Hormone
Definition
A hormone is a chemical messenger produced by endocrine glands and transported through the bloodstream to target organs where it regulates physiological processes. Hormones can be proteins, steroids, or amino acid derivatives. They are essential for growth, metabolism, reproduction, and homeostasis.
Key Points for NEET
- 1Secreted by endocrine glands (ductless glands)
- 2Act on specific target cells with receptors
- 3Three types: peptide, steroid, and amine hormones
- 4Regulated by feedback mechanisms
- 5Examples: insulin, thyroxine, testosterone, estrogen
Example
Insulin released by pancreas to lower blood glucose after a meal
Asked in NEET
Related Terms
Want to Master Human Physiology?
Join Cerebrum Biology Academy for comprehensive NEET preparation with expert faculty.
More Human Physiology Definitions
Homeostasis
Homeostasis is the ability of an organism or cell to maintain internal stability by adjusting its physiological processes. It involves feedback mechanisms that detect changes and trigger responses to restore optimal conditions. Examples include temperature regulation, blood sugar control, and water balance.
Antibody
An antibody (immunoglobulin) is a Y-shaped protein produced by B cells of the immune system in response to foreign substances (antigens). Antibodies specifically recognize and bind to antigens, marking them for destruction by other immune cells. There are five classes: IgG, IgA, IgM, IgE, and IgD.
Neuron
A neuron is a specialized cell that transmits nerve impulses (electrical signals) in the nervous system. It consists of a cell body (soma), dendrites (receive signals), and an axon (transmits signals). Neurons communicate with each other at synapses using neurotransmitters.