Inflammation

The cardinal signs of inflammation include: pain, heat, redness, swelling, and loss of function. Some of these indicators can be seen here due to an allergic reaction.
Micrograph showing granulation tissue. H&E stain.
Infected ingrown toenail showing the characteristic redness and swelling associated with acute inflammation
Neutrophils migrate from blood vessels to the infected tissue via chemotaxis, where they remove pathogens through phagocytosis and degranulation
Inflammation is a process by which the body's white blood cells and substances they produce protect us from infection with foreign organisms, such as bacteria and viruses. The (phagocytes) white blood cells are a nonspecific immune response, meaning that they attack any foreign bodies. However, in some diseases, like arthritis, the body's defense system the immune system triggers an inflammatory response when there are no foreign invaders to fight off. In these diseases, called autoimmune diseases, the body's normally protective immune system causes damage to its own tissues. The body responds as if normal tissues are infected or somehow abnormal.
Asthma is considered an inflammatory-mediated disorder. On the right is an inflamed airway due to asthma.
Colitis (inflammation of the colon) caused by Crohn's Disease.
Acute appendicitis
Acute dermatitis
Acute infective meningitis
Acute tonsillitis

Part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molecular mediators.

- Inflammation
The cardinal signs of inflammation include: pain, heat, redness, swelling, and loss of function. Some of these indicators can be seen here due to an allergic reaction.

500 related topics

Relevance

Innate immune system

Innate immune system

One of the two main immunity strategies in vertebrates.

One of the two main immunity strategies in vertebrates.

Innate immune system
A scanning electron microscope image of normal circulating human blood. One can see red blood cells, several knobby white blood cells including lymphocytes, a monocyte, a neutrophil, and many small disc-shape platelets.
A macrophage
A neutrophil
An eosinophil

Inflammation is one of the first responses of the immune system to infection or irritation.

In the OSHA universe, the Exclamation Mark signifies an immediate skin, eye or respiratory tract irritant, or narcotic.

Irritation

In the OSHA universe, the Exclamation Mark signifies an immediate skin, eye or respiratory tract irritant, or narcotic.
Pearl oyster
Infant with blepharitis on the right eye
Eczema arms
Herpes simplex lesion of lower lip, second day after onset
How tobacco affects your body

Irritation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage.

False-colored electron micrograph showing a malaria sporozoite migrating through the midgut epithelium of a rat

Infection

Invasion of an organism's body tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agents and the toxins they produce.

Invasion of an organism's body tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agents and the toxins they produce.

False-colored electron micrograph showing a malaria sporozoite migrating through the midgut epithelium of a rat
Chain of infection; the chain of events that lead to infection
Infection of an ingrown toenail; there is pus (yellow) and resultant inflammation (redness and swelling around the nail).
This image depicts the steps of pathogenic infection.
A southern house mosquito (Culex quinquefasciatus) is a vector that transmits the pathogens that cause West Nile fever and avian malaria among others.
Four nutrient agar plates growing colonies of common Gram negative bacteria.
Nucleic acid testing conducted using an Abbott Laboratories ID Now device
A temporary drive-in testing site for COVID-19 set up with tents in a parking lot
Washing one's hands, a form of hygiene, is an effective way to prevent the spread of infectious disease.
Mary Mallon (a.k.a. Typhoid Mary) was an asymptomatic carrier of typhoid fever. Over the course of her career as a cook, she infected 53 people, three of whom died.
Deaths due to infectious and parasitic diseases per million persons in 2012
Great Plague of Marseille in 1720 killed 100,000 people in the city and the surrounding provinces
East German postage stamps depicting four antique microscopes. Advancements in microscopy were essential to the early study of infectious diseases.
Herrerasaurus skull.

Mammalian hosts react to infections with an innate response, often involving inflammation, followed by an adaptive response.

An acutely inflamed and enlarged appendix, sliced lengthwise.

Appendicitis

An acutely inflamed and enlarged appendix, sliced lengthwise.
Location of McBurney's point (1), located two thirds the distance from the umbilicus (2) to the right anterior superior iliac spine (3)
Location of the appendix in the digestive system
Drawing of appendicitis.
Appendicitis as seen on CT imaging
Ultrasound image of acute appendicitis
A CT scan demonstrating acute appendicitis (note the appendix has a diameter of 17.1 mm and there is surrounding fat stranding)
A fecalith marked by the arrow that has resulted in acute appendicitis.
Appendicolith as seen on plain X-ray
Coronal CT scan of a person initially suspected of having appendicitis because of right-sided pain. The CT shows in fact an enlarged inflamed gallbladder that reaches the right lower part of the abdomen.
Inflamed appendix removal by open surgery
Laparoscopic appendectomy.
The stitches the day after having the appendix removed by laparoscopic surgery
Ultrasound showing appendicitis and an appendicolith
Ultrasound of a normal appendix for comparison
A normal appendix without and with compression. Absence of compressibility indicates appendicitis.
Micrograph of appendicitis and periappendicitis. H&E stain.
Micrograph of appendicitis showing neutrophils in the muscularis propria. H&E stain.
Acute suppurative appendicitis with perforation (at right). H&E stain.

Appendicitis is inflammation of the appendix.

Radiograph showing bone loss between the two roots of a tooth (black region). The spongy bone has receded due to infection under tooth, reducing the bony support for the tooth.

Periodontal disease

Set of inflammatory conditions affecting the tissues surrounding the teeth.

Set of inflammatory conditions affecting the tissues surrounding the teeth.

