25,729 articles
Human back
Human back: posterior trunk region between neck and gluteal regions, built on a 33-vertebra spinal column with extrinsic and intrinsic muscle compartments; protects the spinal cord, maintains posture, and is a common site of back pain.
Human blood group systems
Human blood group systems are ISBT-recognized sets of red cell antigens controlled by single genes or linked homologous genes; 49 systems, 400 antigens, ABO and Rh clinically dominant, first described by Landsteiner in 1900.
Human body
Human body: the physical structure of a human organism, studied via anatomy and physiology. Six levels of organization, eleven organ systems, homeostatic control, tens of trillions of cells, and modern cell atlas projects like HuBMAP and the Human Cell Atlas.
Human body weight
Human body weight is the total mass of the body, including muscle, bone, fat, and water. Assessed via BMI (weight/height²), waist circumference, and body composition; obesity at BMI 30+, malnutrition at BMI under 18.5 or 10% unintentional loss.
Human brain
Human brain: the three-pound central organ of the human nervous system, with about 100 billion nerve cells, an 80-percent-of-volume cortex, a restrictive blood-brain barrier, and a threefold size increase over two million years of hominin evolution.
Human brain mapping
Human brain mapping: measuring and charting human brain structure and function with PET, fMRI, EEG, MEG, and related methods; also a Wiley neuroimaging journal founded in 1993.
Human Brain Project
The Human Brain Project was Europe's largest brain research initiative, running from 2013 to 2023 with a goal of simulating the human brain on a supercomputer.
Human challenge study
A human challenge study, also called a controlled human infection study, deliberately infects volunteers with a known pathogen dose to test vaccines and treatments quickly.
Human digestive system
Human digestive system: GI tract (mouth, esophagus, stomach, small and large intestines, anus) plus liver, pancreas, gallbladder; breaks food into amino acids, fatty acids, sugars; peristalsis, hormones, gut bacteria.
Human echolocation
Human echolocation: using reflected sound, especially self-generated mouth clicks, to sense silent objects. Practiced by some blind people and trainable by sighted people; term coined 1944; 10-week training studies show broad learning.
Human eye
The human eye is the paired sensory organ that focuses light onto the retina, converting it into electrical signals sent through the optic nerve to the brain.
Human factors
Human factors (human factors and ergonomics, HFE) is the science of designing systems around human capabilities and limitations. It emerged in World War II; HFES was founded in 1957 and publishes the journal Human Factors (1958).
Human feces
Human feces (stool): bowel waste, 75% water, formed as the colon absorbs ~90% of 1.5–2 L daily ileal effluent; classified by the Bristol Stool Chart, used in stool tests, FMT products, and sanitation.
Human hair growth
Human hair growth: the cyclical production of keratin fibers by hair follicles through anagen, catagen, telogen, and exogen phases. Scalp hair grows about 0.35 mm/day; anagen is roughly 90% of the cycle; androgens, DHT, minoxidil, and finasteride regulate it.
Human head
Human head: uppermost body region containing the brain, sensory organs, and the 22-bone skull (cranium), divided into neurocranium and viscerocranium; covers anatomy, development, variation, and head injury.
Human height
Human height (stature) is standing body length, about 80% heritable and shaped by nutrition and disease. It has risen for 150 years, ranges from 158 cm (Indonesia) to 183 cm (Dutch men), and serves as a population health indicator.
Human leg
Human leg: anatomically the knee-to-ankle region (crus), part of the 30-bone lower limb with femur, patella, tibia, fibula, and foot bones; weight-bearing structure central to bipedal walking and prosthetics.
Human leukocyte antigen positive
Human leukocyte antigen positive (ICD-11 MA14.18) is a classification category for a positive HLA test result, paired with MA14.17 negative; used in transplant, transfusion, and disease-association contexts.
Human mouth
Human mouth (oral cavity): first portion of the digestive system, containing lips, teeth, tongue, and palate; divided into vestibule and oral cavity proper; serves eating, speech, breathing, and taste; affected by oral diseases in about 3.7 billion people.
Human musculoskeletal system
Human musculoskeletal system: bones (206 in the adult skeleton), skeletal muscle, joints, tendons, ligaments, and cartilage; supports the body, protects organs, makes blood cells, and produces movement; aging and conditions like osteoarthritis and osteoporosis are its main disorders.
Human nose
Human nose: external nose and paired nasal cavities that warm, filter, and humidify air, enable olfaction, drain the paranasal sinuses, and show a nasal cycle alternating airflow between nostrils.
Human nutrition
Human nutrition: the science of consuming, absorbing, and using nutrients for life and health. Covers macronutrients, micronutrients, bioavailability, DRIs, dietary guidelines, and evidence methods.
Human papillomavirus infection
Human papillomavirus (HPV) infection, a common sexually transmitted infection with about 200 virus types; most clear spontaneously, but persistent high-risk types cause cervical, anogenital, and oropharyngeal cancers, preventable by HPV vaccination and screening.
Human papillomavirus testing
Human papillomavirus testing is a nucleic acid-based diagnostic method detecting high-risk HPV DNA or mRNA in cervical samples, used since 2020 as the primary cervical cancer screening method in many settings.
Human papillomavirus VLP vaccine technology (Gardasil)
HPV VLP vaccine technology (Gardasil): recombinant L1 virus-like particles, invented by Ian Frazer and Jian Zhou at University of Queensland, patented 1991, licensed via CSL to Merck, FDA-approved 2006 as the first cancer-preventing vaccine.
Human pathology
Human Pathology (Hum. Pathol., ISSN 0046-8177) is a monthly peer-reviewed Elsevier journal of clinicopathologic human disease research founded in 1970, MEDLINE-indexed, edited by Lori A. Erickson of Mayo Clinic, with an Impact Factor near 3.
Human penis
Human penis: the external male organ of urination, reproduction, and sexual pleasure, built from two corpora cavernosa and a corpus spongiosum; average 8.9 cm flaccid, 13 cm erect; erection driven by nitric oxide and cGMP.
Human penis size
Human penis size: clinical measurements of length and girth. Pooled means: flaccid 8.70 cm, stretched 12.93 cm, erect 13.93 cm (55,761 men); erect length rose 38% over 29 years; micropenis is SPL 2.5 SD below mean.
Human physiology
Human physiology: study of the life-supporting functions and mechanisms of the human body, from Greek physis and logia. Distinguished by homeostasis (Cannon, 1929), organ-system integration, and clinical uses such as exercise testing.
Human reproductive system
The human reproductive system is the male and female organ system that produces gametes and sex hormones, centered on the testicles and ovaries, enabling fertilization, gestation, and birth of offspring.