Life Cycle, Processes & Properties, THY-VUL
None of us are born looking exactly the way that we do today; this is because humans, like other species, undergo a series of changes as they mature and age, in accordance with their biological life cycle. This process can look very different across different species. In many simple organisms and in higher animals, the life cycle is completed within a single generation, while in most plants, the life cycle is multigenerational.
Life Cycle, Processes & Properties Encyclopedia Articles By Title
thyroiditis, any of many inflammatory diseases of the thyroid gland. Several nonspecific types of thyroiditis,......
tic, (from the 17th-century French tic or ticq, “a twitching”), sudden rapid, recurring contraction in a muscle......
Nikolaas Tinbergen was a Dutch-born British zoologist and ethologist (specialist in animal behaviour) who, with......
tinnitus, ringing or buzzing in the ears. An estimated one-third of adults experience tinnitus at some point in......
tongue, in most vertebrates, an organ, capable of various muscular movements, located on the floor of the mouth.......
tongue-tie, congenital shortening of the flap of mucous membrane (frenum) beneath the tongue, a condition that......
tonsillitis, inflammatory infection of the tonsils caused by invasion of the mucous membrane by microorganisms,......
tooth, any of the hard, resistant structures occurring on the jaws and in or around the mouth and pharynx areas......
tooth germ, embryonic tooth, derived from the mesodermal (middle) and ectodermal (outer) layers of embryonic tissues.......
tooth squeeze, pain caused by the expansion or contraction of air beneath the filling of a tooth when pressure......
torpor, a state of lowered body temperature and metabolic activity assumed by many animals in response to adverse......
torticollis, abnormality in which the neck is in a twisted, bent position such that the head is pulled to one side......
touch reception, perception by an animal when in contact with a solid object. Two types of receptors are common:......
Tourette syndrome, rare inherited neurological disorder characterized by recurrent motor and phonic tics (involuntary......
toxemia of pregnancy, term formerly used to describe hypertensive conditions that can be induced by pregnancy.......
toxic shock syndrome, inflammatory disease characterized by high fever, headache, diarrhea, vomiting, irritability,......
toxin, any substance poisonous to an organism. The term is sometimes restricted to poisons spontaneously produced......
toxoplasmosis, infection of cells of the central nervous system, spleen, liver, and other organs by a parasite,......
trace element, in biology, any chemical element required by living organisms in minute amounts (that is less than......
tracheitis, inflammation and infection of the trachea (windpipe). Most conditions that affect the trachea are bacterial......
trachoma, chronic inflammatory disease of the eye caused by Chlamydia trachomatis, a bacterium-like microorganism......
transdifferentiation, conversion of one differentiated (mature) cell type into another cell type. Transdifferentiation......
transduction, a process of genetic recombination in bacteria in which genes from a host cell (a bacterium) are......
translation, the synthesis of protein from RNA. Hereditary information is contained in the nucleotide sequence......
traumatic brain injury, any damage to the brain from an applied force. The forces involved can be from direct contact,......
trench fever, infectious disease characterized by sudden onset of fever, headache, pain behind the eyes, weakness,......
tricarboxylic acid cycle, the second stage of cellular respiration, the three-stage process by which living cells......
trichinosis, disorder resulting from infestation with roundworms of genus Trichinella, especially the small roundworm......
trichomoniasis, infection by the flagellate protozoan parasite Trichomonas. Infection is most often intestinal,......
trisomy, abnormality in chromosome number (aneuploidy), characterized by the existence of an extra chromosome,......
trisomy 13, human chromosomal disorder that results from an extra (third) copy of chromosome 13. Trisomy 13 can......
trisomy 18, human chromosomal disorder that results from an extra (third) copy of chromosome 18. Infants born with......
trisomy X, sex chromosome disorder of human females, in which three X chromosomes are present, rather than the......
trochophore, small, translucent, free-swimming larva characteristic of marine annelids and most groups of mollusks.......
tropical sprue, rare acquired disease characterized by an impairment of the small intestine’s ability to absorb......
trypanosomiasis, infectious disease in both humans and animals caused by certain members of the flagellate protozoa......
tuber, specialized storage stem of certain seed plants. Tubers are usually short and thickened and typically grow......
tuberculosis (TB), infectious disease that is caused by the tubercle bacillus, Mycobacterium tuberculosis. In most......
tuberous sclerosis, autosomal dominant disorder marked by the formation of widespread benign tumors throughout......
tularemia, acute infectious disease caused by the gram-negative bacterium Francisella tularensis and presenting......
tumour, a mass of abnormal tissue that arises without obvious cause from preexisting body cells, has no purposeful......
turf toe, sprain involving the big toe (hallux) metatarsophalangeal (MTP) joint of the foot. The term turf toe......
