The most important characteristics of junior high school students' physiological development are

Main characteristics of junior middle school students' physiological development 1. The main changes of junior middle school students' physiology The process of human growth and development is not uniform, but fast and slow, obvious and hidden. There are two peaks: one is infancy and the other is adolescence. Junior one students begin to enter adolescence, their physical development is accelerated and their physiology changes greatly. First of all, the physical appearance has changed suddenly, and most physiological indexes such as height, weight, width and girth have increased obviously. Different genders and ages have different amounts of body shape development, but the development patterns of men and women are basically similar. According to relevant research data, in childhood, boys and girls are similar in height, and boys have a slight advantage. But at the beginning of adolescence, the situation changed. Girls began to enter the sudden growth stage at the age of 10, and reached the peak at the age of eleven or twelve, but the process of boys was about two years later than that of girls. I started to catch up at the age of eleven or twelve, and surpassed girls at the age of fourteen or fifteen. Therefore, first-grade girls are often taller than boys. Secondly, the functions of internal organs tend to be mature, especially the functions of the brain and nervous system are gradually improved. At the age of 390, the newborn baby's brain weighs only 380-700g, which is about1280g in primary school. The brain weight of first-year students is similar to that of adults. The development of brain volume and brain weight is similar. After that, the development of the brain shifted from quantitative indicators such as volume and weight to the improvement of brain function. Thirdly, the emergence of secondary sexual characteristics. Sexual development is a slow process, which begins in the fetal period. Newborn babies develop their first sexual characteristics. After puberty, the sexual organs grow rapidly and have perfect functions, forming the second sexual characteristics of human beings, and at the same time producing germ cells and secreting sex hormones. Boys generally enter the stage of voice change at the age of 13, and Adam's apple, voice change, armpit hair and pubic hair appear one after another; Girls have sharp voices, full breasts, enlarged breasts, gradually widened pelvis, enlarged buttocks, pubic hair and armpit hair appeared one after another. Generally speaking, girls' sexual development is 1 and -2 years earlier than boys', and they begin to develop at the age of 10, and the change at the age of 12 has been remarkable. Breast change is the first information for women to enter puberty, and it is also the earliest and most obvious sign. Generally, girls in grade one in senior high school change like this. 2. The main physiological changes of junior two students If the junior one students are in the early stage of the second growth peak, then the junior two students have entered the real peak. Teachers often say that adolescent students are the same every year. What are the main physiological changes of junior two students and special children? At the second peak of growth and development, the thalamus below the brain will release a hormone (a chemical substance) and destroy the pituitary gland. The pituitary gland, also known as pituitary gland, hangs upside down behind the head and weighs about 1 g, slightly larger than a pea. Although small, it has a great effect. It can produce about 10 kinds of hormones. These three hormones are like three keys, which can open the door of gonad, thyroid and long bone growth respectively. In this way, there have been some obvious changes in the human body, forming the second peak of human growth. First, people's attitude has changed obviously. During this period, the average annual growth value of children's height is 6-8 cm, and many of them may reach 10- 1 1 cm. Weight can also be increased by 5-6 kilograms every year. The second feature began to appear, the boy's Adam's apple was prominent and his voice became thicker; Girls have enlarged breasts, enlarged hips and widened pelvis. With the rapid growth of children's body shape, their intake of nutrients has also increased greatly, so parents should pay full attention to it. Second, the function of human internal organs has been rapidly enhanced. During this period, the child's cardiopulmonary development also made a second leap, and his function was rapidly enhanced. The two main parameters representing the function of cardiovascular system are heart rate and blood pressure. During this period, the heart rate is close to that of adults, from 140 at birth to about 75 beats/min, and then it gradually slows down and tends to be stable, reaching 60-70 beats. During this period, the blood pressure also began to go out of the trough, and generally stabilized at110-120/70-. The shape of the lungs is also 9 times larger than that at birth, and the vital capacity can reach about 2000ml, which can be promoted to the third grade. The structure of nervous system is more complex and its function is more perfect. It shows that the sulcus gyrus of cerebral cortex increases, deepens and the surface area expands; The sudden contact between neurons increases, which makes each neuron functionally connected, which is beneficial to the transmission and integration of information (stimulus). Because the process of each meridian element-dendrites and