Pathology Introduction

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Pathology

Any abnormal disturbance of the function or structure of the human body as a result of some type of injury is called a disease.

Pathology is the study of diseases.

Pathogenesis occurs after the injury. Pathogenesis refers to the events producing the cellular changes that lead to the observable changes known as manifestations. Disease manifests as characteristics known as signs and symptoms.

Acute diseases- usually have a quick onset and last a short period of time.

Chronic diseases -usually manifest slowly and last a long time; although some chronic illnesses manifest in acute episodes.

A diagnosis is the name of a disease an individual is believed to have.

A prognosis is the predicted course and outcome of the disease.

 

Disease Classifications

Diseases can be grouped into several broad categories. Those in the same category may not necessarily be closely related.

Inflammation/Infectious Disease

Neoplastic Disease

Congenital and Hereditary Disease

Metabolic Disease

Degenerative Disease

Traumatic Diseases

Inflammation

Inflammation results from the body’s reaction to a localized injurious agent. Types of injury are: infective, traumatic, toxic and allergic diseases.

The body creates an inflammatory reaction to localize the injurious agent and prepares for repair and healing of the damaged tissues.

Events that occur in the inflammatory response are:

Alterations in blood flow to the area , and vascular permeability

White blood cells respond and migrate to injured area

Phagocytosis of necrotic tissue

Repair of tissue (normal cells, fibrinogen, granulation tissue = scar tissue)

Characteristics of an acute Inflammation

Heat – caused by increased blood flow

Redness –increased capillary permeability

Swelling or edema – caused by the shift of protein and fluid into the interstitial space

Pain – results from increased pressure of fluid on the nerves

Loss of function – if cells lack nutrients or if swelling interferes mechanically with an action

 

 

 

Chronic  Inflammation

May arise from acute inflammation when the cause is not completely eradicated.

Chronic inflammation differs from the acute in that the damage caused by the injurious agent may not necessarily result in tissue death. Chronic conditions last for a long period of time.

May develop from chronic irritation (smoking, bacterial infections, long term immune responses).

Increase in tissue damage,  fibrous tissue,  in scar tissue “granuloma”.

 

Infection

Infection refers to an inflammatory process caused by a disease-causing organism.

Examples are: bacterial, viral , parasitic and fungal infections.

The invading pathogen multiplies and causes injurious effects.

Generally, localized infection is accompanied by inflammation, but inflammation can occur without infection.

Factors promoting healing

Youth

Good nutrition

Adequate hemoglobin

Good circulation

Clean wounds

Minimal complications

Factors Delaying Healing

Old age

Poor nutrition

Anemia

Poor circulation

Infection

Morbidity, presence of underlying disease

Long term steroid use/chemotherapy

Complications of healing

Loss of function

Contractures or obstructions

Adhesions

Hypertrophic scar tissue

Neoplasms

Neoplastic disease = new, abnormal tissue growth.

Normally, growing and maturing cells are subject to mechanisms that control their growth rate.

Remove the control mechanism and an overgrowth of cells develops.

These cells do not respond to the normal cellular “start” and “stop” messages of mitosis/cell life cycle

Neoplasms (tumors) are either benign or malignant.

Benign neoplasms remain localized and are generally noninvasive.

Malignant neoplasms (cancer) continue to grow, spread and invade other tissues.

 

Congenital Disease

Congenital diseases or defects refer to diseases that are present at birth resulting from genetic or environmental factors.

A congenital defect is not necessarily hereditary as it may have been acquired in utero.

Intrauterine injury during a critical point in development can occur from maternal infections, radiation or drugs

                       

Hereditary Diseases

Hereditary diseases are caused by developmental disorders genetically transmitted from either parent to a child through abnormalities of individual genes in the chromosomes. Hereditary diseases are passed down generation to generation. Ex. Hemophilia

Inherited diseases may be dominant or recessive.

Metabolic Disease

Metabolism is the physical and chemical processes in the body.

A disturbance of normal physiologic function is classified as metabolic disease.

Included are endocrine disorders (e.g., diabetes and hyperparathyroidism) and disturbances of fluid and electrolyte balance (e.g. dehydration).

Degenerative Diseases

Degenerative diseases are classified as deterioration of the body.

Usually associated with the aging process, but some degenerative conditions may exist in younger patients (e.g. degeneration following a traumatic injury). Hereditary, diet and environmental factors affect the rate of aging.

Examples of degenerative diseases are osteoarthritis, osteoporosis and atherosclerosis

Traumatic Diseases

These diseases may result from mechanical forces such as crushing or twisting of a body part or from the effects of ionizing radiation on the human body.

Disorders resulting from extreme hot or cold ( burns or frostbite) are also classified as traumatic.

 

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