م رحي ل ا لرحمن ا هلل ا سم ب

By:

PhD (Histopathology & Cytopathology), M.BA

(Total Quality Management)

Consultant Medical Laboratory Scientist

Assistant Professor of Histopathology & Cytopathology

Introduction

Pathology is the study of disease

mechanisms.

It is a discipline that bridge clinical

practice and basic sciences, and it

involves the investigation of the

causes (aetiology) of diseases as well

as the under lying mechanisms

(pathogenesis) that result in the

presenting signs and symptoms of the

patients.

Introduction

Pathology concern with the

understanding the structural

(morphology) and functional changes

that occur in the cell, tissues, and

organs so as to render diagnosis and

guide therapy.

Introduction

Traditionally pathology is divided

into: general pathology and systemic

pathology.

General pathology: focuses on the

fundamental cellular and tissue

responses to pathologic stimuli , while

Systemic pathology: examine the

particular responses of specialized

organs.

Cell Injury

Causes of cell injury

The causes of cell injury range from

the gross physical trauma of a motor

vehicle accident to the single gene

defect that result in a defective

enzyme underlying a specific

metabolic disease.

Most injurious stimuli can be grouped

into the following categories:

Cell Injury

Chemical Agents.

Physical Agents.

Infectious Agents.

Genetic Defects.

Aging.

Nutritional Imbalances.

Oxygen Deprivation.

Cell Injury

Chemical Agents

An enormous number of chemical

substance can injure cell such as ;

insecticides, CO, asbestos, ethanol.

These substances can cause severe

damage at the cellular level by

altering membrane permeability.

Cell Injury

Physical Agents

Trauma, extreme of temperatures,

radiations , electric shock, and

sudden change in atmospheric

pressure all have wide range affect on

the cell.

Cell Injury

Infectious Agents

These range from sub-microscopic

viruses to metre long tapeworm.

These organisms can invade the

human body and cause severe cell

injury.

Cell Injury

Genetic Defects

Genetic defects can be conspicuous as

the congenital malformations

associated with Down syndrome or

It may be subtle as the single amino

acid substitution in haemoglobin S

giving rise to sickle cell anaemia.

Cell Injury

Aging

Aging leads to alterations in

replication and repair abilities of

individual cell and tissues.

Cell Injury

Nutritional imbalances

Protein and calorie insufficiency,

vitamins deficiency, and over excesses

of nutrition’s are also important

causes of morbidity and mortality.

Cell Injury

Oxygen Deprivation

Hypoxia; oxygen deficiency, interferes

with the aerobic oxidative respiration

and is an extremely important and

common cause of cell injury and

death.

Ischemia; is loss of blood supply in a

tissue due to impeded arterial follow

or reduced venous supply.

Cell Injury The morphology of cell and tissue injury

(I). Reversible cell injury

The two main morphologic correlates

of reversible cell injury are cellular

swelling and fatty changes.

Cellular swelling: is the result of

failure of energy-dependent ion pump

in the plasma membrane, leading to

an in ability to maintain ionic and

fluid haemostasis.

Cell Injury The morphology of cell and tissue injury

Fatty changes: occurs in hypoxic

injury and various toxic or metabolic

injuries, it is manifested by the

appearance of small and large lipid

vacuoles in the cytoplasm.

Cell Injury The morphology of cell and tissue injury

(II). Irreversible cell injury

Persistent or excessive injury causes

cell to pass (THE POINT OF NO

RETURN) into irreversible cell injury

and death. Although there are no

definitive morphologic or biochemical

correlates of irreversibility, two

phenomenas consistently characterise

irreversibility;

Cell Injury The morphology of cell and tissue injury

The inability to reverse mitochondrial

dysfunction (lack of oxidative

phosphorylation and ATP generation).

Profound disturbances in membrane

function.

The End