Anatomy & Physiology

Lesson 13 of 20

Endocrine system

The endocrine system uses hormones carried through body fluids to influence target cells. Compared with rapid neural signaling, many hormonal effects begin more slowly and last longer, though timing varies. Endocrine glands and hormone-producing tissues contribute to growth, metabolism, reproduction, and internal regulation. Hormone effects depend on receptors in target cells.

Key points

• Endocrine glands release hormones into interstitial fluid and blood rather than through ducts.
• The hypothalamus and pituitary coordinate many endocrine pathways.
• The thyroid influences metabolic regulation; parathyroid hormone helps regulate blood calcium.
• The adrenal glands produce hormones involved in stress responses and other functions.
• Hormone signaling often uses negative feedback to keep levels within useful ranges.

Key terms

Hormone

Chemical messenger that affects cells with appropriate receptors.

Endocrine gland

Ductless gland that releases hormones into internal fluids.

Hypothalamus

Brain region linking neural regulation with endocrine control.

Pituitary gland

Endocrine gland influenced by the hypothalamus and regulating several hormonal pathways.

Target cell

Cell whose receptors allow it to respond to a particular signal.