Our Senses

 

Definition of a sense - a biological system that allows an organism to detect, transduce, and interpret specific stimuli from its internal or external environment.

To be scientifically classified as a sense, a system must typically include three specific parts: 

1. Stimulus: A physical phenomenon (like light, sound, or pressure) or chemical signal.

2. Sensory Organ/Receptor: Specialized cells or organs (like the eyes or skin) that act as biological transducers, converting the stimulus energy into electrical nerve impulses.

3. Brain Processing: Dedicated neural pathways that deliver these signals to specific regions of the brain (the sensory cortices) for interpretation.

Classification by Location

1. Exteroception: Senses that perceive stimuli from the external environment, such as “The big five” - sight, hearing, touch, smell and taste.

2. Interoception: Senses that monitor the internal state of the body, such as hunger, thirst, and blood pressure.

 

While Aristotle famously identified five senses (sight, hearing, smell, touch and taste), modern science recognizes between 22 and 33 distinct senses. This is because general categories like "touch" can be broken down into sub-modalities—such as thermoception (temperature), vibration, pressure  and nociception (pain) —each of which uses entirely different types of receptors and neural pathways.

Further, different senses can blend to create a single, unified experience.

 

Our “Hidden senses”

Proprioception – The sixth sense

Proprioception is often called our "sixth sense" and is absolutely fundamental to maintaining health and independence throughout life. It is considered “the foundation of human movement” and a critical pillar of overall health. Often referred to as the body's "internal GPS," it is the silent sensory system that allows your brain to understand the position, movement, and force of your body parts without needing to look at them.

 

Why It Is Essential for the Body?

• Balance and Safety: It is one of the three main systems (alongside vision and the vestibular system) required for balance. Good proprioception allows you to walk on uneven ground or catch yourself during a trip without conscious thought.

• Precision and Motor Control: Every physical activity, from typing on a keyboard to shooting a basketball, relies on proprioceptive feedback to coordinate muscle force and joint angles.

• Injury Prevention: Receptors in your joints (like the Golgi tendon organs) act as a "safety brake," signalling your muscles to relax if tension becomes too high, which protects against strains and ligament tears.

• Cognitive Support: Emerging research suggests that proprioceptive activities stimulate the brain, potentially improving attention, memory, and executive function.

• Immunity: While proprioception manages movement, it simultaneously regulates the physiological environment where immune cells operate.

• Self-Regulation: In children, strong proprioceptive awareness helps manage activity levels and impulses, leading to better emotional regulation and focus. 

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Consequences of Poor Proprioception associated with Aging.

When this system deteriorates, the body's ability to stabilize itself declines significantly.

• Increased Mortality: In older adults, proprioceptive decline is a primary risk factor for falls and fractures, which are leading causes of hospitalization and immobilization, further reducing proprioception and precipitating long-term health decline.

• Chronic Instability: A common example is a sprained ankle; even after the pain fades, damaged receptors may cause recurrent injuries because the brain no longer receives accurate position data.

• Body Awareness Disorders: Severe deficits can lead to a "disconnection" from one's body, potentially resulting in conditions where patients do not recognize their own limbs (disturbed sensation of ownership).

• Dementia Biomarker: Modern research reveals it is a significant early biomarker and a potential modifiable risk factor for cognitive decline.

  • Dual Decline: Individuals who experience simultaneous declines in both memory and gait (a proxy for proprioception) are at a significantly higher risk of developing dementia than those with memory loss alone.

  • Navigation Issues: Poor spatial navigation (getting lost easily)—which relies heavily on proprioceptive feedback—is now considered one of the earliest diagnostic signals for Alzheimer’s.

  • The “Cognitive Load” Theory: When your "internal GPS" (proprioception) fails, your brain can no longer move on autopilot. It must divert cognitive resources away from thinking and memory to focus on the conscious effort of walking and staying upright.

• Reduced Immunity: Reduced proprioception triggers a "survival mode" in the body that actively suppresses immune function. When your brain loses its clear internal map, it perceives a state of instability and physical stress, leading to several negative systemic effects (Increased cortisol and nociception).

