Animal Hormones

• Hormones


  Signaling molecules produced by specialized glands or tissues within the bodies of animals
• Endocrinology


  The study of hormones
• Types of Hormones

  • Steroid Hormones
  • Amino Acid-Derived
  • Protein Hormones
• Steroid Hormones


  • Diffuse across plasma membranes
  • Derived from cholesterol
  • Include estrogen, testosterone, and cortisol
  • Have a four-ring structure
• Pheromones


  Chemicals released to the surrounding environment by animals to signal attraction to copulation
• Testosterone


  Produced by the testes and is the primary male sex hormone
• Testosterone


  • Contributes to development and maintenance
  • Regulates libido (sex drive)
  • Contributes to overall well-being and mood
• Estrogen


  Produced by ovaries and is the primary female sex hormone
• Estrogen


  • Contributes to development and regulation
  • Regulates the menstrual cycle
  • Promotes the thickening of the uterine lining (endometrium)
  • Influences bone growth during puberty
• Cortisol


  Produced by the adrenal glands and is the "stress hormone"
• Cortisol


  • Levels increase in response to stressors
  • Mobilizes energy reserves
  • Increases blood sugar levels
  • Suppresses non-essential functions
• Thyroxine


  Produced by the thyroid gland
• Thyroxine


  • Regulates metabolism
  • Regulates heart and muscle function
  • Regulates brain development
  • Regulates bone health
• Epinephrine


  Produced by the adrenal gland and some neurons in the brain, also known as "adrenaline"
• Epinephrine


  • Signals the heart to pump harder
  • Increases blood pressure
  • Opens airways in the lungs
  • Increases blood flow to major muscle groups and the rate and force of contraction in the heart
• Melatonin


  Produced by the brain in response to darkness, with levels rising at night and returning to normal during the day
• Melatonin


  • Helps with your body clock and sleep
  • Regulates seasonal physiology
  • Involved in cell protection, neuroprotection, and the reproductive system
• Insulin


  Produced by beta cells of the pancreas
• Insulin


  • Regulates blood sugar levels
  • Promotes the storage of excess glucose as glycogen in liver and muscles
• Growth Hormone


  Produced by the anterior pituitary gland
• Growth Hormone


  • Promotes growth and development
  • Stimulates the growth of bones, muscles, and other tissues
  • Regulates metabolism and helps maintain lean body mass and bone density
• Prolactin


  Produced by the lactotroph cells of the anterior pituitary gland
• Prolactin


  • Regulates lactation (milk production) in females
  • Stimulates the development of mammary glands during pregnancy
  • Promotes milk synthesis and secretion after childbirth
  • Inhibits ovulation during breastfeeding
  • Influences reproductive behavior and immune function
• Endocrine System


  Made up of glands that make hormones which regulate all biological processes in the body
• Types of Glands

  • Endocrine or Ductless Glands
  • Exocrine Glands
• Endocrine Glands


  Organs that are specialized to secrete hormones and release secretions or products directly into the bloodstream
• Exocrine Glands


  Release their secretions or products through ducts
• Hormones located in the anterior portion of the pituitary gland

  • Follicle Stimulating Hormone
  • Luteinizing Hormone
  • Growth Hormone
  • Thyroid-stimulating Hormone
  • Parathyroid Hormone
• Thyroid Gland


  Located in the neck, produces hormones that regulate metabolism, growth, and development
• Parathyroid Glands


  Situated behind the thyroid gland, produce parathyroid hormone (PTH) which regulates calcium and phosphate levels in the blood and bones
• Adrenal Glands


  Found on top of the kidneys, produce hormones like cortisol, adrenaline, and noradrenaline which regulate the stress response, metabolism, and blood pressure
• Pineal Gland


  Located in the brain, produces melatonin which regulates sleep-wake cycles (circadian rhythms) and other biological functions
• Communication Pathways in Hormone Regulation

  1. Target Cell Recognition

  2. Hormone Transport

  3. Hormone Secretion

  4. Signal Transduction

  5. Cellular Response

  6. Feedback Mechanisms