Introduction of Pathology

Dr Prom Phanit, DTM & H, MCTM

Objectives

• Define common terms used in Pathology

• Appreciate the deviations from normal to abnormal structure and functions of the body system.

Definition of pathology

• Pathology is the scientific study of disease. It includes the functional and structural changes in disease.

• It is often studied in specimen obtained post-mortem, or following death.

• The abnormal specimens may be grossly visible with the naked eye, or may only be observed microscopically.

History of Pathology (1)

• Morbid anatomy: The first opportunity for the scientific study of disease come from the thorough internal examination of the body after death- autopsies have been performed scientifically from about 300 BC and have revealed much information of many diseases.

• The term "autopsy" derives from the Ancient Greek autopsia, "to see for oneself",

History of Pathology (1)

• Around 3000 e ancient Egyptians were one of the first civilizations to practice the removal and examination of the internal organs of humans in the religious practice of mummification

History of Pathology (1)

History of Pathology (1)

History of Pathology (2)

• Microscopic and cellular pathology: Pathology was revolutionized by the application of microscopy (1800). 200 years ago nothing was known of bacteria, viruses, ionizing radiation, carcinogenic chemicals.

• Rudolf Virchow (1821-1902) , a German pathologist recognized cells by microscope as cellular pathology.

History of Pathology (3)

•Molecular Pathology: is the techniques with relatively simple principle can reveal of the change of the single nucleotide of genomic DNA resulting in the synthesis of defective gene product for particular disease.

History of Pathology (4)

• Cellular and Molecular alteration in disease : We now have a clearer understanding of the way in which diseases can be attributed to disturbances of normal cellular and molecular mechanism.

• For example: Cellular –nucleus (genes encoded in DNA) – inherited or spontanous mutations (inherited, metabolic disorders, cancer).

Goal and objective of pathology

• Why we study pathology? • The ultimate goal of pathology is the

identification of the causes of disease,

• To help in diagnosis in some specific diseases such as cancers.

• To be successful in therapy and to disease prevention.

Scope of Pathology (1)

• Clinical and experimental pathology:

• Scientific knowledge about human diseases is divided from observation, or from experimental studies of animals and cell cultures.

• The greatest contribution comes from the detailed study of tissues and body fluids from patients.

Scope of Pathology (2)

• Clinical pathology: clinical pathology is concerned with a cross sectional analysis at the level of the disease itself, studies the cause and mechanisms of the disease, and the effects of the disease upon the various organs and systems of the body.

• Experimental pathology: Experimental pathology is the observation of the effects of manipulations on experimental systems such as animal models of disease or cell culture.

Scope of Pathology (3)

• Subdivisions of clinical pathology: • Histopathology: examination of tissues• Cytopathology: examination of isolate

cells• Haematology: the study of disorders of

cellular and coagulable components of blood

• Microbiology : the study of infectious disease and the organisms

Scope of Pathology (4)

• Immunology: the study of specific defense mechanisms of the body

• Chemical pathology: the study and diagnosis of disease from the chemical change in tissue and fluids

• Genetic: the study of abnormal chromosomes and genes

• Toxicology: the study of the effects of know or suspect of poisons

• Forensic pathology: the application of pathology to legal purposes ( e.g investigation of death)

Techniques of Pathology (1)

• Gross pathology- Before microscopy was applied to medical problems (year 1800), observations were confirmed by unaided eye

• Light microscopy- advances in optics and the quality of lenses have resulted in a wealth of new information about the structure of tissues and cells in health and disease from microscopy

Techniques of Pathology (2)

• Histochemistry- is the study of the chemistry of tissues, usually by microscopy of tissue section after they have been treated with specific reagents.

• Immunohistochemistry and immunofluorescence- employ antibodies (immonoglobulins with antigen specificity) to visualise substances in tissues section or cell preparation. These techniques use antibodies linked chemically to emzymes or fluorescent dyes respectively.

Techniques of Pathology (3)

• Electron microscopy- has extended the range of pathology to the study of disorders at the organelle level, and to the demonstration of viruses in tissue samples from same diseases.

• Biochemical Techniques- applied the body’s tissues and fluids in health and diseases. The clinical role of biochemitry is examplified by the importance of monitoring fluid and electrolyte omeostesis in many disorders. Example serum enzymes assay.

Techniques of Pathology (4)

• Haematological Techniques- are used in diagnosis and study of blood disorders.

• Cell cultures – are widely used in research and diagnosis. Cell cultures are used to prepare chromosome spread for cytogenetic analysis.

Techniques of Pathology (5)

• Medical Microbiology- is the study of disease caused by microorgnism such as bacteria, fungi, viruses and parasites.

• Molecular pathology – reveal defects in the chemical structure of molecule arising fromerrors in the genome, the sequence of bases that direct amino acid synthesis. Example DNA microarray can be used to determine patterns of gene expression (mRNA).

Questions

• Define pathology, post mortem (autopsy), specimen?

• What is microscopic and cellular pathology? What is clinical pathology?

• What is molecular pathology?• What is experimental pathology?• What is forensic pathology? • Why we study pathology?