pathology-1 (Introduction To Pathology)

  • View

  • Download

Embed Size (px)


for medical students

Text of pathology-1 (Introduction To Pathology)

Chapter 1

Introduction to PathologyZhao Guoqiang

Introduction to Pathology Definition of Pathology Evolution of Pathology Subdivision of Pathology Methods for the study of pathology

Definition of PathologyThe word Pathology is derived from two Greek word ---pathos meaning suffering logos meaning study

Definition of PathologyPathology is scientific study of structure and function of the body in disease. It deals with causes, effects, mechanisms and nature of disease.

The knowledge and understanding of pathology is essential for all would-be doctors as well as general practitioners and specialists since unless they know the causes and mechanisms of disease and understand the language spoken by the pathologist in the form of laboratory reports, they would not be able to institute appropriate treatment or suggest preventive measures to the patient.

For the medical student, the discipline of pathology forms a vital bridge between initial learning phase of preclinical science and the final phase of clinical subjects.

Evolution of Pathology From religious beliefs to rational approach (Antiquity to AD 1500) Era of gross pathology (AD 1500 to 1800) Era of technology development and cellular pathology (AD 1800 to 1950s) Modern pathology (1950s to dawn of 21st century)

From religious beliefs to rational approach (Antiquity to AD 1500) Hippocrates (Greece) 460-377 BCPermanently dissociated medicine from religious mysticism. Started study of patients symptoms as method of diagnosis.

Cornelius Celsus (Rome) 53 BC-7 ADDescribed 4 cardinal signs of inflammation (redness, heat, swelling, pain)

Hippocrates (Greece) 460-377 BC

Era of gross pathology (AD 1500 to 1800) Giovanni B Morgagni (Italy) 1682-1771Introduced clinicopathologic correlation (CPC) in the study of disease

John Hunter (Scotland) 1728-1793Introduced pathology museum in the study of disease.

R.T.H. Laennec (France) 1781-1826Described several lung diseases such as various tuberculous lesions of lungs, bronchiectasis. Described cirrhosis of liver (later called Laennecs cirrhosis). Invented stethoscope.

John Hunter (Scotland) 1728-1793

R.T.H. Laennec (France) 1781-1826

Era of technology development and cellular pathology (AD 1800 to 1950s) Rudolf Virchow (Germany) 1821-1905Father of cellular pathology Introduced histopathology as a diagnostic branch by his cellular theory

George N. Papanicolaou (USA) 1883-1962Father of exfoliative cytology Developed Pap smear for detection of cervical cancer in 1930s

Rudolf Virchow (Germany) 1821-1905

George N. Papanicolaou (USA) 1883-1962

Modern pathology (1950s to dawn of 21st century) Watson and Crick 1953Described the structure of DNA

Nowell and Hagerford 1960Philadelphia chromosome in CML i.e. t(9;22)

Gall and Pardue 1969In Situ Hybridization

Kary Mullis 1983Introduced polymerase chain reaction (PCR)

Prof. Liang Boqiang 1899-1968

Prof. Qin Guangyu 1902-1969

Subdivision of Pathology General Pathology --- dealing with general principles of disease Systemic Pathology --- includes study of diseases pertaining to the specific organs and body systems

Subdivision of Pathology Histo-Pathology Experimental Pathology Molecular Pathology Chemical Pathology Geographic Pathology Immunology Haematology Medical Genetics

Methods for the study of Pathology Autopsy Biopsy Cytology

What is Autoposy?Autopsy means "see for yourself". It is a special surgical operation, performed by specially-trained physicians, on a dead body. Its purpose is to learn the truth about the person's health during life, and how the person really died.

What is Bioposy?A biopsy is the removal of a sample of tissue from the body for examination. The tissue will be examined under a microscope to assist in diagnosis. Therefore, only very small samples are needed.

What is Cytology?Cytology can also refer to cytopathology, which analyzes cell structure to diagnose disease .

(Xiao Ping) 87330743


Chapter 2Cellular Adaptations and Cell Injury

Cellular Adaptations and Cell Injury Cellular adaptations Causes of cell injury Mechanisms of cell injury Morphology of cell injury

Cellular Responses to Stress and Noxious Sti

Human body is quite complex and is made of 70,000 billion cells. In health, these cells remain in accord with each other. However, most forms of diseases begin with cell injury and consequent loss of cellular function .

Injury is defined as an alteration in cell structure or function resulting from some stress that exceeds the ability of the cell to compensate through normal physiologic adaptive mechanisms.

