How much of the body and its functions are controlled by the brain?

If my introductory dithering is boring or annoying, and you’re looking for entertainment, scroll down to: Doctors of Quora, what’s something you’ve had to tell a patient that you thought for sure was common knowledge?


The topic for this post is, “How much of the body and its functions are actually controlled by the brain?”

This is especially important for neurodiverse people who are “diagnosed” with so-called brain disorders, which attribute even the most trivial human behaviors to specific “control centers” in the brain.

Allergies: Today’s topic of interest began with the usual “waking up to” an alien world = headache, itchy swollen eyes, (itchy everything!), sneezing, and completeley stuffed up nose. A cool, cool wind blowing through the house.

If pressed, I would admit that “time asleep” is a separate life that I live; very active visually with dreams in “another world” that is just as familiar as “this one” but mostly more pleasant – absent are daily problems but big dramas replay and continue that take place “outside time”. Where is this place that I’m “living” during sleep? Who are these people who “know me” when the “land of neurotypicals” is bereft of such understanding or recognition of my existence as an individual “who belongs”?

Sometimes I’n not sure where I am when I wake up. Suddenly, abruptly, the sensations of my body intrude on lovely sleep. This morning, for some reason, I tried to “orient” myself by what I was wearing – I was up late due to the heat, and zonked out in my T-shirt and jeans. Being a “boring” Aspie, I wear the same outfit everyday – different color T-shirts and jeans, but not in any specific color assignment by day of the week or other scheme. Random.

I thought, while still groggy, that if I could remember what color T-shirt I have on (no fair peeking) I would know what day it is, but I couldn’t remember. I waited. An “image” appeared of me in a purple T-shirt, as if my eyes were open and I was “x-raying” myself through the blanket. Oh, good! It’s Thursday morning.

Allergy symptoms: Why no symptoms when I’m asleep? They hit me like a Tsunami only when I awake – wouldn’t it be wonderful if I could “ignore” the plague of swelling, sneezing, itching and painful sinuses, only while asleep, but while I’m awake?

Hmmm… what exactly is going on? What does the brain actually control? There seems to be much that the body does that is automatic… if the brain really dominates, then why can’t I “control” my immune response to pollen and other “stuff” that is carried in the air, or ignore the symptoms while I’m awake?

It would be great to have a brain with a driver or operator named “ME” who can actually order the body to stop overreacting or “doing” annoying things.

Humans tend to think that this is the “way we work” with the “conscious experience” as “who we are”, but attribute the “mysterious driver” to another dimension entirely, made up of invisible beings that track, control, or dictate our physical existence from a “heavenly” control room somewhere “up there”. A control being that is imagined to reside within our body has a name: the Humunculus, which is a projection of our senses as a composite being. The external controllers we call gods, spirits or vague cosmic forces, depending on which culture formed our concept of where this other world of control exists. For some groups, this alternate reality is immanent in Nature and not remote at all. For others it’s a “dimension” that is unseen, but can be located “in the sky” or, now that we are aware of the immensity of space and other probable life forms, the distance to this “domain” is measured to include “space aliens” who deliberately interfere in human life (for some strange reason).

“How much of the body and its functions are actually controlled by the brain?” This question has particular importance for “neurodiversity” and diagnosis of developmental “brain disorders” the characterizations of which attribute even the most trivial human behaviors to specific “control centers” in the brain.

This has always seemed absurd to me and quite a dangerous propositionThis concentration of “all behavior” in one “organ” simply ignores facts about the human body and living creatures, now and throughout the evolution of life. Some creatures have no “brain” as such or more than one brain, each of which operate functions or body parts independently. Some insect species function as “collective” brains, with specific responsibilities carried out by physically independent animals that coordinate in acts of “hive mind” – which to us, focussed as we are on “control by a being or beings” outside our bodies, is “mysterious or magical” but behavior that seems “bizarre” to humans is common throughout Nature. Schooling fish, bait balls, the mass coordinted flight of birds and bats, mass migrations, “magnetic field” navigation, orientation to starlight, moonlight, sunlight, and sensory perception of scent and frequencies all along the electromagnetic spectrum, and responsiveness to the earth’s orbit and solar output (climate) demonstrate that the Earth and its life are inseperable from “physics” (a handful of equations!) that underly the workings of the “solar neighborhood” and beyond.

