Endocrine system

• What processes are under hormonal control?

  Reproduction, metabolism, stress response, digestion, fluid and ion balance, growth
• What are the different fates of a hormone circulating in the blood?

  Excreted in urine or feces

  Inactivated by metabolism

  Activated by metabolism which then goes to target cells

  Directly goes to target cells (binds to receptor and produces a cellular response)
• What are the 2 properties of a hormone receptor?

  High affinity and high selectivity
• Does a small equilibrium dissociation constant (Kd) cause a higher or lower affinity of binding?

  Higher affinity of binding
• What are the types of amine hormones?

  catecholamines and thyroid hormones
• What the types of thyroid hormones?

  T4 (thyroxine) and T3 (triiodothyronine)
• What are the types of catecholamines?

  dopamine, norepinephrine, epinephrine
• What are amino hormones derived from?

  Amino acid tyrosine
• Are catecholamines water soluble?

  Yes, water soluble
• Where are the receptors catecholamines bind to located?

  Extracellular receptors/surface
• Are thyroid hormones water soluble?

  No, water insoluble
• Where are the receptors thyroid hormones bind to located?


  Intracellular receptors
• How are peptide hormones made?

  Secretory pathway
• How are peptide hormones stored?

  secretory vesicles
• How are peptide hormones released?

  by exocytosis in response to specific signals (other hormones, metabolites, etc)
• Where are major sites of steroid hormone synthesis?

  Adrenal gland and gonads
• What enzyme converts androstenedione to estrone & testosterone to estradiol?

  aromatase
• What do steroid hormones require to transport through the blood?

  Binding proteins
• What are the ways non-steroid hormones alter the activity of cytoplasmic proteins?

  Ion channel coupled receptors, receptor tyrosine kinases, other kinase linked receptors, heterotrimeric G protein coupled receptors
• What do secondary messengers allow?

  Allows a hormone signal to be transmitted to multiple target molecules and provide an effective means of signal amplification
• What do steroid hormones regulate?


  gene transcription
• What can hormones upregulate?


  Upregulate the cell surface presentation of receptors for other hormone
• Hypothalamus


  Most important brain center for regulating homeostasis
• What aspects of physiology does the hypothalamus control?

  Hunger, body temperature, thirst, osmolarity, reproduction, lactation, metabolic rate, circadian cycles, fatigue, emotions
• What types of inputs does the hypothalamus receive?

  Photoperiod, olfactory, neural inputs from heart, stomach & reproductive tract, hormones
• Output from the hypothalamus can be what or what?

  hormonal or neural
• What are the two components of the pituitary?


  posterior and anterior
• What is an extension of the hypothalamus?


  posterior pituitary
• What type of cells are contained in the posterior pituitary?

  Neurosecretory
• What is the anterior pituitary made of?

  Collection of endocrine cells that are regulated by the hypothalamus (not neural tissue)
• What type of hormones are released from the hypothalamus that act on the anterior pituitary?

  hypophysiotropic hormones
• Corticotropin-releasing hormone (CRH)


  stimulates release of ACTH
• Thyrotropin-releasing hormone (TRH)


  stimulates release of TSH
• Growth hormone-releasing hormone (GHRH)


  stimulates release of GH
• Somatostatin (SS)


  inhibits secretion of GH
• Gonadotropin-releasing hormone (GnRH)


  Simulates secretion of LH and FSH
• Dopamin


  inhibits secretion of prolactin
• What type of molecule are hypophysiotropic hormones?

  Peptides (besides dopamine which are catecholamine)
• Which two hormones are involved in the posterior putuitary?

  Vasopressin (ADH) and Oxytocin
• What are the main actions of vasopressin?

  Acts on kidney to promote water retention

  Aquaporin insertion in kidney collecting duct cells; contraction of smooth muscle associated with blood vessels to regulate blood pressure