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from article Anthrax

A color-enhanced scanning electron micrograph showing splenic tissue from a monkey with inhalation anthrax. Rod-shaped bacilli of Bacillus anthracis (yellow) and an erythrocyte (red) are shown. (Credit: Arthur Friedlander/National Institute of…

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from article Anthrax

Micrograph (stained with hematoxylin and eosin) showing submucosal hemorrhage in the small intestine of a person fatally affected by gastrointestinal anthrax. (Credit: Marshal Fox/Centers for Disease Control and Prevention)

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from article Bioassay

In conducting bioassays, researchers often employ laboratory culture tests, which use, for example, bacteria cultured in a petri dish (usually to model an effect on the organism of interest or on some basic cellular function). (Credit:…

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from article Dental caries

The disease of dental caries or tooth decay is largely preventable. Bacteria colonize the tooth surface and often produce sufficient acids to demineralize the tooth's enamel. Then, dental plaque can build up on the tooth's surface, creating…

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from article Dental caries

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from article Medical control systems

Diagram of selected portions of the human motor control system. (After G. L. Gottlieb, D. M. Corcos, and G. C. Agarwal, Strategies for the control of voluntary movements with one mechanical degree of freedom, Behav. Brain Sci., 12:189–250, 1989)

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from article Medical control systems

Electric hand, a myoelectric prosthesis. (a) Two views of the hand, 2.5 in. (6 cm) across the knuckles, with the cover removed in one view to show the electric motor drive circuit. (b) Child using the electric hand. (Hugh Steeper Ltd.)

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from article Medical control systems

Hybrid control system using both functional electrical stimulation and orthoses. (a) Hierarchical control scheme. (b) Braces in use. (c) Detail of leg brace. (After Y. Kim and F. A. Spelman, eds., Images of the Twenty-First Century: Proceedings of…

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from article Medical control systems

Autoclavable pacemaker with a lithium silver vanadium pentoxide battery. (After W. Greatbatch, Pacemaker power sources, IEEE Eng. Med. Biol. Mag., 3(2):15–19, June 1984)

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from article Medical control systems

Automatic implantable cardioverter defibrillator (AICD) system with pulse generator, leads, and external programmer. (S. Nisam, Cardiac Pacemakers, Inc.)

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from article Microbiome

Profile of the human microbiome by anatomical niche. DNA sequence analysis reveals the relative abundances of the six most abundant bacterial phyla in the human body. The phyla shown represent 99.6% of the sequences sampled. Cyanobacteria were…

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from article Microbiome

Cup-and-ball diagrams to conceptualize the ecosystem equilibrium of the microbiota. (a) A diverse microbial ecosystem requires a large amount of applied force (blue arrow; for example, an antibiotic disturbance) to push it out of its stable…

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from article Acquired immune deficiency syndrome (AIDS)

HIV targets helper T lymphocytes. This illustration shows HIV cells attaching to CD4 coreceptors on a helper T lymphocyte. The depletion of these helper T lymphocytes leads to acquired immune deficiency syndrome (AIDS). (Copyright © McGraw-Hill…

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from article Acquired immune deficiency syndrome (AIDS)

Scanning electron micrograph of HIV-1 virions budding from a cultured lymphocyte. Multiple round bumps on the cell surface represent sites of assembly and budding of virions (green spheres). (Credit: C. Goldsmith/Centers for Disease Control and…

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from article Reproductive system disorders

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from article Reproductive system disorders

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from article Reproductive system disorders

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from article Reproductive system disorders

The testicles (testes), epididymis, vas deferens and seminal vesicles, prostate gland, urethra, and penis are sites affected by disorders of the human male reproductive system. (Copyright © McGraw-Hill Education)

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from article Cisplatin

Structures of cisplatin and related compounds (transplatin and carboplatin).

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from article Hygiene hypothesis

The hygiene hypothesis suggests that young children should be exposed to various environmental microorganisms, including those found in soils, so that proper development of the immune system can take place. (Credit: Allison Peltzman/Shutterstock)

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from article Hygiene hypothesis

Scanning electron micrograph of a human T cell (T lymphocyte) from the immune system of a healthy donor. (Credit: National Institute of Allergy and Infectious Diseases, National Institutes of Health)

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from article Antimicrobial agents

A researcher examining a disk diffusion antimicrobial susceptibility plate. Antibiotic action can be assessed by measuring the zones of inhibition surrounding antibiotic-impregnated filter paper disks.

