To induce remission of Crohn’s disease, glucocorticoids (whether oral, topical or intravenous) are typically the first line of treatment. 5-ASA drugs are considered a second option for inducing remission of IBD. Azathioprine is more commonly used for maintaining remission. Steroids are specifically used to induce remission of Crohn’s disease. Infliximab is particularly effective for treating refractory disease and fistulating Crohn’s.

Crohn’s disease is a type of inflammatory bowel disease that can affect any part of the digestive tract. The National Institute for Health and Care Excellence (NICE) has published guidelines for managing this condition. Patients are advised to quit smoking, as it can worsen Crohn’s disease. While some studies suggest that NSAIDs and the combined oral contraceptive pill may increase the risk of relapse, the evidence is not conclusive.

To induce remission, glucocorticoids are typically used, but budesonide may be an alternative for some patients. Enteral feeding with an elemental diet may also be used, especially in young children or when there are concerns about steroid side effects. Second-line options include 5-ASA drugs, such as mesalazine, and add-on medications like azathioprine or mercaptopurine. Infliximab is useful for refractory disease and fistulating Crohn’s, and metronidazole is often used for isolated peri-anal disease.

Maintaining remission involves stopping smoking and using azathioprine or mercaptopurine as first-line options. Methotrexate is a second-line option. Surgery is eventually required for around 80% of patients with Crohn’s disease, depending on the location and severity of the disease. Complications of Crohn’s disease include small bowel cancer, colorectal cancer, and osteoporosis. Before offering azathioprine or mercaptopurine, it is important to assess thiopurine methyltransferase (TPMT) activity.

The small bowel receives a daily supply of bile ranging from 500 mL to 1.5 L, with the majority of bile salts being reused through the enterohepatic circulation. The contraction of the gallbladder results in a lumenal pressure of around 25 cm water, which can cause severe pain in cases of biliary colic.

Bile is a liquid that is produced in the liver at a rate of 500ml to 1500mL per day. It is made up of bile salts, bicarbonate, cholesterol, steroids, and water. The flow of bile is regulated by three factors: hepatic secretion, gallbladder contraction, and sphincter of oddi resistance. Bile salts are absorbed in the terminal ileum and are recycled up to six times a day, with over 90% of all bile salts being recycled.

There are two types of bile salts: primary and secondary. Primary bile salts include cholate and chenodeoxycholate, while secondary bile salts are formed by bacterial action on primary bile salts and include deoxycholate and lithocholate. Deoxycholate is reabsorbed, while lithocholate is insoluble and excreted.

Gallstones can form when there is an excess of cholesterol in the bile. Bile salts have a detergent action and form micelles, which have a lipid center that transports fats. However, excessive amounts of cholesterol cannot be transported in this way and will precipitate, resulting in the formation of cholesterol-rich gallstones.

The point at which the oesophagus enters the abdomen is located at T10.

Anatomy of the Oesophagus

The oesophagus is a muscular tube that is approximately 25 cm long and starts at the C6 vertebrae, pierces the diaphragm at T10, and ends at T11. It is lined with non-keratinized stratified squamous epithelium and has constrictions at various distances from the incisors, including the cricoid cartilage at 15cm, the arch of the aorta at 22.5cm, the left principal bronchus at 27cm, and the diaphragmatic hiatus at 40cm.

The oesophagus is surrounded by various structures, including the trachea to T4, the recurrent laryngeal nerve, the left bronchus and left atrium, and the diaphragm anteriorly. Posteriorly, it is related to the thoracic duct to the left at T5, the hemiazygos to the left at T8, the descending aorta, and the first two intercostal branches of the aorta. The arterial, venous, and lymphatic drainage of the oesophagus varies depending on the location, with the upper third being supplied by the inferior thyroid artery and drained by the deep cervical lymphatics, the mid-third being supplied by aortic branches and drained by azygos branches and mediastinal lymphatics, and the lower third being supplied by the left gastric artery and drained by posterior mediastinal and coeliac veins and gastric lymphatics.

The nerve supply of the oesophagus also varies, with the upper half being supplied by the recurrent laryngeal nerve and the lower half being supplied by the oesophageal plexus of the vagus nerve. The muscularis externa of the oesophagus is composed of both smooth and striated muscle, with the composition varying depending on the location.

This patient has been diagnosed with Crohn’s disease, which is characterized by a long history of abdominal pain, weight loss, and diarrhea. Unlike ulcerative colitis, which only affects the colon, Crohn’s disease can affect any part of the gastrointestinal tract. In this case, oral mucosal ulceration is also present. The classic cobblestone appearance on endoscopy is due to deep ulceration in the gut mucosa with skip lesions in between.

On the other hand, loss of haustra is a finding seen in chronic ulcerative colitis on fluoroscopy. The chronic inflammatory process in the mucosal and submucosal layers of the colon can cause luminal narrowing, resulting in a drainpipe colon that is shortened and narrowed. In UC, shallow ulceration occurs in the mucosa, with spared mucosa giving rise to the appearance of polyps, also known as pseudopolyps. These can cause bloody diarrhea.

Inflammatory bowel disease (IBD) is a condition that includes two main types: Crohn’s disease and ulcerative colitis. Although they share many similarities in terms of symptoms, diagnosis, and treatment, there are some key differences between the two. Crohn’s disease is characterized by non-bloody diarrhea, weight loss, upper gastrointestinal symptoms, mouth ulcers, perianal disease, and a palpable abdominal mass in the right iliac fossa. On the other hand, ulcerative colitis is characterized by bloody diarrhea, abdominal pain in the left lower quadrant, tenesmus, gallstones, and primary sclerosing cholangitis. Complications of Crohn’s disease include obstruction, fistula, and colorectal cancer, while ulcerative colitis has a higher risk of colorectal cancer than Crohn’s disease. Pathologically, Crohn’s disease lesions can be seen anywhere from the mouth to anus, while ulcerative colitis inflammation always starts at the rectum and never spreads beyond the ileocaecal valve. Endoscopy and radiology can help diagnose and differentiate between the two types of IBD.

Femoral hernias emerge from the femoral canal situated below and to the side of the pubic tubercle. These hernias are more common in women due to their unique pelvic anatomy. Repairing femoral hernias is crucial as they pose a significant risk of strangulation.

Understanding the Femoral Canal

The femoral canal is a fascial tunnel located at the medial aspect of the femoral sheath. It contains both the femoral artery and femoral vein, with the canal lying medial to the vein. The borders of the femoral canal include the femoral vein laterally, the lacunar ligament medially, the inguinal ligament anteriorly, and the pectineal ligament posteriorly.

The femoral canal plays a significant role in allowing the femoral vein to expand, which facilitates increased venous return to the lower limbs. However, it can also be a site of femoral hernias, which occur when abdominal contents protrude through the femoral canal. The relatively tight neck of the femoral canal places these hernias at high risk of strangulation, making it important to understand the anatomy and function of this structure. Overall, understanding the femoral canal is crucial for medical professionals in diagnosing and treating potential issues related to this area.

Mumps is a known cause of acute pancreatitis, but it has become rare since the introduction of the MMR vaccine. In 2018, there were only 1088 cases of mumps in the UK, which statistically translates to around 54 cases of acute pancreatitis secondary to mumps. Inflammatory bowel disease may also lead to pancreatitis, but it is usually caused by gallstones or medication used to treat IBD. While influenzae and gastroenteritis are not commonly associated with pancreatitis, there have been a few reported cases linking influenzae A to acute pancreatitis, although these occurrences are extremely rare.

Acute pancreatitis is a condition that is primarily caused by gallstones and alcohol consumption in the UK. However, there are other factors that can contribute to the development of this condition. A popular mnemonic used to remember these factors is GET SMASHED, which stands for gallstones, ethanol, trauma, steroids, mumps, autoimmune diseases, scorpion venom, hypertriglyceridaemia, hyperchylomicronaemia, hypercalcaemia, hypothermia, ERCP, and certain drugs. It is important to note that pancreatitis is seven times more common in patients taking mesalazine than sulfasalazine. CT scans can show diffuse parenchymal enlargement with oedema and indistinct margins in patients with acute pancreatitis.

It is probable that he has Peutz-Jeghers syndrome, a condition that is linked to the presence of Hamartomas.

Understanding Peutz-Jeghers Syndrome

Peutz-Jeghers syndrome is a genetic condition that is inherited in an autosomal dominant manner. It is characterized by the presence of numerous hamartomatous polyps in the gastrointestinal tract, particularly in the small bowel. In addition, patients with this syndrome may also have pigmented freckles on their lips, face, palms, and soles.

While the polyps themselves are not cancerous, individuals with Peutz-Jeghers syndrome have an increased risk of developing other types of gastrointestinal tract cancers. In fact, around 50% of patients will have died from another gastrointestinal tract cancer by the age of 60 years.

Common symptoms of Peutz-Jeghers syndrome include small bowel obstruction, which is often due to intussusception, as well as gastrointestinal bleeding. Management of this condition is typically conservative unless complications develop. It is important for individuals with Peutz-Jeghers syndrome to undergo regular screening and surveillance to detect any potential cancerous growths early on.

To remember the order of branches, use the phrase ‘Prostitutes Cause Sagging Swollen Red Testicles [in men] Living In Sin’:

Phrenic [inferior]
Celiac
Superior mesenteric
Suprarenal [middle]
Renal
Testicular [‘in men’ only]
Lumbars
Inferior mesenteric
Sacral

Note that the superior phrenic artery branches from the aorta in the thorax.

Branches of the Abdominal Aorta

The abdominal aorta is a major blood vessel that supplies oxygenated blood to the abdominal organs and lower extremities. It gives rise to several branches that supply blood to various organs and tissues. These branches can be classified into two types: parietal and visceral.

The parietal branches supply blood to the walls of the abdominal cavity, while the visceral branches supply blood to the abdominal organs. The branches of the abdominal aorta include the inferior phrenic, coeliac, superior mesenteric, middle suprarenal, renal, gonadal, lumbar, inferior mesenteric, median sacral, and common iliac arteries.

The inferior phrenic artery arises from the upper border of the abdominal aorta and supplies blood to the diaphragm. The coeliac artery supplies blood to the liver, stomach, spleen, and pancreas. The superior mesenteric artery supplies blood to the small intestine, cecum, and ascending colon. The middle suprarenal artery supplies blood to the adrenal gland. The renal arteries supply blood to the kidneys. The gonadal arteries supply blood to the testes or ovaries. The lumbar arteries supply blood to the muscles and skin of the back. The inferior mesenteric artery supplies blood to the descending colon, sigmoid colon, and rectum. The median sacral artery supplies blood to the sacrum and coccyx. The common iliac arteries are the terminal branches of the abdominal aorta and supply blood to the pelvis and lower extremities.

Understanding the branches of the abdominal aorta is important for diagnosing and treating various medical conditions that affect the abdominal organs and lower extremities.

Bilirubin is formed when haem, a component of red blood cells, is broken down by macrophages. Albumin, a binding protein in blood, can bind to bilirubin but does not contribute to its production. Jaundice in newborns is often caused by the breakdown of red blood cells. Urobilinogen is a byproduct of bilirubin metabolism that can be excreted through the urinary system. Glutamate, an amino acid and neurotransmitter, is not involved in bilirubin synthesis.

Understanding Bilirubin and Its Role in Jaundice

Bilirubin is a chemical by-product that is produced when red blood cells break down heme, a component found in these cells. This chemical is also found in other hepatic heme-containing proteins like myoglobin. The heme is processed within macrophages and oxidized to form biliverdin and iron. Biliverdin is then reduced to form unconjugated bilirubin, which is released into the bloodstream.

Unconjugated bilirubin is bound to albumin in the blood and then taken up by hepatocytes, where it is conjugated to make it water-soluble. From there, it is excreted into bile and enters the intestines to be broken down by intestinal bacteria. Bacterial proteases produce urobilinogen from bilirubin within the intestinal lumen, which is further processed by intestinal bacteria to form urobilin and stercobilin and excreted via the faeces. A small amount of bilirubin re-enters the portal circulation to be finally excreted via the kidneys in urine.

Jaundice occurs when bilirubin levels exceed 35 umol/l. Raised levels of unconjugated bilirubin may occur due to haemolysis, while hepatocyte defects, such as a compromised hepatocyte uptake of unconjugated bilirubin and/or defective conjugation, may occur in liver disease or deficiency of glucuronyl transferase. Raised levels of conjugated bilirubin can result from defective excretion of bilirubin, for example, Dubin-Johnson Syndrome, or cholestasis.

Cholestasis can result from a wide range of pathologies, which can be largely divided into physical causes, for example, gallstones, pancreatic and cholangiocarcinoma, or functional causes, for example, drug-induced, pregnancy-related and postoperative cholestasis. Understanding bilirubin and its role in jaundice is important in diagnosing and treating various liver and blood disorders.

The origin of the superior mesenteric artery is the aorta, and it travels in front of the lower section of the pancreas. If this area is invaded, it is not recommended to undergo resectional surgery.

Anatomy of the Pancreas

The pancreas is located behind the stomach and is a retroperitoneal organ. It can be accessed surgically by dividing the peritoneal reflection that connects the greater omentum to the transverse colon. The pancreatic head is situated in the curvature of the duodenum, while its tail is close to the hilum of the spleen. The pancreas has various relations with other organs, such as the inferior vena cava, common bile duct, renal veins, superior mesenteric vein and artery, crus of diaphragm, psoas muscle, adrenal gland, kidney, aorta, pylorus, gastroduodenal artery, and splenic hilum.

The arterial supply of the pancreas is through the pancreaticoduodenal artery for the head and the splenic artery for the rest of the organ. The venous drainage for the head is through the superior mesenteric vein, while the body and tail are drained by the splenic vein. The ampulla of Vater is an important landmark that marks the transition from foregut to midgut and is located halfway along the second part of the duodenum. Overall, understanding the anatomy of the pancreas is crucial for surgical procedures and diagnosing pancreatic diseases.

Colorectal cancer can be classified into three types: sporadic, hereditary non-polyposis colorectal carcinoma (HNPCC), and familial adenomatous polyposis (FAP). Sporadic colon cancer is believed to be caused by a series of genetic mutations, including allelic loss of the APC gene, activation of the K-ras oncogene, and deletion of p53 and DCC tumor suppressor genes. HNPCC, which is an autosomal dominant condition, is the most common form of inherited colon cancer. It is caused by mutations in genes involved in DNA mismatch repair, leading to microsatellite instability. The most common genes affected are MSH2 and MLH1. Patients with HNPCC are also at a higher risk of other cancers, such as endometrial cancer. The Amsterdam criteria are sometimes used to aid diagnosis of HNPCC. FAP is a rare autosomal dominant condition that leads to the formation of hundreds of polyps by the age of 30-40 years. It is caused by a mutation in the APC gene. Patients with FAP are also at risk of duodenal tumors. A variant of FAP called Gardner’s syndrome can also feature osteomas of the skull and mandible, retinal pigmentation, thyroid carcinoma, and epidermoid cysts on the skin. Genetic testing can be done to diagnose HNPCC and FAP, and patients with FAP generally have a total colectomy with ileo-anal pouch formation in their twenties.

The correct answer is C. difficile, as it is the causative organism in pseudomembranous colitis that can occur after recent use of broad-spectrum antibiotics like ceftriaxone. These antibiotics can disrupt the gut flora, allowing C. difficile to thrive. Other antibiotics that can cause C. difficile include PPI, clindamycin, and fluoroquinolones.

