Pathology Basics

Introduction

In this section, you'll review learning in pathology, etiology, types of diseases, and the method of study in diseases.

 

How Pathologists Learn

Pathologists study by comparison between what's normal and what's abnormal in the human body. They learn what a normal cell looks like and then they can compare it with another cell. If there are differences between the cells, then they document those findings. Pathologists use the following terms when examining cells:

• Diagnosis is the examination of the sample to help to identify the underlying process that's occurring with the patient.
• Grade is the degree of deviation from a normal cell.
• Stage is the extent of the disease.

 

Etiology

Etiology is the study of cause or origination. Finding out the cause of the disease is very important. Knowing the cause is how a diagnosis can be made. An accurate diagnosis is needed so that the treatment is appropriate for the condition.

Disease can be caused by the following:

1. Environmental factors

2. Genetic factors

3. Indirect causes

Environmental Factors

Several environmental factors can affect the human body:

1. Physical agents like radiation, trauma, electricity, x-rays

2. Chemical agents like pesticides, toxins, venoms

3. Nutritional deficiencies or excesses

4. Infections and infestations

5. Abnormal immunological reactions

Genetic Factors

Genetic factors, such as abnormal genes or gene expression, can't be changed or modified easily.

Indirect Causes

Indirect causes include the following:

• Age
• Race
• Sex
• Climate
• Personal habits (for instance, tobacco use)

A disease can be caused by just one etiologic agent that results in one disease, several etiologic agents that result in one disease, or one etiologic agent that results in several diseases. Smoking is an example of one etiologic agent that can cause more than one disease. Heart disease is an example of a disease caused by multiple etiological agents.

 

Types of Diseases and Methods of Study

Acute

A disease with a sudden onset that ends in a short period of time. The common cold is an example of an acute disease.

Chronic

A disease that has a slow onset and a long duration.

Communicable

Diseases that are transmitted by agents, fomites (surfaces), and vectors. A mosquito is an example of a vector. A TV remote control or shopping cart handle is an example of a fomite.

Contagious

A disease that's transmitted by direct contact.

Fulminating

Acute, sudden, severe onset of a disease.

Idiopathic

A disease with unknown cause.

Infectious

Disease caused by pathogenic microorganisms.

Teratogenic

Diseases that are caused by drugs that cross the placental barrier and harm the fetus.

Venereal

Disease that's transmitted by sexual contact.

 

The following methods of studying disease include:

• Autopsy—The systematic dissection and examination of a cadaver to identify any abnormal changes or lesions that may be present.
• Biopsy—The surgical removal and examination of tissues.

 

Key Points

• Pathologists study by comparison between what's normal and what's abnormal in the human body.
• Etiology is the study of cause or origination; determining the cause helps make the diagnosis.
• A disease can be caused by environmental factors, genetic factors, or indirect causes.
• A prognosis is the physician's estimate of the severity and possible outcome of a disease.