physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

, serous fluid or serosal fluid (originating from the

Medieval Latin Medieval Latin was the form of Literary Latin used in Roman Catholic Western Europe during the Middle Ages. In this region it served as the primary written language, though local languages were also written to varying degrees. Latin functioned ...

word ''serosus'', from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''serum'') is any of various

body fluid Body fluids, bodily fluids, or biofluids, sometimes body liquids, are liquids within the human body. In lean healthy adult men, the total body water is about 60% (60–67%) of the total Human body weight, body weight; it is usually slightly lower ...

s resembling serum, that are typically pale yellow or transparent and of a benign nature. The fluid fills the inside of body cavities. Serous fluid originates from

serous gland Serous glands secrete serous fluid. They contain serous acini, a grouping of serous cells that secrete serous fluid, isotonic with blood plasma, that contains enzymes such as alpha-amylase. Serous glands are most common in the parotid gland and ...

s, with secretions enriched with

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s and

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

. Serous fluid may also originate from mixed glands, which contain both

mucous Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

and serous cells. A common trait of serous fluids is their role in assisting digestion,

excretion Excretion is a process in which metabolic waste is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after lea ...

, and respiration. In medical fields, especially cytopathology, serous fluid is a synonym for effusion fluids from various body cavities. Examples of effusion fluid are pleural effusion and

pericardial effusion A pericardial effusion is an abnormal accumulation of fluid in the pericardial cavity. The pericardium is a two-part membrane surrounding the heart: the outer fibrous connective membrane and an inner two-layered serous membrane. The two layers of t ...

. There are many causes of effusions which include involvement of the cavity by

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

. Cancer in a serous cavity is called a serous carcinoma. Cytopathology evaluation is recommended to evaluate the causes of effusions in these cavities.

Examples

Saliva Saliva (commonly referred to as spit) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can be ...

consists of

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

and serous fluid; the serous fluid contains the

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

amylase, which is important for the digestion of

carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...

s. Minor salivary glands of von Ebner present on the

tongue The tongue is a muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper surfa ...

secrete 440px Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical ...

the

lipase Lipase ( ) is a family of enzymes that catalyzes the hydrolysis of fats. Some lipases display broad substrate scope including esters of cholesterol, phospholipids, and of lipid-soluble vitamins and sphingomyelinases; however, these are usually tr ...

. The parotid gland produces purely serous saliva. The other major salivary glands produce mixed (serous and mucus) saliva. Another type of serous fluid is secreted by the serous membranes (serosa), two-layered membranes which line the body cavities. Serous membrane fluid collects on microvilli on the outer layer and acts as a

lubricant A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, t ...

and reduces

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of t ...

from

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...

movement. This can be seen in the

lungs The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of th ...

, with the pleural cavity. Pericardial fluid is a serous fluid secreted by the serous layer of the pericardium into the pericardial cavity. The pericardium consists of two layers, an outer fibrous layer and the inner serous layer. This serous layer has two membranes which enclose the pericardial cavity into which is secreted the pericardial fluid.

Blood serum Serum () is the fluid and solute component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum includes all proteins not u ...

is the component of

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...

that is neither a

blood cell A blood cell, also called a hematopoietic cell, hemocyte, or hematocyte, is a cell produced through hematopoiesis and found mainly in the blood. Major types of blood cells include red blood cells (erythrocytes), white blood cells (leukocytes), ...

, nor a

clotting factor Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism o ...

. Blood serum and

blood plasma Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but contains proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the intra ...

are similar, but serum does not contain any clotting factors, such as fibrinogen, prothrombin,

thromboplastin Thromboplastin (TPL) is derived from cell membranes and is a mixture of both phospholipids and tissue factor, neither of which are enzymes. Thromboplastin acts on and accelerates the activity of Factor Xa, also known as thrombokinase, aiding bloo ...

and many others. Serum includes all

s not used in

coagulation Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism o ...

(clotting), and all the

electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...

antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...

s, and any

exogenous In a variety of contexts, exogeny or exogeneity () is the fact of an action or object originating externally. It contrasts with endogeneity or endogeny, the fact of being influenced within a system. Economics In an economic model, an exogeno ...

substances, like

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via insuffla ...

s and

microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

References

{{reflist Physiology

Examples

See also

References