1、 Chapter 1(2)Conspectus of Disease Chapter 1(2)Conspectus of Disease 1.Concepts of health and disease 2.Etiology 3.Pathogenesis (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 state of
2、only without any evidence of disease,but also a state of complete well-being physically,mentally and plete well-being physically,mentally and socially.Biomedical modelBio-psycho-social medical modelBiomedical modelBio-psycho-social medical model(2)Senescence:(2)Senescence:(3)Sub-health/chronic fatig
3、ue syndrome(CFS):(3)Sub-health/chronic fatigue syndrome(CFS):a situation,in 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 physically and disease,but lives a low-q
4、uality of life both physically and mentally.mentally.1.Concepts of health and disease1.Concepts of health and disease(4)Disease:An abnormal life process which is induced by disorders of homeostasis under the action of certain causes and conditions.A pathologic process with disturbances of function,m
5、etabolism,and structure in the body,which are manifested by a characteristic set of signs and symptoms.2.Etiology2.EtiologyEtiology Etiology studies the contributing factors that studies the contributing factors that cause diseases including causative,cause diseases including causative,predisposing,
6、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 disease(3)Predisposing factors of disease(3)Predisposing fa
7、ctors of disease(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 characteristics.Classification of etiological factors Classification of
8、 etiological factorsBiological factorsBiological factorsPhysical factorsPhysical factorsChemical factorsChemical factorsNutritional factorsNutritional factorsImmunological factorsImmunological factorsHereditary factorsHereditary factorsCongenital factorsCongenital factorsSocial and psychological fac
9、torsSocial and psychological factors Biological factorsBiological factorsBiological agents:microorganisms(such as bacteria,virus,fungi,rickettsia,spirochete,etc.),parasites,and their toxins and metabolic products.Physical factorsPhysical factorsPhysical agents include mechanical injuries,extremes of
10、 temperature,electricity and radiation.Chemical 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 of contact.Other chemicals are selective in their sites of action,such as binding
11、 of carbon monoxide to hemoglobin.Nutritional imbalanceNutritional imbalanceEither excesses or deficiencies of nutrients predispose cells to injury.For example,high lipids and carbohydrates diet predispose a person to obese disease,atherosclerosis and diabetes.The most common nutritional deficiency
12、is the lack in certain constituents,such as vitamins,calcium,and trace elements.Immunological factorsImmunological factorsAlthough the immune response is a normal protective Although the immune response is a normal protective mechanism,it may cause diseases when the response is mechanism,it may caus
13、e diseases when the response is inappropriately strong(allergy or hypersensitivity)inappropriately strong(allergy or hypersensitivity)misdirected(autoimmune disease)misdirected(autoimmune disease)deficient(immunodeficiency disease)deficient(immunodeficiency disease)Genetic factorsGenetic factorsGene
14、tic 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 aberrationCongenital factorsCongenital factors The disorders result from abnormal embryonic development,and most of them are
15、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 diseases but also diet and drug-taking of the mother during intrauterine life;Social and psychological factorsSocial and psy
16、chological 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 related to some diseases,such lead to mental illness and may be related to some diseases,such as hypertension,peptic ulcer,c
17、oronary heart disease,and as hypertension,peptic ulcer,coronary heart disease,and depression.depression.(2)Conditions for disease(2)Conditions for disease Precipitating factor:Precipitating factor:intensify the effects of causative factors and intensify the effects of causative factors and promote t
18、he onset and development of diseases,including natural,promote the onset and development of diseases,including natural,physical,and social conditions.physical,and social conditions.Risk factorRisk factor (3)Predisposing factors of disease(3)Predisposing factors of diseaseA predisposing factor refers
19、 to the factor that influences the susceptibility or resistance to certain disease.It includes the genetic constitution,physiological make up,as well as various psychological characteristics.Genetic predisposition SummarySummarySpecific causes and predisposing factors together determines the disease
20、 occurrence;precipitating factors influence the onset and development of illness.Some diseases only have one cause.However,many diseases are multifactorial in origin,such as hypertension,atherosclerosis and diabetes,etc Environmental and genetic factors 3.Pathogenesis3.Pathogenesis The general rules
