Definition

1. Noun:
   • A hormone: A chemical substance produced by an endocrine gland, released directly into the bloodstream, and carried to target tissues or organs where it exerts a specific regulatory effect.

Usage

• The term "internal secretion" is a technical, somewhat dated synonym for "hormone." It is used to describe a substance secreted internally, contrasting with "external secretions" like sweat or digestive juices that are released outside the body or into body cavities.
• It is primarily used in biological, medical, and endocrinological contexts.

Examples

• Noun:
  • Insulin is a crucial internal secretion that regulates blood sugar levels.
  • The study focused on how internal secretions control growth and metabolism.

Advanced Usage

• "Theory of internal secretions": A historical term referring to the early study of endocrinology.
  • The work of Bayliss and Starling on secretin was foundational for the theory of internal secretions.

Variants and Related Words

• Hormone (n): The modern and more common term for an internal secretion.
  • Adrenaline is a hormone that prepares the body for 'fight or flight'.
• Endocrine (adj): Relating to glands that secrete hormones directly into the bloodstream.
  • The pituitary is a major endocrine gland.

Synonyms

• Hormone: Chemical messenger.
• Chemical messenger: A substance that carries signals between cells.

Related Phrases

• Endocrine secretion: A phrase synonymous with internal secretion, emphasizing its origin from ductless glands.
  • Thyroxine is an endocrine secretion from the thyroid gland.

Noun

1. the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect