Under physiological conditions, when swallowing, the lower esophageal sphincter (lower esophageal sphincter (LES) relaxes, allowing food to pass After entering the stomach, transient LES loosening may also occur without swallowing. Relaxation, a small amount of transient gastroesophageal reflux occurs, due to some antibiotics The existence of reflux mechanism avoids the occurrence of gastroesophageal reflux

antireflux mechanism 1. Esophageal-gastric anti-reflux barrier: the anatomical structure at the junction of the esophagus and the stomach, including the LES, diaphragm crura, diaphragmatic esophageal ligament, and the acute angle between the esophagus and the fundus of the stomach. LES end of esophagus, 3-4cm, circular muscle bundle, high-pressure belt, anti-reflux 2. Esophageal clearance: spontaneous or secondary, 1-2 times, saliva flushing 3. Esophageal mucosal barrier: saliva, stratified squamous epithelium, rich blood supply under the mucosa

Gastric glands: gastric mucosal epithelium is indented

Pyloric gland: secretes mucus and gastrin

Fundic gland: composed of chief cells, parietal cells, neck mucus cells and endocrine cells, secretes gastric acid, pepsin and intrinsic factor, also called oxyntic gland

Cardiac glands: secrete mucus

The pH of gastric juice is about 0.9-1.5. Normal people The secretion amount is 1.5-2.5L/d, in acid Pepsinogen is activated in a sexual environment. In addition, the gastric mucosa is often associated with various pathogens Microorganisms and irritating and damaging substances material contact, but the gastric mucosa can maintain itself intact, making the gastric cavity and gastric mucosa The H concentration in the membrane is maintained at 1000 times Poor high gradient state, which is related to the gastric mucosa The barrier involves three levels.

Molecular groups such as prostaglandins, nitric oxide, epidermal growth factor, calcitonin gene-related peptide, protease-activated receptors, peroxidase proliferator-activated receptors, and capsaicin pathways are involved in the complex regulation of gastric mucosal barrier function. Prostaglandin E has a protective effect on gastric mucosal cells and can promote mucosal blood circulation and secretion of mucus and bicarbonate. It is a type of mucosal protective molecule that is currently well understood.

The information sensed from food in the gastric antrum prompts the G cells of the pyloric gland to secrete gastrin. Most of the gastrin circulates and acts on the enterochromaffin cells of the gastric body in an endocrine manner, stimulating them to secrete histamine, histamine and a small amount of Gastrin promotes the synthesis and secretion of hydrochloric acid by gastric parietal cells through histamine H2 or cholekinin-B receptors. Somatostatin secreted by D cells in the gastric antrum has a negative regulatory effect on all three types of cells involved in the above process.

The process of hydrochloric acid secretion by gastric parietal cells can be roughly divided into three main steps:

In the process of the intestinal tract being exposed to a large amount of food and the symbiosis of microorganisms in the intestinal lumen, its barrier defense system plays an important role. It can effectively block more than 500 types of intestinal parasitic bacteria and bacteria in the intestinal tract at a concentration as high as 1011/ml. Its toxins are displaced to tissues and organs outside the intestinal lumen, preventing the body from being invaded by endogenous microorganisms and their toxins. The intestinal mucosal barrier is a structural and functional unity that isolates the substances in the intestinal lumen from the body's internal environment and maintains the stability of the body's internal environment. It is composed of mechanical barriers, chemical barriers, immune barriers, biological barriers and intestinal peristalsis.

The natural immunity of the intestinal mucosa is innate in the body. It acts quickly and has diverse defense mechanisms. However, it lacks immune memory and has the same response to multiple stimulations of the same pathogen. Participating effector cells include: intestinal mucosal epithelial cells, macrophages, dendritic cells, B cells, eosinophils, mast cells, natural killer cells, etc. After the structural recognition receptors on these cells recognize the antigen, they quickly initiate natural In immune response, nuclear factor-kB is an important hub molecule of inflammatory response. Acquired immunity in the intestine is initiated after specific lymphocytes recognize exogenous antigens, and then function after lymphocyte proliferation and differentiation into effector cells. Although it has a slow onset of action, it has the characteristics of immune memory and specificity, so it has the effect of expanding natural immunity and enhancing its function. Defensins are short cationic peptides rich in cysteine. They penetrate microbial cell membranes through their electron attraction and cause cytoplasm to leak out. Therefore, they have strong antibacterial, fungal and viral effects.

The intestinal microecology is composed of bacteria, fungi, viruses, etc., and its number and number of genes are far greater than the number of cells and genes in the human body itself. It is called the second genome of the human body. Intestinal flora can be roughly divided into: ① Probiotics: mainly anaerobic bacteria such as various bifidobacteria and lactobacilli. They are often close to the mucus layer and are an indispensable element of human health. They can synthesize various vitamins and participate in food. Digestion, promote intestinal peristalsis, prevent contact between pathogenic bacteria and intestinal epithelial cells, decompose harmful and toxic substances, etc.; ② Opportunistic pathogenic bacteria: such as Escherichia coli, enterococci and other bacteria with dual effects, under normal circumstances It is beneficial to health. Once the proliferation is out of control or transferred from the intestine to other parts of the body, it may cause diseases; ③ Harmful bacteria: such as Shigella dysenteriae, Salmonella, etc., once they grow in large numbers, they can cause a variety of diseases or affect the function of the immune system. .

