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.
Back To Cells, Organs & Tissues Page

Cells, Organs & Tissues Encyclopedia Articles By Title

vagus nerve
vagus nerve, longest and most complex of the cranial nerves. The vagus nerve runs from the brain through the face......
vascular system
vascular system, in vascular plants, assemblage of conducting tissues and associated supportive fibres that transport......
ventricle
ventricle, muscular chamber that pumps blood out of the heart and into the circulatory system. Ventricles occur......
vertebral column
vertebral column, in vertebrate animals, the flexible column extending from neck to tail, made of a series of bones,......
Vesalius, Andreas
Andreas Vesalius was a Renaissance physician who revolutionized the study of biology and the practice of medicine......
vessel
vessel, in botany, the most specialized and efficient conducting structure of xylem (fluid-conducting tissues).......
vestibular system
vestibular system, apparatus of the inner ear involved in balance. The vestibular system consists of two structures......
vestibulocochlear nerve
vestibulocochlear nerve, nerve in the human ear, serving the organs of equilibrium and of hearing. It consists......
vibrissae
vibrissae, stiff hairs on the face or nostrils of an animal, such as the whiskers of a cat. Vibrissae often act......
villus
villus, in anatomy any of the small, slender, vascular projections that increase the surface area of a membrane.......
vision
vision, physiological process of distinguishing, usually by means of an organ such as the eye, the shapes and colours......
visual pigment
visual pigment, any of a number of related substances that function in light reception by animals by transforming......
viviparity
viviparity, retention and growth of the fertilized egg within the maternal body until the young animal, as a larva......
vocal cord
vocal cord, either of two folds of mucous membrane that extend across the interior cavity of the larynx and are......
vocal sac
vocal sac, the sound-resonating throat pouch of male frogs and toads (amphibians of the order Anura). Vocal sacs......
vocalization
vocalization, any sound produced through the action of an animal’s respiratory system and used in communication.......
Voit, Carl von
Carl von Voit was a German physiologist whose definitive measurements of gross metabolism in mammals, including......
vulva
vulva, the external female genitalia that surround the opening to the vagina; collectively these consist of the......
Weber, Ernst Heinrich
Ernst Heinrich Weber was a German anatomist and physiologist whose fundamental studies of the sense of touch introduced......
Weiss, Paul Alfred
Paul Alfred Weiss was an Austrian-born American biologist who did pioneering research on the mechanics of nerve......
Wernicke area
Wernicke area, region of the brain that contains motor neurons involved in the comprehension of speech. This area......
whalebone
whalebone, series of stiff keratinous plates in the mouths of baleen whales, used to strain copepods and other......
What Are Turtle Shells Made Of?
Turtle shells are made of bone and cartilage, but it is the form and function of the shells that make them unique......
What Causes a Drought?
Droughts occur when evaporation and transpiration rates consistently exceed precipitation over an extended period......
What Causes Allergies?
Allergic reactions are caused by substances known as allergens. These substances can be found in a variety of sources......
What Happened to Einstein’s Brain?
Albert Einstein, touted as one of the greatest thinkers of the 20th century, died April 18, 1955, as a result of......
What Happens When You Swallow Gum?
Your parents may have warned you not to swallow your chewing gum because it would remain in your stomach for seven......
white blood cell
white blood cell, a cellular component of the blood that lacks hemoglobin, has a nucleus, is capable of motility,......
Why Are Elephants’ Ears So Big?
An elephant’s large ears serve several purposes. Thermoregulation—an organism’s maintenance of its own body temperature......
Why Are Mosquitoes Attracted to Certain People?
Mosquitoes that feed on human blood are attracted to certain people more than others due to a combination of factors......
Why Are Plants Green?
Plants are green because of a pigment found in the chloroplasts of plant cells called chlorophyll. It plays a crucial......
Why Are Robin Eggs Blue?
