Life Cycle, Processes & Properties, IMI-LEA
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
iminoglycinuria
iminoglycinuria, inborn impairment of the transport system of the kidney tubules, which normally reabsorb the amino......
immersion foot
immersion foot, a painful disorder of the foot involving damage to the skin, nerves, and muscle that is caused......
immune system disorder
immune system disorder, any of various failures in the body’s defense mechanisms against infectious organisms.......
immunity
immunity, in biology, the ability of the body to prevent or defeat infection from invading microorganisms or parasites.......
immunization
immunization, process by which resistance to disease is acquired or induced in plants and animals. This discussion......
immunodeficiency
immunodeficiency, defect in immunity that impairs the body’s ability to resist infection. The immune system may......
impact injury
impact injury, the damage caused by the collision of a body with a moving or stationary object. Impact injuries......
impetigo
impetigo, inflammatory skin infection that begins as a superficial blister or pustule that then ruptures and gives......
implantation
implantation, in reproduction physiology, the adherence of a fertilized egg to a surface in the reproductive tract,......
imposter syndrome
imposter syndrome, a persistent unjustified feeling that one’s success is fraudulent. Imposter syndrome is characterized......
impotence
impotence, in general, the inability of a man to achieve or maintain penile erection and hence the inability to......
inborn error of metabolism
inborn error of metabolism, any of multiple rare disorders that are caused by an inherited genetic defect and that......
incidence
incidence, in epidemiology, occurrence of new cases of disease, injury, or other medical conditions over a specified......
incontinence
incontinence, inability to control the excretion of urine or feces. Starting and stopping urination relies on normal......
index case
index case, in public health, the first case of a disease or other condition that is noticed by health authorities.......
indigestion
indigestion, any or all of the symptoms—abdominal discomfort, belching, flatulence, aversion to eating, nausea,......
induction
induction, in embryology, process by which the presence of one tissue influences the development of others. Certain......
industrial melanism
industrial melanism, the darkness—of the skin, feathers, or fur—acquired by a population of animals living in an......
infancy
infancy, among humans, the period of life between birth and the acquisition of language approximately one to two......
infant and toddler development
infant and toddler development, the physical, emotional, behavioral, and mental growth of children from ages 0......
infantile hemangioma
infantile hemangioma, a congenital benign tumour made up of endothelial cells (the cells lining the inner surface......
infarction
infarction, death of tissue resulting from a failure of blood supply, commonly due to obstruction of a blood vessel......
infection
infection, the process by which harmful microorganisms such as bacteria, viruses, fungi, or parasites enter cells......
infectious bovine keratoconjunctivitis
infectious bovine keratoconjunctivitis, an inflammation of the conjunctiva or the cornea of the eye in cattle as......
infectious disease
infectious disease, in medicine, a process caused by an agent, often a type of microorganism, that impairs a person’s......
- Introduction
- Rickettsias, Bacteria, Symptoms
- Fungal, Pathogens, Prevention
- Commensalism, Pathogens, Immunity
- Transmission, Prevention, Control
- Occupation, Commerce, Prevention
- Immune Response, Pathogens, Prevention
- Natural Immunity, Acquired Immunity
- Immunization, Prevention, Vaccines
- Polio Vaccine, Prevention, Eradication
- Hepatitis B, Vaccine, Prevention
inferiority complex
inferiority complex, a psychological sense of inferiority that is wholly or partly unconscious. The term has been......
infertility
infertility, the inability of a couple to conceive and reproduce. Infertility is defined as the failure to conceive......
inflammation
inflammation, a response triggered by damage to living tissues. The inflammatory response is a defense mechanism......
inflammatory bowel disease
inflammatory bowel disease (IBD), chronic inflammation of the intestines that results in impaired absorption of......
influenza
influenza, an acute viral infection of the upper or lower respiratory tract that is marked by fever, chills, and......
Influenza Pandemic of 1918–19 Chart
This infographic explains what influenza and pandemics are and how the influenza pandemic of 1918–19 spread. That......
inner ear
inner ear, part of the ear that contains organs of the senses of hearing and equilibrium. The bony labyrinth, a......
insect bite and sting
insect bite and sting, break in the skin or puncture caused by an insect and complicated by introduction into the......
