Abdomen And Digestive System PDF

 Anterior Abdominal Musculature- Layers The Abdominal Wall consists of 4 muscular layers: 1) External Oblique Muscle 2) Internal Oblique Muscle 3) Transversus Abdominis Muscle 4) Rectus Abdominis...

 Anterior Abdominal Musculature- Layers The Abdominal Wall consists of 4 muscular layers: 1) External Oblique Muscle 2) Internal Oblique Muscle 3) Transversus Abdominis Muscle 4) Rectus Abdominis Clavicle Scapula external oblique layers ? Pectoralis major Internal oblique Tranversus abdominus superficial-deep They continue medially to form a aponeuroses to fuse In the midline - linea alba Serratus anterior Serratus anterior Rectus abdominis External oblique (cut) (covered by anterior layer Tendinous intersections of rectus sheath) Rectus abdominis Linea alba Transversus abdominis (outer) External oblique Aponeurosis of internal oblique (cut) Aponeurosis of external oblique ↳ covers rectus abdominus Internal oblique Each muscle is covered with a fascial layer Aponeurosis of external oblique (cut) Copyright © 2017 by John Wiley & Sons, Inc. All rights reserved. (b) Anterior superficial view (c) Anterior deep view  Abdominal Muscles- Fiber Direction 2 There appears to be a layered homology to the musculature of the Thorax and Abdomen: - 3 layers of muscles oriented in similar directions: - External Oblique and External Intercostal: downward at an angle (like putting hands into front pockets of pants) - Internal Oblique and Internal Intercostal: upward angle (like crossing the hands over the chest) - Transversus Abdominis and Transversus Thoracis: horizontal (transverse) muscle bundles “Hands in pocket” Fibre orientation https://slideplayer.com/slide/7629238/  Schematic- Anterior Abdominal Muscles - The muscle layers end in a set of common Aponeuroses (flat sheets of dense fibrous connective tissue that attach sheet-like muscle) along the anterior midline (forming Linea Alba) - The Internal Oblique Aponeurosis splits above the Naval to form the anterior and posterior layers of the Rectus Sheath that envelopes the Rectus Abdominis Muscle (notice the loops) directoa Sternum ers Linea alba Transversus abdominis muscles and tendons External oblique muscles and tendons Internal oblique muscles and tendons Rectus abdominis Copyright © 2017 by John Wiley & Sons, Inc. All rights reserved. (d) Schematic of muscles and their aponeuroses  Arcuate Line of Rectus Sheath - Approximately 5 cm below the Naval - At this point the Aponeurosis of the Internal Oblique and Transversus Abdominis pass to the front of the Rectus Abdominis muscle - Below this line, the Rectus abdominis is only bordered by the Transversalis Fascia of the inner abdominal wall, on its posterior surface: The aponeuroses of all the abdominal muscles constitute the anterior wall of the rectus sheath in this location (see next slide) Mostly enclosed by the rectus sheath stone rectus ↑ I E Arcuate Line https://s3.studentvip.com.au/ notes/22839-sample.pdf  Rectus Sheath Above and Below Arcuate Line - Two transverse cross-sections are visible to the right, the upper one above the Arcuate line, and the lower one below the Arcuate line - Above the Arcuate line: the Aponeurosis of the Internal Oblique splits to form part of the anterior and posterior walls of the Rectus Sheath; the Aponeurosis of the External Oblique and Transversus Abdominis form the outer layers of the Anterior and Posterior walls of the Rectus Sheath, respectively - Below the Arcuate Line: the Aponeuroses of both the Internal Oblique and Transversus Abdominis pass in front of the Rectus Abdominis so that all three aponeuroses form the anterior wall of the Rectus Sheath; The posterior covering of the Rectus Abdominis consists of only the Transversalis Fascia and Parietal Peritoneum of the internal abdominal wall at this point ofintern slique e sheath S > - depttransdomin above arcuate line ↑ all the transversalis aponeurosesto 3 Fascia & are going parietal perineum infront of form the pass the rects abdominus posterror rectus sheath of ↳ anterior wall , rectus sheath ,  Superficial Dissection- Anterior Abdominal Wall Sternocleidomastoid Trapezius Clavicle Deltoid Rectus abdominis Pectoralis major - Depresses ribs/flexes vertebral column - Has Linea alba (“White Line;” collagenous line) and Tendinous Intersections ↓ External oblique Tendinous f ↳ parto sheath forms us. intersections Rectus abdominis Linea alba Aponeurosis of external oblique Copyright © 2017 by John Wiley & Sons, Inc. All rights reserved. (e) Anterior view  Superficial Dissection- Anterior Abdominal Wall - forced exhaccesat External intercostals External oblique & Serratus - Compresses the abdomen - Depresses ribs J anterior - - Laterally flexes the torso i External oblique Rectus abdominis Aponeurosis of external oblique Linea alba Copyright © 2017 by John Wiley & Sons, Inc. All rights reserved. (f) Right anterolateral superficial view  Intermediate Dissection- Anterior Abdominal Wall External intercostals Internal External intercostals oblique (superficial lamina) cut External oblique Internal (deep lamina) oblique External oblique (superficial lamina) cut Copyright © 2017 by John Wiley & Sons, Inc. All rights reserved. (g) Right anterolateral superficial view  Intermediate Dissection- Anterior Abdominal Wall in muscle accessorred eth Rib 7 & Internal oblique - Compresses the abdomen [- Depresses ribs - Laterally flexes the torso Internal intercostals * * external oblique removed Tendinosus intersections Aponeurosis of internal oblique Internal oblique Copyright © 2017 by John Wiley & Sons, Inc. All rights reserved. (h) Right anterolateral deep view  Deep Dissection- Anterior Abdominal Wall Transversus Abdominis - Compresses the abdomen Rib 7 - Stabilizes “core” ? Innermost Intercostals Transversus Text inter abdominis oblique removed Aponeurosis of transversus abdominis Copyright © 2017 by John Wiley & Sons, Inc. All rights reserved. (i) Right anterolateral deeper view  Posterior Abdominal Wall- Muscles Mening Diaphragm Esophagus Central tendon Aorta acrucate medical - lig > - lateral arcuate Internal Oblique ligament External Oblique Quadratus lumborum Psoas Major Transversus abdominis Psoas Minor Iliacus Iliac crest L5 Vertebral Body Pubic symphysis  in adult hood, there is an asymmetry with the organization of organs. Stomach Is more on the left side of the abdomen, liver is more on the right. abdomen. Abdominal Mesenteries During development, the developing Hef Spleen when organs? abdominal organs undergo a positional shift/rotation. Meaning Dorsal Mesentery the stomach goes towards the left, Gut (Stomach) and liver towards right are organs embedded in peritoneum Ventral Mesentery Gut tube is suspended from dorsal wall by the dorsal mesentary, and the ventral wall Liver by the ventral mesentary As the organs grow, causes the ? gut to rotate, dorsal adn ventral mesentaries rotate along with the organs they are attached to adult Spleen Dorsal Mesentery Stomach * See these features on next slide: top right* Ventral lesser mentum Mesentery Liver https://s3.amazonaws.com/classconnection/27/flas Ventral hcards/2952027/jpg/development_of_the_foregut_ Mesentery wall. ventral_and_dorsal_mesentery- ↳ becomes faciform lig to attach liver to abdominal 14E8D0D086B408155B1.jpg  Abdominal Cavity Lining- Lienorenal= Splenorenal Peritoneum The Peritoneum The serosa (Visceral peritoneum) is continuous with the Parietal peritoneum Serous fluid (Peritoneal Fluid) lubricates the serosal surfaces The abdominal organs lie within the peritoneal cavity maj organs. Intraperitoneal organs- completed surrounded by Visceral Peritoneum (e.g. Stomach, Liver, Jejunum, Ilium) of small intestine ~ my behind Retroperitoneal organs- located behind the Peritoneal cavity within the abdomen- Visceral Peritoneum on Anterior Surface Only (e.g. Kidneys, Ureters, Abdominal Aorta) start as Secondarily retroperitoneal organs- Organs intraperitoneal form as intraperitoneal but become & become retroperitoneal when visceral peritoneum fuses retroparitual with the opposing parietal peritoneum (e.g. Pancreas, Duodenum) The Mesentery The mesentery is a continuous membrane that attaches the intestines to the posterior abdominal wall Formed by the double fold of Peritoneum It stores fat and routes blood vessels, lymphatics, and nerves to supply intraperitoneal organs © 2018 Pearson Education, Inc.  Abdominal Mesenteries double layer of peritoneum, which is a result of Of developing organs? Mesenteries - Fused double sheets of Peritoneal Membrane that stabilize position of Lesser organs, and provide entry for blood Omentum diaphragm vessels, lymphatics and nerves to enter exit the organs cred) - All of the small intestine except the liver duodenum is suspended in a sheet of mesentery called the Mesentery Proper stomach - Large intestine suspended by Mesocolon: Transverse mesocolon (Transverse Colon), Sigmoid lesser mesocolon mesocolon (Sigmoid colon) ↳ links organs transverse - Omenta: Double Sheets “back to to abdominal colon Mesentery walls & links back” of Peritoneum Proper organs together ↳ comes of - Lesser omentum: Lies between the posterior wall stomach and the liver and supports - Greater omentum: Extends from the most of Small intestine & stomach as a double flap and covers the rest of the