This document provides an overview of pathology including definitions, key figures, scope, and core aspects. It discusses cellular adaptations like hypertrophy, hyperplasia, atrophy, and metaplasia. Cell injury mechanisms like free radicals and apoptosis are explained. Necrosis is contrasted with apoptosis. Intracellular accumulations from abnormal metabolism or deficiencies are also summarized. The document aims to explain pathology from a molecular to clinical level.

1. Antecedents
Group no. 01
Group Members:
Rana Ahmed (PHA-14001)
Mahfujul Hasan (PHA-14002)
Shahida Yeasmin Sima (PHA-14005)
Shamima Akter Sumi (PHA-14007)
14 April 2019 1

2. Contents
Introduction to Pathology
Definition
Father of Modern Pathology
Scope
Core aspects
Cellular Injury and Adaptation
Stages of the cellular response
Adaptation
Hypertrophy
Hyperplasia
Atrophy
Metaplasia
Cell injury
Intracellular Accumulations
14 April 2019 2

3. What Is Pathology
• Pathology is the study (logos) of diseases (pathos).
• The study of the structural, biochemical and functional changes in
cells, tissues and organs that underlie diseases.
• It attempts to explain sign and symptoms by use of
Molecular
Microbiologic
Immunologic
Morphologic techniques
14 April 2019 3

4. Rudolf Virchow
Father of Modern Pathology
“Virtually all forms of tissue injury
starts with molecular or structural
alterations in CELLS”
1821-1902
14 April 2019 4

5. The Scope of Pathology
Scientific knowledge about human diseases from observations on
patients or by from experimental studies.
Explain the whys and wherefores of signs and symptoms expressed.
It offers clinical care and therapy.
It serves as the bridge between basic sciences and clinical medicine.
Pathology is the foundation for all medicine.
14 April 2019 5

6. Core aspects of pathology
There are four aspects of diseases process that form the core of
pathology. These are following-
1. Etiology
2. Pathogenesis
3. Molecular and morphological changes
4. Clinical manifestations
14 April 2019 6

7. Etiology
Pathogenesis
Morphological
changes
Clinical
manifestations
1. Genetics
 Inherited mutation
 Diseases gene
mutation
2. Non-genetics
 Infectious
 Nutritional
 Physical
 chemical
14 April 2019 7

8. Etiology
Pathogenesis
Morphological
changes
Clinical
manifestations
 Mechanism of its
developments.
 Sequences of events in the
response of cells or tissues
to the etiologic agents.
 from the initial stimulus to
the ultimate expression of
the diseases.
14 April 2019 8

9. Etiology
Pathogenesis
Morphological
changes
Clinical
manifestations
 Molecular and Morphologic
changes refer to the
structural alterations in
cells or tissues that are
either characteristic of a
disease or diagnostic of an
etiologic process.
14 April 2019 9

10. Etiology
Pathogenesis
Morphological
changes
Clinical
manifestations
 The end results of genetic,
biochemical and structural
changes in cells and tissues
are functional
abnormalities, which lead
to the clinical
manifestations (symptoms
and signs) of disease, as
well as its progress.14 April 2019 10

11. Stages of the Cellular Responses
Fig: Stages of the cellular response to stress and injurious stimuli
14 April 2019 11

12. Adaptation
 Adaptations are reversible changes in the size, number, phenotype,
metabolic activity or functions of cells in response to changes in their
environment.
 Four types of adaptation are occurred-
• Hypertrophy
• Hyperplasia
• Atrophy
• Metaplasia
14 April 2019 12

13. Hypertrophy
• Hypertrophy is an increase in the size of cells resulting in an increase
in the size of the organ.
• There are no new cells, just large cells.
• Hypertrophy can be physiologic or
pathologic.
14 April 2019 13

14. Example
Pathologic hypertrophy
Cardiac enlargement that
occurs with hypertension
or aortic valve disease.
Physiologic hypertrophy
 Bulging muscles of bodybuilders.
14 April 2019 14

15. Physiologic hypertrophy
Enlargement of the uterus during pregnancy
14 April 2019 15

16. Mechanisms of Hypertrophy
Hypertrophy is the result of increased production of cellular proteins.
14 April 2019 16

17. Hyperplasia
• Hyperplasia is an increase in the number of cells in an organ or
tissue, resulting in increased mass of the organ or tissue.
• Hyperplasia can be physiologic or pathologic.
• In both situations, cellular proliferation is stimulated by growth
factors that are produced by a variety of cell types.
14 April 2019 17

18. Types
Physiologic hyperplasia
1. Hormonal hyperplasia:
The proliferation of the glandular epithelium of
the female breast at puberty and during
pregnancy.
2. Compensatory hyperplasia:
When part of a liver is resected, mitotic activity in
the remaining cells begins as early as 12 hours
later, eventually restoring the liver to its normal
size.
14 April 2019 18

