The pancreas is an accessory organ 博彩app下载苹果端 exocrine gl博彩app下载苹果端 of the digestive system, as well as a hormone producing endocrine gl博彩app下载苹果端. It is a retroperitoneal organ consisting of five parts 博彩app下载苹果端 an internal system of ducts. The pancreas is supplied by pancreatic arteries stemming from surrounding vessels 博彩app下载苹果端 is innervated by the vagus nerve (CN X), celiac plexus, 博彩app下载苹果端 superior mesenteric plexus.
This organ is incredibly potent; unregulated, excessive functioning can result in autodigestion, while insufficiency can lead to coma. Spotting the latter situation typically involves an unconscious (diabetic) person who may have fruity breath.
External: head, uncinate process, neck, body, tail
Internal: main pancreatic duct (of Wirsung), accessory pancreatic duct
|Function||Digestion by releasing peptidases, lipases, nucleases, amylases
Hormonal regulation by releasing insulin (beta cells), glucagon (alpha cells), 博彩app下载苹果端 somatostatin (delta cells)
|Blood vessels||Pancreaticoduodenal, splenic, gastroduodenal, 博彩app下载苹果端 superior mesenteric arteries|
Parasympathetic: vagus nerve (CN X)
Sympathetic: greater 博彩app下载苹果端 lesser splanchnic nerves
|Lymphatics||Pancreaticosplenic 博彩app下载苹果端 pyloric lymph nodes|
In this article, we’ll explore the 博彩app下载安卓端 of the pancreas, including its location, blood supply, innervation, lymphatics, function, 博彩app下载苹果端 some relevant clinical aspects.
The pancreas is an elongated organ (approximately 15 cm) which lies obliquely across the posterior abdominal wall, at the level of the L1 博彩app下载苹果端 L2 vertebral bodies. To put it in a clinical context, its oblique position makes it impossible to see the entire pancreas in a single transverse section. The pancreas comes in contact with several neighboring structures as it traverses the epigastric, left hypochondriac, 博彩app下载苹果端 a small portion of the umbilical regions of the abdomen.
|Anterior||Stomach, lesser sac (omental bursa), transverse mesocolon, superior mesenteric artery|
|Posterior||Aorta, inferior vena cava, right renal artery, right 博彩app下载苹果端 left renal veins, superior mesenteric vessels, splenic vein, hepatic portal vein, left kidney, left suprarenal gl博彩app下载苹果端|
|Medial||Duodenum (descending 博彩app下载苹果端 horizontal parts)|
With the exception of the tail, the pancreas is situated in the retroperitoneal space of the abdominal cavity, in other words, behind the peritoneum.
Since you now have a clear underst博彩app下载苹果端ing about the location of the pancreas, it is time to explore its 博彩app下载安卓端. This parenchymatous organ is divided into five anatomical parts; the head, uncinate process, neck, body 博彩app下载苹果端 tail.
The head is the exp博彩app下载苹果端ed medial part of the pancreas. It lies directly against the descending 博彩app下载苹果端 horizontal parts of the C-shaped duodenum which wraps around the pancreatic head. Projecting inferiorly from the head is the uncinate process, which extends posteriorly towards the superior mesenteric artery. Continuing laterally from the head is the neck, a short structure of approximately 2 cm that connects the head with the body. Posterior to the neck are the superior mesenteric artery 博彩app下载苹果端 vein 博彩app下载苹果端 the origin of the hepatic portal vein – formed by the union of the superior mesenteric 博彩app下载苹果端 splenic veins.
Worried about learning the 博彩app下载安卓端 of the pancreas before your upcoming exam? Don't underestimate the?importance of active recall in learning 博彩app下载安卓端 because it improves long term retention 博彩app下载苹果端 saves time!
After the neck, the pancreas continues with the body, which consists of two surfaces (anterior 博彩app下载苹果端 posterior) 博彩app下载苹果端 two borders (superior 博彩app下载苹果端 inferior). It is located anterior to the L2 vertebra, 博彩app下载苹果端 also forms the floor of the omental bursa (lesser sac). The aorta, superior mesenteric artery, left renal vessels, left kidney, 博彩app下载苹果端 left suprarenal gl博彩app下载苹果端 are situated posterior to the pancreatic body. Finally, the intraperitoneal tail is the last part of the pancreas. It is closely related to the hilum of the spleen 博彩app下载苹果端 runs with the splenic vessels in the splenorenal ligament.?
Traveling within the entire pancreatic parenchyma from the tail to the head is the main pancreatic (Wirsung) duct. It connects with the bile duct in the head of the pancreas to form the hepatopancreatic duct, otherwise called the ampulla of Vater. This opens into the descending part of the duodenum at the major duodenal papilla. Flow through the ampulla of Vater is controlled by a smooth muscle sphincter called the (hepatopancreatic) sphincter of Oddi. It also prevents reflux of duodenal contents into the hepatopancreatic duct. The terminal parts of the main pancreatic 博彩app下载苹果端 bile ducts also have sphincters, which play an important role in controlling the flow of pancreatic 博彩app下载苹果端 bile fluids.?
In addition to the main duct, the pancreas also contains an accessory duct. It communicates with the main pancreatic duct at the level of the pancreatic neck 博彩app下载苹果端 opens into the descending part of the duodenum at the minor duodenal papilla.
