Gastrointestinal System: Stomach and Spleen

The Stomach

• The stomach is an intraperitoneal organ located in the upper abdominal cavity.
• It has four parts: cardia, fundus, body, and pyloric region.
• The body of the stomach is a storage site for ingested food, broken down by hydrochloric acid and pepsinogen released from the stomach wall.
• Gastric glands in the body of the stomach contain goblet cells that secrete mucus, protecting the stomach wall from hydrochloric acid.
• Parietal cells secrete intrinsic factor, which helps absorb vitamin B12 in the intestine, and pepsinogen, which helps digest proteins.
• D cells secrete somatostatin, inhibiting acid secretion, while G cells stimulate acid secretion by producing gastrin.

The Pyloric Region

• The pyloric region consists of the pyloric antrum, pylorus, and pyloric canal.
• The pyloric antrum has a high proportion of gastrin-secreting cells, increasing the motility of the intestines.
• There is a lot of mixing and grinding of chyme in the pyloric antrum, with peristaltic waves pushing the chyme towards the pylorus.
• The pylorus contains a sphincter to control what leaves the antrum, formed by a ring of smooth muscle.

The Greater and Lesser Omentum

• The stomach is attached to the lesser curvature by the lesser omentum, which connects to the liver.
• The greater curvature of the stomach gives rise to the greater omentum.

The Wall of the Stomach

• The wall of the stomach consists of multiple layers.

The Relations of the Stomach

• The stomach has various relations, including the lesser sac.

Arterial Supply, Venous and Lymphatic Drainage of the Stomach and Spleen

• The coeliac trunk is the key artery of the foregut, supplying all of the upper abdominal organs.
• The coeliac trunk arises from the anterior aspect of the abdominal aorta, shortly after the aorta appears through the aortic opening in the diaphragm.
• The branches of the coeliac trunk include the common hepatic, splenic, and left gastric arteries.
• The lower half of the stomach takes branches from the common hepatic, while the upper half is mostly supplied by the splenic artery.

Nerve Supply of the Stomach

• The vagus nerves carry parasympathetic preganglionic fibers along the oesophagus and give branches to each of the organs.
• The post-ganglionic parasympathetic nerves are located in the walls of these organs.
• The left vagus nerve forms the anterior vagal trunk for the stomach, while the right vagus nerve forms the posterior vagal trunk.

The Spleen

• The spleen is an organ located in the upper abdominal cavity.

Note: These notes focus on the key points and facts presented in the original text, organized by topic.