Blood is the bodily fluid responsible for transport of materials and waste products throughout the body. It carries oxygen from and carbon dioxide to the lungs, nutrients from the digestive system or storage sites to tissues that require them, and waste products from the tissues to the liver for detoxification and to the kidneys for disposal.
Blood clotting (coagulation) is the process by which blood vessels repair ruptures after injury. Injury repair actually begins even before clotting does, through vascular spasm, or muscular contraction of the vessel walls, which reduces blood loss.
Most cells in the human body use the sugar called glucose as their major source of energy. Glucose molecules are broken down within cells in order to produce adenosine triphosphate (ATP) molecules, energy-rich molecules that power numerous cellular processes.
The cardiovascular system includes the heart (cardio) and blood vessels (vascular). The heart pumps blood throughout the body.
A body cavity can be defined as the space that remains after the organs inside it are removed, but this definition does not do justice to the variety and Schematic diagrams of the bodies of animals with coeloms, with pseudocoeloms, or without body cavities. functions of body cavities.
Bone serves many important functions. Bones support the body, protect underlying organs, and provide a movable skeleton against which the muscles can work.
The class Osteichthyes (literally "bony fish") gets its name from the bony skeleton and scales of its members. The group comprises nearly all living fish, with notable exceptions being sharks and other cartilaginous fish, and the primitive lampreys and their kin.
A botanist is a scientist who studies plants. The study of plants encompasses their evolution, classification, anatomy, physiology, development, genetics, diversity, ecology, and economic uses.
The vertebrate brain is the large anterior portion of the central nervous system. The "cranial vault" of the skull encases the brain in most vertebrates.
Bryophytes are seedless plants without specialized water-conducting tissues. Bryophytes include mosses (phylum Bryophyta), liverworts (phylum Marchantiophyta Hepatophyta), and hornworts (phylum Anthocerophyta).
Georges-Louis Leclerc, Comte de Buffon (Count Buffon), was one of the greatest French naturalists and a key philosopher of the Enlightenment. Born to a wealthy family, Buffon became interested in Newton's physics before turning to biology.
C4 and CAM plants are plants that use certain special compounds to gather carbon dioxide (CO2) during photosynthesis. Using these compounds allows these plants to extract more CO2 from a given amount of air, helping them prevent water loss in dry climates.
Scientists agree that the Cambrian explosion is one of the most significant events in the history of life. It is marked by a series of biological changes that took place over a relatively short period of geologic time during the early Cambrian, 543 to 520 million years ago.
Normal tissue development depends on a balance between cell multiplication and cell death. When cells multiply faster than they die, the result is an abnormal tissue growth called a tumor (neoplasm).
Carbohydrates are one of four major classes of biological molecules, along with nucleic acids, lipids, and proteins. They are the most abundant biological molecules, and are an important nutritional component of many foods.
The carbon cycle involves the circulation of carbon dioxide (CO2) from the atmosphere into plants and other living organisms; the transfer of carbon from these organisms into other temporary storage pools, living or nonliving, containing organic and inorganic carbon compounds; and the return of CO2 to the atmosphere through respiration or combustion processes. The carbon cycle provides a unifying framework for examining exchanges or storage of carbon associated with photosynthesis and energy assimilation by organisms, respiration and metabolism, productivity and biomass accumulation, and the decay and recycling of organic matter at the level of a single organism, an ecosystem, or the global biosphere.
Cardiovascular diseases affect the heart or the blood vessels. Because the cardiovascular system provides oxygen and nutrients to cells and removes wastes from them, these diseases have profound impacts on health.
Rachel Louise Carson was a career government biologist and author who forever changed public attitudes about the environment.
The cartilaginous fish, or Chondricthyes, include the sharks, rays, skates, and chimaeras. There are over eight hundred living species of sharks and rays, and about thirty species of chimaeras.
A cell is the smallest unit of living matter. Cells were first identified in Europe in the seventeenth century by Antoni van Leeuwenhoek and others.
Cell culture describes the laboratory growth of cells derived from plants or animals. To put cells into culture, the tissue of interest is exposed to enzymes that dissociate the tissue to release the component cells.
The cell cycle is the ordered series of events required for the faithful duplication of one eukaryotic cells into two genetically identical daughter cells. In a cell cycle, precise replication of deoxyribonucleic acid (DNA) duplicates each chromosome.