Insects That Wear Things
Insects might be small and common, but their survival strategies are anything but ordinary. While many use camouflage......
insomnia
insomnia, the inability to sleep adequately. Causes may include poor sleeping conditions, circulatory or brain......
intersex
intersex, in biology, an organism having physical characteristics intermediate between a true male and a true female......
intestinal gas
intestinal gas, material contained within the digestive tract that consists principally of swallowed air and partly......
intestinal obstruction
intestinal obstruction, functional or mechanical blockage of the alimentary canal. Functional blockage occurs when......
intestinal squeeze
intestinal squeeze, pain and possible injury to the small or large intestine caused by expansion of trapped gases......
intestine
intestine, tubular part of the alimentary canal that extends from the stomach to the anus. The intestine is the......
intussusception
intussusception, telescoping of a segment of the intestine into an adjacent segment, producing a mechanical obstruction......
iodine deficiency
iodine deficiency, condition in which iodine is insufficient or is not utilized properly. Iodine is an element......
ionizing radiation injury
ionizing radiation injury, tissue destruction or changes caused by deeply penetrating electromagnetic waves of......
iris
iris, in anatomy, the colored muscular part of the eye surrounding the pupil, the small black opening in the center.......
iron-deficiency anemia
iron-deficiency anemia, anemia that develops due to a lack of the mineral iron, the main function of which is in......
irritable bowel syndrome
irritable bowel syndrome (IBS), relatively common disorder of the intestines characterized by abdominal pain, intestinal......
Is It Really Dangerous to Swim After Eating?
Common wisdom holds that it is unsafe to swim after eating unless one waits for some prescribed period of time—usually......
Is It Safe to Reopen Schools During the COVID-19 Pandemic?
This article was originally published on August 19, 2020, during the first year of the COVID-19 pandemic, when......
Is It True That Squirrels Forget Where They Bury About Half of Their Food?
The verdict is out on whether squirrels forget about half of the nuts they bury: surely some squirrels do. Forgotten......
Is Magnesium Good for Sleep?
Despite its reputation as a natural sleep remedy, magnesium is not a cure for insomnia or other sleep disorders.......
Is Spontaneous Human Combustion Real?
Late at night on Christmas Eve 1885, in the small farming town of Seneca, Illinois, a woman named Matilda Rooney......
Is There a Cure for HIV Infection?
No, there is no cure yet for infection with HIV, or human immunodeficiency virus. In fact, despite multiple reports......
itching
itching, a stimulation of free nerve endings, usually at the junction of the dermis and epidermis of the skin,......
Ivory
Ivory, variety of dentin of which the tusk of the elephant is composed and which is prized for its beauty, durability,......
Jacobson’s organ
Jacobson’s organ, an organ of chemoreception that is part of the olfactory system of amphibians, reptiles, and......
jaundice
jaundice, excess accumulation of bile pigments in the bloodstream and bodily tissues that causes a yellow to orange......
jet lag
jet lag, physiological desynchronization caused by transmeridian (east-west) travel between different time zones.......
Johne’s disease
Johne’s disease, serious infectious disease caused by Mycobacterium avium paratuberculosis. Although principally......
joint disease
joint disease, any of the diseases or injuries that affect human joints. Arthritis is no doubt the best-known joint......
Jonathan
Jonathan, who celebrated his 193rd and birthday on December 4, 2025, is considered the oldest living land animal......
kala-azar
kala-azar, infectious disease that is a type of leishmaniasis...
Kaposi sarcoma
Kaposi sarcoma, rare and usually lethal cancer of the tissues beneath the surface of the skin or of the mucous......
Kawasaki syndrome
Kawasaki syndrome, rare, acute inflammatory disease of unknown origin that is one of the leading causes of acquired......
keloid
keloid, benign tumour and chronic skin disorder in which excessive scar tissue (mainly collagen) forms a smooth......
keratitis
keratitis, inflammation of the cornea, the transparent domelike portion of the eyeball in front of the iris and......
keratosis
keratosis, any protuberance on the skin resulting from the overdevelopment of the horny outermost covering of the......
keratosis pilaris
keratosis pilaris, benign noncontagious skin condition characterized by the presence of discrete, tiny follicular......
kernicterus
kernicterus, severe brain damage caused by an abnormal concentration of the bile pigment bilirubin in brain tissues......
