Module 2

• A communication and coordination system in the body
• Systems involved in communication and coordination

  • Endocrine System
  • Nervous System
• Components of the Endocrine System

  • Glands
  • Brain, spinal cord, and nerves
• Endocrine System


  1. Hormones diffuse into cells/bind to receptors

  2. Nerve impulse and neurotransmitter

  3. Blood

  4. Neurons

  5. Slow and sustainable

  6. Fast and short-lived

  7. Widespread response

  8. Localized response

  9. Involuntary

  10. Voluntary and involuntary
• Terminology related to secretions

  • Endocrine secretions (distance signaling)
  • Paracrine secretions (adjacent signaling)
  • Autocrine secretions (self-signaling)
• Some hormones and neurotransmitters, growth factors, cancer cells, interleukins affect target cells/tissues
• Functions of the endocrine system include regulating body functions such as metabolism, growth, reproduction, heart rate, blood pressure, appetite, and sleep/awake cycle
• Nonsteroidal Hormones
• G protein activates adenylate cyclase which increases cAMP, activating protein kinases and other molecules
• Changes in body environment

  1. Release of hormones

  2. Action/sufficient hormone level

  3. Feedback mechanism
• Glandular tissue controlled by releasing hormones from the hypothalamus, Nervous tissue controlled by nerve impulses from the hypothalamus
• Releasing hormones


  • Gonadotropin-releasing hormone
  • Corticotropin-releasing hormone (CRH)
  • Thyrotropin-releasing hormone (TRH)
  • Prolactin-releasing factor and prolactin release inhibiting factor
  • GHRH and GRIH
  • Luteinizing hormone (LH)
  • Follicle stimulating hormone (FSH)
  • Adrenocorticotropic hormone (ACTH)
  • Thyroid-stimulating hormone (TSH)
  • Prolactin hormone
  • Growth hormone
• Functions of various releasing hormones
• Stretch of the uterus, vaginal wall, and stimulation of breast, Change in water concentration in
• Sperms in men


  • Control the release of glucocorticoids
  • Control the secretion of thyroid hormone
  • Sustain milk production after birth
• ↑ the size and the division rate of body cells
• 8


  2023-09-11
• Stretch of the uterus, vaginal wall, and stimulation of breast

  Change in water concentration in body fluids
• Oxytocin (OT)


  Uterine contraction and contraction of milk-secreting glands
• Antidiuretic hormone (ADH) or vasopressin


  Kidneys conserve water and may ↑ blood pressure
• 15


  2023-09-11
• Gigantism due to high level in children and adolescents
• Acromegaly due to high level in adults
• Dwarfism due to low level in children
• 16


  2023-09-11
• What about low level of prolactin hormone?
• Low level of antidiuretic hormone (ADH) or vasopressin or resistance to vasopressin effect → diabetes insipidus
• 18


  2023-09-11
• Vasopressin analogue
• Diabetes insipidus
• Bedtime wetting
• Low level of oxytocin delays labor
• Low level of follicle-stimulating hormone (FSH) and luteinizing hormone (LH): infertility
• 20


  2023-09-11
• Thyroxin
• Calcitonin
• 1. cells
• Synthesis of the thyroid hormone

  Thyroxin (T4) is converted in periphery to → T3 (5x more potent than T4)
• 22


  2023-09-11
• Regulatory functions of Thyroxin