  • Increased nociception: Nociception is a stress signal that results in pain and other stress responses

  • Increased cortisol: High cortisol levels are known to suppress the production of white blood cells and interfere with T-cell activation, leaving you more vulnerable to infections.

  • Stagnant Lymphatic Circulation: Unlike the cardiovascular system, the lymphatic system (the "sewage and defence" network of your immune system) has no central pump. It relies entirely on muscle contractions and joint movement—driven by proprioceptive feedback—to move lymph fluid. Reduced proprioception often leads to less efficient movement or inactivity, causing immune cells to "pool" rather than patrolling the body to find and destroy pathogens.

 

How to maintain proprioception and prevent aging.

The short answer to this is movement. However, the body needs movement on both a macro and a micro scale. Gross movement in the form exercise and sport is essential in providing sensory input from muscles and tendons, but so too is the micro-movements associated with joints and ligaments. Lifestyles today, which include many hours sedentary in offices, classrooms, cars and sofas, promote joint fixation in people who even exercise regularly, resulting in not only pain but decreased proprioception and spinal degeneration as well.

 

Chiropractic care is considered a high-impact tool for maintaining optimum proprioception because it directly targets the spine—the body's most receptor-dense "feedback highway" to the brain.

By focusing on joint mobility and spinal alignment, it helps ensure that the subconscious brain receives accurate, high-quality data about the body's position.

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Immunity – The seventh sense

In recent neuroscience and therapeutic models, immunity is increasingly proposed as the true "seventh sense" because it performs the same fundamental role as your other senses: detecting changes in the environment and informing the brain. It functions as a primary sensory organ that detects threats the other senses cannot, such as bacteria, viruses, and tumours.

 

How does it work?

• Sensing and Transduction: Peripheral immune cells (like macrophages and T-cells) use specialized receptors (Pattern Recognition Receptors or PRRs) to detect molecular signatures of "danger" or "non-self". This information is "translated" into a common chemical language of cytokines and neurotransmitters.

• Pathways to the Brain: The immune system transmits this sensory data to the brain via three main routes:

  • Neural Pathway: Rapid signaling through the vagus nerve, which "senses" inflammation in the organs.

  • Humoral Pathway: Cytokines travel through the blood and cross "leaky" areas of the blood-brain barrier (circumventricular organs).

  • Cellular Pathway: Activated immune cells can physically migrate into brain borders (the meninges) to interact with brain cells directly.

• Brain Processing (Immunoception): The brain integrates this data—primarily in the insular cortex—to create a mental representation of your body's immunological state, a process known as immunoception.

• Memory and Adaptation: Much like the brain stores memories of external events, the immune system stores immunological memory of past threats. Recent research suggests these memories, called "immunengrams," are stored in a distributed fashion between both the brain's neuronal circuits and peripheral immune cells.

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Interoception – The Eighth sense

Interoception is a multidimensional sensory system that monitors the physiological state of the entire body. While there is no single "official count" of functions, scientists generally group its coverage into 11 major biological systems that work together to maintain homeostasis (internal biochemical balance).

 

This includes:

• Cardiovascular: Monitoring heart rate and blood pressure.

• Pulmonary: Sensing breathing rate and "air hunger" (shortness of breath).

• Gastrointestinal: Feelings of hunger, fullness (satiety), and digestion.

• Genitourinary: Sensing a full bladder or the urge to use the bathroom.

• Thermoregulatory: Detecting internal body temperature (feeling hot or cold).

• Nociceptive: Processing internal pain and tissue injury signals.

• Immune: Sensing inflammation and the body's response to infection.

• Endocrine & Osmotic: Monitoring hormone levels and thirst (fluid balance).

• Autonomic & Chemosensory: Tracking blood oxygen, CO2 levels, and pH. 

 

The most important requirement all our senses need is a healthy Nervous System.

Chiropractors are experts in understanding how the nervous system functions and today the internet is full of proven chiropractic studies showing chiropractic treatments are extremely effective not only spinal pain and headaches, but also topics such as athletic performance, concentration, general wellbeing, children’s growth, women’s health, men’s health, factors associated with aging.

 

Start learning today how chiropractic can change your life.