Kerr, Sir John Graham
Sir John Graham Kerr was an English embryologist who became known for his study of lungfishes and who greatly advanced......
ketogenic diet
ketogenic diet, dietary regime that eliminates or severely limits carbohydrates in favour of proteins and fats......
ketosis
ketosis, metabolic disorder marked by high levels of ketones in the tissues and body fluids, including blood and......
kidney failure
kidney failure, partial or complete loss of kidney function. Kidney failure is classified as acute (when the onset......
kidney stone
kidney stone, concretion of minerals and organic matter that forms in the kidneys. Such stones may become so large......
king’s evil
king’s evil, scrofula (q.v.), or struma, a tuberculous swelling of the lymph glands, once popularly supposed to......
kinocilium
kinocilium, filamentous structure occurring on auditory hair cells in the inner ear that functions in the development......
kleptomania
kleptomania, recurrent compulsion to steal without regard to the value or use of the objects stolen. Although widely......
Klinefelter syndrome
Klinefelter syndrome, disorder of the human sex chromosomes that occurs in males. Klinefelter syndrome is one of......
knee injuries
knee injuries, the common afflictions of the knee, a relatively fragile joint, as it is exposed to stress in daily......
Korsakoff syndrome
Korsakoff syndrome, neurological disorder characterized by severe amnesia (memory loss). Many cases result from......
Kovalevsky, Aleksandr Onufriyevich
Aleksandr Onufriyevich Kovalevsky was a Russian founder of comparative embryology and experimental histology, who......
Kuhn, Maggie
Maggie Kuhn was an American social activist who was central in establishing the group that became known as the......
kuru
kuru, infectious fatal degenerative disorder of the central nervous system found primarily among the Fore people......
kwashiorkor
kwashiorkor, condition caused by severe protein deficiency. Kwashiorkor is most often encountered in developing......
Kölliker, Rudolf Albert von
Rudolf Albert von Kölliker was a Swiss embryologist and histologist, one of the first to interpret tissue structure......
labour
labour, in human physiology, the physical activity experienced by the mother during parturition (q.v.), or...
labyrinthitis
labyrinthitis, inflammation, either acute or chronic, of the inner ear (the labyrinth). It is often a complication......
labyrinthodont
labyrinthodont, a type of tooth made up of infolded enamel that provides a grooved and strongly reinforced structure.......
laceration
laceration, tearing of the skin that results in an irregular wound. Lacerations may be caused by injury with a......
lactose intolerance
lactose intolerance, inability to digest lactose, the predominant sugar in dairy products. It affects people by......
Lag phase
Lag phase, period of bacterial cell growth in which the population remains constant as it adjusts to the environmental......
Lamaze
Lamaze, method of childbirth that involves psychological and physical preparation by the mother for the purpose......
Lankester, Sir Edwin Ray
Sir Edwin Ray Lankester was a British authority on general zoology at the turn of the 19th century, who made important......
Larva
Larva, stage in the development of many animals, occurring after birth or hatching and before the adult form is......
laryngeal cancer
laryngeal cancer, malignant disease of the larynx (voice box). The most common type of malignant tumor identified......
laryngeal hemiplegia
laryngeal hemiplegia, in horses, partial or complete paralysis of muscles controlling the vocal fold and other......
laryngectomy
laryngectomy, surgical procedure to remove all or a portion of the larynx (voice box). The procedure most often......
laryngitis
laryngitis, inflammation of the larynx or voice box, caused by chemical or mechanical irritation or bacterial infection.......
Late blight
Late blight, disease of potato and tomato plants that is caused by the water mold Phytophthora infestans. The disease......
lateral line system
lateral line system, a system of tactile sense organs, unique to aquatic vertebrates from cyclostome fishes (lampreys......
lead poisoning
lead poisoning, deleterious effect of a gradual accumulation of lead in body tissues, as a result of repeated exposure......