19. Pathologic Hyperplasia
 Most forms of pathologic hyperplasia are caused by excesses of
hormones or growth factors acting on target cells.
 Example:
Endometrial hyperplasia is an example of abnormal hormone
induced hyperplasia.
14 April 2019 19

20. Mechanisms of Hyperplasia
Hyperplasia is the result of growth factor, driven proliferation of
mature cells.
In some cases, by increased output of new cells from tissue stem
cells.
14 April 2019 20

21. Atrophy
• Atrophy is reduced size of an organ or tissue resulting from a
decrease in cell size and number.
• Atrophy represents a reduction in the structural components of the
cell.
14 April 2019 21

22. Common Causes of Atrophy
Decreased workload
Loss of innervation
Diminished blood supply
Inadequate nutrition
Loss of endocrine stimulation
Pressure
14 April 2019 22

23. Mechanisms of Atrophy
Atrophy results from decreased
protein synthesis and increased
protein degradation in cells.
Reduction metabolic activity.
Nutrient deficiency activates
ubiquitin ligases.
Autophagy
14 April 2019 23

24. Metaplasia
• Metaplasia is a reversible change in which one differentiated cell type
is replaced by another cell type.
• The most common epithelial metaplasia is columnar to squamous, as
occurs in the respiratory tract in response to chronic irritation.
14 April 2019 24

25. Mechanisms of Metaplasia
• Reprogramming of stem cells that are known to exist in normal
tissues.
• The precursor cell differentiated along a new pathway, signaled by
cytokines, growth factor and components of the cell in this
environment.
14 April 2019 25

26. Cell injury
• If the adaptive capability is
exceeded or if the external
stress is inherently harmful or
excessive, cell injury develops.
14 April 2019 26

27. Causes of Cell Injury
• Oxygen Deprivation
• Physical Agents
• Chemical Agents and Drugs
• Infectious Agents
• Immunologic Reactions
• Genetic Derangements
• Nutritional Imbalances
14 April 2019 27

28. Biochemical mechanisms of cell injury
14 April 2019 28

29. Pathologic Effects of Free Radicals
14 April 2019 29

30. Apoptosis
• Apoptosis is a pathway of cell death that is induced by a tightly
regulated suicide program in which cells destined to die activate
enzymes that degrade the cells own nuclear DNA and nuclear and
cytoplasmic proteins.
14 April 2019 30

31. CAUSES OF APOPTOSIS
Apoptosis in Physiologic Situations
Apoptosis serves to eliminate cells that are no longer needed and to
maintain a steady. It is important in the following physiologic situations:
The programmed destruction of cells during embryogenesis
Involution of hormone-dependent tissues upon hormone
withdrawal
Cell loss in proliferating cell populations
Elimination of potentially harmful self-reactive lymphocytes
Death of host cells that have served their useful purpose
14 April 2019 31

32. Apoptosis in Pathologic Conditions
Apoptosis eliminates cells that are injured beyond repair without
eliciting a host reaction, thus limiting collateral tissue damage.
DNA damage
Accumulation of mis-folded proteins
Cell death in certain infections
14 April 2019 32

33. MORPHOLOGIC AND BIOCHEMICAL
CHANGES IN APOPTOSIS
• Cell shrinkage
• Chromatin condensation
• Formation of cytoplasmic blebs and
apoptotic bodies
• Phagocytosis of apoptotic cells by
macrophages.
14 April 2019 33

34. Necrosis
• Necrosis is a form of
cell death in which
cellular membranes
fall apart and cellular
enzymes leak out and
ultimately digest the
cell.
14 April 2019 34

35. Necrosis and Apoptosis
14 April 2019 35

36. Intracellular Accumulations
• Under some circumstances, cells may accumulate abnormal amounts
of various substances, which may be harmless or may cause varying
degrees of injury.
• The substances fall into two categories:
Normal cellular constituents
ex: Water, lipids, proteins etc.
Abnormal substances
ex: Products of infectious agents, abnormal
synthesis/metabolism.
14 April 2019 36

37. Mechanisms of intracellular
accumulation
1. Abnormal metabolism
2. Mutations causing
alterations in protein
folding and transport
3. A deficiency of critical
enzymes
4. Inability to degrade
phagocytosed particles
14 April 2019 37

38. Various components of intracellular
accumulation
A. Depositions of lipids
a. Fatty change
b. Cholesterol deposition
B. Deposition of proteins
C. Deposition of glycogens
D. Deposition of pigments
E. Pathologic calcifications
a. Dystrophic calcification
b. Metastatic calcification
14 April 2019 38

39. THANK YOU
14 April 2019 39

40. 14 April 2019 40