Here is what one person had to say, (an anatomy and physiology student) in answer to a question on Quora:

How much of the human body’s function is controlled by the brain and how much is autonomous chemistry or biology?

“This is a bit of massive question, mostly because of the enormous complexity of the human body. However the simplest answer is, almost every function in the human body is both controlled and not controlled by the brain. Let me explain…”

“Think of your body as a puppet and your brain as the puppeteer.” (Coming up appropriate analogies is a high art; most analogies miss the mark by a mile – this one is no exception. It contradicts the answer given below)

“Almost every cell in the body works independently of any kind of brain involvement, up until the brain is involved. A perfect example of this is reflex arcs; reflexes such as the patellar reflex and achilles reflex exist completely separate from the brain. These reflexes can even be seen in brain dead patients, an exceptionally creepy example is the Lazarus Sign, in which dead patients arms can rise up off the bed.”

“That is to say, the body, for the most part, doesn’t need the brain to operate. There are of course notable exceptions, the most prominent being the autonomic nervous system. The system that controls key parts of your body that help keep you alive. Things like your heart rate and respiratory rate, without a brain, you couldn’t breathe. Although your heart, which keeps its own pace, would still beat and circulate oxygen.”

“So to summarise, the majority of the human body is not controlled by the brain, but it can be. Your muscles and your organs are independent systems, but when they receive electrochemical instructions, the brain is in control.”

In this view, (I have no idea if it’s correct) the brain is like a “behind the scenes” actor that intervenes if a system is “off track” – it’s a monitor that keeps the “whole shebang” within certain parameters that are required to keep the organism from failing. No small task!

The “rest of the answers” to related questions quickly descend into Logic Hell, citing rambling “explanations” that belong to neurotypical nuttiness; magical thinking, supernatural causes, folktales, conspiracy theories, pop-culture, and the like. 


One question provided astounding disclosures by doctors and nurses about their encounters with patients, and not only in the U.S.

Doctors of Quora, what’s something you’ve had to tell a patient that you thought for sure was common knowledge?!n=12/


An important answer – and further indictment of a FAILED U.S. Education system!

As a paramedic, I have met many patients who lacked “common knowledge”. While I can think of many examples, I wanted to link to a government study showing the effects of low “health literacy” which is a real problem and is very much overlooked.

While writing a paper last year, I was very surprised to read that approximately 80 million adults in the US (study conducted in 2003) have “limited health literacy.”

The study found that more than one third of the population had difficulty in understanding basic health information and would struggle to understand the labels on their prescription medication or to follow medication regiments.

Other studies have found that the majority of patients do not discuss these difficulties with their Dr or pharmacist.

Health Literacy Interventions and Outcomes: An Updated Systematic Review

Page 24

Burden of Low Literacy and Low Health Literacy


In 2003, the US Department of Education conducted a survey entitled “National Assessment of Adult Literacy” (NAAL). The most comprehensive examination of adult literacy to date, the NAAL surveyed more than 19,000 adults age 16 and older and included items intended to measure health literacy directly. More than one-third of respondents (36 percent) taking the NAAL scored in the lowest two (“basic” and “below basic”) out of four categories on health literacy items, suggesting that approximately 80 million adults in the United States have limited health literacy, including related prose, document, and quantitative skills. These adults may have difficulty with even simple tasks such as reading and understanding the instructions on a prescription bottle or filling out an insurance form. Although the NAAL did not independently report on prose, document, or quantitative health literacy, its predecessor, the National Adult Literacy Survey (NALS), reported similar proportions of individuals scoring in the lowest proficiency levels across these domains.




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