Peritoneal Cavity - Anatomy & Physiology

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Introduction

The peritoneum is the serous membrane which lines the abdominal cavity. It is a type of loose connective tissue covered by mesothelium. Extensions of the peritoneum form the mesenteries that support the abdominal contents. It functions to lubricate abdominal viscera , enhance the immune response and wall off infection in the abdomen to prevent peritonitis.

Structure

Peritoneum is normally smooth and clear,
Small volume of clear fluid for lubrication - in equilibrium with plasma but doesn't contain high molecular weight molecules like fibrinogen
Small animals
- Low volume of clear straw coloured fluid
- Specific gravity <1.015 to 1.018
- Total protein 25-39g/L
- Nucleated cell count <3x10e9/L
- Mesothelial cells/macrophages

Single layer of mesothelial cells

Many species have lymphoid tissue aggregates and fixed phagocytes in the omentum that are not covered by mesothelial cells
NB Post mortem change and autolysis result in increased volumes of red-brown fluid in the abdomen, not associated with other pathology, no roughening of surfaces of organs or peritoneum.

Function

Vasculature

Innervation

Lymphatics

Histology

Have microvili on their surface
Very fragile but regenerate very quickly
High fibrinolytic activity - protects against the formation of adhesions
Show reactive change with inflammation or effusions
May be confused with neoplastic cells

Species Differences

Peritoneum is normally smooth and clear,
Small volume of clear fluid for lubrication - in equilibrium with plasma but doesn't contain high molecular weight molecules like fibrinogen
Small animals
- Low volume of clear straw coloured fluid
- Specific gravity <1.015 to 1.018
- Total protein 25-39g/L
- Nucleated cell count <3x10e9/L
- Mesothelial cells/macrophages

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