Chapter1(2)ConspectusofDisease1.Conceptsofhealthand

1、1 Chapter 1(2) Conspectus of Disease Chapter 1(2) Conspectus of Disease 1.Concepts of health and disease 2.Etiology 3.Pathogenesis2(1)The definition of health from WHO: health indicates not (1)The definition of health from WHO: health indicates not only without any evidence of disease, but also a st

2、ate of only without any evidence of disease, but also a state of complete well-being physically, mentally and socially. complete well-being physically, mentally and socially. Biomedical modelBio-psycho-social medical modelBiomedical modelBio-psycho-social medical model(2)Senescence:(2)Senescence:(3)

3、Sub-health/chronic fatigue syndrome (CFS): a situation, in (3)Sub-health/chronic fatigue syndrome (CFS): a situation, in which the person does not show specific symptoms and signs of which the person does not show specific symptoms and signs of disease, but lives a low-quality of life both physicall

4、y and disease, but lives a low-quality of life both physically and mentally.mentally.1. Concepts of health and disease1. Concepts of health and disease3(4)Disease: An abnormal life process which is induced by disorders of homeostasis under the action of certain causes and conditions. A pathologic pr

5、ocess with disturbances of function, metabolism, and structure in the body, which are manifested by a characteristic set of signs and symptoms.42. Etiology2. EtiologyEtiology Etiology studies the contributing factors that studies the contributing factors that cause diseases including causative, caus

6、e diseases including causative, predisposing, and precipitating factors.predisposing, and precipitating factors.(1)Etiological factors / Causes of diseases(1)Etiological factors / Causes of diseases (2)Conditions for / Precipitating factors of disease(2)Conditions for / Precipitating factors of dise

7、ase(3) Predisposing factors of disease(3) Predisposing factors of disease5(1)Etiological factors /Causes of diseases(1)Etiological factors /Causes of diseases A etiological factor causes a disease and determines A etiological factor causes a disease and determines its characteristics.its characteris

8、tics. Classification of etiological factors Classification of etiological factorsBiological factorsBiological factorsPhysical factorsPhysical factorsChemical factorsChemical factorsNutritional factorsNutritional factorsImmunological factorsImmunological factorsHereditary factorsHereditary factorsCon

9、genital factorsCongenital factorsSocial and psychological factorsSocial and psychological factors 6Biological factorsBiological factorsBiological agents: microorganisms (such as bacteria, virus, fungi, rickettsia, spirochete, etc.), parasites, and their toxins and metabolic products.7Physical factor

10、sPhysical factorsPhysical agents include mechanical injuries, extremes of temperature, electricity and radiation. 8Chemical factorsChemical factorsChemical agents: can damage cells by varies pathways. For instance, corrosive chemicals, such as strong acids and alkalis, can destroy cells at the site

11、of contact. Other chemicals are selective in their sites of action, such as binding of carbon monoxide to hemoglobin. 9Nutritional imbalanceNutritional imbalanceEither excesses or deficiencies of nutrients predispose cells to injury. For example, high lipids and carbohydrates diet predispose a perso

12、n to obese disease, atherosclerosis and diabetes. The most common nutritional deficiency is the lack in certain constituents, such as vitamins, calcium, and trace elements. 10Immunological factorsImmunological factorsAlthough the immune response is a normal protective Although the immune response is

13、 a normal protective mechanism, it may cause diseases when the response is mechanism, it may cause diseases when the response is inappropriately strong (allergy or hypersensitivity)inappropriately strong (allergy or hypersensitivity)misdirected (autoimmune disease)misdirected (autoimmune disease)def

14、icient (immunodeficiency disease)deficient (immunodeficiency disease)11Genetic factorsGenetic factorsGenetic aberrancies may be caused by single or polygenic mutations. they are transmitted by defective genes, such as sickle cell anemia, and colorblindness. Gene mutation Chromosomal aberration12Cong

15、enital factorsCongenital factors The disorders result from abnormal embryonic development, and most of them are nongenetic. For example, congenital birth defects, mental or physical, may be due to a developmental error during pregnancy. The fetus is usually susceptible to not only infectious disease

16、s but also diet and drug-taking of the mother during intrauterine life; 13Social and psychological factorsSocial and psychological factors S Strong or persistent psychological stimulation or stress may trong or persistent psychological stimulation or stress may lead to mental illness and may be rela

17、ted to some diseases, such lead to mental illness and may be related to some diseases, such as hypertension, peptic ulcer, coronary heart disease, and as hypertension, peptic ulcer, coronary heart disease, and depression.depression.14(2) Conditions for disease (2) Conditions for disease Precipitatin

18、g factor:Precipitating factor: intensify the effects of causative factors and intensify the effects of causative factors and promote the onset and development of diseases, including natural, promote the onset and development of diseases, including natural, physical, and social conditions.physical, a

19、nd social conditions.Risk factorRisk factor 15(3) Predisposing factors of disease(3) Predisposing factors of diseaseA predisposing factor refers to the factor that influences the susceptibility or resistance to certain disease. It includes the genetic constitution, physiological make up, as well as

20、various psychological characteristics. Genetic predisposition 16SummarySummarySpecific causes and predisposing factors together determines the disease occurrence; precipitating factors influence the onset and development of illness. Some diseases only have one cause. However, many diseases are multi

21、factorial in origin, such as hypertension, atherosclerosis and diabetes, etc Environmental and genetic factors17 3. Pathogenesis3. Pathogenesis The general rules and common mechanisms underlying the development of diseases (1) The basic mechanisms of disease(1) The basic mechanisms of disease (2) Ge

22、neral rules of disease development (2) General rules of disease development (3)Outcome of disease (3)Outcome of disease 18(1) The basic mechanisms of disease(1) The basic mechanisms of diseaseAlthough various specific mechanisms may underlie different Although various specific mechanisms may underli

23、e different disorders,they all generally involve the following four levels disorders,they all generally involve the following four levels of deregulations: neural, humoral, cellular and molecular of deregulations: neural, humoral, cellular and molecular mechanisms.mechanisms.19Neural mechanismNeural

24、 mechanism Neural system plays a central role in regulating entire life activities; the disturbance occurred in neural system and in periphery organs are mutually affected. Encephalitis B virus can damage neural system directly; some poisons may interrupt the metabolism of neural cells and the produ

25、ction and release of neurotransmitters. 20Humoral mechanismHumoral mechanism (humoral factors, cytokines) (humoral factors, cytokines) Humoral regulation is crucial in maintaining internal homeostasis. Humoral dysfunction generally indicates the alterations in number and in activities of some humora

26、l factors( hormones, chemical mediators, cytokines). They function through endocrine, paracrine, and autocrine to regulate the metabolism and activities of the cells . . 21During the development of diseases, the regulations in humoral and neural system are usually simultaneous e.g. disturbance of ne

27、ural-humoral regulation in hypertension: constant stress- dysfunction of neural system (cerebral cortex and hypothalamus)- sympathetic-adrenal medulla system-increased secretion of norepinephrine and epinephrine- constriction of arteries/ constriction of renal afferent arterioles will activate renni

28、n-angiotensin-aldosterone system, and finally causes hypertension.22Cellular and molecular mechanismCellular and molecular mechanism Cellular and molecular damages or alterations are fundamental in the development of disease. Strong acid and alkali destroy the cells with no selection; hepatitis viru

29、s damages specifically the hepatocytes. Disease genomics: Disease proteomics23整体水平整体水平细胞水平细胞水平分子水平分子水平研究疾病研究疾病时功能代谢结时功能代谢结构的变化及其构的变化及其发生机制发生机制器官水平器官水平Integrated medicine,Systems biology 24(2) General rules of disease development (2) General rules of disease development The general rules for a diseas

30、e to take place and developDisruption of homeostasis by pathological insultsBodys responses to damages and anti-damage activitiesReversal role of cause-consequence in the disease processRelationship between systemic and local alterations 25Regulation and disruption of homeostasisRegulation and disru

31、ption of homeostasis Homeostasis: the process whereby the internal environment of an organism tends to remain balanced and stable, which is required for optimum functioning. e.g., maintenance of temperature homeostasis. Disruption of homeostasis by harmful agents may cause diseases. e.g., hypertherm

32、ia 26Responses of damages and anti-damages Responses of damages and anti-damages Damages induce anti-damage responses, and the interactions go through the whole process of diseases and determines the development of diseasesOverdo of anti-damages cause new injurese.g. Burning injury (damage)- constri

33、ction of small blood vessels: maintaining proper blood pressure (anti-damage). However, sustained vasoconstriction-hypoxia, cellular necrosis, and dysfunction. 2728Alternation of cause and result in disease process Alternation of cause and result in disease process A cause of a disease leads to a re

34、sult, which can be a new cause for another results in the development of the disease, even forming vicious cycle, e.g. hemorrhagic shock. 29大失血时的因果交替示意图大失血时的因果交替示意图细胞缺氧细胞缺氧微循环障碍微循环障碍休克休克死亡死亡 恶性循环恶性循环血管收缩血管收缩机械力机械力创伤大失血创伤大失血心输出量心输出量交感交感- -肾上腺系统兴奋肾上腺系统兴奋心率心率 心收缩力心收缩力维持动脉血压维持动脉血压恢复恢复 良性循环良性循环30Correlat

35、ion between systemic and local regulationsCorrelation between systemic and local regulations Local alterations and the systemic statues can affect each other and disease development. e.g., a severe furuncle will not only cause local inflammation, but also lead to systemic reactions of fever and elev

36、ated leukocytes. On the other hand, a furuncle may be caused by diabetes and could only be cured by proper control of diabetes. 3132(3) Outcome of disease (3) Outcome of disease -complete recovery, incomplete recovery, death The outcome of a disease is determined by the fight between the evil forces and the defending forces, correct diagnosis and treatment. 33Complete recoveryComplete recoveryThe best outcome of a disease:the etiological factors disappearthe pathologically altered metabolism, structure and function are perfectly restoredthe symptoms a