Body Fluids Pt. 2

A continuation of the investigation of our wet, drippy, sticky bits. Embrace your fluids! Part 2 of 3. (Find pt. 1 here)

Cerebrospinal Fluid:

Flows around your brain and spinal cord. Serves as a liquid medium between blood and nervous tissue

Ependymal cells create the boundary for cerebrospinal fluid…these cells are also called “neuroglia” meaning “brain glue” in Greek. They have very tight junctions between them and hold tightly in place so substances cannot leak between them.

Cerebrospinal fluid can be replaced up to every 7.5 hours, as it is continuously generated by the choroid plexus in the brain and reabsorbed by the body.

This fluid maintains the optimal ionic chemical composition necessary for the firing of nerves, making it not only protective and nourishing, but also assists with proper nerve function. There is generally a higher concentration of chloride and sodium ions in CSF than plasma.


Menstrual blood

Fluid consisting of blood, vaginal secretions, the cells of the inner lining of the uterus and a variety of immune cells. The ratio of each component varies depending on the stage of the menstrual cycle and, of course, each woman

The endometrial lining more than doubles in thickness between periods

This study of the contents of menstrual blood identified 1061 total proteins, of which 385 are specific to menstrual blood alone

Women acquire all the eggs for their lifetime while in the womb. This is the basis for the “biological clock”. No new egg cells are created during a lifetime, so once you’re out, you’re out.



There are 3 main glands that secrete saliva: parotid gland (in front of the ears), sublingual gland (under the tongue) and the submandibular gland (in the floor of the mouth at the base of the tongue--this is where you gleek from!)

A minor amount of digestion occurs from salivary amylase, an enzyme that begins the breakdown of starches

Parasympathetic nervous stimulation (rest and digest mode) promotes continuous secretion of saliva which keeps your mouth and throat nice and moist. Sympathetic nervous stimulation (fight or flight mode) slows own saliva production which explains dry mouth when you get nervous.


Aqueous Humour

Fills the inside of the eyeball, very low protein concentration

Maintains internal pressure and spherical shape of the eye

Produced by a structure near the front of the eye that supports the lense, called the ciliary body, and drains through veins in the back of the eye. It’s continuously being produced and drained.


Vaginal Secretion

“Discharge” is the blanket term used for the mucus, bacteria, and cells of the cervix and vagina that have died or sloughed off

Discharge tends to be slightly acidic, acting as a microbial boundary

“Arousal fluid” is pushed out onto the surface of vaginal walls by pressure created when blood vessels swell upon excitement. Natural lube! Though it’s technically “discharge”, its source is different than its unaroused counterpart. This is also a different substance than squirt (which was featured in part 1 of this series)

“Cervical fluid” is a fluid generated by the passageway between upper and lower reproductive tract. Hormones that moderate the menstrual cycle, like estrogen and progesterone, affect the qualities of cervical fluid.



A rapid accumulation of white blood cells, mostly neutrophils and macrophages (read more on those here) that is a sign of an infection. The presence of pus is partly good, because it is a sign that your body is fighting, but it is also a sign that there is something to fight and that an infection is festering.

Sometimes pus is green because of protein released by white blood cellss called “myeloperoxidase”

The phrase “pus bonum et laudabile” means “good and laudable pus”. Doctors dating back to the 1st century believed that the presence of pus was a sign of a healthy, healing wound. Before we had a grasp of how infections work, surgeries and other operations were performed with unsanitized tools and wounds were often left uncovered. Many patients would need to have “pus buckets” that would literally just collect their oozing, dripping pus. It was not until the 13th century that the idea of “laudable pus” was challenged and not until the 19th century that this idea was put to rest and pus became understood as a sign to take action on an infected wound rather than a part of the healing itself.


Breast milk

“Colostrom” is the name of the first bits produced by the mammary glands after birth. It has lots of antibodies that coat the G.I. tract of the baby. This helps said babe’s immunity immediately after birth and helps with the development of its own immune system.

Milk production is mainly stimulated by the hormones prolactin, while ejection is stimulated by the hormone oxytocin released in response to the baby’s suckling. SMH: So Many hormones.

After production, breast milk travels through a series of compartments. I like to call them “nipple ejection units” but actually they’re called “lactiferous sinuses”. It’s where breast milk is stored until it’s ready to be expelled.


Ear Wax

A.K.A. “cerumen

Produced by modified sweat glands in the inner ear

Provides a sticky barrier that catches things before they enter the ear canal

Seamstresses used to use their own earwax to keep their thread from fraying


“Principles of Human Anatomy” Tortora, G.J., Nielsen, M.T.

"Different Body Fluids: An Overview". Guattnam, N., Singh, S.P., Khinchi, M.P., Nama, N., Jain, S.

"Neuroanatomy, Cerebrospinal Fluid". Huff, T. Tadi, P. Varacallo, M.

"Getting Wet: Discharge vs. Cervical Fluid vs. Arousal Fluid". McWeeney, C.

"Proteomic Analysis of Menstrual Blood". Yang, H., Zhou, B. Prinz, M., Siegel., D.

"The Mythos of Laudable Pus Along with an Explanation for its Origin". Frieberg, J.A.

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