endocrine system

• Hormonal regulation


  • Slower response, longer lasting effects, chemical messengers (hormones)
• Neural regulation


  • Immediate faster response (milliseconds), shorter lasting effects, action potentials (electrical)
• Hypothalamus


  Master endocrine gland that controls secretion of the anterior and posterior pituitary, which in turn control lots of endocrine glands including, ovaries, testes, adrenals, thyroid

  
• Regulation of anterior pituitary hormone secretion

  1. Hypothalamus secretes releasing hormones (stimulatory) and inhibitory hormones

  2. Anterior pituitary makes 6 hormones: Growth hormone, Thyroid stimulating hormone (TSH), Follicle stimulating hormone (FSH), Luteinizing hormone (LH), Prolactin, Adrenocorticotrophic hormone

  
• Regulation of posterior pituitary hormone secretion

  Posterior pituitary secretes Oxytocin and Antidiuretic hormone

  
• Hypothalamus

  Hormonal regulator of secretion from anterior pituitary which in turn is hormonal regulator of other endocrine glands such as gonads and adrenal cortex

  
• Endocrine regulation of gonads

  1. Hypothalamus secretes GnRH

  2. GnRH stimulates secretion of FSH and LH from Anterior Pituitary

  3. FSH stimulates testis to increase mitosis to produce more sperm

  4. LH stimulates testosterone production

  5. Testosterone has negative feedback to FSH/LH secretion

  6. Inhibin secretion negatively feeds back to turn off FSH secretion

  
• Thyroid-stimulating hormone (TSH): Stimulates thyroid gland to produce T3 and T4.
• The posterior pituitary gland stores and releases two hormones produced by the hypothalamus: oxytocin (stimulates uterine contractions during childbirth) and antidiuretic hormone (ADH; regulates water balance).
• The anterior pituitary gland is responsible for producing hormones that regulate growth, metabolism, reproduction, and stress response.
• Adrenocorticotropic hormone (ACTH): Stimulates release of glucocorticoids by adrenal cortex.
• Growth hormone (GH): Regulates growth and metabolism.
• Prolactin: Promotes milk production during lactation.
• Adrenocorticotropic hormone (ACTH): Regulates the release of steroid hormones from the adrenal cortex.
• Prolactin (PRL) stimulates milk production in females.
• Growth hormone (GH), also known as somatotropin, promotes cell division and growth in bones, muscles, and organs.
• Adrenocorticotropic hormone (ACTH) triggers the release of cortisol from the adrenal cortex.
• Growth hormone (GH): Promotes cell division and growth in bones and muscles.
• Prolactin: Stimulates milk production in mammary glands.
• Follicle-stimulating hormone (FSH): Stimulates maturation of eggs in females and spermatogenesis in males.
• Follicle-stimulating hormone (FSH): Stimulates development of eggs in females and sperm cells in males.
• Calcitonin: Inhibits bone resorption and lowers blood calcium levels.
• Oxytocin: Triggers uterine contractions during childbirth and stimulates milk ejection in lactating women.
• Antidiuretic hormone (ADH): Also called vasopressin, regulates water balance by increasing reabsorption of water in the kidneys.
• Antidiuretic hormone (ADH) helps regulate water balance by increasing reabsorption of water in kidneys.
• Luteinizing hormone (LH) plays a role in ovulation and progesterone secretion in women, while it supports testosterone synthesis in men.
• Follicle-stimulating hormone (FSH) is involved in reproduction by promoting follicular development in ovaries and sperm maturation in testes.
• Cortisol: Helps regulate metabolism, suppresses immune response, and increases blood sugar levels.
• Adrenal cortex: Produces steroid hormones such as aldosterone, which regulates salt and water balance, and cortisol, which helps regulate metabolism and immune response.
• Parathyroid glands produce parathyroid hormone (PTH), which increases blood calcium levels.
• Adrenal medulla secretes epinephrine and norepinephrine.
• Prolactin (PRL) triggers milk production in nursing mothers.
• Sex steroids: Involved in sexual differentiation and reproduction.
• Thyroid hormones: Regulate growth, development, and metabolic rate.
• Aldosterone: Regulates salt and water balance by increasing sodium retention and potassium excretion in the kidneys.
• Growth hormone: Promotes cell division and tissue growth.