axons keep branching and extending, various forms of synapses are produced between neurons, thus forming a huge and complex neural network. These changes make children in this period more sensitive and move more quickly. The basic functions of cranial nerves-excitement and inhibition will change according to different tasks, especially the highest regulatory ability of the left hemisphere speech system of the brain is rapidly enhanced, which strengthens children's self-regulation and control ability. It is the accelerated development of human sexual organs and functions. Mainly menarche for girls and spermatorrhea for boys for the first time. Menstruation refers to the arrival of a girl's first menstruation, which is one of the most remarkable signs of female puberty development. It indicates that the sexual development of women is about to mature. The time of menarche is about 12- 15 years old, which has certain differences among different countries, regions or races. The morning and evening of menarche also involves many factors: hot and cold climate, health status, supply and distribution of nutrition, mood and so on. In recent ten years, medical research has also found that trace element zinc is closely related to human growth and development. The preliminary results show that zinc deficiency will lead to growth stagnation and delayed sexual maturity. Male sexual development is reflected in the development of sexual organs. Testis is an organ that produces sperm and secretes androgen. 10 years old only grows slowly, and gradually increases when 1 1 0 years old, and becomes active when 13- 14 years old, and its weight increases to five times that when it was born, and nocturnal emission occurs when 15- 16 years old. This new experience and emotion prompted their interest in the opposite sex to grow, and they began to pay attention to their appearance. Parents should fully understand all kinds of psychological pressures and changes brought about by sexual maturity and give necessary education and guidance in time. 3. The main physiological changes of students in Grade Three After the rapid growth and development of their bodies in Grade One and Grade Two, the physical quality of students in Grade Three is further improved, their sexual development is mature, and their sense of "adult" in appearance and posture is obviously increased. Many parents often say this to others: "My child is wobbling like an adult now." "My girl is getting more and more handsome now. "In this period, children's height, weight, chest circumference, hip circumference, brain function and the development of internal organs have approached the level of adults. The main physiological change is the improvement of overall physical quality. Physical fitness is the energy displayed by muscles when people exercise under the control of the nervous system. Such as speed, endurance, agility, improvement of nervous system function and muscle growth, make the physical quality of middle school students improve rapidly. The first is strength. With the growth of age, muscles gradually develop and strength increases accordingly. In the third year, people's strength has increased considerably and gradually approached the general level of adults. People's strength generally reaches the peak of their lives at the age of 20, especially men. Followed by speed, the physiological basis of "speed" is the flexibility of the brain's excitation and inhibition process. The maturity of brain function improves the coordination and accuracy of all parts of the central nervous system. Reflected in the organ, the actions between parts of the same organ are fast and accurate, and the actions between different organs are fast and closely coordinated, which improves the reaction speed. Because the brain function of junior three students has been basically improved, the growth and development of brain tissue tend to be completed, and the sensitivity and speed are also rapidly improved. Finally, endurance, endurance is the ability of human body to carry out physical activities for a long time, that is, the ability to resist fatigue. Endurance quality is also directly related to the nervous system. During this period, the human brain has the ability to maintain excitement and inhibit rhythm conversion for a long time, enhance the coordination among the sports centers involved in human activities, and rationally distribute physical strength and energy, thus reducing redundant actions in activities, prolonging activity time and improving activity efficiency. At the same time, other organs and systems of internal organs, such as respiratory system, digestive system, circulatory system, muscles and bones, also provide the premise and guarantee for improving endurance quality. In the third grade, boys' vital capacity and heartbeat are bigger than girls', so boys' endurance quality is generally significantly higher than girls'. Of course, in this period, boys are obviously superior to girls in height, weight and other morphological indicators. In addition, the sex organs of junior three students are further developed and their sexual functions tend to be mature. Many children already have normal menstruation or nocturnal emission. Gender issues, gender secrets, fertility, etc. I have learned more about them, but they are still hazy. The gradual maturity of physiology and the immaturity of psychological and social life experience make middle school students have various contradictions and puzzles in their thoughts and psychology at this time, and parents should attach great importance to this.