abdominal organs on Greater the anterior surface Omentum - Contains thick layer of adipose tissue - Functions as an energy reserve and as insulation http://daesfreyprerev.blogspot.com/2018/09/peritoneal-dialysis-physiology.html Intraperitoneal vs. Retroperitoneal Structures Intraperitoneal Structures - 1) Liver + Gallbladder 2) Spleen Falciform Diaphragm 3) Stomach intestine) ligament 4) Duodenum (Part 1) Ismall - - but 5) Jejunum - 6) Ileum Paris intraped a n f 7) Caecum + Appendix 8) Transverse Colon Liver 9) Sigmoid Colon 10) Rectum (Upper third) Lesser 11) Female: Uterus, Fallopian Tubes, omentum Ovaries * Pancreas pancreas tail Stomach. Retroperitoneal Structures Transverse 1) Adrenal Glands Duodenum 2) Kidneys + Ureters mesocolon 3) Aorta Transverse 4) Inferior Vena Cava Mesentery - colon 5) Renal and Gonadal Blood Vessels proper 6) Esophagus Greater 7) Rectum (Middle third) greatea omentum Sigmoid Secondary Retroperitoneal started intrapertoreal , mesocolon Parietal Structures these but - got pushed back then peritoneum 1) Duodenum (Parts 2-4) retroperitoneal & are now 2) Pancreas (except tail) over Small development Rectum 3) Ascending Colon intestine 4) Descending Colon lesser& Urinary bladder Uterus Infraperitoneal Structures (below greater sac ↳ fluid-filled the peritoneal cavity sacs.- > flid can travel 1) Lower 1/3 of rectum byw these 2 sacs. 2) Urinary bladder + Distal Ureters Figure 25.4b Mesenteries b Mesenteries of the abdominopelvic cavity, as © 2018 Pearson Education, Inc. seen in a diagrammatic sagittal section.  How do Secondary Retroperitoneal Organs get there? organsarekoa se - Secondary Retroperitoneal Structures- Duodenum https://www.slide (Parts 2-4), Pancreas (except tail), Ascending Colon, share.net/NamX al1/peritoneum-i Descending Colon are suspended via the Mesenteries - Those organs are pushed back against the Parietal Peritoneum of the Posterior Abdominal Wall - The Visceral and Parietal layers of the Peritoneum fuse (forming Fusion Fascia) - This “pushes” that organ behind the fused peritoneal layers and the organ is only covered by visceral peritoneum on its anterior surface, and fused connective wall posterin tissue on its posterior wall mesentary fuses - Below: The Pancreas and Duodenum flap backwards with producing a fusion fascia with the posterior abdominal parietal layer wall, thereby becoming Retroperitoneal enter ala Inferior Views of Transverse Cross-sections flaps to fuse w/ dorsal mesentary ↳ bringing the 2 parts of the together only covered pancreas by ant surface. https://onlinelibrary.wiley.com/doi/full/10.1007/s005340070017  How do Secondary Retroperitoneal Organs get there? - Similar to the Pancreas and Duodenum, the Mesentery that Inferior Views of Transverse Cross-sections suspends the Ascending and Descending Colon flap backwards against the posterior abdominal wall forming left and right fusion fascia underneath, hence becoming Retroperitoneal - Note that on the right side of the body, the Mesocolon leaf of the Ascending Colon flaps over top of the Head of the Pancreas and Duodenum producing additional fusion fascia Mike M. (2017) Laparoscopic Right Colectomy. In: Laparoscopic Colorectal Cancer Surgery. Springer, Singapore  Mesentery Proper, Mesocolon and Fusion Fascia - The Small Intestine (Except Sections 2-4 of Duodenum) are suspended within the abdominal cavity by the Mesentery Proper, that Greater arises from the Root of Lesser omentum (cut) the Mesentery (where omentum Jejunum, vessels, nerves, lymphatics enter) Transverse mesocolon - The Transverse Colon is suspended from a Transverse Fusion fascia of Mesenteric membrane ascending and colon called the Transverse Mesocolon descending colons Ascending rootmesentary fuses to dorsal - The Left and Right colon peritoneum Fusion Fascia of the Ascending and Mesentery Descending Descending Colons proper push these sections of (mesenterial colon the large intestine sheet) Small behind the Peritoneal wall as they remain intestine covered only on their Sigmoid Anterior Surface by Visceral Peritoneum colon (becoming secondarily retroperitoneal) d The organization of mesenteries in the adult. This is a simplified view; the length of the Figure 25.4d Mesenteries small intestine has been greatly reduced. © 2018 Pearson Education, Inc.  