Answer: ductless.
- A ductless
- B salivary
- C sweat
- D oil
Correct answer: A. ductless
Explanation: Endocrine glands are ductless and pour hormones directly into the blood.
The hypothalamus releases hormones that direct the pituitary, which releases its own trophic hormone to a target gland; that gland's hormone output then feeds back (dashed lines) to suppress both the pituitary and hypothalamus once levels are sufficient - a self-correcting loop running the entire endocrine system.
Concept context
The endocrine glands, hormone classification and mechanism of action, and negative feedback regulation.