Campylobacter, Escherichia coli, and Neisseria gonorrhoeae are incorrect answers. Campylobacter infections are typically caused by undercooked chicken, untreated water, or international travel. E. coli infections are usually caused by contact with infected feces, unwashed foods, or unclean water. Neisseria gonorrhoeae is a sexually transmitted disease that is spread through unprotected sex, not through recent use of broad-spectrum antibiotics. The patient in this case does not have symptoms of gonorrhoeae and there is no indication of unprotected sex after the antibiotic prescription.

Clostridium difficile is a type of bacteria that is commonly found in hospitals. It produces a toxin that can damage the intestines and cause a condition called pseudomembranous colitis. This bacteria usually develops when the normal gut flora is disrupted by broad-spectrum antibiotics, with second and third generation cephalosporins being the leading cause. Other risk factors include the use of proton pump inhibitors. Symptoms of C. difficile infection include diarrhea, abdominal pain, and a raised white blood cell count. The severity of the infection can be determined using the Public Health England severity scale.

To diagnose C. difficile infection, a stool sample is tested for the presence of the C. difficile toxin. Treatment involves reviewing current antibiotic therapy and stopping antibiotics if possible. For a first episode of infection, oral vancomycin is the first-line therapy for 10 days, followed by oral fidaxomicin as second-line therapy and oral vancomycin with or without IV metronidazole as third-line therapy. Recurrent infections may require different treatment options, such as oral fidaxomicin within 12 weeks of symptom resolution or oral vancomycin or fidaxomicin after 12 weeks of symptom resolution. In life-threatening cases, oral vancomycin and IV metronidazole may be used, and surgery may be considered with specialist advice. Other therapies, such as bezlotoxumab and fecal microbiota transplant, may also be considered for preventing recurrences in certain cases.

The cause of pernicious anaemia is an autoimmune response that targets intrinsic factor and possibly gastric parietal cells, leading to their destruction. These cells are responsible for producing intrinsic factor, which is necessary for the absorption of vitamin B12 in the small intestine.

Pernicious anaemia is a condition that results in a deficiency of vitamin B12 due to an autoimmune disorder affecting the gastric mucosa. The term pernicious refers to the gradual and subtle harm caused by the condition, which often leads to delayed diagnosis. While pernicious anaemia is the most common cause of vitamin B12 deficiency, other causes include atrophic gastritis, gastrectomy, and malnutrition. The condition is characterized by the presence of antibodies to intrinsic factor and/or gastric parietal cells, which can lead to reduced vitamin B12 absorption and subsequent megaloblastic anaemia and neuropathy.

Pernicious anaemia is more common in middle to old age females and is associated with other autoimmune disorders such as thyroid disease, type 1 diabetes mellitus, Addison’s, rheumatoid, and vitiligo. Symptoms of the condition include anaemia, lethargy, pallor, dyspnoea, peripheral neuropathy, subacute combined degeneration of the spinal cord, neuropsychiatric features, mild jaundice, and glossitis. Diagnosis is made through a full blood count, vitamin B12 and folate levels, and the presence of antibodies.

Management of pernicious anaemia involves vitamin B12 replacement, usually given intramuscularly. Patients with neurological features may require more frequent doses. Folic acid supplementation may also be necessary. Complications of the condition include an increased risk of gastric cancer.

The ureters are located in the retroperitoneal space and damage to them can result in the accumulation of fluid in this area. This retroperitoneal collection may be caused by leaked fluid from the damaged ureter. It is important to note that the ureter is the only retroperitoneal structure among the provided options, making it the most likely cause of the fluid accumulation in this patient.

To remember the retroperitoneal structures, a helpful mnemonic is SAD PUCKER, which stands for Suprarenal (adrenal) glands, Aorta/inferior vena cava, Duodenum (2nd and 3rd parts), Pancreas (except tail), Ureters, Colon (ascending and descending), Kidneys, Esophagus, and Rectum.

