From birth to adulthood, children are in the process of continuous growth and development. Whether in anatomy, physiology, biochemistry, nutrition and metabolism, immunity and pathology, or in the occurrence, development, symptoms, treatment and prognosis of diseases, there are many differences with adults. Western medical understanding (a) anatomical and physiological characteristics 1. respiratory system: the nasal and nasopharyngeal cavities of children are short, the nasal passage is narrow, the nasal mucosa is tender, the pharynx is relatively small and vertical, and the larynx is relatively long and narrow. The trachea and trachea are narrower than adults, lacking elastic tissues and poor mucosal cilia movement, which cannot expel microorganisms well. The lungs have poorly developed elastic tissues, rich blood vessels, wide capillary and lymphatic tissue gaps, vigorous interstitial development, fewer alveoli, and relatively low lung air content, making them susceptible to infection. In addition, the secretion of immunoglobulin in the respiratory tract of pediatric patients is low, so the immune function is poor. Based on these characteristics, the incidence of respiratory diseases is the highest during the pediatric period, and the reserve capacity of the pediatric respiratory system is lower, and respiratory failure is more likely to occur. Yang Hui, Department of Traditional Chinese Medicine, The First Hospital of Guangzhou Medical University 2, digestive system: the esophagus of newborns and infants lacks glands, the elastic fibers and muscle layer are not fully developed, the stomach is horizontal, the cardia is wide, and the sphincter is not developed enough, so vomiting or overflow is likely to occur. The gastric mucosa of children is rich in blood vessels, with fewer glands and cup cells, and secretes less hydrochloric acid and various enzymes than adults. The intestinal canal of children is relatively long, the intestinal wall is thin, the mucosa is rich in blood vessels, and the permeability is good, so it is conducive to absorption. However, the barrier function of the intestinal wall is poor, and toxins in the intestinal lumen can easily enter the bloodstream through the intestinal wall, causing toxic symptoms. 3.Cardiovascular system: The vagus nerve of the heart is not well developed at birth, and sympathetic nerve is dominant, so the heart rate is faster. 5 years old onwards, the neural structure of the heart gradually has adult characteristics. 4.Urinary system: The kidney is relatively large, the lower end of the kidney is low, the kidney and ureter are wide, the wall muscles and elastic fibers are not fully developed, easy to expand and easy to be pressed and twisted and cause obstruction, resulting in urinary retention and urinary tract infection. The urethra of female infants is very short, with the external opening exposed and close to the anus, making it vulnerable to bacterial contamination. Male infants have a long urethra, but often have a prepuce, when the accumulation of scale can also cause bacterial upstream infection. 5, hematopoietic system: after birth, children are mainly bone marrow hematopoietic. In the first 5 years after birth, all bone marrow is red marrow, all involved in hematopoiesis to meet the needs of growth and development. Later, as the child grows older, the yellow marrow increases while the red marrow decreases accordingly. (B) Clinical characteristics 1. Types of diseases: The types of diseases in pediatric patients are very different from those in adults. Since the immune function is not yet perfect in pediatric patients, immunoglobulins are low, and all systems of the body are not yet anatomically and physiologically sound, the incidence of infectious diseases is higher. Because of the high metabolism of children, the need for nutrients is high, but the gastrointestinal function is immature, so it is very easy to cause nutritional deficiencies and digestive disorders. In addition, it is more common for infants and children to suffer from congenital relic diseases. 2, pathological changes: because the development of children is not mature enough, the response to different causes is often very different from that of adults, so that different pathological changes occur. The same pathogenic factors in different ages of the body will also cause different pathological reactions. For example, in infants and young children, abnormal blood picture can occur when they are slightly stimulated by a disease. Rickets can easily occur when vitamin D is deficient. When the lungs are infected, pathological changes of bronchopneumonia often occur in infants and children. 3, clinical manifestations: children with acute infectious or infectious diseases, often rapid onset, fierce, rapid changes in the condition, easily accompanied by sepsis, respiratory failure, circulatory failure, water and electrolyte disorders. Infectious diseases in newborns are characterized by poor response in all aspects, such as lack of increase in body temperature and high white blood cells. Infants and children with fever are often prone to convulsions, children with diarrhea are prone to dehydration and acidosis, and pediatric pneumonia is more likely to be complicated by heart failure. 4. Prognosis: Although pediatric illnesses have a rapid onset and many changes, they recover quickly if they are treated promptly and appropriately. In addition, the ability to repair all organs and tissues is stronger in children, so there are generally fewer sequelae than in adults. But on the other hand, in some young, weak children, the disease deteriorates quickly, so the mortality rate of pediatrics is also higher than that of adults. Second, the understanding of Chinese medicine (a) physiological characteristics 1, the internal organs are delicate, the shape of gas is not full: the internal organs are the five organs, “shape” refers to the shape of the body structure, that is, the limbs and bones, flesh and bones, essence, blood and fluids, etc.. The “gas” refers to the physiological function activities, such as lung gas, spleen qi, etc. The delicate internal organs refer to the imperfect and fragile development of the systems and organs of the pediatric organism. The form and qi are not fully developed, which means that the structure and functional activities of the child’s body are not yet sound. The lungs, spleen and kidneys are the three most prominent organs in terms of the specific performance of the delicate internal organs of children. The lung is the master of all the qi in the body and the outer skin and hair. If the lung qi is weak, the external function of the body is not solid, therefore, external diseases are most frequent in children. The spleen is the basis of the postnatal period and is responsible for the transportation of nutrients and essence. The kidneys are the foundation of the congenital nature and are responsible for bone and marrow production. Ancient doctors summarized this delicate state of children as “infantile Yin and Yang”. 2, vigorous, rapid development: vigorous refers to the child’s vitality, full of vitality. Rapid development refers to the rapid growth and development of the child. This is another important physiological characteristic of the pediatric period. Because many aspects of the body are not yet mature at birth, therefore, in the process of growth and development, from physical, intellectual and various physiological functions, are constantly to perfect, mature development, the younger the age, the faster the rate of growth and development. The younger the child, the faster the growth and development. Ancient medical practitioners summarized this state of vitality in children as “pure yang”. (2) Pathological characteristics 1, the onset of easy, rapid transmission: because of the delicate internal organs of children, the form of gas is not yet full, the body and function are more fragile, poor resistance to disease, cold and warmth can not be self-regulation, milk and food do not know how to regulate themselves, once the regulation is not appropriate, it is easy to be invaded by the six sexes outside, easy to be injured by the diet, and therefore easy to disease, and the external evil and the lung and spleen evidence of disease is more common, and rapid changes after the disease. The transmission of pediatric diseases is mainly manifested in the mutual transformation of cold, heat, deficiency and reality. In the course of the disease, the cold evidence can easily turn into heat, and the heat can easily produce wind, so clinically, heat evidence and frightening wind are more common in children. The heat evidence can easily lead to Yang deficiency, and the emergence of Yin cold evidence. In children, most of the illnesses start with solid evidence. The actual evidence often quickly turns into deficiency evidence, or the evidence of both deficiency and reality. The ancient medical practitioners summarized this rapid transformation of children as “easy deficiency, easy reality, easy cold, easy heat”. 2, dirty qi clear spirit, easy to recover: pediatric diseases in the process of development and regression, although there is rapid transmission, the condition is easy to deteriorate the side, but also dirty qi clear spirit, vigorous, responsive side. After the disease, after reasonable treatment, the condition will improve quickly and recover quickly, and there are few sequelae. Therefore, timely and correct treatment of children after illness is crucial to the prognosis. The ancient medical practitioners summarized this characteristic of the child’s dirty qi as “the plucking follows the response”.