Abdominal Mesenteries-Posterior Wall - The diagram on the right illustrates the Parietal Peritoneum Falciform Diaphragm that covers the ligament posterior wall of the abdomen, with the cut double-edges Inferior that give rise to the vena cava Esophagus forward projecting Mesentery, Coronary Mesocolon or ligament Pancreas Visceral Peritoneum over of liver organs like the Left kidney Liver Right kidney - You can also see the Duodenum Attachment of cut edges of transverse Visceral mesocolon Peritoneum where the Secondary Superior mesenteric Retroperitoneal Position of artery and vein Structures like the ascending Ascending and Position of Descending Colon colon descending colon were located Root of - The Retroperitoneal mesentery Attachment of Structures like the sigmoid mesocolon proper Kidneys can be seen behind the Parietal Rectum Parietal peritoneum Peritoneum of the posterior abdominal Urinary bladder wall Figure 25.4c Mesenteries c Anterior view of the empty peritoneal cavity showing the attachment of © 2018 Pearson Education, Inc. mesenteries and visceral organs to the posterior wall of the abdominal cavity.  Components of the Digestive Tract The digestive system processes food mechanically and chemically into small molecules for absorption across the epithelial lining of the digestive tract into the surrounding interstitial fluid, and from there into the circulatory system for distribution Major Subdivisions of the Digestive Tract Mouth Oral Cavity Mechanical processing, moistening, Accessory Organs of mixing with salivary secretions the Digestive System Pharynx Salivary Glands Muscular propulsion of materials into the Secretion of lubricating fluid esophagus containing enzymes that break down carbohydrates Esophagus Transport of materials to the stomach Liver Acid helps to sterilize the food, Secretion of bile (important Stomach so it performs an immune for lipid digestion), storage of function nutrients, many other vital Chemical breakdown of materials by acid and enzymes; mechanical processing functions through muscular contractions Gallbladder Small Intestine Storage and concentration of Enzymatic digestion and absorption of bile water, organic substrates, vitamins, and ions Pancreas Large Intestine Exocrine cells secrete buffers and digestive enzymes; Dehydration and compaction of indigestible endocrine cells secrete materials in preparation for elimination hormones Reaching the rectum after to be expelled Anus Z © 2018 Pearson Education, Inc. Figure 25.1 Components of the Digestive System  Histological Organization- Digestive Tract The Mucosa The inner lining of the digestive tract Mucous membrane = layered The mucosal epithelium is either a stratified or simple epithelium: Oral cavity, pharynx, and esophagus are lined with non-keratinized stratified squamous cells (resist stress and abrasion) To Resist abrasion bc of swallowing food Stomach, small intestine, and large intestine are lined with simple columnar cells (for secretion and absorption) These cells are more involved with this © 2018 Pearson Education, Inc.  Histological Organization of the Digestive Tract There are four major layers of the digestive tract 1) The Mucosa- has Circular Folds (Plicae Circulares) to increase surface area for absorption; Lamina Propria has Blood Vessels, Lymphatics, nerves, and Muscularis Mucosae- smooth muscle at border 2) The Submucosa- Lymphatic vessels, Blood vessels 3) The Muscular layer (Muscularis Propria)- Peristaltic contractions to propel food 4) The Serosa- Visceral Peritoneum, secretes Peritoneal fluid. Intraperitoneal organs are covered by Serosa; Retroperitoneal organs are embedded in loose connective tissue (Adventitia) Circular fold Mucosa Contains Mesenteric artery and vein glands that Mucosal secrete epithelium Circular mucuous Lamina & Mesentery fold propria Increase surface Villi & area for secretio absoprtion Visceral Mucosal glands Peritoneum Submucosal gland Muscularis mucosae Muscle se Lymphatic vessel Mucosa Artery and vein Submucosa Submucosal F neural plexus Muscular Circular muscle layer layer Myenteric neural Serosa plexus Serous membrane Longitudinal muscle layer a Three-dimensional view of the histological b An enlarged section of the digestive tract organization of the general digestive tract showing the structure of a circular fold © 2018 Pearson Education, Inc. Figure 25.2ab Histological Structure of the Digestive Tract  Peristalsis- Propels Material in Digestive Tract INITIAL STATE Longitudinal muscle Circular muscle From To mouth anus 1 Contraction Contraction of circular muscles behind bolus 2 Contraction of Contraction longitudinal muscles Pull the distal Repeated contraction ahead of bolus part of digestive Of circular muscle and the drawing tract towards the in of the longitudinal muscle is bolus what propels that food bolus down Contraction the digestive tract 3 A wave of contraction in circular muscle layer forces bolus forward Figure 25.3a Peristalsis and Segmentation a Peristalsis propels materials along the length of the digestive tract by © 2018 Pearson Education, Inc. coordinated contractions of the circular and longitudinal layers.  