General pathology
Lecture - 1 –
Dr. Ali Zeki
Introduction :
Pathology is a Greek word composed of two parts, " pathos" mean
suffering , and " logos" mean study, so the pathology is the science that
study structural and functional changes occur in cells, tissues, and
organs that are expressed as diseases, and its provides the scientific
foundation for the practice of medicine .
Pathology includes the following branches :
1- Anatomical surgical pathology: study diseases from the
structural abnormalities of the cells and tissues ( autopsy and biopsy)
2- Clinical pathology:
A- Hematology: study primary diseases of the blood, as well as
the effects of other diseases on the blood.
B- Chemical pathology: study the disease from perspective of
biochemical abnormalities.
C- Immunology: study primary diseases of immune system, as
well as the effects of other diseases on the immune system.
D- Microbiology: study infectious diseases.
E- Genetics : it’s the study of the genetic disorders
Studying of pathology can be divided into two main parts:
1- general pathology:
this part focus on the mechanisms of the principal types of disease
process. (inflammation , degeneration, tumors).
2- systemic pathology:
this part examines the effects of specific diseases on specialized
organs.(appendicitis, lung cancer,..).
Disease:
It’s the clinical manifestation, through signs and symptoms, of
underlying abnormality. The abnormality may be structural or functional
or both.
The characteristics of disease:
1- etiology: the cause of the disease whether congenital or acquired.
2- pathogenesis: mechanism or serial steps of disease process.
3- manifestations: morphological and functional changes.
4- complications: secondary effects of a particular disease.
5- prognosis: out come of the disease(good to bad).
6- epidemiology: incidence of the disease.
Homeostasis:
Normal steady state of the cell in which the cell handle normal
physiological demands.
Cell adaptation:
It’s a new altered steady state in which cell preserve viability, but
modulate its morphology and function in response to physical stress or
pathological stimuli.
Types of adaptive responses of the cell:
1- Cell atrophy:
shrinkage in size of the cell by the loss of cell substance; and when
sufficient number of cells are involved, the entire tissue or organ
diminishes in size and becoming atrophied.
Causes of cell atrophy:
 Immobilization " fracture".
 Loose of innervation " poliomyelitis".
 Diminished blood supply " ischemia".
 Inadequate nutrition "starvation".
 Lose of endocrine stimuli " uterus after menopause".
 Aging " brain atrophy"
Mechanism of cell atrophy:
Reduction of cellular component underlying by the followings:
1- Protein synthesis decreases because of reduced metabolic activity.
2- The degradation of cellular proteins occurs mainly by the
ubiquitin-proteasome pathway.
3- Increased autophagy, with resulting increases in the number of
autophagic vacuoles. (“self-eating”)
2- Cell Hypertrophy:
Increase in the size of the cells and consequently an increase in the
size of an organ, this increase is due to increase synthesis of structural
proteins and organelles, induced by growth factors produced in
response to mechanical stress or other stimuli; occurs in tissues
incapable of cell division .
Types of hypertrophy:
A- Physiological hypertrophy : as a normal physiological response
like increase muscle mass due to work overload on skeletal muscles
seen in weight lifter and body builder.
B- Pathological hypertrophy " ex. left ventricular hypertrophy in
patient with hypertension or heart valve stenosis, Since the cardiac
muscle push blood through stenosed valve and face much more
resistance than in normal heart valve.
Another example is enlargement of viable cardiac muscle after
Myocardial Infarction to compensate for the death of neighboring cell
die due to ischemia.
3- Cell Hyperplasia:
Increase in number of cells.
Types of hypertrophy:
A- Physiological hyperplasia :
1- Hormonal " proliferation of breast lobules in lactating female.
2- Compensatory " when part of tissue removed or diseased like in
liver partial resection, and connective tissue cells in wound healing,
the neighboring healthy cells proliferate and increased in number .
B- Pathological hyperplasia:
Its mainly due to hormonal access or growth factor stimuli.
 Endometrial hyperplasia due to progesterone-estrogen imbalance,
this hyperplasia presenting as abnormal uterine bleeding .
 Benign prostatic hyperplasia 'BPH' in elderly males presenting as
urine retention .
4- Cell Metaplasia:
Its reversible change in which a type of epithelial or mesenchymal cell
is replaced by another adult cell type, so it’s a cellular adaptation
where by cell sensitive to a particular stress are replaced by other cell
type able to withstand the adverse environment.
Usual site for Metaplasia are:
( a ) squamous metaplasia occur in respiratory epithelium of cigarette
smokers, so the normal ciliated columnar epithelial cells of the trachea
and bronchi are replaced by stratified squamous epithelial cells,
although the squamous cells have survival advantage of respiratory
cells, the important protective mechanism are lost such as mucous
secretion and ciliary movements.
( b ) barrette esophagus in which normally present stratified squamous
epithelial cells of the lower esophagus replaced by gastric or intestinal
type of columnar epithelium, this metaplasia is usually seen in
prolonged or chronic reflux esophagitis.
Note :(in both examples, if influences that induce metaplastic
transformation persist, it may induce cancer transformation).