From birth to adulthood, infants are under constant growth and development. They are physically and functionally different from adults, for they have their own characteristics and laws. The younger they are, the more distinct these characteristics and laws will be. Therefore infants can never be regarded as the epitome of the adults. Doctors of past dynasties had made detailed discussions on the physiological characteristics. Their discussions can be summarized in the following two aspects: delicate zang-fu organs and underdeveloped physique and qi, vigorous vitality and rapid development. A full recognition of the physiological characteristics of the infants is helpful for understanding the developing rules of the infants,health care and diagnosis of diseases.
Delicacy of the zang-fu organs and underdevelopment of physique and qi
The zang-fu organs refer to both the zang organs and fu organs. Delicacy means weakness, liability to attack and tenderness. The physique here refers to the configuration of the human body such as the limbs, skeleton,musculature, essence, blood and body fluid. Qi refers to physiological functional activities, such as lung qi, spleen qi and kidney qi. Delicacy of the Zang fu organs and underdevelopment of the physique and qi mean that, during the childhood, the morphological development and the physiological functions are immature and imperfect, and that the development and functions of the viscera are insufficient. Since the physical substances of the body pertain to yin and the functional activities of the body pertain to yang, doctors
in the ancient times summarized the physiological characteristics of the infants as underdeveloped yin and yang.
The idea that the viscera of the infants are delicate and the body of the infants is underdeveloped is characterized by delicacy of the muscles and skin, loose striae, insufficient qi and blood, weak lung and spleen, insufficient kidney qi, timid will and fragile bones and muscles. For instance, from birth to the infancy, the infants are marked by big head, thin neck, longer upper portion and shorter lower portion. Within the period of one year and a half, the infants are prominent for metopism, thin and soft skin, loose muscular interstitial striae, yellowish and thin hair, liability to sweat during sleep, short voice in crying and instantaneous changes in emotions. The functions of both the five zang organs and six fu organs are underdeveloped, especially the lung, the spleen and the kidney.
Constant insufficiency of the lung
The lung governs qi flowing all through the body. It is related to the skin, the hair and the striae externally. If the lung is delicate, defensive qi will be unconsolidated, making it easier to be attacked by the exogenous patho-genic factors. The lung depends on the spleen to provide nutrients. If the spleen and the stomach are vigorous, defensive qi will be consolidated. However, the spleen of the infants tends to be weak in functions, thus the lung qi of the infants is usually insufficient.
Constant insufficiency of the spleen
The spleen, the postnatal base of life, governs the transformation and transportation of the cereal nutrients and is the source for the generation of blood and qi. Since the spleen and stomach of the infants are underdeveloped, spleen qi is insufficient and the transforming and transporting functions are always weak. On the other hand, the infants are growing fast and need more nutrients than the adults. That is why the spleen qi often appears insufficient.
Constant insufficiency of the kidney
The kidney is the congenital base of life. Kidney yin and kidney yang are the sources of life concerned with the constitution and growth of man. Yin of each organ depends on kidney yin to moisten and nourish it, while yang of each organ relies on kidney yang to warm and nourish it. Many aspects in the development of the infants are concerned with kidney qi, such as the growth, resistance of the body as well as the normal development and functions of the bones, brain, hair, ears and teeth. The kidney qi of the infants is underdeveloped congenitally and gradually becomes abundant with the increase of the age. During the growth and development of the body, the infants are in constant need of sufficient kidney qi to promote the growth. That is why kidney qi of the infants of ten appears insufficient.
Besides, the physiological functions of the infantile five zang organs are also marked by constant abundance of the liver and constant abundance of the heart. The former does not refer to hyperactivity of liver yang which means that during the development of the infants the liver governs smooth flow of qi and has the function of sending up and smoothing flow of qi in the whole body. The latter does not mean hyperactivity of the heart fire. In fact it refers to the phenomena in the infants marked by rapid development, vigorous heart qi and full vitality.
Full vitality and rapid development
Vitality refers to life-force. Full vitality and fast development mean that during the development and growth, the infants quickly become mature and perfect in both the morphological structure and physiological functions. The ancient doctors summarized such characteristics of infatile development as pure yang. The younger the infants are, the more vigorous their vitality and the faster their growth will be. Such a fast development and growth actually follows certain principles and typical changes, the manifestations of which include two aspects: physical development and mental development. Physically the weight of the infants of one year old is three times as much as, the length of their body is one and a half times longer and the head is half a time bigger than that when they were just born. This is the period marked by fast growth and development. As their ages increase, the speed of growth and development gradually slows down.
The pathological characteristics of the infants include two aspects: easy contraction and rapid transmission, pure zang-qi and easy rehabilitation.
Easy contraction and rapid transmission
Susceptibility to diseases means that the infants are subject to the invasion of pathogenic factors. The infantile viscera are delicate and the resistance of the body is weak. Furthermore, the infants are unable to take care of themselves in terms of food and daily life. So they are liable to the attack by six exogenous pathogenic factors and impairment by improper diet. With the other congenital pathological factors, the infants are susceptible to the at tack by exogenous pathogenic factors. The younger the infants are, the higher the morbidity will be.