Digestive Tract- Esophagus - Hollow muscular tube that extends from the Pharynx region to the Stomach Allowing food to pass from Throat to stomach - It is 25 cm long and 2 cm in Vagus Nerve (X) diameter - Located posterior to the Aorta trachea - Enters the peritoneal cavity Esophagus by passing through the esophageal hiatus of the diaphragm - Innervated by the Vagus Vagus Nerve (X) Branches to nerve (CN X) from the Esophageal esophageal plexus Plexus Level of diaphragm - Contains upper and lower esophageal sphincters Diaphragm esphogaiatus © 2018 Pearson Education, Inc.  Histology- Esophagus The esophageal wall is made of: 1) Mucosa- Contains stratified, nonkeratinized squamous epithelium 2) Submucosa- Both mucosa and submucosa have large folds. Contains submucosal glands that produce mucus. Muscularis mucosae very thin or absent 3) Muscularis externa- Mixed skeletal and smooth muscle. Both are under involuntary control - The esophagus does not have a Serosa layer - Has Fibrous adventitia (like other Retroperitoneal structures) The esophagus is a retroperitoneal structure When there’s no food passing through esophagus, the lumen is Kind of collapsed. As there is food passing down, it stretches open ?? Stratified squamous Muscularis epithelium mucosae Lamina Mucosa propria Submucosa Muscular Muscularis layer mucosae Adventitia The esophagus LM × 5 The esophageal mucosa LM × 300 a Low-power view of a section through the esophagus b The esophageal mucosa © 2018 Pearson Education, Inc. Figure 25.9 Histology of the Esophagus  Esophagus Musculature - Cricopharyngeus Muscle - Part of Inferior Pharyngeal Constrictor Muscle - Remains contracted at most times to prevent reflux of stomach contents into the Pharynx - Forms the Upper Esophageal Sphincter (UES) - Anterior surface of Esophagus attaches to the posterior wall of Trachea via fibroelastic membranes and Accessory Muscle Bundles that suspend the Esophagus from the back of the Cricoid Cartilage Cricopharyngeus Remains contracted most Of the time - it forms the UES. (But it opens during the swallowing process These connect the Esophagus to the Trachea  Lower Esophageal Sphincter - The Lower Esophageal Sphincter (LES) consists of a circular muscle layer of the distal esophagus, and is bolstered by the surrounding crura of the diaphragm that help “pinch-off” the esophageal hiatus - it is a barrier that protects the esophagus from acid reflux of stomach contents - The LES relaxes during swallowing to allow contents of the esophagus to pass into the stomach - A Hiatal Hernia occurs when portions of the upper stomach impinge upward through the esophageal hiatus of the diaphragm, producing GERD - GERD: Gastroesophageal reflux disease- acidic stomach contents reflux into the esophagus irritating the esophagus and cavities above (e.g. pharynx) Normal Hiatal Hernia Esophagus GERD Esophageal Diaphragm sphincter Allows food to reflux upwards and squeeze through weakened esp[jhagel sphincter and into the esophagus —-> throat. This food/acid can irritate the esophagus —> GERD Clinical Note 25.1 Esophagitis, GERD, and Hiatal Hernia © 2018 Pearson Education, Inc.  Stomach- Greater and Lesser Omenta Greater Omentum: An apron-like fold of mesentery that attaches between the transverse colon and the greater curvature of the stomach. Contains a lot of fat, energy store. Can also seal off parts of abdominal cavity to prevent infection (immune function) Lesser Omentum: Mesentery that attaches between the liver, stomach, and proximal portion of the duodenum. As a result, the lesser omentum is also referred to as the hepatogastric ligament and hepatoduodenal ligament (contains Portal Triad: Hepatic Artery Proper, Portal Vein, Common Bile Duct) Lesser curvature Retractor (medial surface) Attached to other structures by the mesentary? There are 2 mesentary linings. 