The retroperitoneal structures are those that are located behind the peritoneum, which is the membrane that lines the abdominal cavity. These structures include the duodenum (2nd, 3rd, and 4th parts), ascending and descending colon, kidneys, ureters, aorta, and inferior vena cava. They are situated in the back of the abdominal cavity, close to the spine. In contrast, intraperitoneal structures are those that are located within the peritoneal cavity, such as the stomach, duodenum (1st part), jejunum, ileum, transverse colon, and sigmoid colon. It is important to note that the retroperitoneal structures are not well demonstrated in the diagram as the posterior aspect has been removed, but they are still significant in terms of their location and function.

Budd-Chiari syndrome is the correct diagnosis for this patient, as it is caused by hepatic vein thrombosis. The patient has significant risk factors for thrombophilia and is presenting with the classic triad of right upper quadrant abdominal pain, ascites (as evidenced by shifting dullness on examination), and hepatomegaly.

While decompensated cirrhosis can also cause ascites and hepatomegaly, it is unlikely to cause an acute abdomen and is more likely to present with associated jaundice and encephalopathy. Therefore, this option is incorrect.

Right-sided heart failure can also lead to ascites due to raised portosystemic pressure, but this option is incorrect as the patient does not have risk factors for heart failure apart from smoking and does not have other typical findings of heart failure such as dyspnea and peripheral edema.

Nephrotic syndrome can also cause ascites due to hypoalbuminemia-related fluid retention, but there is no mention of proteinuria or hypoalbuminemia, which typically causes peri-orbital edema. Therefore, this option is also incorrect.

Understanding Budd-Chiari Syndrome

Budd-Chiari syndrome, also known as hepatic vein thrombosis, is a condition that is often associated with an underlying hematological disease or another procoagulant condition. The causes of this syndrome include polycythemia rubra vera, thrombophilia, pregnancy, and the use of combined oral contraceptive pills. The symptoms of Budd-Chiari syndrome typically include sudden onset and severe abdominal pain, ascites leading to abdominal distension, and tender hepatomegaly.

To diagnose Budd-Chiari syndrome, an ultrasound with Doppler flow studies is usually the initial radiological investigation. This test is highly sensitive and can help identify the presence of the condition. It is important to diagnose and treat Budd-Chiari syndrome promptly to prevent complications such as liver failure and portal hypertension.

The correct answer is I cells, which are located in the upper small intestine. The patient is experiencing colicky pain in the right upper quadrant after consuming a fatty meal and has a high body mass index, suggesting a diagnosis of biliary colic. CCK is the primary hormone responsible for stimulating biliary contraction in response to a fatty meal, and it is secreted by I cells.

Beta cells are an incorrect answer because they secrete insulin, which does not cause gallbladder contraction.

D cells are also an incorrect answer because they secrete somatostatin, which inhibits various digestive processes but does not stimulate gallbladder contraction.

G cells are another incorrect answer because they are located in the stomach and secrete gastrin, which can increase gastric motility but does not cause gallbladder contraction.

Overview of Gastrointestinal Hormones

Gastrointestinal hormones play a crucial role in the digestion and absorption of food. These hormones are secreted by various cells in the stomach and small intestine in response to different stimuli such as the presence of food, pH changes, and neural signals.

One of the major hormones involved in food digestion is gastrin, which is secreted by G cells in the antrum of the stomach. Gastrin increases acid secretion by gastric parietal cells, stimulates the secretion of pepsinogen and intrinsic factor, and increases gastric motility. Another hormone, cholecystokinin (CCK), is secreted by I cells in the upper small intestine in response to partially digested proteins and triglycerides. CCK increases the secretion of enzyme-rich fluid from the pancreas, contraction of the gallbladder, and relaxation of the sphincter of Oddi. It also decreases gastric emptying and induces satiety.

