Target organ and receptor types
Different Hormone have different Target organ and receptor types for their functioning. Target Cell is the cells that contain specific receptors for a hormone. Although all cells are exposed to all hormones, only few cells or organs can respond to all specific hormone, termed as target cells or target organ. This is because of highly specific receptor sites in the target organ.
The receptors are large protein molecules. Hormone exerts its physiological actions only after binding to specific receptors. Despite the diversity of hormones, all hormone receptors can be categorized into one of two types, based on their location-
- Membrane-bound receptors called as cell-surface (membrane) receptors
- Receptors located within the cell called as intracellular receptors
| Location of Receptor | Classes of Hormones | Principle Mechanism of Action |
| Cell surface receptors | Proteins and peptides, catecholamines and eicosanoids | Generation of second messengers which alter the activity of other molecules – usually enzymes – within the cell |
| Intracellular receptors | Steroids and thyroid hormones | Alter transcriptional activity of responsive genes and thereby alter the cell’s protein (enzyme) content |
