Life Cycle, Processes & Properties, HIV-ILL
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
hives
hives, a hypersensitive skin reaction characterized by the sudden appearance of very itchy, slightly raised, smooth,......
Hodgkin lymphoma
Hodgkin lymphoma, an uncommon cancer of the lymphatic system (malignant lymphoma) that usually strikes young adults......
hog cholera
hog cholera, serious and often fatal viral disease of swine. Characterized by high fever and exhaustion, the disease......
Homeostasis
Homeostasis, any self-regulating process by which biological systems tend to maintain stability while adjusting......
homocystinuria
homocystinuria, hereditary metabolic disorder involving methionine, a sulfur-containing essential amino acid. The......
hookworm disease
hookworm disease, parasitic infestation of humans, dogs, or cats caused by bloodsucking worms living in the small......
Hormone
Hormone, organic substance secreted by plants and animals that functions in the regulation of physiological activities......
- Introduction
- Vertebrates, Endocrine, Neuroendocrine
- LH, ICSH, Endocrine
- Thyroid Gland, Metabolism, Hormone Production
- Parathyroid, Calcium, Parathormone
- Glucagon, Pancreas, Regulation
- Reproductive, Endocrine, Glands
- Endocrine Glands, Secretions, Hormone Functions
- Molting, Insects, Juveniles
- Plant Growth, Photosynthesis, Reproduction
- Growth Inhibitors
How Can Some Trees Survive for Thousands of Years?
Some of the oldest living things on our remarkable planet are trees. The record holders are bristlecone pines of......
How Deadly Are Australia’s Animals?
Even more than for its gorgeous opera house, sandy beaches, or colourful reefs, Australia has cemented its reputation......
How Did the COVID-19 Pandemic Start?
Despite extensive investigation, the manner in which the COVID-19 pandemic started is yet undetermined. The leading......
How do birds know when to fly south?
In the Northern Hemisphere, migratory birds tend to fly south to spend the winter in warmer locales. (Though in......
How Do Chameleons Change Colour?
Chameleons change colour by dispersing or concentrating pigment granules (melanophore cells) in the cells that......
How do fireflies light up?
Fireflies light up summer nights using a chemical process known as bioluminescence, the key chemical players of......
How do fish breathe?
Fish primarily breathe through gills, which are specialized organs that extract dissolved oxygen from water. The......
How do fish sleep?
Fish enter a restful state marked by minimal movement and decreased responsiveness. During this time, they maintain......
How do frogs breathe?
Frogs have an adaptable respiratory system that allows them to breathe in multiple ways throughout their life cycle......
How Do Glowworms Glow?
There are actually a number of different insects known as "glowworms," and they have a variety of mechanisms for......
How do horses sleep?
Horses sleep both standing up and lying down. Most of their sleeping time is spent standing, which is crucial for......
How do penguins stay warm?
Penguins have a unique feather arrangement and body structure that provides excellent insulation. Their short,......
How do plants grow?
Unlike most animals, plants continue to grow throughout their entire life span. Plant growth and plant development......
How do snakes swallow large prey?
Snakes have a unique and fascinating way of swallowing prey that is much larger than their own heads and even bodies.......
How do spiders make circular webs?
Spiders are a diverse group of arachnids, with over 51,500 identified species. While not all spiders spin webs,......
How Do the Symptoms of COVID-19 Differ from Those of Cold and Flu?
October marks the start of cold and flu season in the Northern Hemisphere, where, in 2020, many countries also......
How Does the Human Body Maintain Its Temperature?
People are mammals, and mammals are warm-blooded creatures, capable of maintaining a relatively constant internal......
How fast are alligators?
In the water, alligators can reach swimming speeds of up to 32.2 kilometers per hour (20 miles per hour), using......
How fast are cheetahs?
Cheetahs are capable of reaching speeds of up to 114 km (71 miles) per hour, making them the fastest land animals.......
How fast are snails?
The speed of a snail varies depending on the species. Most prosobranchs—a group that includes some land, marine,......
How fast can bears run?
Bears, despite their at times lumbering appearance, can move at impressive speeds in pursuit of prey. The fastest......
How fast can eagles fly?
Eagles generally soar at speeds of about 50 km (30 miles) per hour when flying at high altitudes. They can accelerate......
How fast can horses run?
The average horse can reach speeds of 50 km (30 miles) per hour at a gallop, the animal’s fastest gait (pattern......
How fast do hummingbirds fly?
Hummingbirds, those tiny marvels of the avian world, can reach speeds greater than 48 km per hour (30 miles per......
How high do birds fly?
The majority of birds fly at altitudes of about 150 meters (around 500 feet) or lower. During migration, however,......
How intelligent are dolphins?
