Cellular action of hormone action I

• In which type of endocrine signaling does the secreting cell also serve as the target cell?

  Autocrine
• Which class of hormones consists of long chains of amino acids?

  Protein hormones
• What is the primary function of the nervous system in communication throughout the body?

  To convey high-speed electrical signals
• What is the role of the endocrine system in the body?

  To secrete hormones that coordinate slower but long-acting responses
• How are most hormones regulated within the endocrine system?

  By feedback mechanisms
• What type of feedback mechanism is most common for hormone regulation?

  Negative feedback loops
• What is paracrine signaling?

  When target cells lie near the secreting cells
• What is autocrine signaling?

  When the target cell is also the secreting cell
• What is the concentration range for hormones in the body?

  10^-9 – 10^-15 M
• How do hormones typically reach their target tissues?

  They are secreted directly into the blood
• What are the basic principles of hormone action?

  • A stimulus is received by the endocrine gland
  • Hormones are secreted into the blood
  • They bind with specificity to receptors
  • Hormonal action changes tissue/cell conditions
  • Changes are monitored through feedback
• What is the role of feedback in hormonal changes?

  Most hormonal changes result in negative feedback
• What are the general functions of major endocrine glands?

  • Hypothalamus: Master endocrine gland
  • Pituitary gland: Growth hormone and vasopressin
  • Thyroid: Regulates metabolic rate
  • Parathyroid: Calcium release from bones
  • Pancreas: Insulin and glucagon
  • Testes: Testosterone production
  • Ovaries: Estrogen and progesterone
  • Adrenal glands: Epinephrine and glucocorticoids
  • Pineal gland: Melatonin
• What factors influence the degree of cellular response to hormones?

  Delivery of hormone and receptor/tissue status
• How are hormones classified?

  • By chemical composition: steroids, peptides, glycoproteins
  • By solubility: hydrophobic vs. hydrophilic
  • By receptor location: intracellular vs. cell surface
• What are steroid hormones derived from?

  Lipid cholesterol
• How do hydrophobic hormones travel in the blood?

  Bound to a transport protein
• What are amine hormones derived from?

  Modification of amino acids
• What distinguishes peptide hormones from protein hormones?

  Peptide hormones consist of short chains of amino acids
• What is the difference between hydrophobic and hydrophilic hormones?

  • Hydrophobic hormones: poorly water-soluble, bind to transport proteins
  • Hydrophilic hormones: water-soluble, transported readily in blood
• How do hydrophilic hormones interact with cell membranes?

  They bind to receptors on the extracellular surface
• What is the role of second messengers in hormonal signaling?

  They carry out the signaling cascade initiated by hydrophilic hormones
• How do lipid-soluble hormones trigger gene transcription?

  By binding to intracellular receptors and DNA
• What is the hormone-receptor complex?

  A complex formed when a hormone binds to its specific receptor
• What is the significance of receptor density in hormone response?

  It affects the affinity and sensitivity of the target cell to the hormone
• What happens to receptors during desensitization?

  They become less responsive to the hormone
• What is the role of transport proteins for hydrophobic hormones?

  To facilitate their movement in the bloodstream
• How do hormones influence enzyme activity?

  By activating or deactivating enzymes
• What is the effect of hormones on cell division?

  They can stimulate or suppress cell division
• What is the primary function of glucagon?

  To increase blood sugar by stimulating glycogen breakdown
• What is the primary function of insulin?

  To decrease blood sugar by promoting glucose uptake
• What is the role of epinephrine in the body?

  To stimulate the "fight or flight" response
• What is the function of aldosterone?

  To regulate sodium content in the blood
• What is the role of calcitonin?

  To inhibit the release of calcium from the bones
• What is the function of thyroxine?

  To regulate basal metabolic rate
• What is the role of melatonin?

  To regulate sleep cycles
• What is the primary function of progesterone?

  To prepare the uterus to receive a fertilized egg
• What is the role of estrogen?

  To stimulate egg maturation and control secondary sex characteristics
• What is the function of growth hormone?

  To stimulate growth, cell reproduction, and regeneration
• What is the role of vasopressin?

  To increase water reabsorption in the kidney