Physiological Priorities of the Human Body

The human body is a highly coordinated system. Its organs, tissues, and physiological systems are constantly sharing and allocating energy, nutrients, information, and resources for repair and recovery.

When the body is healthy, it is generally able to maintain the normal function of multiple systems at the same time. However, when it is exposed over a prolonged period to illness, inflammation, inadequate nutrition, insufficient sleep, chronic stress, or metabolic dysfunction, the regulation of energy use, repair and other functions may change.

To help patients understand the relationship between different systems of the body, the following eight levels provide a simplified way to organise the discussion.

First Level: Core Organs and Metabolism

The core organs and metabolic systems form the foundation for maintaining life and internal physiological stability.

These primarily include the heart, lungs, liver, kidneys, digestive system, endocrine system, and overall metabolic function.

Together, these systems are involved in oxygen delivery, nutrient absorption, energy production, hormonal regulation, fluid balance, and the processing and elimination of metabolic waste.

When these functions are impaired, the body’s overall energy supply, nutrient utilisation, and capacity for recovery may also be affected. The consequences depend on the specific condition and its severity.

Second Level: The Brain

The brain has a very high demand for oxygen and energy and is also sensitive to changes in sleep, blood glucose, nutrition, hormones, and overall metabolic status.

When the body’s general physiological condition declines, some people may experience fatigue, brain fog, reduced concentration, slower reactions, or changes in mental state.

These symptoms do not necessarily indicate structural disease of the brain itself. In some cases, they may reflect changes in the body’s overall physiological state. They have many possible causes and may require medical assessment.

Third Level: Bones and Connective Tissues

Bones, joints, ligaments, tendons, and fascia are not static structures. They are continuously undergoing metabolism, remodelling, and repair.

Their normal maintenance depends on adequate protein, minerals, vitamins, hormonal balance, blood supply, and appropriate mechanical loading.

Long-term nutritional deficiencies, chronic inflammation, hormonal abnormalities, insufficient physical activity, or abnormal mechanical stress may all affect the body’s ability to maintain and repair these tissues.

Fourth Level: The Nervous System

The nervous system is responsible for sensation, movement, pain transmission, and autonomic regulation, while also connecting and coordinating different organs and systems throughout the body.

Chronic stress, insufficient sleep, inflammation, and metabolic dysfunction may all influence nervous system function or regulation.

Possible symptoms may include sleep disturbances, increased pain sensitivity, numbness, tingling, abnormal sensations, or symptoms related to autonomic nervous system function. These symptoms are not specific to stress or nutrition and should be assessed according to their cause.

Fifth Level: Blood and the Immune System

Blood transports oxygen, nutrients, hormones, and metabolic products throughout the body, while the immune system is involved in defence against infection, regulation of inflammation, and tissue repair.

Normal blood formation and immune function depend in part on adequate nutrition, effective digestion and absorption, and a relatively stable metabolic environment.

For example, anaemia may reduce oxygen delivery, while chronic inflammation or certain nutritional deficiencies may impair tissue recovery throughout the body.

Sixth Level: Muscles

Muscle is a metabolically active tissue that requires a continuous supply of energy, protein, minerals, and normal nervous system control.

When the body remains in a state of inadequate recovery for a prolonged period, symptoms may include weakness, muscle soreness, easy fatigability, reduced strength, or prolonged recovery after physical activity. [1]

Muscle symptoms may result from local mechanical stress, but they may also be influenced by the body’s overall physiological condition.

Seventh Level: The Skin

The skin is the body’s largest organ. Some changes in general health can become visible in the skin.

Changes in nutrition, hormones, immune function, inflammation, sleep, and stress may all influence skin health. [2]

Common manifestations may include dryness, sensitivity, acne, dermatitis, rashes, or changes in wound-healing speed. These also have local and disease-specific causes.

For this reason, recurrent skin problems may sometimes require consideration of both local factors and the person’s overall health.

Eighth Level: Hair and Nails

Hair and nails are relatively less important for immediate survival. Illness, significant psychological or physical stress, nutritional deficiencies, rapid weight loss, and some hormonal or metabolic disorders may affect hair growth and nail quality. [3]

Possible changes include hair loss, thinning hair, reduced hair quality, brittle nails, or changes in nail growth.

These external changes can sometimes provide clues about nutritional status, hormonal balance, or overall health, but they do not identify a specific cause. They do not necessarily appear first; hair shedding after a stressful event is often delayed.

Looking at the Body as a Whole

Illness, inadequate nutrition and prolonged disruption of sleep or recovery can affect energy availability, nutrient utilisation, inflammation and tissue repair. Depending on the underlying cause, symptoms may occur in more than one system.

Therefore, when symptoms such as fatigue, muscle soreness, skin problems, and hair loss occur together or repeatedly, treating only the area where the symptom appears may not always be sufficient.

It may also be necessary to consider the wider physiological context, including nutrition and digestive absorption, sleep, metabolic health, hormonal balance, inflammation, stress, physical activity, and overall lifestyle.

Assessment should address both the symptoms themselves and possible underlying causes. The model is not a reason to postpone evaluation or treatment of a particular symptom.

How to read this model: The illustration and eight levels are an educational model, not an established medical hierarchy or a fixed order in which the body allocates nutrients or repairs tissues.

These systems overlap: the brain is part of the nervous system, and blood and immune function are essential throughout the body. The order does not indicate symptom severity or treatment priority. Skin, muscle, hair or nail symptoms do not by themselves establish an internal organ problem.

These sources support selected points about nutrition, metabolism, skin and hair. They do not establish or validate the eight-level ranking.