1 above and 1 below called the momenta. Mesenteries of the These help to stabilize the structures in the abdomen and they also hallow the passing of blood vessels and nerves Esophagus Stomach Can be broken down into 2 ligaments) Lesser Omentum Diaphragm The lesser omentum extends from the liver to the stomach Liver Fundus and first segment of the Spleen proximal duodenum. Cardia Hepatogastric Ligament The hepatogastric ligament STOMACH connects the liver to the lesser curvature of the stomach. Hepatoduodenal Ligament Body Gall- The hepatoduodenal ligament bladder connects the liver to the Pylorus proximal segment of the duodenum. Greater Omentum The greater omentum forms a large pouch that hangs like an Greater curvature apron from the greater (lateral surface) curvature of the stomach. Right kidney Duodenum Transverse colon © 2018 Pearson Education, Inc. Figure 25.10 Anatomy of the Stomach (1 of 3)  Stomach and Greater Omentum in situ Note: The Lesser Omentum (between the liver and the lesser curvature of stomach) has been removed So we can see the blood vessels Esophagus Diaphragm Part of it has been cut so we can see the gastric artery Left gastric artery Liver, Liver, right lobe left lobe Vagus nerve (X) Lesser curvature Fundus Hepatic artery Gallbladder Cardia Bile duct STOMACH Spleen Pyloric sphincter Body Greater curvature with greater omentum attached Pylorus Greater omentum Has a lot of fat tissue It folds backwards and become continuous with the visceral peritoruneium that is covering transverse colon the GM forms a sac that is filled with peritoneal fluid © 2018 Pearson Education, Inc. Figure 25.10 Anatomy of the Stomach (2 of 3)  Greater and Lesser Sacs of Peritoneal Cavity Greater Omentum: An apron-like fold of mesentery that attaches between the transverse colon to the greater curvature of the stomach. These are filled With peritoneual fluid. The fluid can communicate with one other through an opening - epiploic foramen Lesser Omentum: The lesser omentum and draped inferior portion of the greater omentum form a sac known as the Lesser Sac (omental bursa; shown in blue below), a subdivision of the peritoneal cavity that is continuous with the Greater Sac (the majority of the peritoneal cavity; shown in red below) via a channel called the Epiploic Foramen (of Winslow). Inferior Transverse Section Lesser Sac Lesser Omentum Epiploic Foramen Fluid can travel between the 2 cavities through This opening Liver has been removed so you can Greater See the lesser omentum Omentum Greater Sac  Opened Lesser Sac The Lesser Sac is a pouch of the peritoneal cavity that is enclosed within the Greater Omentum, and walled off at the front by the greater omentum (anterior layer), the stomach, and the lesser omentum. The Epiploic Foramen communicates between the Greater and Lesser Sacs of the Peritoneal Cavity Fluid passes back into Into the lesser omentum This dissection opens up the lesser sac from the front (shaded ~ in blue in the bottom left image), by cutting open the anterior wall of the greater omentum near the upper edge (shown on the left), just below the stomach. The lesser sac continues downward within the greater omentum as the Omental Recess. http://y7177.com/sa/anato/peritoneum/omental_bursa.htm Below: The structures located behind the posterior wall of the lesser sac include some intraperitoneal (transverse colon and mesenteries) and retroperitoneal (Pancreas) structures  Anatomy of the Stomach The stomach performs three major functions: 1) Temporary storage of ingested food, 2) Mechanical digestion of ingested food, 3) Chemical digestion of food- The end result is the production of Chyme Mix of food products that is mixed with acids. This acid helps kill any pathogens that enter ? the digestive tract - Gastric folds (gastric rugae): Relaxed stomach- Mucosa forms numerous muscular ridges. Folds permit expansion of the stomach. A stretched stomach exhibits less prominent folds As food enters, these folds straighten out to increase the volume of the stomach - Smooth muscle layers: 1) Circular muscles, 2) Longitudinal muscles, 3) Oblique muscles Pyloric sphincter —> duodenum These muscles are going to help mix the food products and squeeze them down into the - The Pyloric Sphincter regulates passage of contents into the Small Intestine (Duodenum) Pinch off the lower esophageal spinster to control food into the stomach, adn preventing acid reflux Gastroesophageal junction Regions of the Stomach Fundus Esophagus The fundus is the region superior to the junction between the stomach and the esophagus (the Musculature of gastroesophageal junction). the Stomach Longitudinal Cardia Anterior muscle layer surface The cardia is the superior, medial Circular portion of the stomach within 3 cm of the gastroesophageal junction. muscle layer Oblique Body muscle layer The body, the largest region, is the (overlying mucosa) area between the fundus and the pylorus. Lesser curvature (medial surface) Pyloric Part The pyloric part is divided into the pyloric antrum, pyloric canal, Pyloric sphincter pylorus, and pyloric orifice. Duodenum Gastric folds Pyloric orifice Greater curvature (lateral surface) Pylorus Pyloric part Pyloric canal Right gastro-epiploic vessels Pyloric antrum © 2018 Pearson Education, Inc. Figure 25.10 Anatomy of the Stomach (3 of 3)  