* Tissues or organs: For example, "phototropic" means "attracted to light" and "dermotropic" means "having an affinity for the skin."
* Substances or chemicals: For example, "chemotactic" means "attracted to chemical substances" and "neurotropic" means "affecting the nervous system."
Examples of medical terms using "-tropic":
* Phototropic: Having an affinity for light.
* Dermotropic: Having an affinity for the skin.
* Chemotactic: Attracted to chemical substances.
* Neurotropic: Affecting the nervous system.
* Hepatotropic: Affecting the liver.
* Corticotropic: Affecting the adrenal cortex.
In essence, "-tropic" indicates a directional or affinity relationship between something and a particular target.