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from article Escherichia coli outbreaks

A digitally colorized electron micrographic image of an E. coli O157:H7 bacterium, which is a common cause of foodborne disease outbreaks. The flagella of this bacterium can be seen in the image. (Credit: Elizabeth H. White/Centers for Disease…

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from article Escherichia coli outbreaks

A digitally colorized scanning electron micrographic image of a growing cluster of rod-shaped E. coli O157:H7 bacteria. The O157:H7 strain makes a powerful toxin called Shiga toxin, which causes diarrheal disease and other gastrointestinal ailments…

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from article Medical waste

The uniform international biohazard symbol.

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from article Huntington's disease

Huntington's disease is a hereditary disorder that affects approximately five to ten of every 100,000 persons. The average age at onset is between 35 and 40 years. Invariably fatal, the disease progresses gradually over time. (Copyright ©…

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from article Pain

Neurophysiology of incoming pain. Sensation from peripheral receptors travels along specific pain nerves, and is modulated throughout the spinal cord and brain.

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from article Virus, defective

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from article Virus, defective

Electron micrographs of virion and defective interfering particles of vesicular stomatitis virus. (a) Defective interfering particle with a 50% deleted RNA. (b) Defective interfering particle with an 85% deleted RNA. (c, d, f) Defective interfering…

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from article Lipoprotein

Structural model of a lipoprotein.

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from article Vitamin K

Vitamin K. (a) Natural forms. (b) Regeneration of the hydroquinone for γ-carboxyglutamate (Gla) synthesis; Glu = glutamic acid. Vitamin K functions by carboxylating certain glutamate residues in a few proteins. With each carboxylation reaction, a…

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from article Drug delivery systems

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from article Drug delivery systems

Three levels of polymer drug delivery. (a) A polymer is used as carrier of drugs. (b) The drugs are connected to the polymer via cleavable peptide linkers. (c) A homing device is added to target specific tissue types. (Copyright © Jan van…

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from article Hypertension

A blood pressure monitor (sphygmomanometer) for home use to detect hypertension. This easy-to-use device displays levels of the systolic and diastolic blood pressure (mmHg) and pulse readings (pulses per min). (Credit: Roel Smart, Getty Images)

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from article Fetal alcohol spectrum disorder

Abnormal facial features, including small eye openings and a lack of distinction (or a groove) in the area from below the nose to the upper lip, are common characteristics seen in individuals with fetal alcohol spectrum disorder. (Copyright ©…

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from article Narcotic

Heroin is an extremely addictive narcotic. (Credit: FotoMaximum/Getty Images)

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from article Narcotic

Chemical structure of a morphine alkaloid. Two important natural alkaloids are morphine and codeine. Heroin is synthesized from morphine by acetylation.

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from article Androgenic-anabolic steroids

The use of androgenic-anabolic steroids by athletes is widespread because of the putative muscle-building and performance-enhancing effects of these drugs. (Credit: Erik Isakson/Blend Images)

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from article Androgenic-anabolic steroids

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from article Androgenic-anabolic steroids

Androgenic-anabolic steroids possess strong muscle-building properties. Muscle mass increment can be attributed to enlargement of muscle fibers and an increase of the number of muscle fibers. (Credit: photobac/Getty Images)

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from article Channelrhodopsin

Three-dimensional (3D) protein crystal structure of channelrhodopsin variant C1C2. (Image courtesy of Protein Data Bank 3UG9, Molecular Modeling Database 96737)

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from article Plague

Plague ecology in the United States. The left panel shows how plague occurs in nature among rodents. The right panel shows how plague is spread from rodents to humans and domestic animals. (Credit: Centers for Disease Control and Prevention)

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from article Nursing

Nursing provides physical and emotional care to ailing individuals. (Credit: Fuse/Getty Images)

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from article Blood group

An O-negative (O–) whole blood transfusion bag. (Credit: Dieter Meyrl/Getty Images)

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from article Sports medicine

In one test that is commonly used in sports medicine to assess fitness, a patient rides a stationary bike while sensors monitor his respiration and heart rate. (Photo courtesy of Technotr/Getty Images)

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from article Critical care medicine

A male patient in a hospital intensive care unit bed. Often, the intensive care unit is a crucial aspect of critical care medicine, providing life-support systems that ensure a patient's survival. (Credit: Martin Barraud/age fotostock)

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from article Staphylococcus

A digitally colorized scanning electron micrograph (SEM) depicting a number of mustard-colored, spheroid-shaped Staphylococcus aureus bacteria that were in the process of escaping their destruction by blue-colored human white blood cells. (Credit:…

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from article Staphylococcus

Staphylococcal scalded skin syndrome in a baby. Note the appearance of the skin layers peeling as seen in a severe burn. This syndrome is caused by the production of an exotoxin by S. aureus. (Credit: M. K. Cowan and K. P. Talaro; copyright ©…

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from article West Nile virus