Inflammation

Inflammation is a complex biological response to harmful stimuli, such as pathogens, damaged cells, or irritants. Its primary function is to eliminate the initial cause of cell injury, clear out necrotic cells and tissues damaged from the original insult, and initiate the process of repair.

The cardinal signs of inflammation are redness, swelling, heat, and loss of function. Pain is not a cardinal sign, although it is often associated with inflammation.

Neutrophils are phagocytic cells that engulf and destroy foreign particles, including bacteria and cellular debris. They are among the first cells to arrive at the site of inflammation.

Histamine is a potent vasodilator and increases vascular permeability, leading to the redness and swelling associated with inflammation. It is released by mast cells and basophils.

Prostaglandins are lipid mediators that promote vasodilation and increased vascular permeability, contributing to the redness and swelling of inflammation. They also sensitize pain receptors and contribute to the pain associated with inflammation.

Lymphocytes are not inflammatory cells in the strict sense. They are part of the adaptive immune system and play a role in specific immune responses, such as antibody production and cell-mediated immunity.

Macrophages are phagocytic cells that engulf and destroy foreign particles, including bacteria, cellular debris, and apoptotic cells. They also secrete cytokines and other inflammatory mediators.

Interleukin-1 (IL-1) is a potent pyrogen, meaning it can induce fever. It acts on the hypothalamus, causing an increase in body temperature.

Complement proteins are a group of proteins that work together to lyse foreign cells, such as bacteria and viruses. They also promote inflammation by generating anaphylatoxins, which are potent inflammatory mediators.

Antihistamines are not anti-inflammatory drugs. They are used to treat allergic reactions by blocking the effects of histamine, a potent inflammatory mediator.

Cytokines are small proteins that are released by cells of the immune system in response to infection or injury. They promote vasodilation and increased vascular permeability, leading to the redness and swelling associated with inflammation. They also stimulate the production of antibodies and activate complement proteins.

Serotonin is not an inflammatory mediator. It is a neurotransmitter that is involved in mood, sleep, and appetite regulation.

Leukotrienes are lipid mediators that attract neutrophils to the site of inflammation. They also promote bronchoconstriction and mucus production in the airways.

Basophils are not inflammatory cells in the strict sense. They are involved in allergic reactions and release histamine and other inflammatory mediators.

The lymphatic system drains excess fluid and cellular debris from the site of inflammation, helping to resolve the inflammation and promote healing.