The following protective mechanisms are involved in the fight against microorganisms: natural barriers - mucous membranes of the nose, throat, respiratory tract, skin; nonspecific mechanisms - attraction of certain types of leukocytes and increase in body temperature (fever), as well as specific mechanisms, in particular antibodies.
Typically, if a microbe penetrates natural barriers, nonspecific and specific defense mechanisms destroy it before it begins to reproduce.
Natural barriers
Normally, intact skin prevents microbes from invading the body, and the vast majority of them overcome this barrier only as a result of injury or burn, insect bites, etc. However, there are exceptions: infection with human papillomavirus, causing warts.
Other effective natural barriers include the mucous membranes, particularly those of the respiratory tract and intestines. Normally, the mucous membranes are covered with mucus, which prevents the penetration of microbes.
For example, the mucous membranes of the eyes are irrigated by tear fluid containing an enzyme called lysozyme. It attacks bacteria, helping to protect the eyes from them. The respiratory tract effectively cleans the air entering it. In the winding nasal passages, on their mucus-covered walls, many foreign substances that enter with the air, including microbes, are retained. If the microorganism reaches the lower respiratory tract (bronchi), the coordinated movement of mucus-coated cilia (like hairs) clears it from the lungs. Coughing also helps remove microorganisms.
Gastrointestinal tract has a number of effective barriers: stomach acid, pancreatic enzymes, bile and intestinal secretions have antibacterial activity. Contractions of the intestines (peristalsis) and the normal sloughing of cells lining the intestines help remove harmful microorganisms.
As for the organs of the urinary system, in men they are protected from bacteria due to their large length urethra(approx. 25 cm). The exception is when bacteria are introduced there with surgical instruments. A woman's vagina is protected by an acidic environment. Flushing effect during emptying Bladder- another defense mechanism in both sexes.
People with impaired defense mechanisms are more susceptible to certain infectious diseases /see. p. For example, with low acidity gastric juice susceptibility to tuberculosis and salmonellosis increases. Balance is important to maintain the body's defense mechanisms various types microorganisms opportunistic flora intestines. Sometimes, under the influence of an antibiotic, which is taken to treat an infection not related to the intestines, the balance of opportunistic flora is disrupted, as a result of which the number of pathogens increases.
Nonspecific defense mechanisms
Any damage, including the invasion of pathogens, is accompanied by inflammation. It mobilizes some of the body's defenses towards the site of injury or infection. As inflammation develops, blood supply increases and white blood cells can more easily pass from blood vessels to the inflamed area.
The number of leukocytes in the blood also increases; the bone marrow releases more cells from the depot and intensively synthesizes new ones. Neutrophils appearing at the site of inflammation begin to capture microorganisms and try to trap them in a limited space / see. page 665/. If this fails, monocytes rush to the site of damage in increasing numbers, having an even greater ability to capture microorganisms. However, these nonspecific defense mechanisms may not be sufficient when there are large numbers of microbes or due to the influence of other factors, such as air pollution (including tobacco smoke), which reduce the strength of the body's defense mechanisms.
Increased body temperature
An increase in body temperature (fever) to more than 37 ° C is actually a protective reaction of the body to the introduction of pathogens or other damage. This reaction strengthens the body's defense mechanisms, causing only relatively minor discomfort in the person.
Normally, body temperature fluctuates throughout the day. Its lowest indicators (level) are observed at 6 o'clock, and the highest - at 16-18 o'clock. Although normal temperature bodies are usually considered 36.6° C, upper limit the norm at 6 o'clock is 36.0° C, and at 16 o'clock - 36.9° C.
A part of the brain called the hypothalamus controls body temperature, and therefore an increase in temperature is a consequence of the regulating influence of the hypothalamus. Body temperature rises to a new higher high level due to the redistribution of blood from the surface of the skin to the internal organs, resulting in reduced heat loss. Trembling may occur, indicating increased heat production from muscle contractions. Changes in the body to conserve and produce more heat continue until the blood at a new, higher temperature reaches the hypothalamus. This temperature is then maintained in the usual manner. Later, when she returns to normal level, the body eliminates excess heat through sweating and redistribution of blood to the skin. When body temperature drops, chills may develop.
Body temperature may rise and return to normal every day. In other cases, the rise in temperature may be remitting, meaning it changes but does not return to normal.