Dolphins are highly intelligent animals, and this intelligence appears in many aspects of their lives. One well-documented......
How Is Inflammation Involved in Swelling?
Immediately following an injury, the traumatized area becomes red, warm, and painful, and it begins to swell. The......
How long can alligators live?
Alligators can live for about 50 years in the wild and even longer in captivity, often surpassing the 70-year mark.......
How long can ticks live without food?
Ticks are parasitic, blood-feeding arachnids with more than 800 species worldwide. They are remarkably resilient......
How long can whales hold their breath?
Whales can hold their breath for varying durations depending on the species, with some capable of staying submerged......
How Long Did the Flu Pandemic of 1918 Last?
The influenza pandemic of 1918–19, also called the Spanish flu, lasted between one and two years. Companion, Spanish......
How long do chicken eggs take to hatch?
Chicken eggs typically take about 21 days to hatch. This is the time it takes for a fertilized egg to develop into......
How long do elephants live?
Elephants have varied lifespans depending on whether they live in the wild or in captivity. The lifespan of wild......
How long do queen bees live?
There are a number of species of social bees with colonies dependent on a queen. The most ubiquitous and well known......
How long do tigers live?
Tigers typically live for 10–15 years in the wild but longer in captivity, sometimes reaching 20 years or more.......
How long do tortoises live?
Tortoises are renowned for their impressive life spans, as some species live for more than 60 years. This longevity......
How long does it take food to digest?
The process of food digestion typically takes between 24 and 72 hours. The precise length of time is determined......
How long does it take for rigor mortis to set in?
Rigor mortis sets in about two to six hours after death, starting in the smaller muscles of the body, such as those......
How many eyes does a spider have?
Spiders typically have eight eyes, although some species may have fewer. The number and arrangement of eyes can......
How Many Legs Does a Caterpillar Have?
Caterpillars are the larval form of moths, butterflies, and skippers. Like all insects, they have three pairs of......
How many teeth does a shark have?
The number of teeth a shark has is different for each species, but some can have more than 35,000 teeth in their......
How Much Does a Falcon Eat Each Day?
Although there are many variables that can affect a falcon’s diet, an adult falcon will generally eat 70–154 grams......
How Much Sleep Do You Need?
Sleep is a biological necessity, and sleep needs change throughout life. Newborns may need as many as 17 hours......
How Much Water Should a Person Drink in a Day?
The popular recommendation to drink 8 cups of water every day isn’t as definitive as it may seem. The amount of......
How old is the oldest living Greenland shark?
Scientific data suggest that Greenland sharks (Somniosus microcephalus) may live for more than 500 years and that......
How Other Species Learn
In the wild, animals don’t live and learn. They learn and live. Knowledge equals survival. Certain knowledge is......
How Rye Bread May Have Caused the Salem Witch Trials
In 1692 the small Puritan village of Salem, Massachusetts, was plagued by a sudden and brief cloud of witchcraft......
How strong is a shark’s bite?
When it comes to mighty bites, sharks are exceptionally powerful. In fact, the great white shark has one of the......
How the First Surviving Quintuplets Became a Tourist Attraction
On May 28, 1934, a miracle happened. In a modest farmhouse in Corbeil, Ontario, Canada, parents Oliva and Elzire......
How the Opioid Crisis Devastated Families, Communities, and, Ultimately, a Country
Kateena Haynes’s smile warms the room as she weaves through playing children at her feet to get to the computer......
human aging
human aging, physiological changes that take place in the human body leading to senescence, the decline of biological......
human development
human development, the process of growth and change that takes place between birth and maturity. Human growth is......
human disease
human disease, an impairment of the healthy state of the human body that interrupts or modifies its vital functions.......
- Introduction
- Prevention, Diagnosis, Treatment
- Metabolism, Control, Regulation
- Immune Response, Pathogens, Prevention
- Signs, Symptoms, Diagnosis
- Causes, Pathogens, Symptoms
- Genetic, Inherited, Congenital
- Chemical Injury, Poisoning, Symptoms
- Injury, Trauma, Prevention
- Autoimmune, Allergies, Infections
- Bacteria, Viruses, Fungi
- Fungi, Parasites, Infections
- Cancer, Causes, Treatment
- Carcinogens, Causes, Prevention
- Malnutrition, Deficiencies, Imbalances
- Psychiatric, Mental, Disorders
- Classifications, Causes, Symptoms
human leukocyte antigen
human leukocyte antigen (HLA), any of the numerous antigens (substances capable of stimulating an immune response)......
Hunter’s syndrome
Hunter’s syndrome, rare sex-linked hereditary disorder that varies widely in its severity but is generally characterized......
Huntington disease
Huntington disease , a relatively rare, and invariably fatal, hereditary neurological disease that is characterized......
