Cells, Organs & Tissues, VAG-ZYG
Even if you feel you have nothing in common with a stinkbug or a ficus, you're guaranteed to share one crucial aspect of life with these beings: you are all made up of cells, the fundamental molecules of life, of which all living things are composed. As an individual unit, the cell is capable of metabolizing its own nutrients, synthesizing many types of molecules, providing its own energy, and replicating itself. In a multicellular organism, cooperative assemblies of similar cells form tissues, and a cooperation between tissues in turn forms organs, which carry out the functions necessary to sustain the life of an organism.
Cells, Organs & Tissues Encyclopedia Articles By Title
vagus nerve, longest and most complex of the cranial nerves. The vagus nerve runs from the brain through the face......
vascular system, in vascular plants, assemblage of conducting tissues and associated supportive fibres that transport......
ventricle, muscular chamber that pumps blood out of the heart and into the circulatory system. Ventricles occur......
vertebral column, in vertebrate animals, the flexible column extending from neck to tail, made of a series of bones,......
Andreas Vesalius was a Renaissance physician who revolutionized the study of biology and the practice of medicine......
vessel, in botany, the most specialized and efficient conducting structure of xylem (fluid-conducting tissues).......
vestibular system, apparatus of the inner ear involved in balance. The vestibular system consists of two structures......
vestibulocochlear nerve, nerve in the human ear, serving the organs of equilibrium and of hearing. It consists......
vibrissae, stiff hairs on the face or nostrils of an animal, such as the whiskers of a cat. Vibrissae often act......
villus, in anatomy any of the small, slender, vascular projections that increase the surface area of a membrane.......
vision, physiological process of distinguishing, usually by means of an organ such as the eye, the shapes and colours......
visual pigment, any of a number of related substances that function in light reception by animals by transforming......
viviparity, retention and growth of the fertilized egg within the maternal body until the young animal, as a larva......
vocal cord, either of two folds of mucous membrane that extend across the interior cavity of the larynx and are......
vocal sac, the sound-resonating throat pouch of male frogs and toads (amphibians of the order Anura). Vocal sacs......
vocalization, any sound produced through the action of an animal’s respiratory system and used in communication.......
Carl von Voit was a German physiologist whose definitive measurements of gross metabolism in mammals, including......
vulva, the external female genitalia that surround the opening to the vagina; collectively these consist of the......
Ernst Heinrich Weber was a German anatomist and physiologist whose fundamental studies of the sense of touch introduced......
Paul Alfred Weiss was an Austrian-born American biologist who did pioneering research on the mechanics of nerve......
Wernicke area, region of the brain that contains motor neurons involved in the comprehension of speech. This area......
whalebone, series of stiff keratinous plates in the mouths of baleen whales, used to strain copepods and other......
Turtle shells are made of bone and cartilage, but it is the form and function of the shells that make them unique......
Droughts occur when evaporation and transpiration rates consistently exceed precipitation over an extended period......
Allergic reactions are caused by substances known as allergens. These substances can be found in a variety of sources......
Albert Einstein, touted as one of the greatest thinkers of the 20th century, died April 18, 1955, as a result of......
Your parents may have warned you not to swallow your chewing gum because it would remain in your stomach for seven......
white blood cell, a cellular component of the blood that lacks hemoglobin, has a nucleus, is capable of motility,......
An elephant’s large ears serve several purposes. Thermoregulation—an organism’s maintenance of its own body temperature......
Mosquitoes that feed on human blood are attracted to certain people more than others due to a combination of factors......
Plants are green because of a pigment found in the chloroplasts of plant cells called chlorophyll. It plays a crucial......
Robin eggs are blue due to a fascinating evolutionary adaptation that may help protect them from sun exposure.......
Different blood groups are the result of genetic variations that determine the presence or absence of specific......
At some point in your life you’ve probably been tickled—repeatedly touched in a way that induced smiling, laughter,......
Cats blink slowly as a form of nonverbal communication, often interpreted as a sign of trust and affection toward......
Cats have slit pupils primarily to enhance their ability to see in varying light conditions. They are crepuscular......
Cats have whiskers primarily for tactile sensing, which is crucial for their survival and daily activities. Whiskers,......
Deer shed their antlers as part of a natural cycle that is linked to their survival and mating season. In all but......
Dogs have wet noses mainly to enhance their sense of smell. The moisture on the nose traps scent particles in the......
Gray hairs are indeed unusual, and not only because of their color. Gray hair is stiffer and more wiry than hair......
Eyebrows are like the unsung heroes of the face, quietly doing their job of protecting the eyes from the glare......
Green leaves get their color from the photosynthetic pigment chlorophyll. When deciduous leaves are preparing to......
In many places around the world, autumn is marked by the slow, beautiful change of green foliage to vibrant reds,......
In temperate regions of the world, autumn is marked by the brightly colored foliage that slowly drops from trees......
Salmon are biologically programmed to die after spawning, a phenomenon known as semelparity. This is a reproductive......
Sticky, gooey, oftentimes orange, and homemade within the ears—earwax is considered a gross nuisance that people......
There are several theories about why zebras have stripes. Scientists believe that one of the main reasons is camouflage......
Cilantro (aka the leaves of the coriander plant) is a tasty herb to most people. A pleasing combination of flavors......
Hair turns gray as melanocytes—the cells that generate melanin, which gives hair (and skin) its coloration—deteriorate......
Exercise is painful. As the cliché goes, “No pain, no gain.” When the body exerts itself, pumping action out of......
Sir Vincent Wigglesworth was an English entomologist, noted for his contribution to the study of insect physiology.......
Edmund Beecher Wilson was an American biologist known for his researches in embryology and cytology. In 1891 Wilson......
Wolffian duct, one of a pair of tubes that carry urine from primitive or embryonic kidneys to the exterior or to......
wrist, complex joint between the five metacarpal bones of the hand and the radius and ulna bones of the forearm.......
Wilhelm Wundt was a German physiologist and psychologist who is generally acknowledged as the founder of experimental......
Xg blood group system, classification of human blood based on the presence of proteins called Xg antigens on the......
xylem, plant vascular tissue that conveys water and dissolved minerals from the roots to the rest of the plant......
yolk, the nutritive material of an egg, used as food by a developing, embryonic animal. Eggs with relatively little,......
Yt blood group system, classification of human blood based on the presence of molecules known as Yt antigens on......
zygomatic arch, bridge of bone extending from the temporal bone at the side of the head around to the maxilla (upper......
zygomatic bone, diamond-shaped bone below and lateral to the orbit, or eye socket, at the widest part of the cheek.......
zygote, fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm).......