Arterial Supply of the Stomach There are three branches from the Celiac Trunk that supply the stomach Left gastric artery: Initial branch of Celiac Trunk. Supplies blood to the lesser curvature and cardia Splenic artery: Supplies blood to the fundus. Branches to form the Left Gastro-Epiploic artery, which supplies the greater curvature Common hepatic artery: Branches to form the Right Gastric, Right Gastro-Epiploic, and Gastroduodenal artery to supply the greater and lesser curvatures, and continues to the Liver as the Hepatic Artery Proper Right Gastric Artery originates predominantly from the Hepatic Artery Proper or earlier from the Division of the Common Hepatic Artery Inferior vena cava Thoracic aorta Abdominal aorta Branches of the Common Liver Celiac Trunk Stomach Hepatic Artery Left gastric Hepatic artery proper Common hepatic Cystic Splenic Gastroduodenal Right gastric Spleen Branches of the Right gastro-epiploic Splenic Artery Left gastro-epiploic Pancreatic Pancreas Stomach arteries - has 4 major arteries Right gastric Left gastric Left gastro-epiploic Right gastro-epiploic Small intestine Sigmoid colon Rectum Figure 22.15a Arteries of the Abdomen © 2018 Pearson Education, Inc. a Major arteries supplying the abdominal viscera  Arterial Supply of the Stomach Posterior surface of Posterior Surface of Copyright © stomach 2017 by Stomach (turned John Wiley upward) So we can see the arterial supply? & Sons, Inc. All rights reserved. Left gastro-omental Right gastro-omental Aka left - gastro epiploic artery Right gastric Celiac trunk Left gastric Proper hepatic Spleen Splenic Common hepatic Pancreas Gastroduodenal Superior mesenteric Jejunum of small intestine Duodenum of small intestine Abdominal aorta (a) Anterior view of celiac trunk and its branches  Histology of the Stomach - Lined with simple columnar epithelium - Gastric pits lead to gastric glands - Gastric pits and glands contain gastric secretory cells: 1) Mucous surface cells 2) Mucous neck cells 3) Parietal cells 4) Chief cells 5) Enteroendocrine cells Esophagus Diaphragm Fundus Mucous Body Cardia epithelial Lesser curvature cells Lesser omentum Pyloric part Greater omentum Entrances to gastric pits Gastric folds Greater curvature Gastric mucosa SEM × 35 a Diagram of the stomach and mucosa. b Colorized SEM of the gastric mucosa. © 2018 Pearson Education, Inc. Figure 25.12ab Histology of the Stomach Wall  Histology of the Stomach Prevents acid from digesting the stomach lining - Mucous surface cells: Face the lumen. Secrete mucus to protect the lining of the stomach from autodigestion - Mucous neck cells: Located in the gastric pit. Produce mucous and can divide to replenish mucosal cells Hormone - helps in absorption of vit b12 - Parietal cells: Secrete intrinsic factor and hydrochloric acid. Intrinsic factor- Facilitates the absorption of Vitamin B12 (erythropoiesis) from the small intestine into the bloodstream. Hydrochloric acid- Kills microorganisms, denatures proteins, and activates pepsinogen ENZYME precursor Active enzyme - Chief cells: Secrete Pepsinogen-> Pepsin (digests proteins) - Enteroendocrine cells: Secrete hormones-> G-Cells Secrete Gastrin which stimulates the parietal and chief cells to release Known as G cells bc they secrete gastric their products Hydrocholoric acid, intrinsic factors and pepsin Luminal Layers of the surface Stomach Wall Lamina Mucosa propria produce hormones, secretes Gastric Acid Mucous Gastric pit (opening pit neck cells to gastric gland) Mucous epithelium Cells of Gastric Glands Gastric Parietal Lamina propria gland cells Muscularis mucosae Found throughout the digestive tract Submucosa Vein G cell and Chief cells Muscular Layer artery * Oblique muscle Smooth muscle cell Circular muscle Coorindated contraction helps mix the stomach contents, and move food from Lymphatic Muscularis LM × 200 stomach into the pyloric sphcintoer vessel mucosae Longitudinal muscle Myenteric Serosa neural plexus d Diagram of a gastric gland and micrograph of the gastric mucosa. Visceral serous membrane —> when it passes over the top of the stomach it forms a double layer thats called the lesser omentum, and when it meets the lower edge of the stomach It forms the greater omentum c Diagram of the stomach wall. This corresponds to a sectional view through the © 2018 Pearson Education, Inc. area indicated by the box in part (b). Figure 25.12cd Histology of the Stomach Wall  Histology of the Stomach Gastric pit Lamina propria Surface mucous cell Gastric Mucous neck cell gland G cells Parietal cell Gastric Chief cells gland LM 180x Copyright © 2017 by John Wiley & Sons, Inc. All rights reserved. (c) Fundic