Endocrine system

• What systems work together to coordinate body functions?

  Nervous and endocrine systems
• How do nerve impulses and neurotransmitters function in the nervous system?

  They enable faster responses with briefer effects
• What is the role of hormones in the endocrine system?

  They regulate activity of cells in other parts
• What are the two types of glands in the endocrine system?

  Exocrine and endocrine glands
• How do endocrine glands secrete their products?

  Into interstitial fluid, diffusing into blood
• Name some endocrine glands.

  Pituitary, thyroid, parathyroid, adrenal
• What do hormones affect?

  Specific target tissues with specific receptors
• What is down-regulation in hormone activity?

  Decrease in receptor number or sensitivity
• What is up-regulation in hormone activity?

  Increase in receptor number or sensitivity
• What are circulating hormones?

  Hormones that circulate in blood throughout body
• What are paracrine hormones?

  Hormones that act on neighboring cells
• What are autocrine hormones?

  Hormones that act on the same cell that secreted them
• What type of hormones are lipid-soluble?

  Steroid, thyroid, nitric oxide (NO)
• What type of hormones are water-soluble?

  Amine, peptide/protein, eicosanoid
• How do lipid-soluble hormones act on target cells?

  They bind to receptors inside target cells
• How do water-soluble hormones act on target cells?

  They bind to receptors on the plasma membrane
• What is the role of second messenger systems in hormone action?

  They amplify the original small signal
• What factors influence the responsiveness of target cells to hormones?

  Hormone concentration, receptor abundance, other hormones
• What are permissive effects in hormone action?

  When one hormone enhances the effect of another
• What are synergistic effects in hormone action?

  When two hormones work together for a greater effect
• What are antagonistic effects in hormone action?

  When one hormone opposes the action of another
• What regulates hormone secretion?

  Nervous system, chemical changes, other hormones
• What is the most common regulation method for hormones?

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

  It links the nervous and endocrine systems
• How is the pituitary gland connected to the hypothalamus?

  By the infundibulum
• What are the two parts of the pituitary gland?

  Anterior pituitary and posterior pituitary
• What stimulates the anterior pituitary gland?

  Releasing and inhibiting hormones from hypothalamus
• How are hypothalamic hormones transported to the anterior pituitary?

  By the hypophyseal portal system
• What are tropic hormones?

  Hormones that act on other endocrine systems
• What is the function of the posterior pituitary gland?

  Stores and releases hormones made by hypothalamus
• What hormones are released by the posterior pituitary gland?

  Oxytocin and antidiuretic hormone (ADH)
• How is ADH released from the posterior pituitary?

  Nerve impulses liberate ADH from axon terminals
• What stimulates the release of ADH?

  High blood osmotic pressure
• What is the effect of ADH on the kidneys?

  Increases water retention and decreases urine output
• What is the effect of ADH on arterioles?

  Causes constriction, increasing blood pressure
• What is the role of osmoreceptors in ADH secretion?

  They detect blood osmotic pressure changes
• What happens when blood osmotic pressure is low?

  Inhibition of hypothalamic osmoreceptors occurs
• What hormones do thyroid follicles produce?

  Thyroxine (T4) and triiodothyronine (T3)
• What is the effect of T4 and T3 hormones?

  Increase BMR and stimulate protein synthesis
• What do parafollicular cells produce?

  Calcitonin