1, digestive system
Organs related to digestion and feeding in human body include: mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus, salivary gland, stomach gland, intestinal gland, pancreas, liver, etc. Therefore, it is called digestive organ. These digestive organs work together to digest food and absorb nutrients. The sum of all digestive organs is called digestive system.
The digestive system consists of digestive tract and digestive glands. Responsible for food intake and digestion, so that we can get nutrients such as sugar, fat, protein and vitamins.
Among them, "sugar, fat and protein" are called "three thermogenic nutrients". Sugar is finally digested into glucose; Fat is finally digested into glycerol+fatty acid; Protein is finally digested into amino acids.
Glucose is the energy-supplying substance of human body, fat is the energy-storing substance, and protein is the substance for repairing cells.
2. Nervous system
The nervous system plays a leading role in the human body. All kinds of information of internal and external environment are received by receptors, transmitted to the centers of brain and spinal cord through peripheral nerves for integration, and then controlled and regulated by peripheral nerves to maintain the relative balance between the body and internal and external environment. The nervous system consists of brain, spinal cord, cranial nerve, spinal nerve, autonomic nerve and various ganglia. It can coordinate the activities of various organs and systems in the body, making it a complete whole and interacting with the external environment.
The basic unit of nerve is neuron. Reflex arc consists of receptor, afferent nerve impulse, nerve center, efferent nerve impulse and effector.
3. Respiratory system
The respiratory system includes respiratory tract (nasal cavity, pharynx, larynx, trachea, bronchus) and lung.
In the process of metabolism, animals constantly consume oxygen and produce carbon dioxide. The process of gas exchange between human body and external environment is called breathing. There are two places for gas exchange, one is the gas exchange between the outside world and respiratory organs (such as lungs and gills), which is called lung breathing or gill breathing (or external breathing); The other is the gas exchange between blood and tissue fluid and between body tissues and cells (called internal respiration). In higher animals and humans, the breathing process is completed by three interrelated and simultaneous links: external breathing or lung breathing, including lung ventilation (gas exchange process between outside air and lungs) and lung ventilation (gas exchange process between alveoli and pulmonary capillaries); Transport of gas in blood; Internal respiration or tissue respiration, that is, tissue ventilation (gas exchange process between blood and tissues and cells), sometimes including intracellular oxidation process. It can be seen that the respiratory process depends not only on the respiratory system, but also on the coordination of the blood circulation system. This coordination and their adaptation to the metabolic level of the body are all regulated by nerve and hormone factors.
4. Blood circulation system
The blood circulation system is a system consisting of body fluids (including intracellular fluid, plasma, lymph and tissue fluid) and the pipes through which they circulate. Because animals form the heart, the blood circulation system is divided into two parts: the heart and blood vessels, which is called the cardiovascular system. The circulatory system is a transport system in the organism, which transports nutrients absorbed by the digestive tract and oxygen inhaled through gills or lungs to various tissues and organs, and inputs the metabolites of various tissues and organs into the blood through the same way and excretes them through the lungs and kidneys.
Pulmonary circulation (small circulation): right ventricle → pulmonary artery → pulmonary capillary network → pulmonary vein → left atrium.
Systemic circulation (macrocirculation): left ventricle → aorta → arteries at all levels → capillary network at all levels → veins at all levels → superior/inferior vena cava.
5. Motion system
Exercise system: It consists of bones, joints and muscles, accounting for about 60% of the adult's weight. The bones of the whole body are connected by joints to form bones, which play a role in supporting weight, protecting internal organs and maintaining the basic shape of the human body. Skeletal muscles are attached to bones and contract and relax under the control of the nervous system. When contracting, the joint is used as the fulcrum to pull the bone to change its position and produce movement. Bones and joints are passive parts of the exercise system, while skeletal muscle is the active part of the exercise system. Bone surface is dense and hard, which is called bone density; The interior of the bone is honeycomb, which is called cancellous bone; The cavity in the bone is called marrow cavity, and the center is filled with bone marrow. The bone marrow of fetus and baby is red bone marrow, which is a hematopoietic organ. With the increase of age, the red bone marrow in the bone marrow cavity of long bones is gradually replaced by adipose tissue and becomes yellow bone marrow. Bones are connected together in different forms to form bones. It forms the basic form of human body and provides attachment for muscles. Under the control of nerves, muscles contract and pull the attached bones, and the joint of movable bones is the hub for lever movement. The main function of the motion system is motion. Simple displacement and advanced activities, such as language and writing, are realized through bones, bone connections and skeletal muscles. The second function of the motion system is support. It constitutes the basic form of the human body, including the head, neck, chest, abdomen and limbs, and maintains the posture of the body. The third function of the motion system is protection. Bone, bone integration and skeletal muscle form multiple body cavities, including cranial cavity, chest cavity, abdominal cavity and pelvic cavity, which protect organs. From the point of view of sports, bones are passive parts, skeletal muscles are dynamic parts, and joints are the hub of sports. Some bony or muscular processes that can be seen or touched on the body surface are called body surface scars. They are symbolic for locating organs and structures in the body.
6. Endocrine system
Endocrine glands are some glands in the human body that have no outlet ducts. Its secretions are called hormones. It plays a regulatory role in the growth, development, metabolism and reproduction of the whole body.
The main endocrine glands in human body are hypothalamus, pituitary gland, thyroid gland, adrenal gland, islet, thymus gland and gonad.
7. Urinary system
The urinary system consists of kidney, ureter, bladder and urethra. Its main function is excretion. Excretion refers to the physiological process in which various substances that are not utilized or harmful to the body are transported to the outside world during the metabolism of the body. Part of the discharged substances are metabolites of nutrients; The other part is the product of the destruction of aging cells. In addition, excreta also includes some unnecessary substances ingested with food, such as excess water and inorganic salts.
8. Reproductive system
Reproductive system is the general name of organ components closely related to reproduction in organisms.
The function of reproductive system is to produce germ cells, reproduce new individuals, secrete sex hormones and maintain secondary sexual characteristics.
There are two types of human reproductive system: male and female. According to the position of genitalia, it is divided into two parts: internal genitalia and external genitalia.
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