The hypothalamic pituitary axis and feedback

• What is the role of the hypothalamus in the endocrine system?

  It regulates hormonal secretions
• How does the pituitary gland function within the endocrine system?

  It releases hormones regulating bodily functions
• What are the two portions of the pituitary gland?

  Anterior pituitary and posterior pituitary
• What type of signals regulate the release of hormones from the pituitary gland?

  Neural and vascular signals
• What is the hypophyseal portal system?

  A blood vessel system transporting hormones
• What hormones are produced by the Supraoptic Nucleus (SON)?

  Vasopressin (ADH) and oxytocin
• What is the primary function of oxytocin?

  To help release milk during breastfeeding
• How does ADH help the kidneys?

  By making them more absorbent to water
• What happens to ADH secretion when water levels are low?

  ADH secretion increases to conserve water
• What condition is characterized by excessive urination and thirst?

  Diabetes Insipidus (DI)
• What causes Central Diabetes Insipidus?

  Not enough ADH made by the brain
• What is the role of neurophysins in hormone transport?

  They carry hormones to the posterior pituitary
• How does the hypothalamic-hypophyseal portal system function?

  It transports releasing and inhibiting hormones
• What triggers the release of oxytocin during childbirth?

  Baby moving through the birth canal
• What is the weight of the pituitary gland?

  0.5-1g
• What happens to ADH levels after drinking excess water?

  ADH levels decrease to remove water
• What factors stimulate ADH release?

  Low blood volume or pressure
• What is the role of corticotropin-releasing hormone (CRH)?

  It triggers stress responses
• What are the main functions of the hypothalamus and pituitary gland?

  • Regulates hormonal secretions
  • Controls bodily functions through hormones
  • Integrates signals from the brain and body
• What are the differences between Central DI and Nephrogenic DI?

  Central DI:

  • Not enough ADH made by the brain
  • Causes: brain tumors, autoimmune diseases

  
  

  Nephrogenic DI:

  • Kidneys don’t respond to ADH
  • Causes: kidney problems, genetic mutations
• What are the steps in the release of hormones from the anterior pituitary?

  1. Releasing and inhibiting hormones made in hypothalamus
  2. Travel through hypophyseal portal system
  3. Act on anterior pituitary cells
  4. Release specific hormones into the body
• What are the stimulators and inhibitors of ADH release?

  Stimulators:

  • Low blood volume or pressure
  • Dehydration
  • Physical and emotional stress

  
  

  Inhibitors:

  • High blood volume or pressure
  • Alcohol consumption
• What are the functions of vasopressin (ADH)?

  • Helps kidneys save water
  • Concentrates urine
  • Increases blood pressure through vessel constriction
• What is the significance of the hypothalamic-pituitary axis?

  • Links the nervous system to the endocrine system
  • Coordinates hormone release with brain signals
  • Regulates various bodily functions
• What initiates the secretion process of the anterior pituitary?

  Special hormones from the hypothalamus
• How do hypothalamic hormones reach the anterior pituitary?

  They travel through the hypothalamic-hypophyseal portal system
• What is the function of the hypothalamic-hypophyseal portal system?

  It carries hormones from hypothalamus to pituitary
• What do releasing and inhibiting hormones do?

  They regulate hormone release from the anterior pituitary
• What are the main cell types in the anterior pituitary and their functions?

  • Gonadotropes: Produce FSH and LH for reproduction
  • Corticotropes: Produce ACTH for stress response
  • Thyrotropes: Produce TSH for thyroid regulation
  • Lactotropes: Produce Prolactin for milk production
  • Somatotropes: Produce GH for growth and metabolism
• What does FSH stand for?

  Follicle Stimulating Hormone
• What does LH stand for?

  Luteinizing Hormone
• What does ACTH stand for?

  Adrenocorticotropic Hormone
• What does TSH stand for?

  Thyroid Stimulating Hormone
• What does PRL stand for?

  Prolactin
• What does GH stand for?

  Growth Hormone
• How do hypothalamic hormones control anterior pituitary secretion?

  • Releasing hormones increase pituitary activity
  • Inhibiting hormones decrease pituitary activity
  • Each pituitary hormone is controlled by at least one hypothalamic hormone
• What is the role of GHRH?

  It stimulates the release of Growth Hormone
• What is the role of GHIH?

  It inhibits the release of Growth Hormone
• What is the effect of Prolactin-Inhibiting Hormone (PIH)?

  It inhibits the release of Prolactin
• What are the types of feedback control in hormone regulation?

  • Long Loop Feedback: Hormones from target glands reduce stimulation
  • Short Loop Feedback: Pituitary hormones adjust hypothalamus activity
  • Ultra-Short Loop Feedback: Hypothalamus controls its own hormone release