Secretin is another hormone secreted by S cells in the upper small intestine in response to acidic chyme and fatty acids. Secretin increases the secretion of bicarbonate-rich fluid from the pancreas and hepatic duct cells, decreases gastric acid secretion, and has a trophic effect on pancreatic acinar cells. Vasoactive intestinal peptide (VIP) is a neural hormone that stimulates secretion by the pancreas and intestines and inhibits acid secretion.

Finally, somatostatin is secreted by D cells in the pancreas and stomach in response to fat, bile salts, and glucose in the intestinal lumen. Somatostatin decreases acid and pepsin secretion, decreases gastrin secretion, decreases pancreatic enzyme secretion, and decreases insulin and glucagon secretion. It also inhibits the trophic effects of gastrin and stimulates gastric mucous production.

In summary, gastrointestinal hormones play a crucial role in regulating the digestive process and maintaining homeostasis in the gastrointestinal tract.

The patient in question is likely suffering from chronic pancreatitis due to excessive alcohol consumption. This can lead to poor exocrine pancreatic function and result in diarrhea due to insufficient production of digestive enzymes. To assess pancreatic exocrine function, the patient is undergoing testing with secretin, a hormone that stimulates the secretion of bicarbonate-rich fluid from pancreas and hepatic duct cells, as seen on abdominal MRI.

Somatostatin, on the other hand, is a hormone that decreases the secretion of endogenous hormones from the pancreas and also reduces the exogenous production of bicarbonate. Therefore, it is not useful in testing pancreatic function.

Somatostatin also inhibits the secretion of hydrochloric acid from gastric parietal cells and is released from delta cells in the stomach when the pH is low.

Increased intestinal secretion of bicarbonate is not the primary mechanism for neutralizing gastric acid. It is only supplementary to the pancreatic release of bicarbonate and is stimulated by gastric contents in the duodenum, not by secretin.

There is no specific hormone that increases pancreatic secretion of insulin and glucagon, but somatostatin can decrease the secretion of both hormones.

Overview of Gastrointestinal Hormones

Gastrointestinal hormones play a crucial role in the digestion and absorption of food. These hormones are secreted by various cells in the stomach and small intestine in response to different stimuli such as the presence of food, pH changes, and neural signals.

One of the major hormones involved in food digestion is gastrin, which is secreted by G cells in the antrum of the stomach. Gastrin increases acid secretion by gastric parietal cells, stimulates the secretion of pepsinogen and intrinsic factor, and increases gastric motility. Another hormone, cholecystokinin (CCK), is secreted by I cells in the upper small intestine in response to partially digested proteins and triglycerides. CCK increases the secretion of enzyme-rich fluid from the pancreas, contraction of the gallbladder, and relaxation of the sphincter of Oddi. It also decreases gastric emptying and induces satiety.

Secretin is another hormone secreted by S cells in the upper small intestine in response to acidic chyme and fatty acids. Secretin increases the secretion of bicarbonate-rich fluid from the pancreas and hepatic duct cells, decreases gastric acid secretion, and has a trophic effect on pancreatic acinar cells. Vasoactive intestinal peptide (VIP) is a neural hormone that stimulates secretion by the pancreas and intestines and inhibits acid secretion.

Finally, somatostatin is secreted by D cells in the pancreas and stomach in response to fat, bile salts, and glucose in the intestinal lumen. Somatostatin decreases acid and pepsin secretion, decreases gastrin secretion, decreases pancreatic enzyme secretion, and decreases insulin and glucagon secretion. It also inhibits the trophic effects of gastrin and stimulates gastric mucous production.

In summary, gastrointestinal hormones play a crucial role in regulating the digestive process and maintaining homeostasis in the gastrointestinal tract.

Typically, the pH level in the stomach is 2, but the use of proton pump inhibitors can effectively eliminate acidity.

