Lymphoid system

Hematopoietic and immune system organs

One of the basic conditions of human existence is the ability of the body to resist the introduction of infection or other foreign substances. This function is performed by the protective system.

Immunity (from lat. immunitas – exemption from something) is a protection against any foreign substance, including its own altered cells (e.g. malignant). The main mechanism of immunity is the recognition of one’s own and another’s.

In response to the introduction of any foreign or potentially dangerous substance (antigen), the body begins to produce antibody proteins that circulate in the blood, bind to antigens and neutralize them.

The immune system is a set of organs responsible for the presence of immunity in the body. The Central organs of the immune system (lymphoid organs) are the thymus and bone marrow; peripheral – lymph nodes, spleen, lymphoid tissue of the digestive, respiratory systems and genitourinary apparatus (tonsils, lymphoid nodules, lymphoid plaques of the small intestine) (Fig. 22 per cent. insert.) The main cells of the immune system are lymphocytes, which inhabit all organs of the system and are constantly present in the blood ((1.5–4.0)×109 l-1). They take part in immune reactions and are divided into B-lymphocytes that produce antibodies circulating in the blood, and T-lymphocytes, which are mainly responsible for cellular immunity, i.e. destroy foreign cells or their own modified (eg, malignant) or dead cells.

Bone marrow is located in the bone marrow cavities (see section. “Skeleton and its connections” earlier in this Chapter). In a newborn baby, these cavities are completely filled with hematopoietic tissue (red bone marrow), but subsequently, with age, the red bone marrow in the diaphysis of the tubular bones of the limbs is replaced by adipose tissue (yellow bone marrow). Red bone marrow in an adult is located in the cells of spongy substance of flat and spongy bones, epiphyses of long tubular bones. In an adult male total bone marrow weight is 2.5-3 kg, about half-red bone marrow. The red bone marrow is both the Central organ of hematopoiesis and the immune system. It produces blood cells and lymphocytes. Thymus-the second Central organ of the immune system, located behind the handle of the sternum. In the thymus Mature T cells engaged in cell-mediated immunity. The peripheral organs of the immune system are located on the pathways of possible introduction of microbes and other foreign substances into the body or on the pathways of foreign substances formed in the body itself (e.g., malignant cell.) Lymph nodes are located along the lymphatic vessels. Clusters of lymph nodes are present in many areas of the human body (for example, in the groin, armpits, behind the auricle). They are formed by lymphoid tissue and carry out lymph filtration, preventing the ingress of foreign particles into the bloodstream; in addition, they form lymphocytes. Tonsils are clusters of lymphoid tissue located in the area of the pharynx, tongue root and nasopharynx. These include the paired Palatine and tubal, and lingual and the unpaired pharyngeal tonsil. They protect the body from various infections. In the thickness of the mucous membrane and submucosa of the Appendix, digestive tube, respiratory, urinary and genital organs are lymphoid nodules. They are “guard posts”.

Along with immunity, the human body has nonspecific resistance, which depends on many factors. These include the impermeability of healthy skin and mucous membranes for microorganisms; impermeability of barriers between blood and tissues: the presence of bactericidal substances in the body’s biological fluids (saliva, tear, cerebrospinal fluid, blood); isolation of viruses by the kidneys; phagocytic system (macrophages and microphages-neutrophilic granulocytes); hydrolytic enzymes; interferon; lymphokines; complement system, etc. Non-specific protective factors disinfect even substances with which the body has not previously met. Specific begin to act after initial contact with the antigen.

Human health and the natural aging process depend on the state of the lymphoid system and the body’s nonspecific resistance. Let’s call both these systems the term “protection system”. Most diseases are also associated with these systems. It should be emphasized that the protective system is very vulnerable. A huge number of factors depressing our defenses.

We list some of the main ones:

  • alcohol abuse;
  • Smoking;
  • drugs;
  • psychoemotional stress;
  • hypodynamia (reduced physical activity) and hypokinesia (reduced movement);
  • sleep deficit;
  • overweight;
  • poor nutrition;
  • deficiency of vitamins and some mineral elements;
  • emotional state.

It has long been well known that optimists – people who are satisfied with their lives, work, creativity, happy in love and family life-get sick less often and live longer than pessimists. Indeed, the state of the human psyche affects his health. Endorphins (see section. “Endocrine glands” later in this Chapter) not only change the perception of pain and improve mood, they stimulate protective mechanisms, activate cells of the immune system, increasing the effectiveness of its fight against harmful agents. As shown by studies of the last decade, conducted in the United States, on the surface of immune cells there are receptors for endorphins.

In the US, 5,000 patients were examined. It turned out that about 30% of them were preceded by tragic events (serious illness or death of a spouse, child, divorce, loss of work, retirement, etc.). Subsequently, a large number of people were divided into two groups: I – high – risk group – people who have suffered tragic events; II-low-risk group, people who did not have it. In the high-risk group for the next 8 months. 49% fell ill, in the low – risk group-only 9 %.

Analysis of extensive domestic and foreign literature suggests that alcohol, drugs and tobacco have a detrimental effect on the immune system and factors of nonspecific resistance. Alcohol, tobacco and drugs directly affect immune cells and destabilize the Central regulatory mechanisms of immunity. In addition, these substances increase the peroxidation of fats and increase the formation of free radicals. This causes increased consumption of vitamins a, E and C and leads to an increase in the sensitivity of the human body to infection, an increase in the incidence of malignant tumors, the development of autoimmune diseases, violation of hematopoiesis and recovery processes.

Thus, the protective system, which includes immunity and non-specific factors, protects a person from almost all diseases, ranging from the common cold and ending with malignant and cardiovascular diseases, carries out recovery in already developed diseases, contributing to recovery.

And today there is a serious misconception coming from doctors – there are two States: health or disease. In fact, there are many transitional stages between them. Changing health begins with the appearance of subjective symptoms. Signs of violations of the protective system are extremely diverse and numerous. This tiredness, fatigue, depression, irritability, apathy, depression, insomnia, poor health, coughing, muscle weakness, hair loss, blurred vision, indigestion and appetite, headaches and pains in joints and muscles, swollen lymph nodes. And many, many others. One of the most important factors affecting the protective mechanisms is the state of our psyche, emotions, attitude to life. In this state, a man can still help himself. He must change his diet, increase physical activity; more to be in the fresh air, start taking vitamins, means that increase nonspecific resistance; more to rejoice; to devote time to favorite activities; to regulate sexual relations.

If a man does not do this, the symptoms described are joined by signs of the disease that are already diagnosed by the doctor: an increase (or decrease) in blood pressure, changes in blood composition. At this stage, the intervention of a doctor is already necessary, which in combination with the above-mentioned own actions can return a person to health. Otherwise, a specific disease develops, which requires a certain treatment.

The protective system actively resists premature aging. The great Roman orator Cicero called:it is Necessary to resist old age, in every possible way supporting in itself vital forces“. Today, paraphrasing Cicero, we can say:should resist old age, strongly supporting and strengthening the immune system and nonspecific resistance of the body.

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