With severe infectious diseases, in some cases, for example in alcoholics, the elderly and young children, body temperature may decrease.
Substances that cause an increase in body temperature are called pyrogens. They can be formed inside the body or come from outside. Pyrogens formed outside the body include microorganisms and the substances they produce, such as toxins.
In fact, pyrogens entering the body from the outside cause an increase in body temperature, stimulating the formation of the body's own pyrogens. Pyrogens inside the body are usually produced by monocytes. However, an infectious disease is not the only cause of increased body temperature; the temperature may increase due to inflammation, malignancy, or allergic reaction.
Causes of increased body temperature
Typically, an increase in body temperature is obvious reason. This could be, for example, the flu or pneumonia. But sometimes the cause is difficult to detect, for example when the membrane is infected heart valve(septic endocarditis). When a person has a fever of at least 38.0°C and careful testing does not reveal the cause, the doctor may label the condition a fever unknown origin.
Such cases include any disease accompanied by an increase in body temperature, but the most common causes in adults are infectious diseases, conditions associated with the formation of antibodies against the body's own tissues ( autoimmune diseases), And malignant tumors(especially leukemia and lymphoma).
To determine the cause of an increase in body temperature, the doctor asks the patient about existing and previous symptoms and diseases, medications taken, possible contacts with infectious patients, recent travel, and so on, since the nature of the increase in temperature usually does not help with diagnosis. However, there are some exceptions. For example, for malaria, a fever that occurs every other day or every third day is typical.
History of recent travel, especially overseas, or exposure to certain materials or animals may provide clues to the diagnosis. A person who has consumed contaminated water (or ice made from contaminated water) may become ill typhoid fever. Anyone who works in a meat processing plant can become infected with brucellosis.
After clarifying such questions, the doctor conducts full examination to find the source of infection and other signs of disease. Depending on the degree of fever and the patient's condition, the examination may be carried out on an outpatient basis or in a hospital. A blood test can detect antibodies against microorganisms. You can also do blood cultures on various nutrient media; determine the number of leukocytes in a blood test. Increased levels of certain antibodies help identify the “culprit” microorganism. An increase in the number of white blood cells usually indicates an infection.
Ultrasound examination (ultrasound), CT scan(CT) and magnetic resonance imaging (MRI) also help in diagnosis. Scanning with radioactively labeled leukocytes can be used to identify the source of inflammation. Because the white blood cells are delivered to areas where infectious agents have accumulated, and the injected white blood cells have a radioactive marker, the scan helps detect the infected area. If the scan results are negative, the doctor may perform a biopsy of liver tissue. bone marrow or other “suspected” organ, followed by examination under a microscope.
Should I reduce it? elevated temperature body
The positive effect of increasing body temperature has already been mentioned. However, the question of the need to reduce it raises some controversy. So, in a child who has previously had an attack of convulsions due to an increase in body temperature (febrile convulsions), it should be reduced.
An adult with heart or lung disease requires the same approach, since heat body increases oxygen demand by 7% for every degree above 36.6 ° C. An increase in body temperature can also cause problems with brain function. Medicines that can lower body temperature are called antipyretics. The most widely used and effective antipyretics are paracetamol and non-steroidal anti-inflammatory drugs such as aspirin. However, aspirin should not be used to reduce body temperature in children and adolescents, as it increases the risk of developing Reye's syndrome, which may result in fatal.
Specific protection mechanisms
The infection unleashes its full power immune system. The immune system produces substances that specifically attack pathogens. For example, antibodies attach to a microorganism and help immobilize it. Antibodies can directly destroy microorganisms or make it easier for white blood cells to recognize and destroy them. The immune system can also send cells called killer T cells (a type of white blood cell) that specifically attack the pathogen. The body's natural defense mechanisms are aided by anti-infective medications, such as antibiotics, antifungals, or antivirals. However, if a person's immune system is significantly impaired, these medications are often ineffective.
1) saturated with carbon dioxide;
2) oxygenated;
3) arterial;
4) mixed.
A2. Applying a splint to a broken limb:
1) reduces its swelling;
2) slows down bleeding;
3) prevents displacement of broken bones;
4) prevents the penetration of microorganisms into the fracture site.
A3. In humans, in connection with upright posture in the process of evolution:
1) the arch of the foot has formed;
2) claws turned into nails;
3) the phalanges of the fingers are fused;
4) thumb opposed to everyone else.