mucosa  The Stomach- Gastric Regulation Regulation of Gastric Activity Gastric motility and the production of stomach acid and enzymes are controlled by the CNS and by hormones Release of hormones locally, within the gastric pits. CNS regulation involves: Promotes digestion Vagus nerve (parasympathetic innervation) Parasympathetic stimulation is going to stimulate gastric secretion and gastric motility. So seeing food or thinking about food triggers secretions, also Triggered by the sight and thought of food tasting food (taste buds activate) which trigger secretions and motility) Celiac plexus (sympathetic innervation) Reduce gastric secretions within the digestive tract and prevent digestive activity to shunt blood/o2 to the skeletal muscles instead. The gastric folds, stretch out Food enters the stomach and the stomach stretches Stretching causes the G cells to release gastrin Acts locally within the pits Gastrin causes the parietal and chief cells to release their products © 2018 Pearson Education, Inc.  Stomach "sore" or break in membrane Peptic Ulcer Disease (PED) - 5–10 percent of the population develops peptic ulcer disease (PUD). An ulcer is a craterlike lesion in a membrane; ulcers that develop in areas of the GI tract exposed to acidic gastric juice are called peptic ulcers. The most common complication of peptic ulcers is bleeding, which can lead to anemia if enough blood is lost. In acute cases, peptic ulcers can lead to shock and death. Three distinct causes of PUD are recognized: (1) the bacterium Helicobacter pylori; (2) nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin; and (3) hypersecretion of HCl, as occurs in Zollinger-Ellison syndrome, which involves a gastrin-producing tumor, usually of the pancreas. (Tortora, 2016-10-03, p. 799) Tortora, G. J., Nielsen, M. (2016-10-03). Principles of Human Anatomy, 14th Edition [VitalSource Bookshelf version]. Retrieved from vbk://9781119320593 Peptic Ulcer Disease If the sore goes Stomach Ulcer deep it can erode the underlying blood vessels and cause bleeding Esophagus Ulcer Duodenum Muscle Submucosa Mucosa © 2018 Pearson Education, Inc. Clinical Note 25.3 Gastritis and Peptic Ulcers  Small Intestine Approximately 6 meters (20 feet) in length and 2.5–4 cm (1–1.6 inches) in diameter s Transverse producteduodem Consists of: colon food 1) Duodenum: 25 cm (10 & inches) long; receives digestive enzymes from the pancreas, bile Regions of the Section 2 and 3 of from the liver and gallbladder Will help to buffer the incoming acidic Small Intestine duodenum is secondary retroperitoneal chyme - buffers made by the pancreas 2) Jejunum: 2.5 m (8 feet) long; most of the digestion and Duodenum absorption occurs in the jejunum 3) Ileum: 3.5 m (12 feet) long Jejunum - Jejunum and ileum are supported by the Mesentery Proper - Duodenum is not Ileum associated with any mesentery (Majority is retroperitoneal Ascending - Blood Supply: Branches of the colon Superior Mesenteric Artery and intestinal arteries Cecum - Nerve supply: Descending Parasympathetic colon innervation via the Vagus nerve (X) Sigmoid colon - Sympathetic innervation via the Superior Mesenteric Rectum Ganglion © 2018 Pearson Education, Inc. Figure 25.13 Regions of the Small Intestine  Venous blood will feed Histology- Small Intestine Back into hepatic portal vein. So venous blood that contains the nutrients picked up from digestive processes is fed to the liver where it’s going to take them up, process and sore them to - The lining contains Circular folds (plicae circulares) Bc maj of nutrients are absorbed in small intensities, there is more folding in deliver them to the body via the systemic this part of the digestive tract circulation. So first the blood supply from the - Each plica consists of numerous intestinal Villi digestive tract goes to the Liver for processing - The apical surface of the epithelial mucosa has tiny Microvilli and storing then for delivery to the rest of the body through inferior vena cava —> RA - The plicae circulares, villi, and microvilli function to increase surface area for digestion and absorption - Intestinal glands (intestinal crypts): Indentations of the mucosa that occur at the base of the villi - New epithelial cells are formed in this area Goblet cell - Contain enteroendocrine cells produce intestinal hormones, including Cholecystokinin and Secretin - Paneth cells: innate immunity- secrete antimicrobial proteins e.g. lysozyme Columnar epithelial cell Circular fold Villi Central lympathic capillary within each villi is called A lacteal Lacteal Villi Intestinal Lymphoid Lacteal gland nodule Nerve Characteristic features of the intestinal