Chapter 5 Flashcards
Homeostasis
Condition of a relatively stable internal environment maintained within narrow limits.
Stimulus
Event that evokes a specific functional reaction in an organ or tissue.
Receptor
Chemical structures that receive signals from hormones, neurons or cytokines.
Negative Feedback
Change in a variable and action to produce a change in the opposite direction.
Secondary messenger
Acts as an intermediary in the transfer of messages.
Endocrine System
System of ductless glands that produce hormones and release them directly into the bloodstream.
Endocrine Gland
Glands that secrete hormones directly into the blood, rather than via ducts.
Exocrine Gland
Gland that releases a secretion external to or at the surface of an organ by means of a canal or duct. (eg. sweat or salivary gland)
Abscisic acid
Plant hormone that inhibits growth and influences stomatal closure.
Auxins
Group of plant hormones that control cell elongation.
Cytokinins
Plant hormones that regulate cell reproduction in shoots, roots and fruit.
Geotropism
Response of a shoot or root to gravity.
Phototropism
Movement of a plant in response to light.
