26 Body fluids

 All parts of the body require nutrients and the metabolic wastes produced in them need to be removed from the body. Hence, there is a need to transport various substances like digested food materials, hormones, catabolites, enzymes, and various gases from one part of the body to another. These movements are achieved through body fluids.

Depending on the location fluids are divided in two groups - Intracellular fluid (IEF) and Extracellular fluid (ECF). 

Intracellular fluid is the fluid present within all the cells of the body. Intracellular fluid is two thirds of TBW i.e. 40% of body weight. Collectively, the fluid present in the blood and in the spaces surrounding cells is called extracellular fluid (ECF), that is, all the fluid that is outside of cells. The ECF is one thirds of TBW i.e. 20% of body weight.

Blood 

Blood plays a major role in the body’s defense against infection by carrying waste away from our cells and flushing them out of the body in urine, feces, and sweat. Blood also supplies the body with essential substances such as hormones, sugar, and oxygen that the body needs to function and survive. The total blood volume in an adult is about 5 litres. 

Cerebrospinal fluid (CSF)

The cavities of the brain (ventricles), the spinal cord and subarachnoid region is filled with CSF. The total volume of CSF is 100 – 150 ml. It is a clear, transparent and colorless fluid. It has a similar pH as that of blood. It protects the brain and spinal cord from shocks and maintains a uniform pressure on the nervous structures. It acts as a reservoir to regulate the contents of the cranium. To a limited extent, it acts as a medium for nutrient exchange in the nervous system.

Lymph

The fluid present in the lymphatic system is called lymph. Lymph is a colorless fluid. It is composed of fluid matrix, plasma and leucocytes. It bathes tissues and organs in its protective covering. There are no erythrocytes in lymph and it has lower protein content than blood. Its pH is as same as that of blood. 

Urine 

Made of 95% water, urine flushes out chemicals and dead blood cells from the body and is a way for your body to get rid of extra water that it does not need.

Saliva

Mostly made of water, saliva contains proteins and minerals that prevent gum disease, tooth decay, and helps you chew and swallow comfortably.

Tears 

The tears refer to the watery secretion of the lacrimal glands that serve to moisten the conjunctiva. The secretion is slightly alkaline and saline. 

Gastric Juice 

It is just one of the various digestive juices secreted in the body to aid in food digestion. It is made up of hydrochloric acid, potassium chloride, sodium chloride, pepsinogen and other digestive enzymes, intrinsic factor, gastrin, mucus, and bicarbonates.

Mucus

Mucus contains antibodies, enzymes, and proteins that help fight bacteria and viruses and prevents the mouth, nose, throat, sinuses, and lungs from drying out.

Bile

A greenish-yellow bodily fluid secreted by the liver and stored in the gallbladder, and discharge into the duodenum where it aids in the digestion of fats. 

Pus

A viscous exudate formed and discharged from an inflamed tissue as an end-result of suppuration. 

Aqueous humour

The aqueous humour is a thin, transparent fluid similar to plasma. It’s made up of 99.9% water ­­– the other 0.1% consists of sugars, vitamins, proteins and other nutrients. This fluid nourishes the cornea and the lens, and gives the eye its shape.

Amniotic fluid 

The protective fluid surrounding the developing fetus within the amniotic sac of a pregnant female. 

Synovial fluid 

A clear, viscid fluid in the synovial joints and secreted by the membrane that lines the joints. 

Pericardial fluid 

The pericardium is a two-layered, sac-like membrane that surrounds the heart. Pericardial membranes produce pericardial fluid, a liquid that sits between the pericardium’s membranes. The fluid acts as a lubricant for the movement of the heart, reducing friction as the heart pumps blood.

Peritoneal fluid 

Peritoneal fluid is a liquid that acts as a lubricant in the abdominal cavity. It is found in small quantities (generally 5-20 mL) between the layers of the peritoneum that line the abdominal wall.

Pleural fluid 

The pleura is a two-layer membrane that covers the lungs and lines the chest cavity. The area that contains pleural fluid is known as the pleural space. 

Nasal fluid 

commonly known as a runny nose. The terms "rhinorrhea" and "rhinitis" are often used to refer to a runny nose.

Otic fluid 

thick or sticky fluid behind the eardrum in the middle ear. It occurs without an ear infection.

Vomit 

The contents of a stomach expelled through the mouth. 

Sebum 

An oily substance produced and secreted by sebaceous gland. 

Sputum 

Sputum is mucus that is coughed up from the lower airways (the trachea and bronchi). 

Cerumen 

Commonly known as earwax, is a hydrophobic protective covering in the ear canal. 

Chyle

A body fluid in the small intestine, containing mainly of emulsified fats and aids in the digestion. 

Exudates

A fluid containing solutes, proteins, cells, or cellular debris discharged into nearby tissues or on tissue surfaces, caused by inflammation or injury. 

Semen

In males, semen is released during ejaculation and contains protein, fructose, and catecholamines.

Vaginal fluids

Biological fluids that are within or expelled from the vagina and contain carbohydrates, amino acids, proteins, and other acids produced by the normal lactobacillus bacteria.

Breast milk

Produce by mammary glands and the primary source of nutrition for newborn.