It is divided into central and peripheral. Depending on the nature of the innervation of organs and tissues, the nervous system is divided into somatic and autonomic.
Brain located in the brain part of the skull. It consists of five sections that perform various functions: medulla oblongata, posterior (pons and cerebellum), midbrain, diencephalon, forebrain (cerebral hemispheres).
1. Medulla responsible for breathing, cardiac
activity, protective reflexes (vomiting, coughing).
2. Hindbrain. The pons is the pathway between the cerebellum and
hemispheres. The cerebellum regulates motor acts (balance, coordination of movements).
3. Midbrain- maintains muscle tone, is responsible for orientation, guard and defensive reflexes to visual and sound stimuli.
4. Diencephalon consists of the thalamus, epi- and hypotholamus. The epiphysis is adjacent to it above, and the pituitary gland below. He regulates all complex
motor reflexes, coordinates the work of internal organs and participates
in the humoral regulation of metabolism, water and food consumption, maintaining a constant body temperature.
5. Forebrain carries out mental activities: memory, speech,
thinking, behavior. Consists of gray and white matter. Gray matter
forms the cortex and subcortical structures and is a collection of bodies
neurons and their short processes (dendrites), white matter - long from
sprouts - dexons.
Spinal cord located in the bony spinal canal. It looks like a white cord with a diameter of about one centimeter. It has 31 segments from which a pair of mixed spinal nerves arise. It has two functions - reflex and conductive.
1. Reflex function- implementation of motor and autonomic reflexes (vasomotor, food, respiratory, defecation, urination, sexual).
2. Conductor function- conduction of nerve impulses from the brain to the body and vice versa.
Autonomic nervous system controls the activity of internal organs, glands and does not obey the will of man. It consists of nuclei - a collection of neurons in the brain and spinal cord, vegetative nodes - a collection of neurons outside the central nervous system and nerve endings. The autonomic system is divided into sympathetic and parasympathetic.
Sympathetic system mobilizes the body's strength in extreme situations. Its nuclei are located in the spinal cord, and its nodes are located near it. When it is excited, heart contractions become more frequent and intensified, blood is redistributed from internal organs to muscles, and the glandular motor function of the stomach and intestines decreases.
Parasympathetic system. Its nuclei are located in the medulla oblongata, midbrain and partly in the spinal cord, and its function is the opposite of the sympathetic one - the “lights out” system - promotes the occurrence of recovery processes in the body. Structure and function of the humoral regulatory system of the human body.
Humoral regulation carry out endocrine and mixed secretion glands.
1. Endocrine glands(endocrine glands) do not have excretory ducts and secrete their secretions directly into the blood.
2. Glands of mixed secretion- simultaneously carry out both external and internal secretion (pancreas, gonads) - secrete secretions into the blood and into the organ cavity.
Endocrine glands release hormones. All of them are characterized by a high intensity of the impact, its distance - providing an effect at a distance from the place of production; high specificity of action, as well as the identity of the actions of hormones in animals and humans. Hormones exert their influence on the body in various ways: through the nervous system, the humoral system and directly affecting working organs and physiological processes.
There are a large number of endocrine active glands: hypothalamus, pituitary gland, pineal gland, thymus, gonads, adrenal glands, thyroid gland, parathyroid gland, placenta, pancreas. Let's look at the functions of some of them.
Hypothalamus- participates in the regulation of water-salt metabolism through the synthesis of antiurinary hormone; in homoethermy incontinence; control of emotions and behavior, activity of reproductive organs; causes lactation.
For hypofunction Diabetes insipidus develops due to very strong and abundant diuresis. With hyperfunction, edema, arterial hyperemia appear, and sleep is disturbed.
Pituitary located in the brain, it produces growth hormone, as well as the activity of other glands. Production of lactogenic hormone and hormone that regulates skin and hair pigmentation. Pituitary hormones involve lipid oxidation. For hypofunction dwarfism (nanism) develops in childhood. With hyperfunction, gigantism develops in childhood, and acromegaly in adults.
Thyroid secretes the iodine-dependent hormone thyroxine. With hypofunction in childhood, cretinism develops - growth retardation, mental and sexual development. In adulthood - thyroid goiter, intellectual capabilities decrease, cholesterol levels in the blood increase, the menstrual cycle is disrupted, and miscarriage (premature birth and miscarriages) often occurs. With hyperthyroidism, Graves' disease develops.