The lung is a delicate organ governing respiration and being related to the skin and hair. Since the infants are usually deficient in the lung and the function of defending the superficies is weak, pathogenic factors can invade the lung either from the nose and mouth or from the skin and hair. Therefore, it is said that the pathogenic cold attacks the lung and the upper invasion of warm pathogenic factors affects the lung first. During the infancy, the infants are liable to disorders of the pulmonary system, such as common cold, cough, pneumonia and dyspnea with cough.
Since the infants are insufficient in the spleen and weak in transformation and transportation, they are likely to be affected by improper feeding, leading to such symptoms as anorexia, retention of food and diarrhea. Since the spleen is often insufficient, the food and water taken into the body cannot be transformed into cereal nutrients, leading to insufficiency of the production of qi and blood, which further results in asthenia of qi and blood and poor development.
Constant asthenia of the infants refers to insufficiency of infantile kidney essence. Essence includes prenatal essence and postnatal essence. The former is stored in the kidney and the latter is derived from the spleen. Before the infant birth, the prenatal essence nourishes the postnatal essence. That is to say, the prenatal essence promotes the development of the postnatal essence. Mter the infant birth, the postnatal essence nourishes the prenatal essence. That is to say, the cereal nutrients transformed by the spleen and stomach infuse into the kidney when it is abundant. The pathological implication of constant asthenia of the kidney refers to various diseases likely to becaused by insufficiency of the congenital kidney essence, such as metopism, timidity, weakness, five kinds of retardation and five kinds of flaccidity. It may also refer to such pathological conditions as rickets caused by insufficiency of gastrosplenic essence which affects the function of the kidney to store essence.
The infantile abundance of the liver physiologically signifies the vigorous development of shaoyang like sprouting of plants. However, this expression also implies pathological changes, such as sthenic syndromes due to flaring up of liver fire and hyperactivity of liver yang as well as appearance of wind syndrome, convulsion and coma due to high fever.
Fast transmission means that in the course of development, the infantile diseases are liable to changes marked by susceptibility to asthenia and sthenia, and susceptibility to cold and heat.
Asthenia and sthenia refer to the conditions of the healthy qi and the pathogenic factors. Susceptibility to asthenia and sthenia means when the infants are ill, the pathogenic factors tend to be sthenic and the healthy qi tends to be asthenic, and that the sthenic syndrome can immediately transform into an asthenic one and vice versa or simultaneous appearance of both the asthenic and sthenic syndromes. Take pneumonia for example. At the early stage, stagnation of the lung qi may bring on fever, cough, sputum rale and dyspnea. Missed or wrong treatment will lead to pale complexion, cold limbs, profuse sweating, cyanosis of the lips and palpitation which manifest as the asthenic syndromes due to penetration of the pathogenic factors with asthenia of the healthy qi and sudden loss of the heart yang. Take infantile diarrhea for another example. At the primary stage, improper diet or stagnation of the pathogenic factors may bring on such sthenic syndromes as abdominal distension, diarrhea with acid and putrid odour, scanty brownish urine, reddish tongue with greasy fur, slippery and forceful pulse. If diarrhea is not stopped, it will lead to consumption of body fluid or exhaustion of yin and loss of yang, immediately resulting in dry lips, no tears, unconsciousness, cold limbs, thin and weak pulse. Such a quick change of pathological conditions is typical among the infants.
Cold and heat are the generalization of the nature of the pathological changes, while the symptoms of cold and heat mean the clinical manifestation of symptoms due to the difference of the pathological nature, or the transformation of the pathological nature under certain circumstances during the development of the disease. Susceptibility to cold and heat means that the infants present with heat syndrome in the coure of a disease because of their immature yin. So the syndrome is liable to be characterized by impairment of yin due to excess of yang appearing in heat syndrome. On the other hand, the delicate body of an infant due to immature yang is liable to cause yang deficiency or yang exhaustion and yin-cold syndrome occurs.Take the cold syndrome caused by attack of cold and wind for example. The pathogenic factors can be stagnated to transform into heat, the extreme development of which generates wind, leading to heat syndrome marked by high fever and convulsion due to interaction of wind and fire. As to the infants with convulsion, apart from high fever, convulsion and internal closure due to interaction between wind and fire, they may manifest asthenic cold syndromes marked by such symptoms as pale complexion, sweating, cold limbs, weak and indistinct pulse. These are the manifestations of infantile susceptibility to cold and heat.
In short, the changes of cold and heat as well as asthenic and sthenic syndromes in the infants are quicker and more complicated than those in the adults. Therefore in the treatment of infantile diseases, correct differentiation of syndrome, accurate diagnosis and timely treatment are very important.
Purity of the viscera and easiness to rehabilitate
Although the pathological transmission in the infants is fast and the transformation from cold to heat and from asthenia to sthenia in the infants are complicated, the regeneration and repair of the tissues are strong due to the purity of the infantile body, vigorous development and full vitality. Furthermore, the causes of infantile diseases are usually simple. During the course of the pathological development, fewer mental factors are involved. That is why infantile diseases are easier to cure. Even serious diseases can be cured if timely treatment is given and proper cares are taken. Take diseases of the lung system, spleen system and pestilence for example. Though they are commonly encountered, most of them have shorter duration and are quicker to heal. Even some diseases with longer duration, such as infantile malnutrition, can also be cured quickly through replenishing qi and blood, regulating diet and adapting to the climate.