1. Pathophysiology is the study of the underlying mechanisms by which diseases occur and develop, and the study of the changes within the body caused by diseases. It provides a theoretical basis for prevention, diagnosis, and treatment of diseases. 2. Pathophysiology focuses on the alterations in structure, function, and metabolism that occur in the body and the mechanisms underlying the development of diseases. It emphasizes the developmental process of diseases. 3. Pathophysiology plays an important role in bridging basic medical sciences and clinical medicine. It examines both the normal and abnormal functioning of the body.

1. Chapter 1
Introduction of Pathophysiology
Dr. Liu Rui (dr.liurui@Hotmail.com)
Department of Physiology and Pathophysiology
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2. 1. Nature and Aims of Pathophysiology
Basic medicine ―→ Clinical medicine ―→ Practice
―→ Qualified doctor
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Pathophysiology is one of basic medical
sciences, which focus on sick or disordered
life.

3. Basic medical courses
normal body disordered body
structure function structure function
metabolism metabolism
Anatomy Pathoanatomy
Biology Physiology Pathophysiology
Histology Biochemistry
about drugs----Pharmacology
Clinical medical courses
Internal medicine, Surgery, Pediatrics, et al.
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4. Pathophysiology is the study of the underlying
mechanisms by which diseases occur and
develop, and the study of the changes by
diseases within the body. It provides a
theoretical basis for the prevention, diagnosis
and treatment.
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5. Structure
Intact body
Function Metabolism
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6. Alterations
in structure
Disease
Alterations
in function
Alterations in
metabolism
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7. Pathophysiology emphasizes the
developmental process of diseases.
Disruption of the body’s homeostasis;
Alterations in function, metabolism
Mechanisms involved.
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8. 2. Content of pathophysiology
Systemic and organic pathophysiology
Fundamental pathological process
General concept of disease
Pathophysiology in diseases
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9. Experimental study Reproduce disease model in
animals, isolated organs and cells, and observe or
perform something.
Clinical study Observe directly the patient’s symptom,
laboratory testing, the rules of evolution; study the
treatment and prognosis.
Epidemiological study Study the cause or conditional
factors, risk factors, rules of development of some
infective diseases
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3. Research Methods for Pathophysiology

10. Summary
1. Pathophysiology is one of basic medical sciences which
study the rules of origin and evolution of diseases and
the underlying mechanisms --- “the physiology of
disease”.
2. Pathophysiology focuses on the alterations in function
and metabolism of the body and the mechanisms
underlying the development of diseases.
3. Pathophysiology plays an important role in bridge
linking basic medical sciences to clinical medicine.
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11. Pathophysiology Physiology
Different targets
Normal body
Sick body
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12. Pathophysiology Pathoanatomy
Different Points
Function
Metabolism
Mechanism
Structure
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13. Pathophysiology
Bridge course
Basic medicine Clinical medicine
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14. Chapter 2
General Concepts of Diseases
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15. 1. Basic Concepts
1-1 Health
No diseases or infirmity.
A state of complete well-being of all aspects: physical,
mental, social.
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1-2 Disease
 Disease is an abnormal life process caused by certain
pathogenic factors, deviation from the normal status
including structure, function or metabolism.

16. Disease is a disordered state of the body due to
pathogenic agents-host interactions.
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Homeostasis: the process that the internal
environment of an organism tends to remain
balanced and stable, which is required for
optimum functioning.
 Disease can be viewed as a disturbance of
homeostasis.

17. Manifestations of diseases:
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1) Symptom: a subjective complaint
2) Sign: a manifestation that is noted by an
observer, doctor or nurse, through physical
examination, e.g. an elevated body temperature.
3) Laboratory finding: alterations found by
laboratory test, X-ray examination (routine or
CT), electrocardiogram (ECG),
ultrasonography, magnetic resonance imaging
(MRI), etc.

18. Sub-health
There is a situation, in which the person does
not show specific symptoms and signs of illness,
but lives a low-quality of life both physically
and mentally; this is called “sub-health”.
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19. Sub-health
75%
Health
5%
Disease
20%
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20. Senescence (Aging)
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Aging is a natural, lifelong process. There
is a general decline in the structure and
function of the body with advancing age,
resulting in a decreased reserve capacity of
the various organ systems. This results in a
reduction of homeostatic capabilities, making
the older adult more vulnerable to stressors
such as illness, surgery, medical administration,
and environmental changes.

21. 1-4 Two very important concepts
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1) Pathological Process
A series of structural, functional and
metabolic changes that appear in
different diseases, e.g.
fever, inflammation, edema, etc.