Pancreas- secretes two opposite hormones that regulate carbohydrate metabolism - glucagon, which is responsible for the breakdown of glycogen into glucose, and insulin, which is responsible for the synthesis of glycogen from glucose. In case of shortage
glucagon and excess insulin develops a severe hypoglycemic coma. With an excess of glucagon and a deficiency of insulin - diabetes mellitus.
Regulatory systems of the human body - Dubynin V.A. - 2003.
The manual, at a modern level, but in a form accessible to the reader, sets out the basic knowledge of the anatomy of the nervous system, neurophysiology and neurochemistry (with elements of psychopharmacology), the physiology of higher nervous activity and neuroendocrinology.
For university students studying in the field of study 510600 Biology, biological, as well as medical, psychological and other specialties.
TABLE OF CONTENTS
PREFACE - 5 p.
INTRODUCTION - 6-8s.
1 BASICS OF CELLULAR STRUCTURE OF LIVING ORGANISMS - 9-39p.
1.1 Cell theory - 9p.
1.2 Chemical organization of the cell -10-16s.
1.3 Cell structure - 17-26s.
1.4 Protein synthesis in the cell - 26-31s.
1.5 Tissues: structure and functions - 31-39s.
2 STRUCTURE OF THE NERVOUS SYSTEM - 40-96s.
2.1 The reflex principle of the brain - 40-42s.
2.2 Embryonic development of the nervous system - 42-43s.
2.3 General idea of the structure of the nervous system - 43-44s.
2.4 Shells and cavities of the central nervous system - 44-46s.
2.5 Spinal cord - 47-52s.
2.6 General structure of the brain - 52-55s.
2.7 Medulla oblongata - 56-57s.
2.8 Bridge - 57-bOS.
2.9 Cerebellum - 60-62s.
2.10 Midbrain - 62-64s.
2.11 Diencephalon - 64-68s.
2.12 Telencephalon - 68-74s.
2.13 Conducting pathways of the brain and spinal cord - 74-80s.
2.14 Localization of functions in the cerebral cortex - 80-83s.
2.15 Cranial nerves - 83-88s.
2.16 Spinal nerves - 88-93s.
2.17 Autonomic (autonomic) nervous system - 93-96s.
3 GENERAL PHYSIOLOGY OF THE NERVOUS SYSTEM - 97-183s.
3.1 Synaptic contacts of nerve cells - 97-101 pp.
3.2 Resting potential of a nerve cell - 102-107s.
3.3 Action potential of a nerve cell -108-115s.
3.4 Postsynaptic potentials. Propagation of the action potential along the neuron - 115-121s.
3.5 Life cycle of nervous system mediators -121-130s.
3.6 Acetylcholine - 131-138s.
3.7 Norepinephrine - 138-144s.
3.8 Dopamine-144-153С.
3.9 Serotonin - 153-160s.
3.10 Glutamic acid (glutamate) -160-167c.
3.11 Gamma-aminobutyric acid-167-174c.
3.12 Other non-peptide mediators: histamine, aspartic acid, glycine, purines - 174-177c.
3.13 Peptide mediators - 177-183s.
4 PHYSIOLOGY OF HIGHER NERVOUS ACTIVITY - 184-313p.
4.1 General ideas about the principles of organizing behavior. Computer analogy of the work of the central nervous system - 184-191p.
4.2 The emergence of the doctrine of higher nervous activity. Basic concepts of the physiology of higher nervous activity -191-200s.
4.3 Variety of unconditioned reflexes - 201-212p.
4.4 Variety of conditioned reflexes - 213-223s.
4.5 Non-associative learning. Mechanisms of short-term and long-term memory - 223-241s.
4.6 Unconditional and conditional inhibition - 241-251s.
4.7 System of sleep and wakefulness - 251-259s.
4.8 Types of higher nervous activity (temperaments) - 259-268p.
4.9 Complex types of associative learning in animals - 268-279p.
4.10 Features of human higher nervous activity. Second signaling system - 279-290s.
4.11 Ontogenesis of human higher nervous activity - 290-296 p.
4.12 System of needs, motivations, emotions - 296-313p.
5 ENDOCRINE REGULATION OF PHYSIOLOGICAL FUNCTIONS -314-365p.
5.1 General characteristics of the endocrine system - 314-325p.
5.2 Hypothalamic-pituitary system - 325-337s.
5.3 Thyroid gland - 337-341s.
5.4 Parathyroid glands - 341-342s.
5.5 Adrenal glands - 342-347s.
5.6 Pancreas - 347-350s.
5.7 Endocrinology of reproduction - 350-359 p.
5.8 Epiphysis, or pineal gland - 359-361s.
5.9 Thymus - 361-362s.
5.10 Prostaglandins - 362-363s.
5.11 Regulatory peptides - 363-365s.
LIST OF RECOMMENDED READINGS - 366-367 pp.
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Section 1 THE HUMAN BODY AS A BIOLOGICAL SYSTEM
§ 8. Regulatory systems of the human body
Humoral regulation (Latin humor - liquid) is carried out with the help of substances that affect metabolic processes in cells, and therefore the functioning of organs and the body as a whole. These substances enter the blood, and from it into the cells. Thus, increasing the level of carbon dioxide in the blood increases the breathing rate.
Some substances, such as hormones, perform their function even if their concentration in the blood is very low. Most hormones are synthesized and released into the blood by the cells of the endocrine glands, which form the endocrine system. Traveling with the blood throughout the body, hormones can enter any organ. But a hormone affects the functioning of an organ only if the cells of that organ have receptors for this hormone. The receptors combine with hormones (Figure 8.1), and this causes a change in cell activity. Thus, the hormone insulin, attaching to liver cell receptors, stimulates the penetration of glucose into it and the synthesis of glycogen from this compound.
Rice. 8.1. Scheme of action of the hormone:
1 - blood vessel; 2 - hormone molecule; 3 - receptor on the plasma membrane of the cell
The endocrine system ensures the growth and development of the body, its individual parts and organs. It is involved in the regulation of metabolism and adapts it to the needs of the body, which are constantly changing.
Nervous regulation. Unlike the humoral regulatory system, which responds primarily to changes in the internal environment, the nervous system responds to events occurring both inside and outside the body. With the help of the nervous system, the body responds to any influence very quickly. Such reactions to stimuli are called reflexes. The reflex is carried out due to the work of a chain of neurons that form a reflex arc (Fig. 8.2). Each such arc begins with a sensitive, or receptor, neuron (neuron - receptor). It perceives the action of the stimulus and creates an electrical impulse, which is called a nerve impulse. Impulses arising in the receptor neuron travel to the nerve centers of the spinal cord and brain, where information is processed. Here a decision is made to which organ a nerve impulse should be sent in order to respond to the action of the stimulus. After this, the commands are sent through the effector neurons to the organ that responds to the stimulus. Typically, this response is the contraction of a specific muscle or the release of gland secretion. To imagine the speed of signal transmission along a reflex arc, remember how long it takes you to remove your hand from a hot object.
Nerve impulses are transmitted using special substances - mediators. The neuron in which the impulse arose releases them into the sinus gap - the junction of neurons (Fig. 8.3).
Rice. 8.2. Reflex arc:
1 - receptor neuron; 2 - neuron of the nerve center of the spinal cord; 3 - effector neuron; 4 - muscle that contracts
Rice. 8.3. Scheme of information transfer between neurons:
1 - end of the process of one neuron; 2 - mediator;
3 - plasma membrane of another neuron; 4 - synaptic cleft
Mediators attach to the receptor proteins of the target neuron, and in response it generates an electrical impulse and transmits it to the next neuron or other cell.
Immune regulation is provided by the immune system, the task of which is to create immunity - the body’s ability to resist the effects of external and internal enemies. They are bacteria, viruses, various substances that disrupt the normal functioning of the body, as well as its cells that have died or degenerated. The main fighting forces of the immune regulation system are certain blood cells and special substances contained in it.
The human body is a self-regulating system. The task of self-regulation is to support all chemical, physical and biological indicators of the body’s functioning within certain limits. Thus, the body temperature of a healthy person can fluctuate between 36-37°C, blood pressure 115/75-125/90 mm Hg. Art., blood glucose concentration - 3.8-6.1 mmol/l. The state of the body during which all parameters of its functioning remain relatively constant is called homeostasis (Greek homeo - similar, stasis - state). The work of the body's regulatory systems, which operate in constant interconnection, is aimed at maintaining homeostasis.
MAN AND HIS HEALTH
Health and illness
What do people understand by the word “health” when they wish each other “Be healthy!”? Physiologically, an organism is considered healthy if all its cells, tissues, and, accordingly, organs work in accordance with the functions assigned to them. If disruptions occur at any level of the body system, disease may develop.
Diseases are divided into infectious and non-infectious. The former are transmitted from a sick organism to a healthy one and are caused by various pathogens (bacteria, viruses, protozoa). Non-infectious diseases can develop due to insufficient amounts of certain substances in the diet, due to the effects of radiation, and the like.
Increasingly, the deterioration of people's health is becoming a consequence of their own negligent activities. Thus, due to environmental pollution, the number of diseases of cancer and asthma has increased. Smoking, drinking alcohol and drugs cause irreparable harm to all human organ systems.
A separate group consists of hereditary diseases. They are transmitted from parents to children along with the life program contained in the chromosomes. These diseases also include birth defects that can occur during fetal development. They often occur in cases where a pregnant woman smokes, drinks alcohol, suffers from infectious diseases, and the like.
Everyone knows the rules of a healthy lifestyle from childhood. You should eat rationally, exercise, avoid drinking alcohol, nicotine, drugs, watch less TV and limit computer use.
What is cancer?
The famous French scientist B. Perille wrote: “Cancer is a disease that is difficult to both identify and cure.” Unfortunately, these words, spoken about 200 years ago, are still relevant today.
Every day, about 25 million cells die and are formed as a result of division in the human body. For normal functioning of the body, it is necessary that the number of cells in it remains unchanged. If this constancy is disrupted and uncontrolled cell proliferation begins, a tumor can form. Based on their growth pattern and biological characteristics, tumors can be benign or malignant. One of the main signs of benign tumors is the lack of ability to spread throughout the body (metastasis). Malignant tumors are called cancer. Cancer cells differ from normal cells in the absence of characteristic specialization. For example, cancer cells formed in the liver are not able to neutralize and remove harmful substances. Malignant tumor cells are more durable than normal ones, multiply much faster, penetrate into neighboring tissues, destroying them.
What are the causes of malignant tumors? First of all, this is food containing a lot of dyes, food additives and flavorings, tobacco smoking, which leads not only to lung cancer, but also to cancer of the respiratory tract, esophagus, bladder and other organs. Cell degeneration can also be caused by various types of radiation (especially radioactive), some microorganisms and viruses, and impaired immune defense.
Stem cells
It is no coincidence that stem cells received this name: all 350 types of cells in the human body come from them, just as all its branches are formed from the trunk of a tree. From stem cells at the earliest stages of development, a human embryo. As a result of the division of such a cell, one of the daughter cells becomes a Stovbur cell, and the second specializes, acquiring the properties of one or another type of body cell. After some time, the number of cells with unlimited capabilities (as stem cells are sometimes called) in the embryo decreases. A newborn has only a few hundredths of a percent, and with age it becomes even less. In the adult body, stem cells are found mainly in the red bone marrow, but are also found in other organs.
Stem cells are the body's reserve, which it can use to “repair” any damaged tissues. After all, it is known that usually mature specialized cells do not reproduce, so it is impossible to restore tissue at their expense. In this case, help
stem cells can come. They actively divide, specialize and replace dead cells, eliminating damage. A similar stem cell is the so-called cambial cell. One of its daughter cells, as a result of specialization, becomes a cell of the tissue to which the mother cambial cell belongs. Cambial cells are found in almost all tissues; they ensure their growth and renewal. Thus, thanks to cambial cells, the skin epithelium is continuously restored. Scientists are carefully studying the properties of stem and cambial cells in search of ways to use their properties in medicine.
The human body is a multi-level open system that is studied at the molecular, cellular, tissue levels, at the level of organs and physiological systems, as well as at the level of the whole organism.
The chemical components of the body are inorganic (water, salts, oxygen, carbon dioxide) and organic (proteins, fats, carbohydrates, etc.) substances. The main structural and functional unit of the body is the cell, in which metabolic reactions occur all the time and ensure the growth and development of the body. Cell reproduction occurs by division.
Cells similar in structure, function and origin, and intercellular substance form a tissue of a certain type. Organs are formed from tissues, and physiological systems are made from organs. Based on the nature of their functions, they are divided into regulatory (nervous, endocrine, immune) and executive (musculoskeletal, digestive, respiratory, sexual, etc.).
The interaction of executive and regulatory systems is aimed at maintaining the constancy of the body’s vital signs - homeostasis.
Depending on the nature of the innervation of organs and tissues, the nervous system is divided into somatic And vegetative. The somatic nervous system regulates voluntary movements of skeletal muscles and provides sensation. The autonomic nervous system coordinates the activity of internal organs, glands, and the cardiovascular system and innervates all metabolic processes in the human body. The work of this regulatory system is not controlled by consciousness and is carried out thanks to the coordinated work of its two departments: sympathetic and parasympathetic. In most cases, activation of these departments has the opposite effect. The sympathetic influence is most pronounced when the body is under stress or intense work. The sympathetic nervous system is a system of alarm and mobilization of reserves necessary to protect the body from environmental influences. It sends signals that activate brain activity and mobilize protective reactions (thermoregulation process, immune reactions, blood clotting mechanisms). When the sympathetic nervous system is activated, the heart rate increases, digestion processes slow down, the respiratory rate increases and gas exchange increases, the concentration of glucose and fatty acids in the blood increases due to their release by the liver and adipose tissue (Fig. 5).
The parasympathetic division of the autonomic nervous system regulates the functioning of internal organs in a state of rest, i.e. This is a system of ongoing regulation of physiological processes in the body. The predominance of activity of the parasympathetic part of the autonomic nervous system creates conditions for rest and restoration of body functions. When activated, the frequency and strength of heart contractions decreases, digestion processes are stimulated, and the lumen of the respiratory tract decreases (Fig. 5). All internal organs are innervated by both the sympathetic and parasympathetic divisions of the autonomic nervous system. The skin and musculoskeletal system have only sympathetic innervation.
Fig.5. Regulation of various physiological processes of the human body under the influence of the sympathetic and parasympathetic divisions of the autonomic nervous system
The autonomic nervous system has a sensory (sensitive) component, represented by receptors (sensitive devices) located in the internal organs. These receptors perceive indicators of the state of the internal environment of the body (for example, the concentration of carbon dioxide, pressure, the concentration of nutrients in the bloodstream) and transmit this information along centripetal nerve fibers to the central nervous system, where this information is processed. In response to information received from the central nervous system, signals are transmitted through centrifugal nerve fibers to the corresponding working organs involved in maintaining homeostasis.
The endocrine system also regulates the activity of tissues and internal organs. This regulation is called humoral and is carried out with the help of special substances (hormones) that are secreted by endocrine glands into the blood or tissue fluid. Hormones – These are special regulatory substances produced in some tissues of the body, transported through the bloodstream to various organs and affecting their functioning. While the signals that provide nervous regulation (nerve impulses) travel at high speed and require fractions of a second to respond from the autonomic nervous system, humoral regulation occurs much more slowly, and under its control are those processes in our body that require minutes to regulate and a watch. Hormones are powerful substances and produce their effects in very small quantities. Each hormone affects specific organs and organ systems called target organs. Cells of target organs have specific receptor proteins that selectively interact with specific hormones. The formation of a complex of a hormone with a receptor protein includes a whole chain of biochemical reactions that determine the physiological effect of this hormone. The concentration of most hormones can vary within wide limits, which ensures the maintenance of the constancy of many physiological parameters with the continuously changing needs of the human body. Nervous and humoral regulation in the body are closely interconnected and coordinated, which ensures its adaptability in a constantly changing environment.
Hormones play a leading role in the humoral functional regulation of the human body. pituitary gland and hypothalamus. The pituitary gland (lower cerebral appendage) is a part of the brain belonging to the diencephalon, it is attached by a special leg to another part of the diencephalon, hypothalamus, and is in close functional connection with it. The pituitary gland consists of three parts: anterior, middle and posterior (Fig. 6). The hypothalamus is the main regulatory center of the autonomic nervous system; in addition, this part of the brain contains special neurosecretory cells that combine the properties of a nerve cell (neuron) and a secretory cell that synthesizes hormones. However, in the hypothalamus itself, these hormones are not released into the blood, but enter the pituitary gland, into its posterior lobe ( neurohypophysis), where they are released into the blood. One of these hormones antidiuretic hormone(ADH or vasopressin), mainly affects the kidney and the walls of blood vessels. An increase in the synthesis of this hormone occurs with significant blood loss and other cases of fluid loss. Under the influence of this hormone, the loss of fluid by the body is reduced; in addition, like other hormones, ADH also affects brain functions. It is a natural stimulant of learning and memory. Lack of synthesis of this hormone in the body leads to a disease called diabetes insipidus, in which the volume of urine excreted by patients sharply increases (up to 20 liters per day). Another hormone released into the blood by the posterior pituitary gland is called oxytocin. The targets for this hormone are the smooth muscles of the uterus, muscle cells surrounding the ducts of the mammary glands and testes. An increase in the synthesis of this hormone is observed at the end of pregnancy and is absolutely necessary for labor to proceed. Oxytocin impairs learning and memory. Anterior pituitary gland ( adenohypophysis) is an endocrine gland and secretes a number of hormones into the blood that regulate the functions of other endocrine glands (thyroid, adrenal glands, gonads) and are called tropic hormones. For example, adenocorticotropic hormone (ACTH) affects the adrenal cortex and under its influence a number of steroid hormones are released into the blood. Thyroid-stimulating hormone stimulates the thyroid gland. Somatotropic hormone(or growth hormone) affects bones, muscles, tendons, and internal organs, stimulating their growth. In the neurosecretory cells of the hypothalamus, special factors are synthesized that influence the functioning of the anterior pituitary gland. Some of these factors are called Liberins, they stimulate the secretion of hormones by the cells of the adenohypophysis. Other factors statins, inhibit the secretion of corresponding hormones. The activity of neurosecretory cells of the hypothalamus changes under the influence of nerve impulses coming from peripheral receptors and other parts of the brain. Thus, the connection between the nervous and humoral systems is primarily carried out at the level of the hypothalamus.
Fig.6. Diagram of the brain (a), hypothalamus and pituitary gland (b):
1 – hypothalamus, 2 – pituitary gland; 3 – medulla oblongata; 4 and 5 – neurosecretory cells of the hypothalamus; 6 – pituitary stalk; 7 and 12 – processes (axons) of neurosecretory cells;
8 – posterior lobe of the pituitary gland (neurohypophysis), 9 – intermediate lobe of the pituitary gland, 10 – anterior lobe of the pituitary gland (adenohypophysis), 11 – median eminence of the pituitary stalk.
In addition to the hypothalamic-pituitary system, the endocrine glands include the thyroid and parathyroid glands, the adrenal cortex and medulla, islet cells of the pancreas, secretory cells of the intestine, gonads, and some heart cells.
Thyroid– this is the only human organ that is capable of actively absorbing iodine and incorporating it into biologically active molecules, thyroid hormones. These hormones affect almost all cells of the human body; their main effects are related to the regulation of growth and development processes, as well as metabolic processes in the body. Thyroid hormones stimulate the growth and development of all body systems, especially the nervous system. When the thyroid gland is not functioning properly in adults, a disease called myxedema. Its symptoms are a decrease in metabolism and dysfunction of the nervous system: the reaction to stimuli slows down, fatigue increases, body temperature drops, edema develops, the gastrointestinal tract suffers, etc. A decrease in thyroid levels in newborns is accompanied by more severe consequences and leads to cretinism, mental retardation up to complete idiocy. Previously, myxedema and cretinism were common in mountainous areas where glacial water is low in iodine. Now this problem is easily solved by adding sodium iodine salt to table salt. Increased functioning of the thyroid gland leads to a disorder called Graves' disease. In such patients, the basal metabolism increases, sleep is disturbed, the temperature rises, breathing and heart rate increase. Many patients develop bulging eyes, and sometimes a goiter forms.
Adrenal glands- paired glands located at the poles of the kidneys. Each adrenal gland has two layers: the cortex and the medulla. These layers are completely different in their origin. The outer cortical layer develops from the middle germ layer (mesoderm), the medulla is a modified unit of the autonomic nervous system. The adrenal cortex produces corticosteroid hormones (corticoids). These hormones have a wide spectrum of action: they affect water-salt metabolism, fat and carbohydrate metabolism, the immune properties of the body, and suppress inflammatory reactions. One of the main corticoids, cortisol, is necessary to create a reaction to strong stimuli that lead to the development of stress. Stress can be defined as a threatening situation that develops under the influence of pain, blood loss, and fear. Cortisol prevents blood loss, constricts small arterial vessels, and enhances the contractility of the heart muscle. When the cells of the adrenal cortex are destroyed, it develops Addison's disease. Patients experience a bronze tint to the skin in some parts of the body, develop muscle weakness, weight loss, and suffer from memory and mental abilities. Previously, the most common cause of Addison's disease was tuberculosis, now it is autoimmune reactions (erroneous production of antibodies to one's own molecules).
Hormones are synthesized in the adrenal medulla: adrenalin And norepinephrine. The targets of these hormones are all tissues of the body. Adrenaline and norepinephrine are designed to mobilize all a person’s strength in the event of a situation requiring great physical or mental stress, in case of injury, infection, or fear. Under their influence, the frequency and strength of heart contractions increases, blood pressure rises, breathing quickens and the bronchi dilate, and the excitability of brain structures increases.
Pancreas It is a mixed type gland; it performs both digestive (production of pancryotic juice) and endocrine functions. It produces hormones that regulate carbohydrate metabolism in the body. Hormone insulin stimulates the flow of glucose and amino acids from the blood into the cells of various tissues, as well as the formation in the liver from glucose of the main reserve polysaccharide of our body, glycogen. Another pancreatic hormone glucagon, in its biological effects, is an insulin antagonist, increasing blood glucose levels. Glucagon stimulates the breakdown of glycogen in the liver. With a lack of insulin, it develops diabetes, Glucose received from food is not absorbed by the tissues, accumulates in the blood and is excreted from the body in the urine, while the tissues are sorely lacking glucose. Nervous tissue is especially severely affected: the sensitivity of peripheral nerves is impaired, a feeling of heaviness in the limbs occurs, and convulsions are possible. In severe cases, diabetic coma and death may occur.
The nervous and humoral systems, working together, excite or inhibit various physiological functions, which minimizes deviations of individual parameters of the internal environment. The relative constancy of the internal environment in humans is ensured by regulating the activity of the cardiovascular, respiratory, digestive, excretory systems, and sweat glands. Regulatory mechanisms ensure the constancy of the chemical composition, osmotic pressure, number of blood cells, etc. Very advanced mechanisms ensure the maintenance of a constant human body temperature (thermoregulation).
Basic concepts and key terms: regulatory systems, nervous, endocrine, immune systems.
Remember! What is the regulation of human body functions?
Regulation (from Latin regulation) - to put in order, to arrange.
Think!
The human body is a complex system. It contains billions of cells, millions of structural units, thousands of organs, hundreds of functional systems, dozens of physiological systems. And why do they all work harmoniously as a single whole?
What are the features of the regulatory systems of the human body?
REGULATORY SYSTEMS
a set of organs that have a leading influence on the activity of physiological systems, organs and cells. These systems have structural and functional features related to their purpose.
Regulatory systems have central and peripheral sections. Leadership teams are formed in central bodies, and peripheral bodies ensure their distribution and transfer to working bodies for implementation (the principle of centralization).
To monitor the execution of commands, the central bodies of regulatory systems receive feedback from the working bodies. This feature of the activity of biological systems is called the feedback principle.
Information from regulatory systems throughout the body is transmitted in the form of signals. Therefore, the cells of such systems have the ability to produce electrical impulses and chemicals, encode and distribute information.
Regulatory systems regulate functions in accordance with changes in the external or internal environment. Therefore, the leadership teams that are sent to the authorities have either a stimulating or retarding nature (the principle of double action).
Such features in the human body are characteristic of three systems - nervous, endocrine and immune. And they are the regulatory systems of our body.
So, the main features of regulatory systems are:
1) the presence of central and peripheral sections; 2) the ability to produce guidance signals; 3) activities based on feedback; 4) double mode of regulation.
How is the regulatory activity of the nervous system organized?