Robin eggs are blue due to a fascinating evolutionary adaptation that may help protect them from sun exposure.......
Why Are There Different Blood Types?
Different blood groups are the result of genetic variations that determine the presence or absence of specific......
Why Can’t You Tickle Yourself?
At some point in your life you’ve probably been tickled—repeatedly touched in a way that induced smiling, laughter,......
Why Do Cats Blink Slowly?
Cats blink slowly as a form of nonverbal communication, often interpreted as a sign of trust and affection toward......
Why Do Cats Have Slit Pupils?
Cats have slit pupils primarily to enhance their ability to see in varying light conditions. They are crepuscular......
Why Do Cats Have Whiskers?
Cats have whiskers primarily for tactile sensing, which is crucial for their survival and daily activities. Whiskers,......
Why Do Deer Shed Their Antlers?
Deer shed their antlers as part of a natural cycle that is linked to their survival and mating season. In all but......
Why Do Dogs Have Wet Noses?
Dogs have wet noses mainly to enhance their sense of smell. The moisture on the nose traps scent particles in the......
Why Do Gray Hairs Have a Different Texture?
Gray hairs are indeed unusual, and not only because of their color. Gray hair is stiffer and more wiry than hair......
Why Do Humans Have Eyebrows?
Eyebrows are like the unsung heroes of the face, quietly doing their job of protecting the eyes from the glare......
Why Do Leaves Change Color in the Fall?
Green leaves get their color from the photosynthetic pigment chlorophyll. When deciduous leaves are preparing to......
Why Do Leaves Change Colors in the Fall?
In many places around the world, autumn is marked by the slow, beautiful change of green foliage to vibrant reds,......
Why Do Leaves Fall in Autumn?
In temperate regions of the world, autumn is marked by the brightly colored foliage that slowly drops from trees......
Why Do Salmon Die After Spawning?
Salmon are biologically programmed to die after spawning, a phenomenon known as semelparity. This is a reproductive......
Why Do We Have Earwax?
Sticky, gooey, oftentimes orange, and homemade within the ears—earwax is considered a gross nuisance that people......
Why Do Zebras Have Stripes?
There are several theories about why zebras have stripes. Scientists believe that one of the main reasons is camouflage......
Why Does Cilantro Taste Like Soap to Some People?
Cilantro (aka the leaves of the coriander plant) is a tasty herb to most people. A pleasing combination of flavors......
Why Does Hair Turn Gray?
Hair turns gray as melanocytes—the cells that generate melanin, which gives hair (and skin) its coloration—deteriorate......
Why Does Heat Relax Your Muscles?
Exercise is painful. As the cliché goes, “No pain, no gain.” When the body exerts itself, pumping action out of......
Wigglesworth, Sir Vincent
Sir Vincent Wigglesworth was an English entomologist, noted for his contribution to the study of insect physiology.......
Wilson, Edmund Beecher
Edmund Beecher Wilson was an American biologist known for his researches in embryology and cytology. In 1891 Wilson......
Wolffian duct
Wolffian duct, one of a pair of tubes that carry urine from primitive or embryonic kidneys to the exterior or to......
wrist
wrist, complex joint between the five metacarpal bones of the hand and the radius and ulna bones of the forearm.......
Wundt, Wilhelm
Wilhelm Wundt was a German physiologist and psychologist who is generally acknowledged as the founder of experimental......
Xg blood group system
Xg blood group system, classification of human blood based on the presence of proteins called Xg antigens on the......
xylem
xylem, plant vascular tissue that conveys water and dissolved minerals from the roots to the rest of the plant......
yolk
yolk, the nutritive material of an egg, used as food by a developing, embryonic animal. Eggs with relatively little,......
Yt blood group system
Yt blood group system, classification of human blood based on the presence of molecules known as Yt antigens on......
zygomatic arch
zygomatic arch, bridge of bone extending from the temporal bone at the side of the head around to the maxilla (upper......
zygomatic bone
zygomatic bone, diamond-shaped bone below and lateral to the orbit, or eye socket, at the widest part of the cheek.......
zygote
zygote, fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm).......

Cells, Organs & Tissues Encyclopedia Articles By Title