Lecturer: QU Hongyan

The cause of disease , refers to the factors that damage the relative equilibrium and result in disease.
The etiology , an important component of the theoretical system of traditional Chinese medicine, studies the concept of various pathogenic factors, their formation, nature, pathogenic characteristics and the clinical manifestations of the disease caused by them.

Exogenous pathogenic factors
Endogenous pathogenic factors
Pathogenic factors
Pathological products

A characteristic of etiology in TCM seeking the cause by syndrome differentiation
TCM studies the cause of a disease , by understanding objective conditions that may become pathogenic factors according to the manifestations of the disease and through analysis of symptoms and signs of disease to infer its cause

 Exogenous pathogenic factors --refer to the pathogenic factors which originate from the nature and invade the body from the body surface, or through the mouth and nose, causing exogenous disease.
Six excesses
Pestilential qi

Six qi ： a collective term for six normal climate changes in nature including wind, cold, summerheat, dampness, dryness and heat (fire).
Six excesses ： a collective term for six exogenous pathogens including pathogenic wind, pathogenic cold, pathogenic summer-heat, pathogenic dampness, pathogenic dryness and pathogenic heat (fire).

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six qi changes sharply, which goes beyond the normal adaptive ability ； body resistance becomes weak due to deficiency of healthy qi.
Fall ill
Climatic changes
（ six qi ）
Healthy qi
Six excesses
Healthy
Six qi

 1 ．
Exogenousness ： the six excesses usually invade the body through the body surface, the mouth and nose.
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2 ． Seasonality ： diseases caused by the six excesses are often characteristic of distinct seasonality.
In spring there are more wind diseases; dryness disease more in autumn

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3 ． Regionality
：
Diseases caused by the six excesses are often connected with the environments and regions where people live and work.
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4 ． Combination
： each of the six excesses can cause disease either alone or in combination with another.
e.g. wind-heat cold wind-cold-dampness arthralgia

 5 ．
Transformability ：
Under certain conditions, the natures of diseases caused by six excesses can transform into one another. e.g. Wind-cold syndrome of exterior may turn into interior heat syndrome .

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All exogenous pathogenic factors characteristic of lightness, rising, and opening-dispersing and migrating are called wind pathogen.

Natures and characteristics
 Wind pertains to yang and is characteristic of lightness, rising and opening-dispersing and tends to attack yang location
 Characteristic of wind being mobile and rapid changeable
 Characteristic of wind being mobile
 Wind being primary pathogen

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All exogenous pathogenic factors characteristic of cold, coagulation and contraction are called cold pathogen.
 Cold is prevalent in winter so there are more diseases caused by cold in this season. Diseases caused by cold can also be seen in other seasons.

Natures and characteristics
 Cold pertains to yin and is apt to attack yang qi
 Cold having property of coagulation and stagnation
 Cold having property of contraction

All exogenous pathogenic factors characteristic of heavy turbidity, stickiness and stagnation and downward are called dampness pathogen .
 Dampness is the dominant qi in late-summer or in the intersection of summer and autumn, it is the dampest in the year because there is steaming damp-heat and vaporizing water.
 In addition, diseases caused by dampness can also result from swimming and drenching, living in wet and damp places and working in the water.

Natures and characteristics
 Dampness is a yin pathogen and apt to hamper qi movement and damage yang qi
 Characteristic of dampness being heavy and turbid
 Characteristic of dampness being sticky and stagnant
 Characteristic of dampness being descending and apt to attack yin locations

During the time from summer solstice to autumn begins, the exogenous pathogenic factors characteristic of scorching-hot, ascending and dispersive, mixed with dampness are called pathogenic summer-heat .
 Summer-heat is the dominant qi in summer and transformed from fire-heat qi. It is only seen in summer, which is characterized by an apparent seasonality. So summer-heat is a pure exogenous evil and attacks the body usually not from the interior, but the exterior .

 Summer-heat pertains to yang and is characteristic of scorching-hot
 Characteristic of summer-heat being ascending and dispersive, impairment of fluids and exhaustion of qi
 Summer-heat being likely to be mixed with dampness

All exogenous pathogenic factors characteristic of dryness and astringency are called dryness pathogen .
 Dryness, the dominant qi in autumn marked by depurating, descending, astringency and dryness, can be seen in four seasons of the year.

 Characteristic of dryness being dry and puckery and apt to impair fluids
 Dryness likely to injure lung
The lung is a tender viscus. It is externally connected with skin and hair, opens into the nose and aversion to dryness

All exogenous pathogenic factors characteristic of torridity and flaming up are called fire (heat) pathogen .
 Fire (heat) blooms in summer but is not so seasonal as summer-heat and it is no affected by seasons and climates. therefore fire diseases are seen in four seasons.

