endocrine system

• Endocrine glands


  ductless glands produce hormones
• target cells


  Hormones are transported by the blood to ______ _____
• metabolic


  Hormones control _________ activites
• expression; function


  Hormones bin to receptors and induce a change in gene ________ or cell _________
• Amino acid-derivatives; Peptide hormones; Lipid derivatives


  Three Classes of hormone (according to chemical structure)
• Amino acid derivatives

  -Derivatives of amino acid Tyrosine, Derivatives of tryptophan
• Derivatives of tyrosine

  -Thyroid hormones (Thyroxine and Triiodothyronine)

  -Catecholamines (Epinephrine, Norepinephrine, and Dopamine)
• Derivatives of tryptophan

  serotonin and melatonin
• Peptide hormones


  -composed of amino acids

  -two groups: (Glycoproteins, Short chain polypeptides, and small proteins)
• Peptide hormones

  -thyroid stim. hormone

  -Luteinizing Hormone

  -Follicle stim. hormone

  -antidiuretic hormone

  -oxytocin

  -growth hormone

  -prolactin
• glycoproteins

  What kind of peptide hormone are the following hormones?

  -thyroid stimulating hormone

  -luteinizing hormon

  -follicle stimulating hormone
• short chain polypeptides

  What kind of peptide hormone are the following hormones?

  -Antidiuretic hormone

  -oxytocin
• small proteins

  What kind of peptide hormone are the following hormones?

  -Growth hormone

  -prolactin
• Lipid derivatives

  -Steroid hormones

  -derived from cholesterol

  -(E.g. Testosterone (testes), estrogen, progesterone (ovaries), corticosteroids (adrenal cortex), and calcitriol (kidneys
• peptide hormones

  Which hormone is:

  -polar / cannot pass through plasma membrane

  -can freely travel in blood stream

  -can bind to extracellular receptors and trigger the second messengers
• steroid hormones

  Which hormone is:

  -can pass through cell membrane

  -insoluble in blood and needs to be carries by specific proteins

  -binds to intracellular receptors

  -remain in circulation longer than peptide hormones since transported by carrier proteins
• receptor


  hormone must interact with a _______
• protein


  a receptor is a _______ molecule to which a (loved) molecule binds strongly
• hormonal sensitivity


  ________ _________ depends on the presence or absence of specific receptors
• plasma membrane receptors


  To what kind of receptors do catecholamines (epinephrine, norepinephrine and dopamine) and peptide hormones bind to?
• plasma membrane receptors


  cannot affect target cells directly but produce second messengers to bring about the affect
• cytoplasm


  where are second messengers formed?
• second messengers

  cAMP

  cGMP

  Ca2+
• G proteins


  guanine nucleotide-binding proteins; transmits signals from outside of a cell to the inside; activated when a hormone binds to its receptor
• adenylate cyclase


  Activated by a G-protein. Converts ATP to cyclic AMP in response to an extracellular signal.
• cAMP

  Second messenger that activates protein a kinase that phosphorylates proteins
• kinase


  an enzyme that attaches a phosphate group to another molecule (phosphorylation)
• ion channels


  phosphorylation of plasma proteins open ____ ________
• enzyme phosphodiesterase (PDE)

  converts cAMP to AMP
• inactive


  enzymes remain _________ without phophorylation
• intracellular receptors


  -steroid hormones

  diffuse through the plasma membrane and bind to receptors in the cytoplasm or nucleus

  -The hormone receptor complex activateor deactivate specific genes

  -Alter the rate of DNA transcription,

  which affects the protein synthesis

  -it will affect the metabolic activity and the structure of the target cell.
• ATP production


  Thyroid hormones bound to mitochondria affect the rate of ___ ___________
• quantity


  the nature and number of receptors on the plasma membrane depends on the _______ of hormones
• down regulation


  High levels of hormone > cells become less sensitive > decrease in number of hormone receptors
• up regulation


  Low levels of hormone > cells become more sensitive > increase the number of hormone receptors
• Endocrine reflexes

  -humoral stimuli

  -hormonal stimuli

  -neural stimuli
• humoral stimuli


  secretion of hormones in direct response to changing blood (extracellular fluid) levels of ions and nutrients
• hormonal stimuli


  arrival or removal of specific hormone
• neural stimuli


  arrival of neurotransmitters at neuroglandular junctions
• humoral stimulus


  What kind of stimulus takes place in regards to Ca and PTH?

  -when blood is low in CA2+ parathyroid glands produce PTH