From the subatomic to the astronomical there are surprises at every order of magnitude. This post focuses one of many mysteries of the human immune system. Could it be a seventh sense?
Your immune system (skin, tonsils, thymus, lymph system and glands, and more) is a guardian of your health which keeps you alive day to day. It is an amazing multi-layered intelligent system with many tools to protect you from things that have no business in your body. Fairly recently, it has been discovered to have connections to the brain and to constitute what one paper calls a seventh sense.
We have five senses—visual, olfactory, gustatory, somatosensory, and auditory. In addition, the vagus nerve delivers information about our visceral organs to the brain, referred to by some as the sixth sense … The immune response… hardwired in our brain… makes the immune system our “seventh sense” (Source)
Other Candidates for a Seventh Sense
Common understanding is that we have 1. Sight, 2. Hearing, 3. Smell, 4. Touch, 5. Taste, and 6. Proprioception (body position sense. If you aren’t up to speed on proprioception, see below.) Several things have been proposed as a seventh sense. These things have each been called a seventh sense:
1. Spiritual Intuition. On the Internet you can find people claiming that we have a spiritual connection to all knowledge and that this intuitive insight is the seventh sense, a link to something New Age followers refer to as the Akashic Records. For this to qualify as a sense, however, human thoughts will need to take data directly from reality instead of from a combination of memory storage and other sensory organs.
2. The Internet. The Internet itself has also been called our seventh sense. As above, until we have direct brain implants, the Internet remains a separate network.
3. Proprioception (body position). Some separate the vestibular system which we use for balance–it has sensors in the stomach and inner ear–calling that the sixth human sense, separating it from the seventh sense of proprioception, that is, our sense of where our limbs are and what our body position is.
4. Equilibrioception: our sense of balance. If you do count proprioception as the 6th sense, then the sense of balance, can be considered the seventh sense.
5. Thermoception: This sense, also known as the sense of heat, was once thought to be a simple variation on the sense of touch, but it is different as heat can be sensed without actually touching an object.
6. Chronoception: This is the sense of the passage of time. It is not accepted to be a direct sense, rather a measure of the time it takes to think the thoughts and to have the experiences that took place between a start time and an ending time. Still some consider it a seventh sense.
7. Magnetoreception: Birds have cells that allow them to navigate using the earth’s magnetic fields during migration and humans have some of these cells as well. Humans, while not believed to have a magnetic sense do have cryptochrome (a flavoprotein, CRY2), a class of flavoproteins that are sensitive to blue light in the retina which has a light-dependent magnetosensitivity. In humans, these receptors may play a part in circadian rhythms. Blue light can be used to treat circadian and sleep dysfunctions. Therefore, blue light receptors separate from the rods and cones we use for vision, may be part of a Chronoception system that helps us orient to night and day separate from what our other senses tell us.
How Many Senses Do We Have?
If you break up the basic senses, there can be as many as 21 or more human senses. The sense of taste has, for example, separate sensors for each of these four: sweet, salt, sour, bitter, and umami. Our sense of smell may work as more of a pallet where our 10 to 20 million olfactory receptor neurons bind to odor molecules with varying affinities and the strength of different molecular bindings give activation patterns which we experience as unique odors. A disputed study says that we can humans can distinguish between more than one trillion different odors.
A Brain State Sense?
Your brain weighs about 2 percent of your adult body mass yet it consumes an impressive 20 to 25 percent of your body’s total energy. As with all cellular metabolism, brain cell activity generates metabolic waste. A part of your body’s immune system, the lymph system is there, luckily, to take out the cellular trash. For the brain, this happens primarily as we sleep and it is one reason sleep is essential. During sleep, the brain shrinks and fluid (CSF) circulates through the glymphatic system (neural lymphatic system) flushing proteins and other wastes out. Does the brain sense how much junk has accumulated and or what types and take action based on this? What pathways could the immune system use for communication with the brain?
To qualify as a sense, it makes sense to us that you’d have to be able to sense the sense, at least in some sense. Does that make sense? With the immune system, it may tell the brain that it is being attacked to a certain degree based on chemical signalling and this could result in many physical sensations, such as nausea not triggered by anything else. This is the closest we can recall to having any sort of sensory experience from what might be the immune system.
Gut Sense
Having once consumed a bad duck egg, we became instantly nauseous and nothing would help until, with an amazing precision, some sense directed our stomach to gyrate in a very specific way causing the ejection (to put it politely) of the bit of bad egg. Right after this, all nausea vanished.
Have you had any experiences that might be the result of your immune system acting as a seventh sense? Although we’ve learned a lot, the human body is still full of mysteries.