Natures and characteristics
 Fire (heat) is a yang pathogen which characteristic being flaring up
 Fire (heat) being likely to disturb heart-mind
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Fire (heat) being likely to consume body fluids and exhaust qi
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Fire (heat) being likely to cause convulsion and bleeding
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Fire (heat) being likely to cause sores and abscesses

Concept
 It is an exogenous pathogenic factor which is strongly infective, and it can cause diseases through air, food, bites by insects and animals, dermal contact, etc.
Pathogenic characteristics of pestilential qi
 Strong infective and epidemic
 Acute onset and severe condition
 Diseases vary with pestilential qi but symptoms are similar

 Internal injury cause of disease are those generated internally, which can directly lead to disorders of qi and blood as well as impairment of visecra.
Internal injury due to seven emotions
Improper diet
Overstrain and overease

Seven emotions
： refer to seven emotional activities including joy, anger, worry, anxiety, sadness, fear and fright .
Internal injury due to seven emotions
： when the emotional stimulations are too abrupt, violent, and prolonged and beyond one’s adaptability or when there is diminished adaptability due to imbalanced yin-yang, qi and blood of viscera, can they turn into pathogenic factors.

Emotional stimulus
Healthy qi
Fall ill
Be healthy
Internal
Injury due
To seven emotions
Seven emotions

五脏 liver heart spleen lung kidney store impair essence transform hurt
generate injure
情志 anger joy anxiety sadness fear

 Impairing the viscera
 Affecting the visceral qi movement
 Tending to cause emotional diseases
 Affecting the sequelae of diseases
Rage leading to qi ascending, excessive joy leading to qi loose
Fear leading to qi sinking
Fright leading to qi turbulance.

Unhygienic diet
Improper diet
Food preference

Conscious control of eating
Obstinate
Psychological diseases
Anorexia, lusterless
Complexion, palpitations
Short breath, general lassitude
Overeating impairs the spleen and stomach
Gastric and abdominal fullness and distention eruction, acid regurgitation anorexia, vomiting and diarrhea

 This refers to eating unclean food, such as taking food gone bad, polluted by pestilent evils, parasites or mistaken intake of poisonous food.
Take in the food that has gone bad
Gastric and abdominal pain, nausea and vomiting, diarrhea with borborygmus, or dysentery
Take in the food contaminated by epidemic toxin
Infectious diseases

 This refers to the phenomenon that diseases can start due to the liking of foods with certain taste or specially eating certain foods, including predilection for cold or hot food, or predilection for one of the five tastes or predilection for alcohol.
Predilection for cold or heat
Predilection for alcohol
Predilection for the five tastes
Predilection for one type of food

Predilection for cold or heat
Excessive intake of cold food
Partiality to spicy-hot food
Impair the yang qi of spleen and stomach
Impair the stomach yin
Cold-dampness is produced internally
Abdominal pain diarrhea
Thirst, halitosis, abdominal distention pain, constipation etc

Predilection for the five tastes
Long term of preferring food with a certain taste can cause the preponderance of its corresponding viscera, thus causing disharmony among viscera.
e.g.
acid liver bitter heart sweet pungent spleen lung salt kidney

Predilection for one type of food
 It refers to a long period of special taking of some foods or not taking some foods or lack of certain food.
Long time of excessive ingesting rich food
Production of
Phlegm and transformation of heat
Obesity, vertigo stroke, consumptive thirst and so on
Long time for lacking of some nutrients
Night blindness goiter and tumor

It refers to long time of overstrain or indulgence in easy life.
Normal work can help build the body and improve health
Proper rest can remove fatigue and help recover strength

overexcertion overstrain
Mental overstrains
Sexual overstrains
Overease/ indulgence in easy life

Overexertion
It refers to prolonged engagement of physical labor or exercise, beyond a normal limit.
Consumption of qi
Impair the functions of viscera and cause asthenia of visceral qi
Reluctant to speak fatigue and tiredness sweating, dyspnea etc
Impairment of the body
Injure muscles, tendons and bones

Mental overstrains
It refers to long time of attention or pensiveness.
mental overstrains
Impair the heart and the spleen and consume qi and blood
Heart throb, amnesia, insomnia dreaminess, poor appetite, abdominal distention and diarrhea, etc.

Sexual overstrains
It refers to excessive sexual activities, masturbation, or early pregnancy or giving many births.
sexual overstrains
Consume essence
In the kidney
Aching and weakness in the waistand knees, vertigo, tinnitus, dispiritedness, or spermatorrhea prospermia, and impotence in men and dysmenorrhea leukorrhea or sterility in women

Indulgence in easy life
Absence of physical work sports
Qi stagnation of the spleen and stomach
Reduced appetite, abdominal distention, limb heaviness, muscular flaccidity, oppression in chest and shortness of breath

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