A4. Life processes occurring in the human body are studied by:
1) anatomy;
2) physiology;
3) ecology;
4) hygiene.
A5. Blood, lymph and intercellular substance– types of fabric:
1) nervous;
2) muscular;
3) connecting;
4) epithelial.
A6. The excretory function in the human body and mammals is performed by:
1) kidneys, skin and lungs;
2) small and large intestines;
3) liver and stomach;
4) salivary and lacrimal glands.
A7. Arterial blood in humans it turns into venous into:
1) hepatic vein;
2) capillaries of the pulmonary circulation;
3) capillaries of the systemic circulation;
4) lymphatic vessels.
A8. Primary urine is the liquid that comes from:
1) from blood capillaries into the capsule cavity renal tubule;
2) from the cavity of the renal tubule into the adjacent blood vessels;
3) from the nephron to the renal pelvis;
4) from renal pelvis into the bladder.
A9. You should breathe through your nose, because in the nasal cavity:
1) gas exchange occurs;
2) a lot of mucus is formed;
3) there are cartilaginous half-rings;
4) the air is warmed and purified.
A10. A nerve impulse is called:
1) an electrical wave traveling along a nerve fiber;
2) a long process of a neuron covered with a membrane;
3) the process of cell contraction;
4) a process that ensures inhibition of the recipient cell.
When completing tasks B1–B3, choose three correct answers. In task B4, establish the correspondence.
IN 1. Blood flows through the arteries of the systemic circulation in humans:
1) from the heart;
2) to the heart;
3) saturated with carbon dioxide;
4) oxygenated;
5) faster than in other blood vessels;
6) slower than in other blood vessels.
AT 2. Vitamins are organic matter, which:
1) in negligible quantities they have a strong effect on metabolism;
2) participate, for example, in the processes of hematopoiesis and blood coagulation;
3) found only in vegetables and fruits;
4) balance the processes of heat formation and release;
5) are a source of energy in the body;
6) enter the body, as a rule, with food.
AT 3. To the central nervous system include:
1) sensory nerves;
2) spinal cord;
3) motor nerves;
4) cerebellum;
5) bridge;
6) nerve nodes.
AT 4. Establish a correspondence between the type of neuron processes and their structure and functions.
Structure and functions
1. Provides signal transmission to the neuron body.
2. Externally covered with a myelin sheath.
3. Short and highly branched.
4. Participates in the formation of nerve fibers.
5. Provides signal transmission from the neuron body.
Neuron processes
A. Axon.
B. Dendrite.
Task C. Give a complete, detailed answer to the question: what structural features of the skin help lower body temperature?
Additional task.
Indicate the sequence of blood movement in big circle blood circulation in humans.
A. Left ventricle.
B. Capillaries.
B. Right atrium.
G. Arteries.
D. Vienna.
E. Aorta.
When meeting with pathogenic microbes our body launches a series of protective and adaptive reactions that remove them from the body. Some of them defense mechanisms work with all pathogens (nonspecific mechanisms), others are able to influence only a specific microorganism (specific mechanisms).
Specific mechanisms
Specific defense mechanisms are the work of the body's immune system. It is formed before birth and throughout a person’s life and fights germs and infections after they enter the body.
Nonspecific mechanisms
The first barrier that protects the body from germs, bacteria and infections is nonspecific mechanisms. These include:
- Barrier functions of the skin and mucous membranes. Most microbes are unable to enter the human body through the skin and mucous membranes. This only happens if the skin and mucous membranes have been damaged. The same barrier function, which does not allow germs and infections into the body, has the blinking epithelium of the bronchi and the brush border of the intestinal mucosa. In order to barrier functions worked it is necessary to avoid dysbacteriosis.
- Secretory processes. There is a special secretion on the skin and mucous membrane that contains lysozyme and immunoglobulins. It guarantees bactericidal properties and creates unfavorable conditions for the development of microbes.
- The lymph nodes and lymphoid tissue on internal organs are a biological filter that does not allow germs into the body.
- Humoral mechanisms immunity is formed by interferons, lysozyme and beta-lysines, which provide antiviral protection.
- Cellular resistance occurs due to phagocytosis. Pathogenic microorganisms are absorbed and eliminated from the body without causing harm.