Microorganisms and humans have co-evolved and formed a symbiotic relationship of mutual dependence and interdependence. There is mutual influence and two-way regulation between the intestinal mucosal barrier and intestinal microecology. The intestinal microecology affects the body's nutrition, metabolism, immunity, development and aging, and is related to many chronic diseases such as metabolic diseases, neuropsychiatric diseases, immune-related diseases, and tumors.

Intestinal microorganisms have the following functions: 1. Metabolic function: It can secrete complex proteases, which have a redox effect, can promote the decomposition of components in food, and decompose, metabolize or transform endogenous and exogenous other substances. 2. Nutritional function: Synthesizes a variety of vitamins, amino acids, peptides, and short-chain fatty acids. The metabolites of microorganisms promote the absorption of minerals and nutrients, thus affecting the nutritional metabolism of the host. 3. Host immune function: regulates the development and maturation of the host's immune organs, and serves as a broad-spectrum antigen to stimulate the host's immune response, including humoral immunity and cellular immunity. 4. Intestinal defense function: It is an important part of the intestinal mucosal barrier. It can prevent the invasion or colonization of potential pathogenic bacteria and maintain the intestinal mucosal barrier function and structural integrity.

Endocrine cells scattered in the gastrointestinal tract can produce more than 50 kinds of gastrointestinal peptides, such as cholecystokinin, somatostatin, intestinal vasoactive peptides, substance P, etc. The digestive tract is therefore the largest endocrine organ in the body. These gastrointestinal peptides are important for The secretion, motility, material transport, immunity and intestinal epithelial cell repair of the gastrointestinal tract have important and complex regulatory effects, and also affect the functions of other organs in the body.

1. Sugar: Starch in food - pancreatic amylase - disaccharide - small intestinal epithelial cell brush border disaccharidase - monosaccharide - absorbed into the blood Part of glycogen provides energy for the body, and the other part is stored in the muscles and liver in the form of glycogen. Muscle glycogen supplies muscle contraction, and liver glycogen stabilizes blood sugar, which is particularly important for the brain and red blood cells. When blood sugar concentration drops, liver glycogen is broken down into glucose and released into the blood to replenish blood sugar.

2. Fat Lipids are emulsified by bile salts in the small intestine, digested by pancreatic lipase into monoglycerides, fatty acids and cholesterol, and then absorbed into the portal vein in the upper jejunum. In the smooth endoplasmic reticulum of small intestinal epithelial cells, long-chain fatty acids and 2-monoglycerides can be synthesized into triglycerides, which are combined with apolipoproteins, phospholipids and cholesterol to form chylomicrons, which enter the blood circulation through lymphatic vessels. . True chyloperitoneum is caused by rupture of lymphatic vessels in the small intestine.

3. Protein Under the hydrolysis of gastric juice and pancreatic juice proteases, 1/3 of the protein becomes amino acids and 2/3 becomes oligopeptides. The oligopeptides at the brush border of the small intestinal epithelial cells can finally hydrolyze the oligopeptides into amino acids, which are passed through the amino acid carrier proteins of the small intestinal epithelial cells. Active transport transports it into cells with Na, and the γ-glutamyl cycle promotes the transport process of amino acids into intestinal cells. The amino acids absorbed through digestion (exogenous) are mixed with the amino acids produced by protein degradation in the body (endogenous), and are distributed throughout the body. It is called the amino acid metabolic pool, and its main function is to synthesize amino acids and peptides.

Under various physiological stimuli, glandular cells increase the intracellular calcium ion concentration, prompting the release of zymogen granules, which enter the duodenum through the pancreatic duct and duodenal papilla, where they are activated under the action of enterokinase and exert their ability to digest food. Function. Since trypsin can activate many other pancreatic enzymes, the activation of trypsinogen to trypsin is the most critical in the activation of multiple pancreatic enzyme cascades. Under physiological conditions, trypsinogen secreted from acinar cells can be slightly activated in the pancreas, but enzyme-specific inhibitors (a1-antitrypsin, a2-macroglobulin, etc.) produced by pancreatic interstitial cells can Quickly inactivate trypsin that is activated in advance in the pancreas to avoid autodigestion.

Gastroscopy, endoscopic ultrasound, duodenoscopy Colonoscopy capsule endoscopy Enteroscopy

Capsule endoscopy is a non-invasive examination method of the digestive tract that uses special equipment to observe the morphology of the digestive tract mucosa. 1. Capsule endoscopy is a device that is similar to the size of a capsule and contains a tiny camera. After swallowing, the mucosa on the inner wall of the digestive tract is recorded and photographed, and then the image is observed through a computer connected to it to determine whether there are lesions. 2. Capsule endoscopy is different from ordinary endoscopy. The intestines need to be cleaned in advance before the examination. If there are complications such as digestive tract obstruction, capsule endoscopy should not be used. In clinical practice, capsule endoscopy is specifically used to observe the stomach and small intestine.

(1) Diagnosis of hepatitis B virus infection The diagnosis of hepatitis B virus (HBV) infection includes the detection of 5 serum immune markers of HBV, serum virus detection and tissue virology detection.

(2) Helicobacter pylori detection Helicobacter pylori (Hp) detection plays an important role in the diagnosis and treatment of gastric precancerous diseases and lesions, peptic ulcer, gastric mucosa-associated lymphoma and other diseases.

(3) Liver function assessment

1. Ultrasound (ultrasonography, US) 2. Computed tomography (CT) 3. Magnetic resonance imaging (MRI) Magnetic resonance cholangiopancreatography (MRCP)