22. Pathological Process and Disease
Disease Cause Site Fundamental
Pathological Process
Pneumonia Pneumococcus Lung Fever, inflammation,
hypoxia, acid-base
disturbances, shock
Dysentery Dysentery
bacilli
Intestine Fever, inflammation,
water and electrolytes
disturbances, acid-base
disturbances, shock
Epidemic
meningitis
Meningococcus Meninges Fever, inflammation,
DIC, shock
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23. 2) Syndrome
A set of signs and symptoms that occur
together and are characteristics of a group of
diseases or a specific disease, e.g. ARDS, AIDS
etc.
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24. Acute respiratory distress syndrome
(ARDS)
Shock, infection
acute and severe lung damage
pulmonary edema
lung volumes and compliance↓,
gas exchange impaired
tachypnea, labored breathing, cyanosis,
chest radiograph shows diffuse, symmetrical
interstitial and alveolar infiltration.
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25. 3. Etiology of Disease
Etiology is a science to study the factors
associated with or involved in initiation and
development of diseases. According to their
different roles in the development of diseases,
these pathogenic factors are classified into
cause of disease and conditional factors.
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26. Causes of diseases are the factors that provoke
or cause the particular disease. It determines
the characteristics of the disease and is
absolutely necessary for disease to occur.
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Conditional factors are the factors that do not
cause disease directly but rather influence the
pathogenesis and the natural time course of the
disease.

27. Precipitating factors belong to conditional
factors that promote the development of
diseases by enhancing the roles of cause of
diseases or susceptibility of the body to diseases.
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28. e.g. Infection, arrhythmias, pregnancy, water-
electrolytes and acid-base disturbances are
precipitating factors of heart failure
Tubercle bacillus is the cause of tuberculosis.
Not all people who inhale the organism will
suffer from pulmonary tuberculosis, which
occurs in malnutrition, over fatigue and long-
term depress.
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29. Controlling conditional factors is easier than
eliminating the causes.
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30. Causes of diseases
Extrinsic Factors Biological agents
Physical factors
Chemical factors
Nutritional factors
Pathogenic factors
Intrinsic Factors Genetic factors
Congenital factors
Immunological factors
Psychological factors
Conditional factors Body condition
(predisposing factors) Nature condition
Social condition
Precipitating factors
of diseases
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31. 3-2 Cause of Disease
1) Biological agents bacteria, viruses,
2) Physical factors: trauma and fracture, heatstroke, frostbite.
3) Chemical factors
Corrosive chemicals such as strong acid and bases can
destroy cells at the site of contact. Cell-injurious chemicals are
often called toxic substances or poison. They induce tissue
and cell damage when they enter the body through certain
pathways and reach a sufficient amount. These called
intoxication or poisoning. The toxic substances often act on
specific cells or organs, e.g. CO poisoning.
Electrical injuries
Radiation injuries
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32. 4) Nutritional factors
Excesses: high lipids and carbohydrates
diet obesity, atherosclerosis, diabetes
Deficiencies: lack of certain elements in diet
(1) Vitamin B: beriberi
(2) Vitamin A: night blindness
(3) Vitamin C: scurvy
(4) Vitamin D: rickets
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33. 3-2-2 Intrinsic Factors
1) Genetic factors
Altered genetic material passed from parent to offspring
is called genetic factors, which is classified into three
groups.
Genetic disorders
 Chromosome disorders: the defect results from
numerical and structural abnormalities of chromosome.
 Single-gene disorders: the defect is caused by a single
defective or mutant gene.
 Multifactorial inheritance: polygenetic disorder.
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34. Common Examples of Genetic Disorders
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Disorder Classification Genetics
Huntington
disease
Single-gene disorder Autosomal
dominant
Cystic fibrosis Single-gene disorder Autosomal
dominant
Hypophosphatemia
(vitamin D-
resistant rickets)
Single-gene disorder X-lined dominant
Hemophilia Single-gene disorder X-lined dominant
Down syndrome Chromosome disorder Trisomy 21
Turner syndrome Chromosome disorder 45, X

35. 36
Down syndrome
47, +21

36. Inherited disease: disease caused by altered
genetic material, either single gene mutation or
chromosome aberrations. e.g. color blindness,
Albinism, Down syndrome.
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37. 38
Disorder of multifactorial inheritance
result from a combination of the multiple gene
variations with environmental factors. Therefore
the disease on phenotype are not hereditary, but
these diseases do have a genetic background
(genetic susceptibility), such as congenital heart
disease, cleft lip, coronary artery disease and
hypertension.

