Defend

Defend is a term often used in the context of the immune system's role in protecting the body against harmful substances. These substances can include bacteria, viruses, toxins, cancer cells, and blood or tissues from another person or species. The immune system uses a series of steps known as the immune response to attack these substances.

Immune System

The immune system is a complex network of cells, tissues, and organs that work together to defend the body against attacks by "foreign" invaders. These are primarily microbes—tiny organisms such as bacteria, parasites, and fungi that can cause infections. Viruses also cause infections, but are too primitive to be classified as living organisms. The human body provides an ideal environment for many microbes. It is the immune system’s job to keep them out or, failing that, to seek out and destroy them.

Immune Response

When the immune response is triggered by the presence of a foreign substance, it begins to produce proteins known as antibodies. These antibodies are designed to target the specific foreign substance and neutralize it. The immune response also involves a process called phagocytosis, where certain cells engulf and destroy the foreign substance.

Immune Cells

There are several types of cells involved in the immune response. These include white blood cells, T cells, and B cells. White blood cells are the first line of defense and are responsible for identifying and destroying foreign substances. T cells and B cells are specialized types of white blood cells that play a crucial role in the immune response.

Immune System Disorders

Sometimes, the immune system does not function as it should. This can result in a variety of immune system disorders, such as allergies, autoimmune diseases, and immunodeficiency disorders. In these cases, the immune system may overreact to harmless substances, attack the body's own cells, or be unable to effectively defend against foreign substances.

See Also

• Immune System
• Immune Response
• White Blood Cells
• T Cells
• B Cells
• Immune System Disorders

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