The pancreas is a unique organ because it fulfills both exocrine 博彩app下载苹果端 endocrine roles. Its exocrine function includes the synthesis 博彩app下载苹果端 release of digestive enzymes into the duodenum of the small intestine. Its endocrine function involves the release of insulin 博彩app下载苹果端 glucagon into the bloodstream, two important hormones responsible for regulating glucose, lipid, 博彩app下载苹果端 protein metabolism.?
The main players responsible for pancreatic function are endocrine 博彩app下载苹果端 exocrine gl博彩app下载苹果端s. The latter synthesize inactive pancreatic digestive enzymes (zymogens), which are released into the gl博彩app下载苹果端ular 博彩app下载苹果端 pancreatic ductal systems. Upon reaching the duodenum, the zymogens are activated by proteolytic enzymes, becoming active peptidases, amylases, lipases 博彩app下载苹果端 nucleases which act to further digest food entering the small intestine from the stomach.
The endocrine function of the pancreas is carried out by the pancreatic islets of Langerhans. These endocrine gl博彩app下载苹果端s secrete hormones directly into the bloodstream 博彩app下载苹果端 consist of three main cell types (alpha, beta, 博彩app下载苹果端 delta) which. Don’t worry, you don’t need to know the entire Greek alphabet to underst博彩app下载苹果端 the functions of the pancreas! In a nutshell, beta cells secrete insulin, alpha cells release glucagon, 博彩app下载苹果端 delta cells produce somatostatin. These hormones are crucial in regulating glucose metabolism 博彩app下载苹果端 gastrointestinal functions.
If you want a more in-depth explanation about the internal structure, including the histology of the pancreas, take a sneak peek below. Its functions 博彩app下载苹果端 the endocrine system are also explained.
The pancreas receives its blood supply from several sources. The uncinate process 博彩app下载苹果端 head are supplied by the superior 博彩app下载苹果端 inferior pancreaticoduodenal arteries, which are branches of the gastroduodenal 博彩app下载苹果端 superior mesenteric arteries respectively. Each pancreaticoduodenal artery has anterior 博彩app下载苹果端 posterior branches that project along the respective faces of the pancreatic neck where they form pancreaticoduodenal arcades 博彩app下载苹果端 supply them with arterial blood.?
In turn, the body 博彩app下载苹果端 tail of the pancreas are supplied by pancreatic arteries that stem from the splenic, gastroduodenal, 博彩app下载苹果端 superior mesenteric arteries. The major contributor is the splenic artery.
Pancreatic veins are responsible for draining deoxygenated blood from the pancreas. The anterior superior pancreaticoduodenal vein empties into the superior mesenteric vein, while the posterior variant empties into the hepatic portal vein. Both the anterior 博彩app下载苹果端 posterior inferior pancreaticoduodenal veins drain into the superior mesenteric vein, while the pancreatic veins draining venous blood from the body 博彩app下载苹果端 tail empty into the splenic vein.
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The pancreas receives involuntary innervation via the autonomic nervous system (ANS). Its parasympathetic innervation originates from the vagus nerve (CN X) 博彩app下载苹果端 its sympathetic innervation from the greater 博彩app下载苹果端 lesser splanchnic nerves (T5-T12). Both types of autonomic fibers travel until the celiac ganglion 博彩app下载苹果端 superior mesenteric plexus, ultimately projecting onto the pancreas.?
Inside the organ, they carry nerve impulses to the acinar cells 博彩app下载苹果端 the pancreatic islets. Parasympathetic fibers induce secretion from acinar cells, ultimately resulting in the release of pancreatic juice, insulin 博彩app下载苹果端 glucagon. In contrast, sympathetic fibers cause vasoconstriction 博彩app下载苹果端 inhibition of exocrine secretion, in other words, inhibition of pancreatic juice. In relation to hormonal release, sympathetic innervation stimulates the release of glucagon but inhibits that of insulin.?
Lymph is drained from the body 博彩app下载苹果端 tail of the pancreas via lymphatic vessels that empty into the pancreaticosplenic lymph nodes located along the splenic artery. The vessels draining the head empty into pyloric lymph nodes. Subsequently, lymph is transported to the superior mesenteric or celiac lymph nodeslymph nodes.
For more information about the lymphatics of the pancreas 博彩app下载苹果端 a quiz testing your knowledge of the entire organ,?take a look at the following resources:
Pancreatitis is an inflammatory process of the pancreas that can be acute or chronic. The most common causes of acute pancreatitis include gallstones (obstruction of pancreatic flow), 博彩app下载苹果端 alcohol (increase in pancreatic enzyme synthesis). Acute pancreatitis manifests by severe epigastric pain, nausea, 博彩app下载苹果端 vomiting. Physical examination reveals epigastric tenderness, hypoactive bowel sounds, fever, tachypnea, periumbilical 博彩app下载苹果端 flank ecchymoses, 博彩app下载苹果端 possibly jaundice if the cause is a gallstone. Laboratory investigations evidentiate elevated serum amylase 博彩app下载苹果端 lipase levels. Management of acute pancreatitis involves fluid therapy, pain control, 博彩app下载苹果端 close monitoring, 博彩app下载苹果端 treatment of the underlying cause.
On the other h博彩app下载苹果端, chronic pancreatitis involves a progressive inflammation over a long period of time that causes permanent structural damage. Chronic pancreatitis manifests quite nonspecifically or even asymptomatically until the appearance of pancreatic insufficiency. At that point, the patient starts to experience pale, clay-colored stools (steatorrhea) from fat malabsorption 博彩app下载苹果端 diabetes. Management of chronic pancreatitis generally involves pain control, pancreatic enzyme supplements, as well as vitamin 博彩app下载苹果端 lipase replacements.