What is Peritoneum?
The Peritoneum meaning can be better understood as we define peritoneum as the membrane that lines many organs in the body. Peritoneum meaning is better explained as it is a serous membrane that forms the lining of the abdominal cavity or coelom which is the main body cavity in most animals. And the peritoneum is positioned inside the body to surround the organs that contain the digestive tract in the coelom and it also lines the other organs. The coelomic organs are also referred to as the intra-abdominal organs. The peritoneum is supported by a thin layer of connective tissue over the mesothelium cells layer lining. The physiology of the peritoneum is not just limited to a membrane lining it serves many purposes. Now that we have understood what is peritoneum let us understand the various roles the peritoneum meaning caters to in location and function.
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Anatomy of the Peritoneum
Peritoneum Location- The Peritoneum membrane location is very important to note as it wraps up the abdominal cavity, and the abdominal cavity is an open space. And that is surrounded by the vertebrae, abdominal muscles, diaphragm, and pelvic floor. the visceral organs and many organs that exist within the membrane and even behind it. The peritoneal location can be understood in three ways.
The Peritoneum Membrane - It is a layer of mesothelial cells that are surrounded by supportive connective tissue and it consists of two layers; the outer layer called outer parietal layer and the inner layer that is the inner visceral layer. Both are composed of the same tissues and yet they have very different stimuli and physiological functions.
Layers of Peritoneum Membrane
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The Peritoneum Membrane Development
The mesoderm is the origin of the peritoneum membrane development. From the trilaminar embryo of the mesoderm, the peritoneal membrane is formed. The first stage of development- It is when the intraembryonic coelom separates and splits the lateral plate of the mesoderm into two layers the mesoderm starts to differentiate.
The two layers of the differentiated mesoderm then start developing into the two layers in the serous cavities. The layers that are known as the outer layer called the parietal peritoneum layer and the inner visceral layer. The two layers are the components of the developed peritoneum.
As an embryo develops, in the initial stages within the abdominal wall the various abdominal organs grow into the abdominal cavity from structures. And during this developmental process, the organs in the abdomen become enveloped in a layer of peritoneum membrane. The growing organs very organically "take their blood vessels with them" with them as there is no growth without blood supply from the abdominal wall. And mesentery the double layer within the inner visceral layer of the peritoneum is formed as it covers the blood vessels.
What is Peritoneal Cavity?
Peritoneal Cavity- The peritoneal cavity is the peritoneal space between the separated area of the two layers of the peritoneum. The peritoneal cavity is bound by thin membranes and it is basically between the organ structures that the peritoneum covers or lines. It is an open space surrounded by the vertebrae and other abdominal parts.
The folds of the peritoneum are called Omentum and these folds occur due to their association with the stomach in the gastrointestinal tract. There are two kinds of omentum: the greater omentum and the lesser omentum. Omentum also participates and aids the peritoneum function in the body. The greater omentum descends from the greater curvature of the stomach and proximal part of the duodenum, which are the first and the second fold of the greater omentum then folds back up making it the third layer and follows by attaching to the anterior surface of the transverse colon which is the fourth layer making it four layers of the greater omentum. The lesser omentum, on the other hand, is a double layer that attaches from the stomach’s lesser curvature to the proximal part of the duodenum following the liver. The lesser omentum is further divided into two kinds: the flat, broadsheet called the hepatogastric ligament and the free edge, which contains the portal triad called the hepatoduodenal ligament. The peritoneal cavity has two subdivisions which can be called the Larger Greater Sac and the Smaller Lesser Sac.
Two Subdivisions Peritoneal Cavity
Peritoneum Function
The peritoneum covers nearly all visceral organs within the gut in the abdominal area and it functions by conveying neurovascular structures to the intraperitoneal viscera from the body wall.
Acts as a conduit for the passage of blood vessels, lymphatics and nerves.
Supports the organs of the abdomen.
The omentum provides visceral mobility.
The folds that are the omentum also function as a pathway for the nerves and other blood vessels.
The damage of the organs during any rough movements is prevented by providing lubrication via the secretion of peritoneal fluid into the peritoneal cavity by the peritoneum.
Fat storage is aided by the peritoneum.
The healing of wounds and protecting from damage to the organs as the mesothelial cells of the peritoneum transform themselves into fibroblasts.
The phagocytic cells in the peritoneum membrane protect the visceral organs by guarding against any kinds of infections.
Due to the physicality of the greater omentum in the stomach, it can wrap around an infected area and that limits the spread of any intraperitoneal infections within the body.