Radiograph showing bone loss between the two roots of a tooth (black region). The spongy bone has receded due to infection under tooth, reducing the bony support for the tooth.
1: Total loss of attachment (clinical attachment loss, CAL) is the sum of 2: Gingival recession, and 3: Probing depth
This X-ray film displays two lone-standing mandibular teeth, the lower left first premolar and canine, exhibiting severe bone loss of 30–50%. Widening of the periodontal ligament surrounding the premolar is due to secondary occlusal trauma.
The excess restorative material that exceeds the natural contours of restored teeth, such as these, are termed "overhangs", and serve to trap microbic plaque, potentially leading to localized periodontitis.
Person with periodontitis
This section from a panoramic X-ray film depicts the teeth of the lower left quadrant, exhibiting generalized severe bone loss of 30–80%. The red line depicts the existing bone level, whereas the yellow line depicts where the gingiva was located originally (1–2 mm above the bone), prior to the person developing periodontal disease. The pink arrow, on the right, points to a furcation involvement, or the loss of enough bone to reveal the location at which the individual roots of a molar begin to branch from the single root trunk; this is a sign of advanced periodontal disease. The blue arrow, in the middle, shows up to 80% bone loss on tooth No. 21, and clinically, this tooth exhibited gross mobility. Finally, the peach oval, to the left, highlights the aggressive nature with which periodontal disease generally affects mandibular incisors. Because their roots are generally situated very close to each other, with minimal interproximal bone, and because of their location in the mouth, where plaque and calculus accumulation is greatest because of the pooling of saliva, mandibular anteriors are affected excessively. The split in the red line depicts varying densities of bone that contribute to a vague region of definitive bone height.

Periodontitis has been linked to increased inflammation in the body, such as indicated by raised levels of C-reactive protein and interleukin-6.

A micrograph demonstrating cryptitis, a microscopic correlate of colitis. H&E stain.

Colitis

A micrograph demonstrating cryptitis, a microscopic correlate of colitis. H&E stain.
Micrograph showing intestinal crypt branching, a histopathological finding of chronic colitis. H&E stain.
Micrograph of collagenous colitis. H&E stain.
Micrograph of a colonic pseudomembrane, as may be seen in Clostridioides difficile colitis, a type of infectious colitis.

Colitis is an inflammation of the colon.

MRI scan image shows high signal in the temporal lobes and right inferior frontal gyrus in someone with HSV encephalitis.

Encephalitis

MRI scan image shows high signal in the temporal lobes and right inferior frontal gyrus in someone with HSV encephalitis.
Rabies virus
Spinal tap on a newborn
Encephalitis deaths per million persons in 2012

Encephalitis is inflammation of the brain.

A scanning electron microscope image of a single neutrophil (yellow/right), engulfing anthrax bacteria (orange/left) – scale bar is 5 µm (false color)

Immune system

Network of biological processes that protects an organism from diseases.

Network of biological processes that protects an organism from diseases.

A scanning electron microscope image of a single neutrophil (yellow/right), engulfing anthrax bacteria (orange/left) – scale bar is 5 µm (false color)
A scanning electron microscope image of normal circulating human blood. One can see red blood cells, several knobby white blood cells including lymphocytes, a monocyte, a neutrophil, and many small disc-shaped platelets.
Overview of the processes involved in the primary immune response
An antibody is made up of two heavy chains and two light chains. The unique variable region allows an antibody to recognize its matching antigen.
The time-course of an immune response begins with the initial pathogen encounter, (or initial vaccination) and leads to the formation and maintenance of active immunological memory.
Joints of a hand swollen and deformed by rheumatoid arthritis, an autoimmune disorder
Skeletal structural formula of the immunosuppressive drug dexamethasone
Polio vaccination in Egypt
Macrophages have identified a cancer cell (the large, spiky mass). Upon fusing with the cancer cell, the macrophages (smaller white cells) inject toxins that kill the tumor cell. Immunotherapy for the treatment of cancer is an active area of medical research.
Paul Ehrlich (1854–1915) was awarded a Nobel Prize in 1908 for his contributions to immunology.

Dysfunction of the immune system can cause autoimmune diseases, inflammatory diseases and cancer.

Meninges of the central nervous system: dura mater, arachnoid mater, and pia mater.

Meningitis

Meninges of the central nervous system: dura mater, arachnoid mater, and pia mater.
Neck stiffness, Texas meningitis epidemic of 1911–12
Charlotte Cleverley-Bisman developed severe meningococcal meningitis as a young child; in her case, the petechial rash progressed to gangrene and required amputation of all limbs. She survived the disease and became a poster child for a meningitis vaccination campaign in New Zealand.
Streptococcus pneumoniae—a causative bacteria of meningitis (illustration).
Cloudy CSF from a person with meningitis due to Streptococcus
Gram stain of meningococci from a culture showing Gram negative (pink) bacteria, often in pairs
Histopathology of bacterial meningitis: autopsy case of a person with pneumococcal meningitis showing inflammatory infiltrates of the pia mater consisting of neutrophil granulocytes (inset, higher magnification).
Structural formula of ceftriaxone, one of the third-generation cefalosporin antibiotics recommended for the initial treatment of bacterial meningitis.
Disability-adjusted life year for meningitis per 100,000 inhabitants in 2004.
Demography of meningococcal meningitis.
Deaths from meningitis per million persons in 2012

Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges.

Enlarged kidney (anatomy)

Nephritis

Enlarged kidney (anatomy)
Renin–angiotensin system

Nephritis is inflammation of the kidneys and may involve the glomeruli, tubules, or interstitial tissue surrounding the glomeruli and tubules.