BHSC 202
Systems Anatomy & Physiology
The Endocrine System
Basic Health Sciences (BHSC) Program
Academic Year 2024–2025
, 1. Overview of the Endocrine System
The endocrine system consists of glands and tissues that secrete hormones directly into
the bloodstream. Hormones are chemical messengers that regulate metabolism,
growth, reproduction, and homeostasis.
Endocrine vs. Endocrine glands secrete hormones into the blood (ductless). Exocrine
Exocrine glands secrete products into ducts leading to body surfaces.
2. Types of Hormones
2.1 By Chemical Structure
Amino Acid–Based Hormones (water-soluble):
• Peptide hormones: chains of amino acids (e.g., insulin, glucagon, ADH, oxytocin)
• Amine hormones: derived from single amino acids (e.g., epinephrine, thyroid
hormones)
• Act on cell surface receptors; use second messenger systems (cAMP, IP3)
Steroid Hormones (lipid-soluble):
• Derived from cholesterol (e.g., cortisol, aldosterone, estrogen, testosterone)
• Cross cell membrane and bind intracellular receptors
• Directly activate gene transcription
3. Major Endocrine Glands
3.1 Hypothalamus
The hypothalamus links the nervous and endocrine systems:
• Produces releasing hormones (e.g., TRH, CRH, GnRH) that control the pituitary
• Synthesizes ADH and oxytocin (stored and released by posterior pituitary)
• Regulates body temperature, hunger, thirst, and sleep
3.2 Pituitary Gland (Hypophysis)
Anterior Pituitary (adenohypophysis) — FLAT PiG:
Systems Anatomy & Physiology
The Endocrine System
Basic Health Sciences (BHSC) Program
Academic Year 2024–2025
, 1. Overview of the Endocrine System
The endocrine system consists of glands and tissues that secrete hormones directly into
the bloodstream. Hormones are chemical messengers that regulate metabolism,
growth, reproduction, and homeostasis.
Endocrine vs. Endocrine glands secrete hormones into the blood (ductless). Exocrine
Exocrine glands secrete products into ducts leading to body surfaces.
2. Types of Hormones
2.1 By Chemical Structure
Amino Acid–Based Hormones (water-soluble):
• Peptide hormones: chains of amino acids (e.g., insulin, glucagon, ADH, oxytocin)
• Amine hormones: derived from single amino acids (e.g., epinephrine, thyroid
hormones)
• Act on cell surface receptors; use second messenger systems (cAMP, IP3)
Steroid Hormones (lipid-soluble):
• Derived from cholesterol (e.g., cortisol, aldosterone, estrogen, testosterone)
• Cross cell membrane and bind intracellular receptors
• Directly activate gene transcription
3. Major Endocrine Glands
3.1 Hypothalamus
The hypothalamus links the nervous and endocrine systems:
• Produces releasing hormones (e.g., TRH, CRH, GnRH) that control the pituitary
• Synthesizes ADH and oxytocin (stored and released by posterior pituitary)
• Regulates body temperature, hunger, thirst, and sleep
3.2 Pituitary Gland (Hypophysis)
Anterior Pituitary (adenohypophysis) — FLAT PiG:
