Farmasevtika instituti farmakologiya va klinik farmatsiya kafedrasi
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Internet 1. http://www.ziyonet.uz 2. http://www.wikipedia.ru 3. http://www.shemist.som 4. http://www.himiki.ru 5. http://www.organicchem.com 6. http://www.rutrecker.org 3. Prezentatsiyalar Mavzu: 1 Mavzu: 2 Mavzu: 3 Mavzu: 4 Mavzu: 5 Mavzu: 6 Mavzu: 7 Mavzu: 8 Mavzu: 9 Mavzu: 10 Ferment Murakkab Oddiy Aminokislotalar Oqsil qismi (apofement) Oqsil bo`lmagan qismi (kofaktor) Metall ionlari Kofermentlar Vitaminli Vitamin bo`lmagan Mavzu: 11 Mavzu: 12 Mavzu: 13 Mavzu: 14 МУШАКЛАРНИНГ МУШАКЛАРНИНГ Қ Қ ИС ИС Қ Қ АРИШ АРИШ ТУРЛАРИ ТУРЛАРИ ß êêà µè ñµà ð è ø ( À ) , à ñóì ì à ö è ÿ ( Á ) , òå òà í óñ (  ) 1 . á è ð è í ÷ è òà ú ñè ð î ò á å ð è ø â à µòè . 2 - òà ú ñè ð î ò á å ð è ø â à µòè Mavzu: 15 Mavzu: 16 Mavzu: 17 Mavzu: 18 4. Tarqatma materiallar, mustaqil ta‘lim uchun materiallar Functional Organization of the Human Bodyand Control of the ―Internal Environment‖ The goal of physiology is to explain the physical and chemical factors that are responsible for the origin, development, and progression of life. Each type of life, from the simple virus to the largest tree or the complicated human being, has its own functional characteristics. Therefore, the vast field of physiology can be divided into viral physiology, bacterial physiology, cellular physiology, plant physiology, human physiology, and many more subdivisions. Human Physiology. In human physiology, we attempt to explain the specific characteristics and mechanisms of the human body that make it a living being. The very fact that we remain alive is the result of complex control systems, for hunger makes us seek food and fear makes us seek refuge. Sensations of cold make us look for warmth. Other forces cause us to seek fellowship and to reproduce. Thus, the human being is, in many ways, like an automaton, and the fact that we are sensing, feeling, and knowledgeable beings is part of this automatic sequence of life; these special attributes allow us to exist under widely varying conditions. Cells as the Living Units of the Body The basic living unit of the body is the cell. Each organ is an aggregate of many different cells held together by intercellular supporting structures. Each type of cell is specially adapted to perform one or a few particular functions. For instance, the red blood cells, numbering 25 trillion in each human being, transport oxygen from the lungs to the tissues. Although the red cells are the most abundant of any single type of cell in the body, there are about 75 trillion additional cells of other types that perform functions different from those of the red cell.The entire body, then, contains about 100 trillion cells. Although the many cells of the body often differ markedly from one another, all of them have certain basic characteristicsthat are alike. For instance, in all cells, oxygen reacts with carbohydrate, fat, and protein to release the energy required for cell function. Further, the general chemical mechanisms for changing nutrients into energyare basically the same in all cells, and all cells deliver end products of their chemical reactions into the surrounding fluids. Almost all cells also have the ability to reproduce additional cells of their own kind. Fortunately, when cells of a particular type are destroyed, the remaining cells of this type usually generate new cells until the supply is replenished. Extracellular Fluid —The ―Internal Environment‖ About 60 percent of the adult human body is fluid, mainly a water solution of ions and other substances. Although most of this fluid is inside the cells and iscalled intracellular fluid, about one third is in the spaces outside the cells and is called extracellular fluid. This extracellular fluid is in constant motion throughout the body. It is transported rapidly in the circulating blood and then mixed between the blood and the tissue fluids by diffusion through the capillary walls. In the extracellular fluid are the ions and nutrientsneeded by the cells to maintain cell life. Thus, all cells live in essentially the same environment—the extracellular fluid. For this reason, the extracellular fluid is also called the internal environment of the body, or the milieu intérieur, a term introduced more than 100 years ago by the great 19th-century French physiologist Claude Bernard. Cells are capable of living, growing, and performing their special functions as long as the proper concentrations of oxygen, glucose, different ions, amino acids, fatty substances, and other constituents are available in this internal environment. Origin of Nutrients in the Extracellular Fluid Respiratory System. Figure 1-1 shows that each time the blood passes through the body, it also flows through the lungs. The blood picks up oxygen in the alveoli, thus acquiring the oxygen needed by the cells. The membrane between the alveoli and the lumen of the pulmonary capillaries, the alveolar membrane, is only 0.4 to 2.0 micrometers thick, and oxygen rapidly diffuses by molecular motion through this membrane into the blood. Gastrointestinal Tract. A large portion of the blood pumped by the heart also passes through the walls of the gastrointestinal tract. Here different dissolved nutrients, including carbohydrates, fatty acids, and amino acids, are absorbed from the ingested food into the extracellular fluid of the blood. Protection of the Body Immune System. The immune system consists of the white blood cells, tissue cells derived from white blood cells, the thymus, lymph nodes, and lymph vessels that protect the body from pathogens such as bacteria, viruses, parasites, and fungi. The immune system provides a mechanism for the body to (1) distinguish its own cells from foreign cells and substances and (2) destroy the invader by phagocytosis or by producing sensitized lymphocytes or specialized proteins (e.g., antibodies) that either destroy or neutralize the invader. Reproduction Sometimes reproduction is not considered a homeostatic function. It does, however, help maintain homeostasis by generating new beings to take the place of those that are dying. This may sound like a permissive usage of the term homeostasis, but it illustrates that, in the finalanalysis, essentially all body structures are organized such that they help maintain the automaticity and continuityof life. Control Systems of the Body The human body has thousands of control systems. The most intricate of these are the genetic control systems that operate in all cells to help control intracellular function and extracellular functions. This subject is discussed in Chapter 3. Many other control systems operate within the organs to control functions of the individual parts of the organs; others operate throughout the entire b ody to control theinterrelations between the organs. For instance, the respiratorysystem, operating in association with the nervous system, regulates the concentration of carbon dioxide in the extracellular fluid. The liver and pancreas regulate the concentration of glucose in the extracellular fluid, and the kidneys regulate concentrations of hydrogen, sodium, potassium, phosphate, and other ions in the extracellular fluid. ―Gain‖ of a Control System. The degree of effectiveness with which a control system maintains constant conditions is determined by the gain of the negative feedback. For instance, let us assume that a large volume of blood is transfused into a person whose baroreceptor pressurecontrol system is not functioning, and the arterial pressure rises from the normal level of 100 mm Hg up to175 mm Hg. Then, let us assume that the same volume of blood is injected into the same person when the baroreceptorsystem is functioning, and this time the pressure increases only 25 mm Hg. Thus, the feedback control system has caused a ―correction‖ of −50 mm Hg—that is, from Summary — Automaticity of the Body The purpose of this chapter has been to point out, first, the overall organization of the body and, second, the means by which the different parts of the body operate in harmony.To summarize, the body is actually a social orderof about 100 trillion cells organized into different functionalstructures, some of which are called organs. Eachfunctional structure contributes its share to the maintenanceof homeostatic conditions in the extracellular fluid,which is called the internal environment. As long as normalconditions are maintained in this internal environment,the cells of the body continue to live and functionproperly. Each cell benefits from homeostasis, and in turn,each cell contributes its share toward the maintenance ofhomeostasis. This reciprocal interplay provides continuousautomaticity of the body until one or more functional systems lose their ability to contribute their share of function.When this happens, all the cells of the body suffer.Extreme dysfunction leads to death; moderate dysfunctionleads to sickness. BibliographyAdolph EF: Physiological adaptations: hypertrophies and superfunctions, Am Sci 60:608, 1972. Bernard C: Lectures on the Phenomena of Life Common to Animals and Plants, Springfield, IL, 1974, Charles C Thomas. Cannon WB: The Wisdom of the Body, New York, 1932, WW Norton. Chien S: Mechanotransduction and endothelial cell homeostasis: the wisdom of the cell, Am J Physiol Heart Circ Physiol 292:H1209, 2007. Csete ME, Doyle JC: Reverse engineering of biological complexity, Science 295:1664, 2002. Danzler WH, editor: Handbook of Physiology, Sec 13: Comparative Physiology, Bethesda, 1997, American Physiological Society. DiBona GF: Physiology in perspective: the wisdom of the body. Neural control of the kidney, Am J Physiol Regul Integr Comp Physiol 289:R633,2005. Dickinson MH, Farley CT, Full RJ, et al: How animals move: an integrative view, Science 288:100, 2000. Garland T Jr, Carter PA: Evolutionary physiology, Annu Rev Physiol 56:579,1994. Gao Q, Horvath TL: Neuronal control of energy homeostasis, FEBS Lett 582:132, 2008. Guyton AC: Arterial Pressure and Hypertension, Philadelphia, 1980, WB Saunders. Guyton AC, Jones CE, Coleman TG: Cardiac Output and Its Regulation, Philadelphia, 1973, WB Saunders. Guyton AC, Taylor AE, Granger HJ: Dynamics and Control of the Body Fluids, Philadelphia, 1975, WB Saunders. Herman MA, Kahn BB: Glucose transport and sensing in the maintenance of glucose homeostasis and metabolic harmony, J Clin Invest 116:1767, 2006. Krahe R, Gabbiani F: Burst firing in sensory systems, Nat Rev Neurosci 5:13,2004. Orgel LE: The origin of life on the earth, Sci Am 271:76, 1994. Quarles LD: Endocrine functions of bone in mineral metabolism regulation, J Clin Invest 118:3820, 2008. Smith HW: From Fish to Philosopher, New York, 1961, Doubleday. Tjian R: Molecular machines that control genes, Sci Am 272:54, 1995. The Cell and Its Functions Each of the 100 trillion cellsin a human being is a livingstructure that can survive for months or many years,provided its surroundingfluids contain appropriatenutrients. To understand the function of organs and other structures of the body, it is essential that we first understand the basic organization of the cell and the functions of its component parts. Organization of the Cell A typical cell, as seen by the light microscope, is shown in Figure 2-1. Its two major parts are the nucleus and the cytoplasm. The nucleus is separated from the cytoplasm by a nuclear membrane, and the cytoplasm is separated from the surrounding fluids by a cell membrane, also called the plasma membrane. The different substances that make up the cell are collectively called protoplasm. Protoplasm is composed mainly of five basic substances: water, electrolytes, proteins, lipids, and carbohydrates. Water. The principal fluid medium of the cell is water, which is present in most cells, except for fat cells, in a concentration of 70 to 85 percent. Many cellular chemicals are dissolved in the water. Others are suspended in the water as solid particulates. Chemical reactions take place among the dissolved chemicals or at the surfaces of the suspended particles or membranes. Ions. Important ions in the cell include potassium, magnesium, phosphate, sulfate, bicarbonate, and smaller quantities of sodium, chloride, and calcium. These are all discussed in more detail in Chapter 4, which considers the interrelations between the intracellular and extracellular fluids. The ions provide inorganic chemicals for cellular reactions. Also, they are necessary for operation of some of the cellular control mechanisms. For instance, ions acting at the cell membrane are required for transmission of electrochemical impulses in nerve and muscle fibers. Proteins. After water, the most abundant substances in most cells are proteins, which normally constitute 10 to 20 percent of the cell mass. These can be divided into two types: structural proteins and functional proteins.Structural proteins are present in the cell mainly in the Lipids. Lipids are several types of substances that are grouped together because of their common property ofbeing soluble in fat solvents. Especially important lipids are phospholipids and cholesterol, which together constitute only about 2 percent of the total cell mass. The significance of phospholipids and cholesterol is that they are mainly insoluble in water and, therefore, are used to formthe cell membrane and intracellular membrane barriersthat separate the different cell compartments. In addition to phospholipids and cholesterol, some cells contain large quantities of triglycerides, also called neutral fat. In the fat cells, triglycerides often account for as much as 95 percent of the cell mass. The fat stored in these cellsrepresents the body‘s main storehouse of energy-givingnutrients that can later be dissoluted and used to provide energy wherever in the body it is needed. Physical Structure of the Cell The cell is not merely a bag of fluid, enzymes, and chemicals; it also contains highly organized physical structures, called intracellular organelles. The physical nature of eachorganelle is as important as the cell‘s chemical constituents for cell function. For instance, without one of theorganelles, the mitochondria, more than 95 percent of the cell‘s energy release from nutrients would cease immediately.The most important organelles and other structuresof the cell are shown in Figure 2-2. Membranous Structures of the Cell Most organelles of the cell are covered by membranes composed primarily of lipids and proteins. These membranesinclude the cell m embrane, nuclear membrane,membrane of the endoplasmic reticulum, and membranesof the mitochondria, lysosomes, and Golgi apparatus.The lipids of the membranes provide a barrier thatimpedes the movement of water and water-soluble substances from one cell compartment to another because water is not soluble in lipids. However, protein molecules in the membrane often do penetrate all the way through the membrane, thus providing specialized pathways, often organizedinto actual pores, for passage of specific substances through the membrane. Also, many other membrane proteins are enzymes that catalyze a multitude of different chemical reactions, discussed here and in subsequent chapters. Cell Membrane The cell membrane (also called the plasma membrane),which envelops the cell, is a thin, pliable, elastic structureonly 7.5 to 10 nanometers thick. It is composed almost entirely of proteins and lipids. The approximate compositionis proteins, 55 percent; phospholipids, 25 percent;cholesterol, 13 percent; other lipids, 4 percent; and carbohydrates, 3 percent. Lipid Barrier of the Cell Membrane Impedes Water Penetration. Figure 2-3 shows the structure of the cell membrane. Its basic structure is a lipid bilayer, which is a thin, double-layered film of lipids—each layer only one molecule thick—that is continuous over the entire cell surface. Interspersed in this lipid film are large globular protein molecules. The basic lipid bilayer is composed of phospholipid molecules. One end of each phospholipid molecule is soluble in water; that is, it is hydrophilic. The other end is soluble only in fats; that is, it is hydrophobic. The phosphate end of the phospholipid is hydrophilic, and the fatty acid portion is hydrophobic.Because the hydrophobic portions of the phospholipidmolecules are repelled by water but are mutually attracted to one another, they have a natural tendency to attach to one another in the middle of the membrane, as shown in Figure 2-3. The hydrophilic phosphate portions then constitute the two surfaces of the complete cell membrane, in contact with intracellular water on the inside of the membrane and extracellular water on the outside surface. The lipid layer in the middle of the membrane is impermeable to the usual water-soluble substances, such as ions, glucose, and urea. Conversely, fat-soluble substances, such as oxygen, carbon dioxide, and alcohol, can penetrate this portion of the membrane with ease. Integral and Peripheral Cell Membrane Proteins. Figure 2-3 also shows globular masses floating in the lipid bilayer. These are membrane proteins, most of which are glycoproteins. There are two types of cell membrane proteins: integral proteins that protrude all the way through the membrane and peripheral proteins that are attached only to one surface of the membrane and do not penetrate all the way through. Many of the integral proteins provide structural channels (or pores) through which water molecules and watersoluble substances, especially ions, can diffuse between the extracellular and intracellular fluids. These protein channels also have selective properties that allow preferential diffusion of some substances over others. Other integral proteins act as carrier proteins for transporting substances that otherwise could not penetrate the lipid bilayer. Sometimes these even transport substances in the direction opposite to their electrochemical gradients for diffusion, which is called ―active transport Cytoplasm and Its Organelles The cytoplasm is filled with both minute and large dispersed particles and organelles. The clear fluid portion of the cytoplasm in which the particles are dispersed is called cytosol; this contains mainly dissolved proteins, electrolytes, and glucose. Dispersed in the cytoplasm are neutral fat globules, glycogen granules, ribosomes, secretory vesicles, and five especially important organelles: the endoplasmic reticulum, the Golgi apparatus, mitochondria, lysosomes, and peroxisomes. Endoplasmic Reticulum Figure 2-2 shows a network of tubular and flat vesicular structures in the cytoplasm; this is the endoplasmic reticulum. The tubules and vesicles nterconnect with one another. Also, their walls are constructed of lipid bilayer membranes that contain large amounts of proteins, similar to the cell membrane. The total surface area of this structure in some cells—the liver cells, for instance—can be as much as 30 to 40 times the cell membrane area. The detailed structure of a small portion of endoplasmic reticulum is shown in Figure 2-4. Ribosomes and the Granular Endoplasmic Reticulum. Attached to the outer surfaces of many parts of the endoplasmic reticulum are large numbers of minute granular particles called ribosomes. Where these are present, the reticulum is called the granular endoplasmic reticulum. The ribosomes are composed of a mixture of RNA and proteins, and they function to synthesize new protein molecules in the cell, as discussed later in this chapter and in Chapter 3. Agranular Endoplasmic Reticulum. Yüklə 2,35 Mb. Dostları ilə paylaş:
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