Ohjauselin

Ohjauselin is a Finnish term meaning “control organ.” It is used in biology to describe an organ that coordinates the activity of other organs, typically by signaling molecules such as hormones or neurotransmitters. In this sense, an ohjauselin acts as a regulatory hub within a physiological network, integrating inputs and helping maintain homeostasis through feedback mechanisms.

In vertebrates, the hypothalamus and the pituitary gland are classic examples of ohjauselin function. The hypothalamus receives neural inputs and releases releasing and inhibiting hormones that regulate the pituitary. The pituitary then secretes hormones that control endocrine glands such as the thyroid, adrenal cortex, and gonads. Through these hormonal cascades, the ohjauselin coordinates growth, metabolism, reproduction, and stress responses.

The term is primarily functional, not tied to a single anatomical structure. Depending on the organism and context, different organs may serve as the primary regulatory center. The concept emphasizes the role of signaling networks and feedback loops in controlling multiple organ systems rather than naming one fixed “master organ.”

See also: endocrine system, hypothalamus, pituitary gland, hormonal regulation, feedback mechanisms.