- Reflex reactions of the body. These include coughing, sneezing and other reactions of the body that remove germs from it.
- Reactions of physiological systems. During illness, blood flow is redistributed, the functions of the excretory organs are enhanced, and the liver has an antitoxic effect on the body.
Immunity. A person constantly encounters numerous pathogenic microorganisms - bacteria, viruses. They are everywhere: in water, soil, air, on plant leaves, animal fur. With dust, droplets of moisture during breathing, with food, water, they can easily enter our body. But the person does not necessarily get sick. Why?
Our body has special mechanisms that prevent microbes from penetrating into it and causing infection. Thus, mucous membranes act as a barrier through which not all microbes are able to penetrate. Microorganisms are recognized and destroyed by lymphocytes, as well as leukocytes and macrophages (cells connective tissue). Antibodies play a major role in fighting infections. These are special protein compounds (immunoglobulins) formed in the body when foreign substances enter it. Antibodies are secreted mainly by lymphocytes. Antibodies neutralize and neutralize waste products of pathogenic bacteria and viruses.
Unlike phagocytes, the action of antibodies is specific, that is, they act only on those foreign substances that caused their formation.
Immunity is the body's immunity to infectious diseases. It comes in several types. Natural immunity is developed as a result of illnesses or is inherited from parents to children (this immunity is called innate immunity). Artificial (acquired) immunity occurs as a result of the introduction of ready-made antibodies into the body. This occurs when a sick person is injected with blood serum from recovered people or animals. It is also possible to obtain artificial immunity by administering vaccines - cultures of weakened microbes. In this case, the body actively participates in the production of its own antibodies. This immunity remains for many years.
The English country doctor E. Jenner (1749-1823) drew attention to dangerous disease- smallpox, epidemics of which in those days devastated entire cities. He noticed that milkmaids get sick from smallpox much less often, and if they do get sick, then mild form. He decided to find out why this was happening. It turned out that many milkmaids during work become infected and suffer from cowpox, which people easily tolerate. And Jenner decided on a bold experiment: he rubbed liquid from an abscess on a cow’s udder into the wound of an eight-year-old boy, that is, he made the world’s first vaccination - he inoculated him cowpox. A month and a half later he infected the child smallpox, and the boy did not get sick: he developed immunity to smallpox.
Gradually, smallpox vaccination began to be used in most countries of the world, and terrible disease was defeated.
Blood transfusion. The doctrine of blood transfusion originates from the works of W. Harvey, who discovered the laws of blood circulation. Experiments on blood transfusions to animals began back in 1638, and in 1667 the first successful blood transfusion of an animal was carried out - a young lamb who was dying from repeated bloodletting - a fashionable method of treatment at that time. However, after the fourth blood transfusion, the patient died. Experiments with human blood transfusions ceased for almost a century.
The failures suggested that only human blood could be transfused. The first blood transfusion from person to person was carried out in 1819 by the English obstetrician J. Blundell. In Russia, the first successful blood transfusion from person to person was carried out by G. Wolf (1832). He saved a woman who was dying after giving birth from uterine bleeding. Scientifically based blood transfusion became possible only after the creation of the doctrine of immunity (I. I. Mechnikov, P. Ehrlich) and the discovery of blood groups by the Austrian scientist K. Landsteiner, for which he was awarded the Nobel Prize in 1930.
Human blood groups. The idea of blood groups was formed on turn of XIX-XX centuries In 1901 Austrian researcher K. Landsteiner investigated the problem of blood compatibility during transfusion. By mixing erythrocytes with blood serum in an experiment, he discovered that with some combinations of serum and erythrocytes agglutination (sticking) of erythrocytes is observed, with others - not. The process of agglutination occurs as a result of the interaction of certain proteins: antigens present in erythrocytes - agglutinogens and antibodies contained in plasma - agglutinins. Upon further study of the blood, it turned out that the main agglutinogens of erythrocytes were two agglutinogens, which were named A and B, and in the blood plasma - agglutinins a and p. Depending on the combination of both in the blood, four blood groups are distinguished.
As was established by K. Landsteiner and J. Jansky, in the red blood cells of some people there are no agglutinogens at all, but in the plasma there are agglutinins a and p (group I), in the blood of others there are only agglutinogen A and agglutinin p (group II), in others - only agglutinogen B and agglutinin a ( group III), the erythrocytes of the fourth contain agglutinogens A and B, and do not have agglutinins (group IV).