Hurler’s syndrome
Hurler’s syndrome, one of several rare genetic disorders involving a defect in the metabolism of mucopolysaccharides,......
Huxley, Sir Julian
Sir Julian Huxley was an English biologist, philosopher, educator, and author who greatly influenced the modern......
Hwang Woo-Suk
Hwang Woo-Suk is a South Korean scientist whose revolutionary claims of having cloned human embryos from which......
hydatidiform mole
hydatidiform mole, in human pregnancy, abnormal growth of the chorion, the outermost vascular membrane that in......
hydramnios
hydramnios, excess of amniotic fluid, the liquid that surrounds the fetus in the uterus. Chronic hydramnios, in......
hydrocele
hydrocele, excessive accumulation of fluids in the scrotal sac that surrounds the testes in the male reproductive......
hydrocephalus
hydrocephalus, accumulation of cerebrospinal fluid (CSF) in the ventricles, or cavities, of the brain, causing......
hyperaldosteronism
hyperaldosteronism, increased secretion of the hormone aldosterone by the cells of the zona glomerulosa (the outer......
hyperammonemia
hyperammonemia, disorder due to excessive amounts of ammonia in the blood caused by a genetic defect present at......
hypercalcitoninemia
hypercalcitoninemia, abnormally high blood concentrations of calcitonin, a protein hormone secreted by parafollicular......
hyperglycemia
hyperglycemia, elevation of blood glucose concentrations above the normal range; it is the laboratory finding that......
hyperhidrosis
hyperhidrosis, excessive sweating, either general or local. A person may sweat profusely in armpits and on palms,......
hyperkeratosis
hyperkeratosis, in cattle, a disease characterized by inflammation and thickening of the horny covering of the......
hyperopia
hyperopia, refractive error or abnormality in which the cornea and lens of the eye focus the image of the visual......
hyperparathyroidism
hyperparathyroidism, abnormal increase in the secretion of parathormone by one or more parathyroid glands. Hyperparathyroidism......
hypertension
hypertension, condition that arises when the blood pressure is abnormally high. Hypertension occurs when the body’s......
hyperthelia
hyperthelia, abnormal presence of accessory nipples, a condition of relatively frequent occurrence (1 percent of......
hyperthyroidism
hyperthyroidism, excess production of thyroid hormone by the thyroid gland. Most patients with hyperthyroidism......
hypertrichosis
hypertrichosis, excessive abnormal hairiness that may be localized or cover the entire body. Hypertrichosis is......
hypoaldosteronism
hypoaldosteronism, abnormally low serum levels of aldosterone, a steroid hormone secreted by the adrenal gland.......
hypoglycemia
hypoglycemia, reduction of the concentration of glucose in the blood below normal levels, commonly occurring as......
hypogonadism
hypogonadism, in men, decreased testicular function that results in testosterone deficiency and infertility. Hypogonadism......
hypoparathyroidism
hypoparathyroidism, inadequate secretion of parathormone. Hypoparathyroidism can be due to decreased secretion......
hypophosphatasia
hypophosphatasia, rare hereditary disorder characterized by very low levels of tissue and serum alkaline phosphatase......
hypophosphatemia
hypophosphatemia, reduction in the concentration of phosphate in the blood serum, thus disrupting the body’s energy......
hypopituitarism
hypopituitarism, deficiency of pituitary hormones caused by damage to the pituitary gland. Patients may have a......
hypoprothrombinemia
hypoprothrombinemia, disease characterized by a deficiency of the blood-clotting substance prothrombin, resulting......
hypotension
hypotension, condition in which the blood pressure is abnormally low, either because of reduced blood volume or......
hypothermia
hypothermia, abnormally low body temperature in a warm-blooded creature, associated with a general slowing of physiologic......
hypothyroidism
hypothyroidism, a deficiency in hormone production by the thyroid gland. Hypothyroidism usually results from a......
hypoxia
hypoxia, in biology and medicine, condition of the body in which the tissues are starved of oxygen. In its extreme......
hystero-epilepsy
hystero-epilepsy, hysterical seizures that resemble epilepsy and, in diagnosis, must be distinguished from it.......
ich
ich, parasitic disease that affects a variety of freshwater fish species and that is caused by the ciliated protozoan......
ichthyosis
ichthyosis, a hereditary condition involving dryness and scaliness of the skin brought about by excessive growth......
ileitis
ileitis, chronic inflammation of one or more sections of the intestine. In its strict sense, the term refers to......
iliotibial band syndrome
iliotibial band syndrome (ITBS), inflammation of the band of fibrous tissue known as the iliotibial band (or tract),......
illness anxiety disorder
illness anxiety disorder, mental disorder characterized by an excessive preoccupation with illness and a tendency......