Cells typically respond to potentially injurious stress in one of two ways: Adaptation - Cells can alter their structure and/or biochemical processes in order to achieve a new "steady state" and maintain near-normal physiologic functions (homeostasis). Injury - If stressed cells cannot adequately adapt, critical cell functions may be impaired, and the cell is said to be injured.

Reversible and irreversible injuryIf injured cells recover their normal functions when the stress is removed, the injury is said to be reversible. If the injury is severe enough, however, a Point of no return is reached and the cell suffers irreversible injury and dies.

Cellular Responses to Stress and Noxious Stimuli

Adaptation, Reversible injury, Irreversible injury (Cell death)may be considered as different stages of a progressive impairment of the cells normal function and structure.

Cellular adaptations Atrophy Hypertrophy Hyperplasia Metaplasia

AtrophyReduction of the number and size of parenchymal cells of an organ or its parts which was once normal is called atrophy. It may occur from physiologic or pathologic causes.

Physiologic Atrophy Atrophy of thymus after puberty Atrophy of gonads after menopause Atrophy of brain with aging

Pathologic Atrophy Malnutrition atrophy Denervation atrophy Disuse atrophy Pressure atrophy Endocrine atrophy Ischaemic atrophy

Atrophy of one kidney, gross

Atrophy, muscle fibers, microscopic

HypertrophyHypertrophy is an increase in the size of parenchymal cells resulting in enlargement of the organ or tissue, without any change in the number of cells. It may be physiologic or pathologic.

Physiologic Hypertrophy

Pathologic Hypertrophy Hypertrophy of cardiac muscle Hypertrophy of smooth muscle Hypertrophy of skeletal muscle Compensatory hypertrophy

. Hypertrophy, heart, gross

HyperplasiaHyperplasia is an increase in the number of parenchymal cells resulting in enlargement of the organ or tissue. Hyperplasia occurs due to increased recruitment of cells from C0 (resting) phase of the cell cycle to undergo mitosis,when stimulated.

Hyperplasia, prostate, gross

MetaplasiaMetaplasia is defined as a reversible change of one type of epithelial or mesenchymal adult cells to another type of adult epithelial or mesenchymal cells, usually in response to abnormal stimuli, and often reverts back to normal on removal of stimulus.

Metaplasia Epithelial metaplasia 1. Squamous metaplasia 2. Columnar metaplasia Mesenchymal metaplasia 1. Osseous metaplasia 2. Cartilaginous metaplasia

Metaplasia, squamous, larynx, microscopic

Metaplasia , gastric columnar mucosa in esophagus, microsc

Causes of cell injury Hypoxia and ischaemia Physical agents Chemical agents and drugs Infection agents Immunologic reactions Genetic derangements Nutritional imbalances

Hypoxia and ischaemiaHypoxia is the most common causes of cell injury. The causes of hypoxia are as under: The most common mechanism of hypoxic cell injury is by reduced supply of blood to cell i.e. ischaemia. Oxygen deprivation of tissues may result from other causes as well e.g. in anaemia, CO poisoning, cardiorespiratory insufficiency, and increased demand of tissues.

Physical agentsPhysical agents in causation of disease are: Mechanical trauma (e.g. road accidents); Thermal trauma (e.g. by heat and cold); Electricity; Radiation (e.g. ultraviolet and ionising); Rapid changes in atmospheric pressure.

Chemicals and DrugesImportant example include: Chemical poisons such as cyanide, arsenic, mercury; Strong acids and alkalis; Environmental pollutants; Insecticides and pesticides; Oxygen at high concentration; Hypertonic glucose and salt; Social agents such as alcohol and narcotic drugs; Therapeutic administration of drugs.

Infection agentsInjuries by microbes include infections caused by : Bacteria; Rickettsiae; Viruses; Fungi; Protozoa; Metazoa; Other parasites.

Immunologic reactionsImmunity is a double-edged sword --- it protects the host against various injurious agents but it may also turn lethal and cause cell injury e.g. Hypersensitivity reactions; Anaphylactic reactions; Autoimmune reactions.

Genetic derangementsGenetic defects as causes of cell injury are of major interest to scientists and physicians today. The genetic injury may result in a defect caused by a chromosomal abnormality (e.g. the congenital malformations associated with Down syndrome). Variations in the genetic makeup can also influence the susceptibility of cells to injury by chemicals and other environmental insults.

Nutritional imbalancesA deficiency or an excess of nutrients may result in nutritional imbalances. Nutritional deficiency diseases may be due to overall deficiency of nutrients (e.g. starvation), of protein calorie (e.g. marasmus, kwashiorkor), of minerals (e.g. anaemia), or of trace elements. Nutritional excess is a problem of affluent societies r