38. Genetic predisposition (genetic susceptibility):
a state of body favorable to or showing a
tendency to certain diseases because of
polygenetic abnormalities.
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39. 2) Congenital factors
Environment factors that occurred during
embryonic or fetal development are called
congenital factors, including the physiologic
status of the mother (maternal disease) and
teratogenic agents (infections or drugs taken
during pregnancy), which acts on the embryo or
fetus, causing abnormalities in form or function.
Diseases caused by congenital factors
called congenital disease. e.g. congenital syphilis.
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40. 3) Immunological factors
Although the immune response is a normal
protective mechanism, it may cause disease while
the response is deficient (immunodeficiency
disease), inappropriately strong (allergy or
hypersensitivity----penicillin), or misdirected
(autoimmune disease----ankylosing spondylitis).
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41. 4) Psychological factors
Anxiety, strong or persistant psychological
stimulation or stress may lead to mental illness
and may be related to some disease such as
hypertension, peptic ulcer(duodenal ulcer), and
coronary heart disease.
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42. 3-3 Conditional Factors
1) Body’s condition: age, sex, race; physical
training, mental condition, fatigue, smoking,
lifestyle.
2) Nature condition: weather condition and
geographical environment influence some
epidemical diseases.
3) Social condition: labor and hygiene
conditions----occupational diseases, social
life events----person’s mood and life pattern.
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43. Cause
Conditional factors
Body
Disease
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44. Causes of diseases
Extrinsic Factors Biological agents
Physical factors
Chemical factors
Nutritional factors
Pathogenic factors
Intrinsic Factors Genetic factors
Congenital factors
Immunological factors
Psychological factors
Conditional factors Body condition
(predisposing factors) Nature condition
Social condition
Precipitating factors
of diseases
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45. 4. Pathogenesis of disease
Pathogenesis of disease refers to the rules and
mechanisms underlying the development or
evolution of the diseases.
4-1 General rules for pathogenesis of disease
1) Disruption of homeostasis
If homeostasis is disrupted by a variety of
harmful agents, the body cannot function
optimally, and illness may occur.
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46. 2) Process of damage and anti-damage
Damage can induce body’s anti-damage
responses. The development of a disease
depends on the strength of damage and anti-
damage factors.
Too much anti-damage process will cause new
injury to the body (SIRS----MODS)
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47. 3) Reversal role of cause and result
The cause of the disease lead to a result, which can
be another cause of the disease in the evolution
process.
(Cause) (Result)
Chronic hypoxia erythrocyte￪ polycythemia
(Cause) (Result)
blood viscosity ￪ thrombus
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48. Mechanical trauma Hemorrhage
Cardiac output↓↓
Returned blood
volume ↓ Blood pressure↓↓
Microcirculation
congestion Sympathetic nerve excite
Capillary open Vasoconstriction
Hypoxia in tissure
vicious cycle
Maintain BP
Heart rate ↑
Contractility ↑
beneficial cycle
Recovery
(Cause) (Result)
(Cause)
(Result)
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49. 4) Correlation between systemic and local
regulations
Local alterations can affect the whole body
through neural and humoral regulation, and
the systemic functional statues can in turn
affect the development of local damages via
the same regulating strategies.
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50. e.g. a severe furuncle congestion and edema (local)
fever, chill and WBC ￪ (systemic)
e.g. a recurrent furuncle may represent systemic metabolic
disorder caused by diabetes.
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51. 5. Outcome of Diseases
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Recovery
Death
Complete recovery
Incomplete recovery

52. 5-1 Complete recovery
 The alterations of the function, metabolism
and structure of the body, which appeared in
disease, are perfectly restored.
 The signs and symptoms of the disease are
disappear entirely.
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53. 5-2 Incomplete recovery
The main symptoms are absent.
Some pathological changes are still present in the body.
It is brought about by the compensatory response to
maintain a relatively normal life activity.
--e.g. Heart disease patients
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54. 5-3 Death
5-3-1 Definition:
Irreversible cessation of the function of the body as a
whole.
Contemporary concept of death is brain death.
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55. 5-3-3 Definition of brain death
Prolonged irreversible cessation of all brain
functions, including the brain stem.
5-3-4 Diagnosis of Death
The bases for demonstrating brain death
are the absence of brain stem reflexes, absence
of cortical activity and demonstration of
irreversibility of the state.
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56. Criteria indicating brain death
◆ Irreversible coma and cerebral
unresponsiveness: complete lack of cerebral
response to any form of external excitation.
◆ Absence of all brain stem reflexes: It
includes the absences of pupilary reflex,
corneal reflex, cough reflex and swallowing
reflex.
◆ Cessation of spontaneous respiration
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57. ◆ Absence of any electrical activity of brain
indicated by EEG (electroencephalogram)
for at least 6 hours.
◆ Cessation of cerebral circulation
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58. Summary
1. Disease is an abnormal life process in which
the body’s homeostasis is disrupted by the
interactions of certain pathogenic factor and
the body. Intrinsic changes of diseases are
alterations in structures, functions and
metabolisms of the body.
2. A set of structural, functional and metabolic
changes that occur together in different disease
is called pathologic process.
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59. 3. Pathologic factors include cause of disease
that provoke disease and determine its
characteristics and conditional factors that
participate in and influence the pathogenesis of
disease. Conditional factors that promote the
pathogenesis of disease are called precipitating
factors.
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60. 4. Irreversible cessation of all brain functions,
including the brain stem is called brain death.
The bases for determine it are absence of
cortical activity, absence of brain stem reflexes,
and demonstration of irreversibility of the state.
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