Difference Between Pathology and Pathophysiology

Main Difference – Pathology vs Pathophysiology

Pathology and pathophysiology are two areas that study the conditions of diseases in organisms. The main difference between pathology and pathophysiology is that pathology is a medical discipline, describing the physical conditions observed within an organism during the disease whereas pathophysiology is a biological discipline, describing the changes of the biochemical processes or mechanisms, operating within an organism during the disease. The causes of a particular disease are studied in etiology. The symptoms of the disease are studied in pathology. The functional changes within the organism during the disease is studied in pathophysiology.

Key Areas Covered

1. What is Pathology
     – Definition, Facts, Types
2. What is Pathophysiology
     – Definition, Facts, Tools
3. What are the Similarities Between Pathology and Pathophysiology
     – Outline of Common Features
4. What is the Difference Between Pathology and Pathophysiology
     – Comparison of Key Differences

Key Terms: Biochemical Processes, Cytopathology, Molecular Pathology, Pathophysiology, Surgical Pathology

What is Pathology

Pathology refers to the study of essential nature of diseases. It is a medical discipline used in the diagnosis of a disease through the physical examination of surgically-removed tissues (biopsy samples), organs, body fluids, or the whole body (autopsy). The appearance of the cells and the gross anatomical makeup is studied during pathology. The causes of the disease, disease mechanism, and the extent of the disease are also studied during pathology. Necrosis (death of cells or tissues), neoplasia (abnormal new cell growth), cellular adaptation to injury, inflammation, and wound healing can be studied during the anatomical examination of the samples. Majority of cancers are diagnosed during the pathological examination of the body. The neurofibrillary tangles in the hippocampus that can be observed in Alzheimer-related pathology are shown in figure 1.

Figure 1: Neurofibrillary Tangles(dark purple) in the Hippocampus

Surgical pathology, cytopathology, and molecular pathology are the three main areas of pathology. The tissues are examined under the microscope (histologic) or with the naked eye (gross) in surgical pathology. Autopsy is a type of surgical pathology in which the whole body is examined to find the cause and manner of death. During cytopathology, free cells or tissue fragments are observed for the diagnosis of cancers, infectious diseases or inflammatory conditions. In molecular pathology, the molecules in the body fluids, tissues, and organs are examined through PCR, microarray, hybridization, antibody-based immunofluorescence assays, etc.

What is Pathophysiology

Pathophysiology refers to the study of disordered physiological processes associated with diseases. Physiology describes the biochemical mechanisms of the body under normal conditions. Pathophysiology describes the abnormal biochemical conditions of the body caused by the disease. The deficiency/absence of enzymes in a biochemical pathway of usual amino acid metabolism of phenylalanine and tyrosine, which causes abnormal metabolites or diseases such as phenylketonuria and alkaptonuria is shown in figure 2.

Figure 2: Pathophysiology of Metabolic Disorders

A disease may affect the functioning of the body by means of biochemical and physical aspects. By measuring the levels of biochemical compounds such as sodium, potassium, bicarbonate, glucose, creatinine, amino acids, etc., the change in the physiology of the body due to the disease can be examined.   

Similarities Between Pathology and Pathophysiology

• Pathology and pathophysiology are two areas that study the diseases of a particular organism.
• Both pathology and pathophysiology are important in the identification and treating a disease.

Difference Between Pathology and Pathophysiology

Definition

Pathology: Pathology refers to the study of essential nature of diseases.

Pathophysiology: Pathophysiology refers to the study of disordered physiological processes associated with diseases.

Type of Study

Pathology: The physical conditions of an organism during the disease are studied in pathology.

Pathophysiology: The biochemical changes of the body are studied in pathophysiology.

Area

Pathology: Pathology is a medical discipline.

Pathophysiology: Pathophysiology is a biological discipline.

Tools

Pathology: Direct observation of the symptoms of the disease are studied during pathology.

Pathophysiology: Experimental measurements are studied during pathophysiology.

Examples

Pathology: Gross and microscopic examination of tissues, organs, and the whole body is done in pathology.

Pathophysiology: The levels of biochemical compounds such as sodium, potassium, bicarbonate, glucose, and creatinine are examined in pathophysiology.

Conclusion

Pathology and pathophysiology are two types of studies that focus on different conditions of an organism during a disease. The symptoms of the disease are studied in pathology while the biochemical changes of the body are studied in pathophysiology. The main difference between pathology and pathophysiology is the type of conditions studied in each area.

Reference:

1. “What is Pathology?” DEPARTMENT OF PATHOLOGY, 28 Jan. 2015, Available here.

Image Courtesy:

1. “Neurofibrillary tangles in the Hippocampus of an old person with Alzheimer-related pathology, HE 2” By Patho – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Pathophysiology of metabolic disorders of phenylalanine and tyrosine” By LHcheM – Own work (CC BY-SA 3.0) via Commons Wikimedia

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