Description of the System

Peritoneal Development and Anatomy

The peritoneal cavity has not been designed as an efficient organ of solute or water exchange, in the same fashion as the kidney. The yolk sac of the primitive embryo is the progenitor of the peritoneal cavity. Analogous to the collapse of an inflated balloon around a tube, the peritoneal cavity develops as a potential space due to intricate folding of the yolk sac into which grow associated elements of the digestive and genitourinary systems. The surface area of the peritoneum approximates the body surface area, and therefore there is potentially a large area of transfer with a multitude of well-perfused organs in the abdominal and pelvic cavities. The peritoneum covers a portion of the diaphragm and liver, a large part of the stomach and spleen, the small and large intestines, the uterus, ovaries, fallopian tubes, retroperitoneal muscles, kidneys, and a broad expanse of the anterior abdominal wall. The multiple tissues with their different blood circulations lead to the question of which parts are most important to the transport processes.

Tissue Space interstitial matrix

Tissue Space interstitial matrix

submesothelial connective tissue

Peritoneal Cavity

Mesothelium

Blood Capillary

Figure 1 Distributed model concept of peritoneal transport in dialysis. Solutes in the blood transport across the wall of the capillaries distributed in the subperitoneal tissues. Solutes must follow a tortuous path through the interstitium, restricted by matrix molecules and by cells. The final barrier is the peritoneum, made up of a single layer of mesothelial cells and several layers of connective tissue. All solutes must pass across the peritoneum to the therapeutic solution in the cavity, which is replaced with fresh solution periodically to maintain the blood-to-peritoneal cavity concentration gradient that drives diffusion.

Blood Capillary submesothelial connective tissue

Peritoneal Cavity

Mesothelium

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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