The nervous system is a set of human organs that perceive, analyze and ensure the activity of physiological organ systems in a very fast manner. According to its structure, the nervous system is divided into two parts - central and peripheral. The central cord includes the brain and spinal cord, and the peripheral cord includes the nerves. The activity of the nervous system is reflexive, carried out with the help of nerve impulses arising in nerve cells. A reflex is the body's response to stimulation that occurs with the participation of the nervous system. Any activity of physiological systems is reflexive in nature. Thus, with the help of reflexes, the secretion of saliva to tasty food, withdrawal of the hand from the thorns of a rose, etc. are regulated.
Reflex signals are transmitted at high speed by nerve pathways that form reflex arcs. This is the path along which impulses are transmitted from receptors to the central parts of the nervous system and from them to the working organs. The reflex arc consists of 5 parts: 1 - receptor link (perceives irritation and converts it into impulses); 2 - sensitive (centripetal) link (transmits excitation to the central nervous system); 3 - central link (information is analyzed in it with the participation of plug-in neurons); 4 - motor (centrifugal) link (transmits guiding impulses to the working body); 5 - working link (with the participation of a muscle or gland a certain action occurs) (ill. 10).
The transfer of excitation from one neuron to another is carried out using synapses. This is a plot of con
tact of one neuron with another or with a working organ. Excitation in synapses is transmitted by special mediator substances. They are synthesized by the presynaptic membrane and accumulate in synaptic vesicles. When nerve impulses reach the synapse, the vesicles burst and transmitter molecules enter the synaptic cleft. The dendrite membrane, called the postsynaptic membrane, receives information and turns it into impulses. The excitation is transmitted further by the next neuron.
So, due to the electrical nature of nerve impulses and the presence of special pathways, the nervous system carries out reflex regulation very quickly and provides a specific effect on organs.
Why are the endocrine and immune systems regulatory?
The endocrine system is a collection of glands that provide humoral regulation of the functions of physiological systems. The highest department of endocrine regulation is the hypothalamus, which, together with the pituitary gland, controls the peripheral glands. The cells of the endocrine glands produce hormones and send them into the internal environment. Blood, and subsequently tissue fluid, delivers these chemical signals to cells. Hormones can slow down or speed up cell function. For example, the adrenal hormone adrenaline revives the heart, while acetylcholine slows it down. The influence of hormones on organs is a slower way of controlling functions than through the nervous system, but the influence can be general and long-term.
The immune system is a collection of organs that form special chemical compounds and cells to provide protective effects on cells, tissues and organs. The central organs of the immune system include the red bone marrow and thymus, and the peripheral organs include the tonsils, appendix, and lymph nodes. The central place among the cells of the immune system is occupied by various leukocytes, and among chemical compounds - antibodies produced in response to foreign protein compounds. Cells and substances of the immune system spread through internal fluids. And their effects, like hormones, are slow, long-lasting and general.
So, the endocrine and immune systems are regulatory systems and carry out humoral and immune regulation in the human body.
ACTIVITY
Learning to know
Independent work with the table
Compare the nervous, endocrine and immune regulatory systems, determine the similarities and differences between them.
Biology + Neurophysiology
Platon Grigorievich Kostyuk (1924-2010) is an outstanding Ukrainian neurophysiologist. The scientist was the first to construct and use microelectrode technology to study the organization of nerve centers, penetrated into a nerve cell, and recorded its signals. He studied how information is converted from electrical to molecular form in the nervous system. Platon Kostyuk proved that calcium ions play an important role in these processes. What is the role of calcium ions in the nervous regulation of the functions of the human body?
Biology + Psychology
Each person reacts to colors differently, depending on their temperament and health. Psychologists, based on their attitude to color, determine a person’s character, his inclinations, intelligence, and type of psyche. Thus, the red color strengthens memory, gives vigor and energy, stimulates the nervous system, and the purple color enhances creativity, has a calming effect on the nervous system, and increases muscle tone. Using your knowledge of regulatory systems, try to explain the mechanism by which color affects the human body.
RESULT
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Questions for self-control |
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1. What are regulatory systems? 2. Name the regulatory systems of the human body. 3. What is a reflex? 4. What is a reflex arc? 5. Name the components of the reflex arc. 6. What are the endocrine and immune regulatory systems? |
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7. What features do the regulatory systems of the human body have? 8. How is the regulatory activity of the nervous system organized? 9. Why are the endocrine and immune systems regulatory? |
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10. Name the similarities and differences between the nervous, endocrine and immune regulatory systems of the body. |
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