Endocrine System

• What is the primary function of the endocrine system?

  To maintain the body’s homeostasis
• How does the endocrine system communicate with distant organs?

  Through chemical signals called hormones
• What is the difference in communication speed between the endocrine and nervous systems?

  Endocrine communication is slower than nervous communication
• Where are hormones secreted from?

  From ductless glands into the bloodstream
• What will students learn about the endocrine system in this section?

  • Function of the endocrine system
  • Types of hormones and their action
  • Structure and function of major glands:
  • Pituitary
  • Pancreas
  • Adrenal glands
  • Gonads
  • Thyroid gland
• What are the three types of hormones based on their chemical structure?

  Steroid, monoamines, and peptide hormones
• What are steroid hormones derived from?

  Cholesterol
• How are peptide hormones characterized?

  They consist of chains of amino acids
• How do peptide and monoamine hormones travel in the blood?

  They are hydrophilic and travel free in solution
• How do steroid and thyroid hormones travel to their target tissues?

  Bound to specific binding proteins or plasma proteins
• What are target cells?

  Cells that express specific hormone receptors
• What happens when steroid hormones bind to their receptors?

  They induce transcription of specific genes
• What are the three basic mechanisms through which peptide and monoamine hormones alter cell function?

  Open ion channels, activate kinases, or activate G-proteins
• What physiological parameters exhibit circadian rhythms?

  Temperature, heart rate, and blood pressure
• What is a negative feedback loop in hormone secretion?

  One hormone inhibits the secretion of another
• How does the thyroid gland regulate TSH secretion?

  Through negative feedback from T3 and T4
• Where is the pituitary gland located?

  At the base of the skull
• What are the two portions of the pituitary gland?

  Anterior pituitary and posterior pituitary
• What hormones does the anterior pituitary secrete?

  Growth hormone, TSH, ACTH, FSH, LH, and PRL
• What is the role of growth hormone (GH)?

  Stimulates growth of body tissues
• How is the secretion of growth hormone regulated?

  By growth hormone releasing and inhibiting hormones
• What does thyroid-stimulating hormone (TSH) promote?

  Development and activity of the thyroid gland
• What stimulates the release of adrenocorticotropic hormone (ACTH)?

  Corticotropin-releasing hormone (CRH)
• What do gonadotropins regulate?

  Functions of the gonads in both sexes
• What does prolactin (PRL) promote?

  Milk production in women
• What does oxytocin stimulate?

  Uterine contractions and milk ejection
• What does vasopressin (ADH) stimulate?

  Kidney tubules to reabsorb water
• Where is the thyroid gland located?

  At the base of the neck
• What are the two hormones produced by the thyroid gland?

  Thyroxine (T4) and triiodothyronine (T3)
• What is the function of thyroid hormones (TH)?

  Increase the rate of cellular metabolism
• What does calcitonin do?

  Depresses blood calcium levels
• What hormone do the parathyroid glands secrete?

  Parathyroid hormone (PTH)
• What effect does parathyroid hormone (PTH) have on blood calcium levels?

  It increases blood calcium levels
• What does glucagon stimulate?

  The liver to release glucose into the blood
• When is insulin released?

  When blood glucose levels are rising
• What are the major endocrine glands and their functions?

  • Pituitary Gland: Controls other endocrine glands
  • Thyroid Gland: Regulates metabolism
  • Adrenal Glands: Produce corticosteroids
  • Pancreas: Regulates blood sugar levels
  • Gonads: Produce sex hormones
• What is the effect of parathyroid hormone (PTH) on blood calcium levels?

  PTH increases blood calcium levels
• What triggers the release of parathyroid hormone (PTH)?

  Falling blood calcium levels
• What inhibits the release of parathyroid hormone (PTH)?

  Rising blood calcium levels
• Where is the pancreas located?

  In the abdomen close to the stomach