21、 and common mechanisms underlying the development of diseases(1)The basic mechanisms of disease(1)The basic mechanisms of disease (2)General rules of disease development(2)General rules of disease development (3)Outcome of disease(3)Outcome of disease(1)The basic mechanisms of disease(1)The basic me
22、chanisms of diseaseAlthough various specific mechanisms may underlie different Although various specific mechanisms may underlie different disorders,they all generally involve the following four levels disorders,they all generally involve the following four levels of deregulations:neural,humoralof d
23、eregulations:neural,humoral,cellular and molecular,cellular and molecular mechanisms.mechanisms.Neural mechanismNeural 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.Encephaliti
24、s B virus can damage neural system directly;some poisons may interrupt the metabolism of neural cells and the production and release of neurotransmitters.HumoralHumoral mechanism mechanism(humoral(humoral factors,cytokines)factors,cytokines)Humoral regulation is crucial in maintaining internal homeo
25、stasis.Humoral dysfunction generally indicates the alterations in number and in activities of some humoral factors(hormones,chemical mediators,cytokines).They function through endocrine,paracrine,and autocrine to regulate the metabolism and activities of the cells.During the development of diseases,
26、the regulations in humoral and neural system are usually simultaneous e.g.disturbance of neural-humoral regulation in hypertension:constant stress-dysfunction of neural system(cerebral cortex and hypothalamus)-sympathetic-adrenal medulla system-increased secretion of norepinephrine and epinephrine-c
27、onstriction of arteries/constriction of renal afferent arterioles will activate rennin-angiotensin-aldosterone system,and finally causes hypertension.Cellular and molecular mechanismCellular and molecular mechanism Cellular and molecular damages or alterations are fundamental in the development of d
28、isease.Strong acid and alkali destroy the cells with no selection;hepatitis virus damages specifically the hepatocytes.Disease genomics:Disease proteomics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 (2)General rules of disease developmen
29、t(2)General rules of disease development The general rules for a disease 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 alt
30、erations Regulation and disruption of homeostasisRegulation and disruption 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 ho
31、meostasis by harmful agents may cause diseases.e.g.,hyperthermia Responses 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-dam
32、ages cause new injurese.g.Burning injury(damage)-constriction of small blood vessels:maintaining proper blood pressure(anti-damage).However,sustained vasoconstriction-hypoxia,cellular necrosis,and dysfunction.Alternation of cause and result in disease process Alternation of cause and result in disea
33、se process A cause of a disease leads to a result,which can be a new cause for another results in the development of the disease,even forming vicious cycle,e.g.hemorrhagic shock.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
34、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Correlation 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 syste
35、mic reactions of fever and elevated leukocytes.On the other hand,a furuncle may be caused by diabetes and could only be cured by proper control of diabetes.(3)Outcome of disease(3)Outcome of disease -complete recovery,incomplete recovery,death The outcome of a disease is determined by the fight betw
36、een the evil forces and the defending forces,correct diagnosis and treatment.Complete recoveryComplete recoveryThe best outcome of a disease:the etiological factors disappearthe pathologically altered metabolism,structure and function are perfectly restoredthe symptoms and signs of the disease disap
37、pear entirely homeostasis is recovered Incomplete recoveryIncomplete recovery The main symptoms and signs disappear but some pathological changes are left behind,namely sequela.Sequela is generally brought about by the compensatory response to maintain a relatively normal activity.For example,the pe
38、rmanent damage to the heart valve after rheumatic fever.DeathDeathagonal stagestage of clinical deathstage of biological death Brain deathBrain deathBrain death is a state of prolonged irreversible cessation of all brain activity with the complete absence of conscious and voluntary movements,respons
39、es to stimuli,brain stem reflexes,and spontaneous respirations.Criteria for brain death(WHO)Criteria for brain death(WHO)Irreversible coma cerebral unresponsibilityCessation of spontaneous respirationAbsence of cephalic reflexes and dilated pupils Absence of electrical activity of brainCessation of
40、cerebral circulation Precise diagnosis of brain death is important for having proper donors in organic transplantation.Brain death(脑死亡)Vegetative state（植物状态）定义自主呼吸意识脑干反射恢复的可能性全脑功能丧失无丧失无无脑的认知功能丧失有有睡眠醒觉周期，但无意识有有SummarySummaryResearch(Molecular,genetic,comprehensive,multi-discipline)Purpose:mechanisms,prevention,diagnosis,and treatment Disease spectrum changes
