The parietal (oxyntic) cells, secrete HCl and
intrinsic factor Peptic (chief) cells secrete pepsinogen, the
precursor of pepsin Mucous cell secrete mucus
Pyloric glands are located in antrum and pyloric. They contain G cells and some mucous cell. G cells produce gastrin hormone
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Secretion of the Stomach
Hydrochloric Acid (HCl) Pepsinogen Intrinsic Factor Mucus
Glycoprotein products which primary function as lubricant, but can also have many other regionally specialized function
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FASE SEKRESI ASAM
Chepalic phase : penglihatan, penciuman, menelan makanan, terapi ADO atau pemberian insulin ---> 1/3-1/2 sekret HCL
Gastric phase : saat makanan masuk ke lambung -----> distensi lambung, sekresi gastrin -----> 2/3 sekret HCL
Intestinal phase : adanya makanan dalam duodenum disebabkan duodenum menghasilkan gastrin
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HCl Secretion
Mechanism HCl secretion HCl is secreted into the parietal cells canaliculi
by three step process: The active transport process is begun by the
transport of K+ and Cl- into the canaliculi H+ is then exchanged for K+ by a H+-K+ ATPase Water enters the canaliculi down the osmotic
gradient created by movement of HCl- The H+ entering the canaliculi is supplied by the
dissociation of H2CO3 into H+ and HCO3-
The active transport process involved in the generation of HCl- secretion require a large amount of ATP
The pH of acid secretion as low as 0.8
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Control of HCl Secretion
Stimulation of HCl secretion Acetylcholine (Ach) Histamine; histamine can stimulate
HCl secretion directly or can potentiate the secretion produced by ACh or gastrin
Gastrin Inhibition of HCl secretion
Somatostatin
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PEPSINOGEN SECRETION
Function of pepsinogen. Pepsin the active form of pepsinogen is proteolytic enzyme that begins the process of protein digestion
Regulation of pepsinogen secretion. Cephalic state, vagal nerve stimulate
secretion of pepsinogen Gastric phase, low pH stimulate secretion Intestinal phase, secretin stimulate
pepsinogen release
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MUCOSAL BARRIER
The gastric mucosal barrier protects the gastric lining cells from damage
The main component of mucus is a thick viscous alkaline mucous layer secreted by the mucous cells
Mildly injury results in increased mucus secretion and surface desquamation
More serious injury denudes the mucosal surface, forming an ulcer, and produce bleeding
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PANKREAS
Enzim pankreas sangat penting untuk proses digesti, dan sekresi enzim ini diatur oleh kontrol hormon sekretin dan CCK
Secretin merangsang duktus pakreas menghasilkan juice yang alkalis (HCO3 banyak, enzim )
CCK merangsang sel acinus produksi juice pankreas yg volumenya sedikit tapi enzimnya
Stimulasi vagus merangsang sekresi pankreas
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Anatomy and Histology of Pancreas
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Pancreatic Secretory Cells
Pancreatic exocrine cells are arranged in grape-like clusters called acini.
The exocrine cells themselves are packed with membrane-bound secretory granules which contain digestive enzymes that are exocytosed into the lumen of the acinus.
From there these secretions flow into larger and larger, intralobular ducts, which eventually coalesce into the main pancreatic duct which drains directly into the duodenum.
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Composition of Pancreatic Secretion
Pancreatic juice is composed of two secretory products critical to proper digestion: Digestive enzymes, secreted by acinar cells Bicarbonate (HCO3
-), secreted from epithelial cells
Digestive enzymes digesting all three major types of nutrients
HCO3- play important role in neutralizing
the acid chyme from the stomach
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Enzim Pankreas dan fungsinya ENZIM FUNGSI Enzim proteolitik (protease) Tripsinogen Memecah ikatan peptida antara arginin dan lisin Khimotripsin Memecah ikatan peptida asam amino aromatik Elastase Memecah ikatan peptida asam amino alifatik Karboksipeptidase A Memecah ikatan karboksil asam amino aromatik dan alifatik Enzim amilolitik (amilase) Alfa-amilase Hidrolisa glikogen, gula Enzim lipolitik (lipase) Lipase Hidrolisa monogliserida, asam lemak Fosfolipase Memecah asam lemak dan fosfolipid Kholesterol esterase Hidrolisis kolesterol blueberry
Phase of Pancreatic Secretion
Cephalic phase Vagal stimulation
Stimulates enzyme secretion Non-cholinergic
HCO3- secretion
Gastric phase Distension of the antrum and corpus
Secretion of low volume of enzymes and HCO3-
Food breakdown (primarily amino acids) Secretion of pancreatic secretion
Intestinal phase Cholecystokinin Secretin
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Control of Pancreatic Secretion
Hormonal Control Secretin (from increased HCl in
duodenum) stimulates fluid and electrolyte secretion
CCK (from increased fatty acids, peptides, amino acids) stimulates release of enzymes
Nervous System Parasympathetic input
initiates secretion during cephalic and gastric phases
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HATI & BILIARY SYSTEM
Empedu dibuat di hati dan disekresi lewat duktus biliaris menuju duodenum saat makan.
Saat tdk makan, empedu dibawa ke kandung empedu, dan akan disekresi saat makan oleh pengaruh CCK (kontraksi kdg empedu)
Sekresi empedu meningkat oleh pengaruh vagus, secretin
Empedu sangat penting pada proses emulsifikasi lemak
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Usus halus
Sel goblet, kelenjar Brunner (duodenum), kel. Lieberkun menghasilkan mucin yang alkalis pada mukosa usus halus,
Mucin ini gel-hydrat untuk melapisi usus, lubrikasi, mengandung antibakteria dan Ig,
Hormon TGI (VIP) dan stimulasi vagus menstimulasi sekresi mucin
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Sekian
Mohon Maaf dan Terimah Kasih
Wassalamu Alaikum WrWb
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