Turner syndrome, relatively uncommon sex-chromosome disorder that causes aberrant sexual development in human females.......
twin, either of two young who are simultaneously born from one mother. Twinning, common in many animals, is of......
tympanic membrane, thin layer of tissue in the human ear that receives sound vibrations from the outer air and......
typhoid fever, acute infectious disease caused by the bacterium Salmonella enterica serovar Typhi. The bacterium......
typhus, series of acute infectious diseases that appear with a sudden onset of headache, chills, fever, and general......
tyrosinemia, inherited inability of the body to metabolize normally the amino acid tyrosine. In the normal metabolic......
ulcer, a lesion or sore on the skin or mucous membrane resulting from the gradual disintegration of surface epithelial......
ulcerative colitis, inflammation of the large intestine (colon), especially of its mucous membranes, characterized......
umami, savory or meaty taste, one of the five fundamental taste sensations. The taste of umami is derived from......
umbilical cord, narrow cord of tissue that connects a developing embryo, or fetus, with the placenta (the extra-embryonic......
unisexuality, in biology, the condition of an organism or species capable of producing only male or female gametes......
uremia, medical condition produced by the toxic effects of abnormally high concentrations of nitrogenous substances......
urethritis, infection and inflammation of the urethra, the channel for passage of urine from the urinary bladder......
urinary tract infection (UTI), in humans, inflammation of the renal system characterized by frequent and painful......
urinary tract obstruction, blockage or constriction at any point in the urinary tract that impedes the normal flow......
urination, the process of excreting urine from the urinary bladder. Nerve centres for the control of urination......
urine, liquid or semisolid solution of metabolic wastes and certain other, often toxic, substances that the excretory......
urogenital malformation, any defect in the organs and tissues responsible for the formation and excretion of urine......
uterine bleeding, abnormal bleeding from the uterus, which is not related to menstruation. Menstruation is the......
uterine cancer, a disease characterized by the abnormal growth of cells in the uterus. Cancers affecting the lining......
uterine fibroid, benign tumour that originates from the smooth muscle wall of the uterus and may be single but......
uveitis, inflammation of the uvea (or uveal tract), the middle layer of tissue surrounding the eye that consists......
vaccine-associated feline sarcoma, malignant tumour of cats that develops at the site of a vaccine injection. The......
vaginismus, involuntary muscle spasm that closes the opening to the vagina in the female reproductive tract. The......
vaginitis, inflammation of the vagina, usually due to infection. The chief symptom is the abnormal flow of a whitish......
varicose vein, vein that is twisted and distended with blood. The term varix is also used for similar abnormalities......
veganism, the theory or practice of abstaining from the consumption and use of animal products. While some vegans......
vegetarianism, the theory or practice of living solely upon vegetables, fruits, grains, legumes, and nuts—with......
vegetative reproduction, any form of asexual reproduction occurring in plants in which a new plant grows from a......
veliger, larva typical of certain mollusks such as marine snails and bivalves and a few freshwater bivalves. The......
venom, the poisonous secretion of an animal, produced by specialized glands that are often associated with spines,......
ventricular fibrillation, a type of arrhythmia (abnormal heart rhythm) characterized by the irregular and uncoordinated......
ventricular septal defect, opening in the partition between the two ventricles, or lower chambers, of the heart.......
vertigo, sensation of spinning or tilting or that one’s surroundings are rotating. Usually the state produces dizziness,......
vesicular exanthema of swine, viral disease of swine causing eruption of painful blisters on feet and snout. Blisters......
vesicular stomatitis, viral disease causing blisters in the mouths of cattle, horses, and mules and on the snouts......
vesiculitis, inflammation and infection of the seminal vesicles in the male reproductive tract. The seminal vesicles......
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......
Vincent gingivitis, acute and painful infection of the tooth margins and gums that is caused by the symbiotic microorganisms......
viral disease, disease caused by viruses. Long-term immunity usually follows viral childhood diseases (see chickenpox).......
viral hemorrhagic fever, any of a variety of highly fatal viral diseases that are characterized by massive external......
viroid, an infectious particle smaller than any of the known viruses, an agent of certain plant diseases. The particle......
vision, physiological process of distinguishing, usually by means of an organ such as the eye, the shapes and colours......
visual field defect, a blind spot (scotoma) or blind area within the normal field of one or both eyes. In most......
visual pigment, any of a number of related substances that function in light reception by animals by transforming......
vitamin, any of several organic substances that are necessary in small quantities for normal health and growth......
vitamin A deficiency, nutritional disorder caused by a deficiency of vitamin A (also called retinol), a fat-soluble......
vitiligo, patchy loss of melanin pigment from the skin. Though the pigment-making cells of the skin, or melanocytes,......
vocalization, any sound produced through the action of an animal’s respiratory system and used in communication.......
Volkmann contracture, disorder of the wrist and hand in which the hand and fingers become fixed in a characteristic......
volvulus, twisting of a portion of the digestive tract on its mesentery (the fold of membrane that attaches the......
vomiting, the forcible ejection of stomach contents from the mouth. Like nausea, vomiting may have a wide range......
von Gierke’s disease, most common of a group of hereditary glycogen-storage diseases. It is inherited as an autosomal-recessive......
von Willebrand disease, inherited blood disorder characterized by a prolonged bleeding time and a deficiency of......
voyeurism, human sexual behaviour involving achievement of sexual arousal through viewing the sexual activities......
vulvitis, inflammation and infection of the vulva—the external genitalia of the female. The external organs of......