Lengdevekst

Lengdevekst, or longitudinal growth, refers to the increase in length of an organism or a structure, most commonly the height of a human or the length of plant shoots. In humans, lengdevekst describes the elongation of long bones during development, driven by growth at the epiphyseal plates.

In the growing skeleton, chondrocytes in the growth plate proliferate and are progressively replaced by bone tissue in a process called endochondral ossification. The rate and final height depend on genetic factors and a complex hormonal balance. Growth hormone, produced by the pituitary, stimulates IGF-1 production and bone growth; thyroid hormones are essential; sex steroids accelerate growth during puberty but eventually close the epiphyseal plates, ending height increase. Nutrition, sleep, and chronic illness influence growth. Pathologies can alter lengdevekst: growth hormone deficiency, hypothyroidism, malnutrition, Turner syndrome; excessive growth hormone can cause gigantism in youth and acromegaly after epiphyseal closure.

In plants, lengdevekst occurs mainly at the apical meristems in roots and shoots, through cell elongation driven by turgor pressure and cell-wall loosening. Hormones such as auxins and gibberellins promote elongation. Environmental factors like light, water availability, temperature, and mechanical constraints shape the rate and direction of growth.

Growth is monitored by measuring height over time, with reference percentiles or growth curves to detect abnormal growth patterns.