[Biology Class Notes] on Necrosis Pdf for Exam

Necrosis is a cell tissue that is generated during the injury. It is a death tissue formed and has no reverse action. With the impact of injury to the skin or bone, the amount of blood supply will reduce gradually. Due to the lack of blood supply, necrosis tissues were formed. The death of cells caused by noxious stimuli. 

Let’s get more ideas on necrotic tissue along with noxious stimuli.

The agents of noxious stimuli are – 

• bacteria

• parasites

• viruses

• fungi

The formation of necrosis is due to various reasons. The major reasons are – 

oxygen deprivation or hypoxia, and extreme environmental conditions such as heat, radiation, or exposure to ultraviolet irradiation, etc 

Types of Necrosis

By observing the necrosis meaning, it is clear that the necrosis forms due to a single reason. But, the variation in types of necrosis can be found when the cells die due to necrosis. Those types classified by appearance are – 

• Liquefactive necrosis

• Coagulative necrosis

Liquefactive Necrosis:- 

Is also known as colliquative necrosis. It has a microscopic appearance. Here the dead tissue is dissolved or transformed into a liquid or viscous fluid either partially or completely. All the transformation can be done within the hours.

Coagulative Necrosis:- 

It is completely different from the about type. It is a macroscopic appearance, and the result can be observed after several days of cell death. It has a default pattern connected to all parts of the body using ischemia or hypoxia except the brain.

Besides these two types, there is another classification based on morphological patterns. They are – 

• caseous necrosis

• fibrinoid necrosis

• fat necrosis

• Gangrenous necrosis

Caseous Necrosis:- 

This is a unique type of necrosis. It is found only in tuberculosis patients. 

Fibrinoid Necrosis:- 

It has a damaged vascular pattern. It can be observed due to deficiency of immune, rickettsia, autoimmunity, immune complex infections, etc. It is also known as avascular necrosis

Fat Necrosis:- 

The other name is acute tubular necrosis. Because it is caused due to acute inflammation of tissues. They affect several adipocytes and damage the enzymes required for digestion and usually observed in the breast and pancreas.

Gangrenous Necrosis:- 

This type of necrosis is usually observed in the lower and upper parts of limbs. The affected area of skin turns into black color. The symptoms of both liquefactive necrosis and

coagulative necrosis was found.

The observations of various types of necrosis are tabulated as follows- 

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Risk Factors and Causes of Necrosis

The major cause of necrosis is a decrease in blood supply to the tissue. If the blood supply completely stops, the cell tissue will die and results in necrosis. It has several risk factors. Every Factor that leads to necrosis is nothing but the risk factor. It includes – infections, injuries, sudden attacks, usage of steroids and bisphosphonates, accidents by vehicles, etc. will be considered as risk factors. Also, the necrosis can be attacked at various parts of the internal and external organs like skin tissues may damage, bones, muscles may get damaged. based on the type and severity of the damage, necrosis can be observed in various forms and colors. All these were discussed above. 

Conclusion 

Hence one can get a clear thought of necrosis’s meaning. It is caused by death cells due to various factors like accidents, deficiency, infections, etc. by examining properly and understanding the type of necrosis, It can be treated appropriately. So following the doctor is always better than unknown assu
mptions.