The omentum connects the abdomen to the viscera inside the body.
Due to the high number of arteries and veins in the peritoneal cavity, it serves as a great medium within the system to help in the clinical way of dealing with peritoneal dialysis.
The greater omentum can migrate to any part of the infected viscera and even any site of surgical disturbances and acts as a form of the immune mechanism and therefore is referred to as the ‘abdominal police’.
Peritoneum Damage and Problems
The peritoneum travels and is connected through many organs and when any damage or problem arises there is a high probability of it spreading through the peritoneal cavity and other organs that it is associated through the intraperitoneal layer, retroperitoneal layer or the supra peritoneal layer.
When there is portal hypertension then there is excess secretion of the peritoneal fluid within the peritoneal cavity which leads to Ascites. This abnormal build-up of fluid can be life-threatening when it leads to infection.
Peritonitis is the inflammation of the peritoneum when one is undergoing peritoneal dialysis therapy.
The cancer of the cells lining the peritoneum leads to primary peritoneal carcinoma.
Conclusion
The Peritoneum protects and helps the body moving and going through many changes and when it is damaged the results can be fatal. One must not ignore any symptoms or signs of the possibility of a problem. Preservation of this important membrane is very important and the ways one can do so is by having high-quality protein and avoiding foods with high amounts of sodium and phosphorus and avoiding canned foods, chillies etc. One is responsible for their own health and a good diet is an important part of it so one can help themselves by consulting a nutritionist. Peritoneal health is as necessary as any other organ as it protects all organs it covers.
FAQs on Peritoneum
1. What is the peritoneum in human anatomy?
The peritoneum is a large, continuous serous membrane that lines the cavity of the abdomen and covers the abdominal organs. It acts as a protective layer, providing support and reducing friction between the organs. It consists of two main layers: the parietal peritoneum and the visceral peritoneum.
2. What are the two main layers of the peritoneum?
The peritoneum is composed of two distinct layers:
- Parietal Peritoneum: This is the outer layer that lines the internal surface of the abdominopelvic wall. It is sensitive to pressure, pain, and temperature.
- Visceral Peritoneum: This is the inner layer that folds inward to cover the surface of most abdominal organs, such as the stomach and intestines. It is less sensitive to pain but can sense stretch and chemical irritation.
3. What are the primary functions of the peritoneum?
The peritoneum serves several vital functions for the abdominal organs. Its key roles include:
- Support: It helps to hold the abdominal organs in place within the abdominal cavity.
- Lubrication: It secretes a serous fluid called peritoneal fluid, which lubricates the surface of the organs, allowing them to move smoothly against each other without friction.
- Protection: It provides a barrier against the spread of infection within the abdomen.
4. How can one differentiate between the peritoneum and the perineum?
Students often confuse these two terms due to their similar spelling. The peritoneum is the serous membrane lining the abdominal cavity and its organs. In contrast, the perineum is an external anatomical region in the pelvis, specifically the area between the anus and the scrotum (in males) or the vulva (in females).
5. What is the relationship between the mesentery and the peritoneum?
The mesentery is not a separate structure but a part of the peritoneum. Specifically, it is a double fold of the visceral peritoneum that attaches the intestines to the posterior abdominal wall. It provides a pathway for blood vessels, nerves, and lymphatic vessels to reach the intestines, anchoring them while allowing for movement.
6. What is the peritoneal cavity?
The peritoneal cavity is the potential space between the parietal peritoneum and the visceral peritoneum. It is not an empty space but contains a small amount of lubricating peritoneal fluid (about 50 mL), which minimises friction during organ movement, such as the contractions of the digestive tract.
7. Why are some abdominal organs called 'intraperitoneal' while others are 'retroperitoneal'?
This classification depends on an organ's relationship with the peritoneum. Intraperitoneal organs are completely surrounded by the visceral peritoneum (e.g., the stomach, liver, and spleen). This allows them significant mobility. In contrast, retroperitoneal organs are located behind the peritoneum and are only partially covered by it on their anterior surface (e.g., the kidneys, pancreas, and aorta). This position makes them more fixed and less mobile.
8. What is the clinical importance of the peritoneum, for example, in a condition like peritonitis?
The peritoneum's extensive surface area and rich blood supply make it clinically significant. Peritonitis, the inflammation of the peritoneum, is a serious medical condition. It can result from an infection spreading from a ruptured organ like the appendix. The inflammation can quickly spread throughout the abdominal cavity, leading to severe pain, fever, and potentially life-threatening systemic infection if not treated promptly.