If, during a transfusion, the blood groups of the donor and the patient (recipient) are selected incorrectly, then a threat is created for the recipient. Once in the patient’s body, red blood cells stick together, which leads to blood clotting, blockage of blood vessels and death of the person.
Rh factor. The Rh factor is a special protein - an agglutinogen, found in the blood of people and monkeys - rhesus macaques (hence the name), discovered in 1940. It turned out that 85% of people have this agglutinogen in their blood, they are called Rh positive (Rh+ ), and y 15% of people do not have this protein in their blood, they are called Rh negative (Rh-). After transfusion of Rh-positive blood to a Rh-negative person, the latter’s blood produces specific antibodies to the foreign protein. Therefore, repeated administration of Rh-positive blood to the same person can cause agglutination of red blood cells and a severe state of shock.
This virus does not spread through sneezing, coughing, kissing, through water, shaking hands, or sharing a plate and spoon. There are no known cases of transmission of the virus from person to person through the bite of a mosquito or flea. It is believed that HIV infection requires contact with blood, semen, cerebrospinal fluid or breast milk patient, and this contact must occur in the body of the infected person. HIV is mainly transmitted by injection with a needle that contains an infected HIV blood, when such blood is transfused, from an infected mother to a baby through blood or milk, during any sexual contact. In the latter case, the likelihood of infection naturally increases in cases where the mucous membrane or skin at the site of contact is damaged.
Test your knowledge
- What is the essence of phagocytosis?
- What mechanisms prevent microbes from entering the body?
- What are antibodies?
- What phenomenon is called immunity?
- What types of immunity are there?
- What is innate immunity?
- What is whey?
- How is the vaccine different from serum?
- What is the merit of E. Jenner?
- What are the blood types?
Think
- Why is it necessary to take into account the blood group and Rh factor when giving a blood transfusion?
- Which blood groups are compatible and which are not?
The outer membranes of our body prevent microbes from entering the body. Microbes that enter the body are destroyed by phagocytes. Immunity is the body's immunity to infectious diseases. There are natural and artificial immunity. Based on the presence or absence of certain antigens and antibodies in a person’s blood, four blood groups are distinguished. Depending on the presence of an antigen called “Rh factor” in red blood cells, people are divided into Rh positive and Rh negative.
“Cardiovascular system” - The wall of the heart consists of three layers - the epicardium, myocardium and endocardium. Nikita Pavlov practices judo, karate, swimming, and table hockey. Harvard step test. Duration recovery period(in seconds). Conclusion. It is automatic. Located in chest retrosternal. The work of the heart is described by mechanical phenomena (suction and expulsion).
“Structure of the heart” - Identify the right and left half of the heart. The structure of the heart of reptiles. The structure of the mammalian heart. Pulmonary artery. Left ventricle. Aristotle. The structure of the human heart. What is the significance of the fluid secreted by the mass covering the heart? Locate the flapper valves in the pictures. Find the vessels flowing into the right and left halves of the heart.
“Lesson Circulatory Organs” - Introducing the techniques of self-observation of activities of cardio-vascular system; Blood vessels. Which statements are true. Study of the human circulatory system. Excessive mental stress does not affect the cardiovascular vascular system. Biology lesson in 8th grade. Heart. Capillaries.
“Blood lesson” - 3. Lesson topic. Hb + O2. Insoluble fibrin thrombus about 400 thousand. The mechanism of erythrocytes performing their functions. 1. Platelets 2. Ca 2+ ions 3. blood serum 4. to the fourth and to itself 5. by the recipient. 4. Summing up. Lesson plan. Fibrin. The person who receives a blood transfusion is called……….. Rh factor.
“Human blood” - blood group III. There are agglutinogens A and B, there are no agglutinins. 1667 – a lamb blood transfusion was carried out to a sick young man. Presentation for a biology lesson on the topic: “Immunity”, grade 8. Special mechanisms that prevent the penetration of microbes. Special antibodies are produced. Repeated transfusion of Rh-positive blood.
“Blood group” - IV (AB) - the youngest. They respond to stress with panic. The oldest is Group I (00). Smart, inventive, purposeful, sensitive and aggressive at the same time. Group I. Blood groups in Russia. Blood map. Objectives: Apparently as a result of the sexual activity of nomads.
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