Stomach ulcer, often caused by Cox-1 analgesic NSAIDs (nonsteroidal anti-inflammatory drugs). Cox-1 drugs block Cox-1 enzymes, which are present at inflammation sites and help maintain the mucous lining of the stomach. Depletion of this lining can lead to indigestion and ulcers. Cox-2 inhibitors do not target Cox-1 enzymes, avoiding the ulcer side effect.

Stomach ulcer, often caused by Cox-1 analgesic NSAIDs (nonsteroidal anti-inflammatory drugs). Cox-1 drugs block Cox-1 enzymes, which are present at inflammation sites and help maintain the mucous lining of the stomach. Depletion of this lining can lead to indigestion and ulcers. Cox-2 inhibitors do not target Cox-1 enzymes, avoiding the ulcer side effect.

Illustration of an arthritic knee joint with osteophytes and a depleted meniscus. Cox-2 inhibitors, a type of NSAID (nonsteroidal anti-inflammatory drug), target specific areas of pain and inflammation without the gastrointestinal side effects (indigestion and ulcers) caused by Cox-1 analgesics. Cardiovascular problems may result from using Cox-2 medication.

Illustration of an arthritic hip with osteophytes, a femoral head deformation, and joint space narrowing. Cox-2 inhibitors, a type of NSAID (nonsteroidal anti-inflammatory drug), target specific areas of pain and inflammation without the gastrointestinal side effects caused by Cox-1 analgesics. Cardiovascular problems may result from taking Cox-2 medication.

Lyme disease montage: Borrelia burgdorferi, the spirochete bacteria that cause Lyme disease (background); deer tick, a carrier of Borrelia burgdorferi (bottom right); bull's-eye rash (erythema migrans) on human skin (far left), a symptom of Lyme disease; molecular model of DEET, the main ingredient in most tick repellents (top).

Transplanted liver with vascular and ductal anastomosis.

Malaria cycle of Plasmodium sp. (the malaria parasite): human liver stages (exo-erythrocytic cycle), human blood stages (erythrocytic cycle), and mosquito stages (sporogonic cycle). A female anopheles mosquito passes plasmodium sporozoites to a human, infecting liver cells and then red blood cells. Another mosquito ingests plasmodium gametocytes, which grow.

Illustration of immune cells inside a blood vessel: B cells (blue), T cells (red), macrophages (white), and dendritic cells (green).

Illustration of immune cells: B cells (blue), T cells (red), macrophages (white), and dendritic cells (green).

Illustration of nasal polyps, saclike growths arising from the mucous membranes of the nasal passage and sinuses, side view. Symptoms include loss of smell (anosmia), congestion, runny nose, sinusitis, and headache. Nasal polyps are most prevalent in patients with asthma, hay fever, sinus infections, or cystic fibrosis. Large polyps may block the airway.

Conceptual illustration of hypertension (high blood pressure). Hypertension is a leading cause of heart attack, stroke, aneurysm, and kidney disease.

Illustration of tumor angiogenesis. The growing tumors outpace their blood supply. Vascular endothelial growth factor (VEGF) molecules (blue) are released by the tumor and stimulate endothelial mitosis and capillary budding in adjacent capillaries. These are aided by vascular support cells, pericytes (yellow). A natural angiogenesis inhibitor is angiostatin.

Illustration of the death of a tumor after effective anti-angiogenic therapy, static "time lapse" rendering. The treatment causes new tumor vasculature (angiogenesis) to collapse and retreat. The tumor is shown changing from robust (upper left corner) to anoxic and dying (lower right corner). Tumor necrosis occurs from the inside out.

Illustration of a crystalline lens that is yellow and clouded from a cataract, cross section of the eye.

Illustration of a crystalline lens that is yellow and clouded from a cataract, cross section of the eye.

Illustration of a crystalline lens that is yellow and clouded from a cataract, cross section of the eye.

Illustration of the two main sources of total blood cholesterol. These sources are dietary (digestive) and systemic (mainly in the liver) synthesis. A drug that reduces intestinal absorption of cholesterol from dietary sources and reabsorption of secreted (bile) cholesterol complements the diminished hepatic synthesis caused by statins.

Schematic illustration of the main types of cholesterol (LDL, HDL, VLDL), their components and receptors, and the circulation of these elements among the digestive tract, the blood, and the liver.

Illustration of the prostate gland, located below the bladder, and its palpable proximity to the sigmoid colon. This proximity argues for simple, effective digital prostate exams.

Illustration of a healthy mouth. For comparison with the progression of an inflammatory mucositis in the mouth, see related images. Mucositis is a secondary response to radiation treatment for cancer elsewhere in the head. It proceeds from mild redness and irritation to blisters, ulcers, necrotic patches, and gum erosion.