Describe two mechanisms that operate to restore homeostasis after infection by a pathogen?

1. Innate immune response:

The innate immune system provides immediate, non-specific defense mechanisms against infections. Several mechanisms contribute to restoring homeostasis:

- Phagocytosis: Specialized cells like macrophages and neutrophils engulf and destroy pathogens through phagocytosis.

- Inflammation: Infected tissues release chemical signals that trigger inflammation, leading to increased blood flow, recruitment of immune cells, and enhanced pathogen clearance.

- Natural killer (NK) cells: NK cells recognize and kill infected cells and tumor cells without prior sensitization.

- Interferons: These proteins are released in response to infections and help inhibit viral replication and enhance immune cell activity.

2. Adaptive immune response:

The adaptive immune system develops over time and provides specific and long-lasting immunity against specific pathogens. Two key mechanisms involved in restoring homeostasis are:

- Antibody production: B cells produce antibodies that bind to specific antigens on pathogens, marking them for destruction by immune cells or preventing their entry into cells.

- T cell response: Helper T cells activate other immune cells, including B cells and cytotoxic T cells. Cytotoxic T cells can directly kill infected cells.

- Memory response: After an infection, memory B cells and memory T cells remain in the body, providing rapid and robust protection against future encounters with the same pathogen.

These mechanisms work together to eliminate invading pathogens, control infection, and restore the body's internal balance, promoting healing and preventing further complications.