Innate Immunity Overview

Normal microbiota compete for resources like space and nutrients, preventing pathogens from establishing themselves. This is called competitive exclusion.

Normal microbiota produce substances that kill or suppress pathogens. These substances can include bacteriocins (produced by E. coli) and hydrogen peroxide (produced by Lactobacillus).

Normal microbiota alter the environment around them, making it less hospitable for pathogens. This could include changes in pH, oxygen levels, or nutrient availability.

Normal microbiota can prevent the overgrowth of harmful microbes. For example, the gut microbiota can keep C. difficile in check.

Normal microbiota play a crucial role in the development of the immune system. Their presence in early life helps train the body to recognize and fight off harmful invaders.

A relationship where one organism benefits, while the other is not harmed or helped.

Most commensal organisms are found on the skin and digestive tract. They are highly specialized, with specific attachment mechanisms and environmental requirements.

A series of proteins that play a crucial role in the immune system's defense against microbes. It acts like a cascade, each step triggering the next. The system destroys microbes via cytolysis, inflammation, and opsonization.

The first step in activating the complement system, triggered by an antigen-antibody interaction. It's essential as it initiates the chain reaction that leads to the destruction of microbes.

These are serum proteins produced by the liver that enhance the immune system in destroying microbes. They are activated in a cascade process during complement activation.

A mechanism where complement proteins directly puncture holes in the membranes of pathogens, disrupting their integrity and leading to their destruction.

A process where complement proteins coat microbes, making them more easily identifiable and targeted by phagocytic cells like macrophages.

Lymphoid tissues and organs that are found in mucous membranes lining the digestive, respiratory, urinary, and genital tracts.

A type of white blood cell that engulfs and destroys pathogens through phagocytosis.

The process by which a cell ingests a microbe or other substance.

The process of differentiation where monocytes leave the bloodstream and develop into macrophages.

A type of macrophage that resides in specific tissues and organs, performing phagocytosis.

Macrophages that move through tissues and gather at sites of infection or inflammation.

A network of cells that includes monocytes and macrophages, responsible for phagocytic activity.

A type of white blood cell that is abundant during the initial phase of bacterial infection, actively phagocytosing bacteria.

Macrophages become more dominant during the later stages of a bacterial infection, scavenging and phagocytosing remaining bacteria.

The inability to move due to a loss of function in an area caused by severe inflammation.

Swelling caused by the accumulation of fluids in an area.

An increase in blood flow to the affected area, leading to a rise in temperature.

The process of inflammation aims to destroy or remove the harmful agent and repair the damaged tissue.

Inflammation that develops quickly and usually lasts for a short period of time, often involving neutrophils as the main immune cells.

Inflammation that develops slowly and can last for months or years, often involving monocytes and macrophages as the main immune cells.

Chemicals released by macrophages, such as TNF-α, that attract other white blood cells to the site of inflammation.

Specialized receptors on macrophages that recognize microbial structures like LPS and flagellin, triggering an inflammatory response.

The process by which immune cells, such as neutrophils and macrophages, engulf and destroy foreign invaders or cellular debris.

The widening of blood vessels during inflammation, allowing more blood and immune cells to reach the affected area.

The movement of phagocytes towards a site of infection, guided by chemical signals.

Molecules on the surface of pathogens that are recognized by phagocytes.

Receptors on phagocytes that bind to PAMPs, triggering the phagocytosis process.

The attachment of a phagocyte's plasma membrane to the surface of a microorganism.

Chemicals released by damaged cells, pathogens, or immune cells that attract phagocytes.

The engulfment of a pathogen by a phagocyte, forming a phagosome.

The breakdown of a pathogen within a phagosome by enzymes and other chemicals, destroying it.

A type of phagocyte that plays a role in both innate and adaptive immunity.