What is a Serous Membrane?

Victoria Blackburn
Victoria Blackburn
Serous membranes in the body cavities surrounding the heart and lungs help ease expansion and contraction.
Serous membranes in the body cavities surrounding the heart and lungs help ease expansion and contraction.

A serous membrane is a thin membrane that helps body parts move more easily and reduces friction between them. Also known as serosa, these membranes are found throughout the body, usually surrounding organs. There are several medical conditions associated with the serous membane, some of which can be life threatening.

Characteristics and Location

Serosa are made up of two layers of tissue with a thin layer of serous fluid in the middle. One layer is made up of mesothelium, which produces the fluid, while the other is made up of connective tissue, which attaches the membrane to other parts of the body and provides blood and nerves for the epithelial layer. Serous fluid itself is a thin liquid that's normally pale yellow, but can become milky, dark yellow, or red in people with infections or other medical conditions.

Serous membranes are found in the abdominal and pelvic areas around the stomach and reproductive organs.
Serous membranes are found in the abdominal and pelvic areas around the stomach and reproductive organs.

Many places in the body have serosa, including the body cavities surrounding the heart, lungs, and the abdomen and pelvic area. It's also found in the stomach, uterus, testicles, and vagina. Depending on where the membrane is located in the body, it may be called different things: for instance, the serous membrane around the heart is called the pericardium, while that around the lungs is called the pleura, and that surrounding the testes is called the tunica vaginalis.

Function

Serosa are found throughout the human body, usually around organs like the stomach.
Serosa are found throughout the human body, usually around organs like the stomach.

Though all serosa are primarily used for reducing friction, their exact function differs slightly by location. The pericardium, for example, makes it easy for the heart to expand and contract as it beats as well as protecting is and holding it in place. Similarly, the pleura makes it easier for the lungs to expand by reducing friction between them and the surrounding tissues, but also makes the outer layer of the lungs cling to the surrounding tissue, which helps keep them from collapsing inwards.

Related Problems

Serous membranes can be found in the testicles.
Serous membranes can be found in the testicles.

Problems with a serous membrane can be related to the serous fluid or to the two tissue layers. An overproduction of fluid can cause serious problems, especially if enough fluid is produced to put pressure on a person's organs. This is called effusion when it happens around the heart or lungs, and ascites if it happens in the peritoneum. All three can be life-threatening if not treated promptly, and usually have to be treated by draining the fluid with a needle. Serous fluid can also become infected with bacteria or mixed with blood because of a problem somewhere else in the body.

The serous membrane around the heart is called the pericardium.
The serous membrane around the heart is called the pericardium.

Another condition that affects the tissue layers of the serous membrane, rather than the fluid, is malignant mesothelioma. This is a cancer that most often affects the pleura, though it can affect any of the serosa. It's primarily associated with exposure to asbestos, and is generally very difficult to treat.

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Discussion Comments

anon253611

What would happen if the serous membrane lined the gut?

anon235881

Thanks so much! This was a huge help! I'm cramming for an RN exam and this helped me out a lot!

anon124190

thanks a lot. Your articles help me especially in my anatomy assignment and physiology.

suleiman m., from windsor university school of medicine

anon71989

my name is brian. i want to say thanks a lot for this article. it really helped me with my assignment about body membranes in my anatomy assignment.

randolfh

i'm Randolf.. thanks for the article "serous membranes." It helped me here in my research about the four types of epithelial membranes. i found the article informative and that's why i joined your community.

as a student it really pays to have a reliable reference to equip me with knowledge. i major in biology so that's why i found it a must for me to get accurate information about life's questions. thanks again for the warm welcome. i like your website. it's great.

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    • Serous membranes in the body cavities surrounding the heart and lungs help ease expansion and contraction.
      Serous membranes in the body cavities surrounding the heart and lungs help ease expansion and contraction.
    • Serous membranes are found in the abdominal and pelvic areas around the stomach and reproductive organs.
      Serous membranes are found in the abdominal and pelvic areas around the stomach and reproductive organs.
    • Serosa are found throughout the human body, usually around organs like the stomach.
      Serosa are found throughout the human body, usually around organs like the stomach.
    • Serous membranes can be found in the testicles.
      Serous membranes can be found in the testicles.
    • The serous membrane around the heart is called the pericardium.
      The serous membrane around the heart is called the pericardium.