2. Introduction
Pathology:
• Derived from Greek words ‘pathos’ meaning
suffering or disease and ‘logos’ meaning study
• Father of modern pathology: Rudolf Virchow
Definition:
The study of the structural and functional
changes in cells, tissues and organs that underlie
the disease.
Pathology is the scientific study of structure and
function of body in disease.
3. Divisions of pathology:
• General pathology:
It deals with the basic reaction of cells and
tissues to abnormal stimuli that underlie the
disease.
• Systemic(special) pathology:
It deals with the specific responses of
specialized organs and tissues to more or less
well defined stimuli.
4. Aspects of a disease process
There are 4 aspects of a disease process that form
the core of pathology . They are:
• Etiology (cause)
• Pathogenesis (mechanism of disease
development)
• Morphologic changes (structural alterations
induced in cells and organs of the body)
• Clinical significance (functional consequences of
morphologic changes)
5. Etiology or cause of the disease
They are divided into 2 classes:
• Intrinsic or genetic
example: cancer
• Acquired
example: infections,
nutritional, chemical,
physical
Pathogenesis:
It refers to the sequence of events in the response of
cells or tissues to the etiologic agent, from the initial
stimulus to the ultimate expression of the disease.
6. Morphologic changes:
It refers to the structural alterations in cells or
tissues that are either characteristic of the disease
or diagnostic of the etiologic process.
Functional derangements and clinical
manifestations:
The nature of the morphologic changes and the
distribution in different organs or tissues influence
normal function and determine the clinical
features (symptoms and signs), course and
prognosis of the disease.
7. Common Terminologies
• Patient: is the person affected by the disease
• Lesions: are the characteristic changes in tissues and
cells produced by disease in an individual or
experimental animal.
• Pathologic changes or morphology: consist of
examination of diseased tissues.
• Gross or macroscopic changes: the pathologic
changes that can be recognized by naked eye.
• Etiology: causal factors of disease(‘why’ of disease)
• Pathogenesis: mechanism by which lesions are
developed(‘how’ of disease)
8. Common Terminologies
• Symptoms: functional implications of the disease
felt by patient
• Signs: those discovered by the clinician
• Diagnosis: the clinical significance of the
morphologic and functional changes together with
results of other investigations help to arrive at an
answer to what is wrong.
• Prognosis: what is going to happen
• Treatment: what can be done about it
• Prevention: what should be done to avoid
complications and spread
9. Evolution of pathology
• From religious belief to rational
approach(antiquity to AD1500)
• Era of gross pathology(AD 1500 to AD1800)
including physician-pathologists Richard Bright,
Thomas Addison, and Thomas Hodgkin.
• Era of technology development and cellular
pathology (AD1800 to AD 1950s) including Louis
Pasteur, G. H. A. Hansen, Paul Ehrlich, Robert
Koch, Christian Gram, Karl Landsteiner etc.,
• Modern pathology(1950s to dawn of 21st century),
including:
10. Evolution of pathology
i. DNA structure description by Watson and
Crick(1953)
ii. Identification of chromosomes and their correct
number by Tijo and Levan (1956)
iii. Identification of Philadelphia chromosome in CML
by Nowell and Hagerford (1960)
iv. Recombinant DNA technique developed in 1972
v. In 1983, Kary Mullis introduced PCR(Polymerase
Chain Reaction)
vi. In 1997, Ian Wilmut used a technique of somatic
cell nuclear transfer to create the clone of a
sheep.(era of mammalian cloning)
vii. In 2004, therapeutic cloning of human embryos
11. Subdivisions of pathology
• Based on species studied:
a. Human pathology
b. Animal pathology
c. Plant pathology
d. Veterinary pathology
e. Poultry pathology
Human pathology is the largest branch of pathology.
1. General pathology
2. Systemic pathology
