Abdomen and Stomach are two major body parts for animals. The stomach is a part of the abdomen and together they help to absorb and digest the food taken. Apart from the stomach, the abdomen also contains other organs such as small intestine, colon and Liver. Both of the organs are separated from Chest with the diaphragm, and the inner wall of these organs is muscular, and interconnected with other organs. They both differ in terms of their functionality and anatomy.
The abdominal wall is split into the posterior (back), lateral (sides) and anterior (front) walls. Whereas the Stomach, a “J” shaped organ, is split in Anterior wall, curvature, cardiac, angular notch, pyloric canal, gastric canal and rugal fold.
Functionally, the human abdomen is where the alimentary tract is placed and so most of the absorption and digestion of food occurs here. This is the system of organs within multicellular animals that takes in food, digests it to extract energy and nutrients, and expels the remaining waste. The major functions of the tract are ingestion, digestion, absorption, and excretion.
In stomach, when the food enters, muscles in the stomach wall create a rippling motion (peristalsis) that mixes and mashes the food. At the same time, juices made by glands in the lining of the stomach help digest the food. After about 3 hours, the food becomes a liquid and moves into the small intestine, where digestion continues.
The human stomach is a muscular, elastic, J-shaped bag, lying crosswise in the abdominal cavity beneath the diaphragm. It changes size and shape according to is position of the body and the amount of food inside. It is about 12 inches (30.5 cm) long and is 6 inches (15.2 cm) wide. The stomach's capacity is about 1 qt (0.94 liters) in an adult. But the size changes with the food inside, the human stomach can produce and secrete about 2 to 3 liters of gastric acid per day with basal secretion levels being typically highest in the evening. It is surrounded by parasympathetic (stimulant) and orthosympathetic (inhibitor) plexuses (anterior gastric, posterior, superior and inferior, celiac and myenteric), which regulate both the secretory activity and the motor activity of the muscles.
The abdomen contains most of the tubelike organs of the digestive tract, as well as several solid organs. Liver, is attached with gallbladder, and the pancreas all function in close association with the digestive tract and communicate with it via ducts. The spleens, kidneys, are also part of the abdomen, along with many blood vessels. The abdomen contains an extensive membrane called the peritonenium.
Hollow abdominal organs include the stomach, the small intestine, and the colon with its attached appendix. The spleen, kidneys, and adrenal glands also lie within the abdomen, along with many blood vessels including the aorta and inferior vena cava. Anatomists may consider the urinary bladder, uterus, fallopian tubes, and ovaries as either abdominal organs or as pelvic organs. The abdomen contains an extensive membrane called the peritoneum.
The stomach, on the ither hand is divided into four parts: Cardia, Fundus, Body or Corpus and Antrum or Pylorus. Cardia is where the contents of the esopahgus are emptied in the stoamch while Fundus is the upper curvature of the stomach. Corpus forms the central region and Antrum is the lower section that helps in emptying the contents in the small intestine.
edit Common diseases
Diseases occur in abdomen or stomach mainly due to wrong food habits. Too much smoking or drinking can even cause cancer. Diarrhea, Constipation, Abdominal swelling, Gastroparesis are few very common problems related with the Abdomen. Some Stomach ailments are stomach pain, peptic ulcer, gastroparesis etc.