Human Immunology Overview

The body's immediate response to injury or infection, characterized by rapid onset and usually resolving within a few days.

A prolonged inflammatory response lasting weeks, months, or years, occurring when the initial acute response fails to remove the cause of injury.

The presence of bacteria on a body surface without causing disease or an inflammatory response. The body coexists with these microorganisms as part of its normal flora.

The presence of microorganisms on a body surface or object, usually transient, without causing infection or an inflammatory response.

The body's response to harmful stimuli, characterized by immune cell activation, increased blood flow, and chemical mediator release to remove the cause of injury and initiate healing.

The invasion and multiplication of pathogenic microorganisms within the body, leading to an inflammatory response. Infection is often associated with clinical symptoms such as fever, pus formation, and tissue damage.

The suffix '-itis' indicates inflammation of a specific organ or tissue.

A common way to denote inflammation in medical terminology.

Increased blood flow to the inflamed area due to vasodilation of blood vessels.

Caused by increased blood flow and metabolic activity of inflammatory cells at the site of injury.

Accumulation of exudate (fluid) in the tissue spaces due to increased vascular permeability.

Caused by the release of chemicals like prostaglandins and bradykinin, which stimulate nerve endings.

Loss of function due to pain, swelling, and tissue damage. This can cause limitations in movement or other specific functions.

Red blood cells, responsible for oxygen transport and carbon dioxide removal. They are present in inflamed tissues but don't directly participate in inflammation.

Platelets are key for blood clotting and wound healing, releasing factors that contribute to inflammation and tissue repair.

The movement of leukocytes (white blood cells) from the bloodstream into the inflamed tissue.

White blood cells, the frontlines of the immune response and inflammation. They are vital for fighting infection and initiating healing.

Fluid buildup in the tissue spaces, primarily due to increased vascular permeability during inflammation.

The most abundant type of WBCs, acting as first responders to infection and injury. They engulf and destroy invaders, playing a key role in battling infection.

A type of WBC, mainly responsible for fighting parasites and modulating allergic reactions. They release enzymes to manage inflammatory responses.

The least common type of granulocytes, these cells release histamine and other substances that contribute to both inflammation and allergic reactions.

Crucial for the adaptive immune response, lymphocytes include B cells that produce antibodies and T cells that help fight infection.

These cells circulate in the blood, transforming into macrophages or dendritic cells, which are involved in engulfing invaders and presenting threats to other immune cells.

A prolonged inflammatory response caused by the body's inability to eliminate the initial trigger of injury.

They amplify the immune response and facilitate healing by acting as messengers in the bloodstream.

A chemical released by various cells that causes vasodilation and increased vascular permeability, contributing to the redness, heat, and swelling of inflammation.

A chemical released by platelets, similar in function to histamine, causing vasodilation and increased vascular permeability.

A process involving the release of arachidonic acid from cell membranes, which is then processed through two main pathways.

A group of proteins that play a crucial role in tissue repair by promoting cell proliferation, differentiation, and angiogenesis.

Signaling proteins that regulate the immune response by promoting inflammation, cell recruitment, and activation.

A chemical mediator produced by various cells that enhances leukocyte adhesion to the endothelium, increases vascular permeability, and stimulates the release of other inflammatory mediators.

Nitric oxide (NO) is a molecule produced by endothelial cells and macrophages, primarily known for its role in vasodilation, increasing blood flow during inflammation. It also helps fight infections by directly attacking microorganisms.

The immediate response to injury is vascular spasm, causing blood vessel constriction to reduce blood flow to the injured area. This helps limit blood loss and allows for the healing process to begin.

Platelet plug formation occurs when platelets stick to exposed collagen at the wound site, forming a temporary, sticky plug to prevent further leakage. This is a crucial step in stopping minor bleeding.

The coagulation cascade is a complex series of reactions that convert fibrinogen to fibrin, forming a stable blood clot. Think of it as a series of dominoes, each reaction activating the next, to form a strong clot.

The intrinsic pathway of coagulation is triggered by damage within the blood vessel itself. It starts with Factor XII (Hageman factor) and works its way through several steps to finally activate Factor X.

The extrinsic pathway is activated by external trauma, specifically the release of tissue factor (Factor III) from damaged tissues. This factor activates Factor VII, starting the chain reaction.

Both the intrinsic and extrinsic pathways converge at the activation of Factor X. This activates prothrombin (Factor II) into thrombin, which then converts fibrinogen to fibrin, creating the clot.

The coagulation system and inflammation are closely linked. Thrombin, a key enzyme in coagulation, also triggers inflammation by increasing vascular permeability and attracting leukocytes to the wound site.

Neutrophils are the first white blood cells to arrive at the site of inflammation. They are phagocytic and engulf and destroy pathogens.

Histamine causes blood vessels to dilate, increasing blood flow to the area. It also makes the blood vessels leaky, allowing fluid and immune cells to move into the tissue.

Diapedesis is the process of white blood cells squeezing through the walls of blood vessels to reach the site of inflammation.

Prostaglandins are a group of chemicals produced from arachidonic acid. They are involved in causing pain, fever, and swelling.

Tissue factor (Factor III) is a protein that initiates the extrinsic pathway of blood clotting, leading to a cascade of events that ultimately form a clot to stop bleeding.

Acute appendicitis is an inflammation of the appendix. It's characterized by neutrophil infiltration, increased vascular permeability, and tissue swelling. If left untreated, it can lead to serious complications like perforation, abscess formation, and peritonitis.

Deep vein thrombosis (DVT) is a blood clot in a deep vein, often in the legs. The coagulation cascade plays a crucial role in its formation. Inflammation can worsen DVT by further increasing blood clotting and damaging blood vessel walls.

Inflammation is the body's natural response to injury or infection. It involves a cascade of events, including immune cell activation, increased blood flow, and chemical mediator release, all designed to fight off the harmful stimuli and initiate healing.