Understanding Gastric Secretions for Surgical Procedures

A basic understanding of gastric secretions is crucial for surgeons, especially when dealing with patients who have undergone acid-lowering procedures or are prescribed anti-secretory drugs. Gastric acid, produced by the parietal cells in the stomach, has a pH of around 2 and is maintained by the H+/K+ ATPase pump. Sodium and chloride ions are actively secreted from the parietal cell into the canaliculus, creating a negative potential across the membrane. Carbonic anhydrase forms carbonic acid, which dissociates, and the hydrogen ions formed by dissociation leave the cell via the H+/K+ antiporter pump. This leaves hydrogen and chloride ions in the canaliculus, which mix and are secreted into the lumen of the oxyntic gland.

There are three phases of gastric secretion: the cephalic phase, gastric phase, and intestinal phase. The cephalic phase is stimulated by the smell or taste of food and causes 30% of acid production. The gastric phase, which is caused by stomach distension, low H+, or peptides, causes 60% of acid production. The intestinal phase, which is caused by high acidity, distension, or hypertonic solutions in the duodenum, inhibits gastric acid secretion via enterogastrones and neural reflexes.

The regulation of gastric acid production involves various factors that increase or decrease production. Factors that increase production include vagal nerve stimulation, gastrin release, and histamine release. Factors that decrease production include somatostatin, cholecystokinin, and secretin. Understanding these factors and their associated pharmacology is essential for surgeons.

In summary, a working knowledge of gastric secretions is crucial for surgical procedures, especially when dealing with patients who have undergone acid-lowering procedures or are prescribed anti-secretory drugs. Understanding the phases of gastric secretion and the regulation of gastric acid production is essential for successful surgical outcomes.

The following factors increase the likelihood of developing gallstones and can be remembered as the ‘5 F’s’:

– Being overweight (having a body mass index greater than 30 kg/m2)
– Being female
– Being of reproductive age
– Being of fair complexion (Caucasian)
– Being 40 years of age or older

Gallstones are a common condition, with up to 24% of women and 12% of men affected. Local infection and cholecystitis may develop in up to 30% of cases, and 12% of patients undergoing surgery will have stones in the common bile duct. The majority of gallstones are of mixed composition, with pure cholesterol stones accounting for 20% of cases. Symptoms typically include colicky right upper quadrant pain that worsens after fatty meals. Diagnosis is usually made through abdominal ultrasound and liver function tests, with magnetic resonance cholangiography or intraoperative imaging used to confirm suspected bile duct stones. Treatment options include expectant management for asymptomatic gallstones, laparoscopic cholecystectomy for symptomatic gallstones, and surgical management for stones in the common bile duct. ERCP may be used to remove bile duct stones, but carries risks such as bleeding, duodenal perforation, cholangitis, and pancreatitis.

The inferior mesenteric artery is responsible for supplying blood to the hindgut, which includes the distal third of the colon and the rectum superior to the pectinate line. In this case, the patient’s sudden onset of severe abdominal pain and history of atrial fibrillation suggest acute mesenteric ischemia, with the affected artery being the inferior mesenteric artery. Therefore, if a thrombus were to block this artery, the distal third of the colon and superior rectum would experience ischaemic changes. It is important to note that the ascending colon, caecum, ileum, appendix, greater omentum, and stomach are supplied by different arteries and would not be affected by a thrombus in the inferior mesenteric artery.

The Inferior Mesenteric Artery: Supplying the Hindgut

The inferior mesenteric artery (IMA) is responsible for supplying the embryonic hindgut with blood. It originates just above the aortic bifurcation, at the level of L3, and passes across the front of the aorta before settling on its left side. At the point where the left common iliac artery is located, the IMA becomes the superior rectal artery.

The hindgut, which includes the distal third of the colon and the rectum above the pectinate line, is supplied by the IMA. The left colic artery is one of the branches that emerges from the IMA near its origin. Up to three sigmoid arteries may also exit the IMA to supply the sigmoid colon further down the line.

Overall, the IMA plays a crucial role in ensuring that the hindgut receives the blood supply it needs to function properly. Its branches help to ensure that the colon and rectum are well-nourished and able to carry out their important digestive functions.