Endocrine System

• Endocrine system

  • 2nd control system of the body
  • releases chemicals (hormones) that regulate complex body processes
• Amino acid-based hormones:

  • Proteins
  • Peptides
  • Amines
• Steroids

  • made from cholesterol
• Lipids

  • Prostaglandin - inflammatory mediator, have hormone-like function
• Pituitary gland

  • "Master endocrine gland"
  • size of a pea
  • hangs by a stalk from the inferior surface of the hypothalamus of the brain
  • controls the activity of many other endocrine glands
• Hypothalamus

  • produces and releases several hormones that control the pituitary gland's function
  • secretes releasing hormones that stimulate the pituitary gland to release its hormones
  • secretes inhibiting hormones that suppress pituitary hormone release when needed
• Anterior pituitary gland (adenohypophysis)

  • are peptide hormones
  • produces 6 hormones, 2 are non-endocrine glands, 4 are endocrine glands
• Growth hormone

  • "Somatotropin"
  • general metabolic hormone
  • plays an important role in determining final body size
  • causes the building of amino acids into proteins
  • causes fats to be broken down and used for energy
  • bones & muscles
• Prolactin

  • "luteotropic hormone"
  • stimulates and maintains milk production of mother’s breast
  • mammary glands
• Follicle-stimulating hormone

  • stimulates follicle development in ovaries
  • as follicles mature, they produce estrogen, and eggs are readied for ovulation
  • in Men: stimulates sperm development by the testes
  • testes & overies
• Luteinizing hormone

  • secretes estrogen and progesterone for females
  • secretes testosterone for males
• Thyrotropic hormone

  • TSH and thyrotropin
  • Stimulates the thyroid gland to produce primarily T3 and T4
  • growth of thyroid gland
  • thyroid
• Adrenocorticotropic hormone

  • Corticotropin
  • Cortisol - stress hormone
  • stimulates the adrenal cortex to produce and release cortisol
  • adrenal cortex
• Posterior pituitary gland (Neurohypophysis)

  • nervous tissue
  • not an endocrine gland
  • acts as a storage for the hormones made by the hypothalamic neurons
• Oxytocin

  • Love hormone"
  • released in significant amounts during childbirth and nursing
  • stimulates contraction of uterine muscle during sexual relations and childbirth
  • causes milk ejection in a nursing woman
• Antidiuretic hormone

  • "Vasopressin"
  • water balance
  • blood pressure regulation
• Thyrotropin-Releasing Hormone

  • stimulates the anterior pituitary gland to release thyroid-stimulating hormone
• Corticotropin-Releasing Hormone

  • stimulates the anterior pituitary gland to release adrenocorticotropic hormone
• Gonadotropin-Releasing Hormone

  • stimulates the anterior pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
• Growth Hormone-Releasing Hormone

  • stimulates the anterior pituitary gland to release growth hormone (GH)
• Growth Hormone Release-Inhibiting Hormone

  • inhibits the release of growth hormone (GH) from the anterior pituitary gland.
• Prolactin-Releasing Hormone

  • stimulates the anterior pituitary gland to release prolactin
• Prolactin-Inhibiting Hormone

  • inhibits prolactin release
• Pineal gland

  • small, cone-shaped gland that hangs from the roof of the third ventricle of the brain
  • melatonin
  • sleep trigger
  • sleep-wake cycle = circadian rhythm
• Thyroid gland

  • Located at the base of the throat, inferior to the Adam’s apple
  • large gland, consist of two lobes, joined by a central mass called isthmus
  • internally, is composed of hollow structures called follicles
• Thyroid hormone

  • "Thyrotropin"
  • major metabolic hormone
  • T3 & T4
  • controls the rate at which glucose is burned or oxidized
  • normal tissue growth and development, especially in reproductive and nervous systems
• Calcitonin

  • produced by parafollicular cells
  • lower blood calcium level by inhibiting release of calcium
  • involved in bone remodeling
• Thyroxine (T3)

  • major hormone produced by the thyroid follicles
• Triiodothyronine (T4)

  • product of conversion from thyroxine
• Parathyroid glands

  • tiny masses of glandular tissue
  • found on the posterior surface of the thyroid glands
  • parathyroid hormone - increases blood calcium levels
• Thymus

  • large in infants and children, decreases in size throughout adulthood
  • Thymosin
  • site maturation of T cells
• Adrenal glands

  • there are two glands; each sits at the top of the kidneys
  • structurally and functionally two endocrine organs in one
  • Adrenal Cortex: glandular tissue
  • Adrenal Medulla: neural tissue
• 3 major groups of steroid hormones produced by the adrenal cortex:

  • Mineralocorticoids
  • Glucocorticoids
  • Sex hormones
  • collectively called, Corticosteroids
• Aldosterone

  • produced by the outermost adrenal cortex cell layer
  • helps regulate water and electrolyte balance in body fluids
  • blood pressure regulation
• Cortisol

  • “Hydrocortisone”
  • “Stress hormone”
  • metabolism - promotes gluconeogenesis – production of sugar other than carbs & glycogenolysis – conversion to glycogen to glucose
  • aids in CHON & fat metabolism
  • can lead to immunosuppression, bone destruction, edema
• Cortisone

  • precursor of cortisol
  • produced by the middle cortical layer
  • function: metabolism & anti-inflammatory
• Androgens

  • produced by the inner-most cortex layer
  • function: development of male sexual characteristics, spermatogenesis, libido and sexual function, bone density and muscle mass
• Estrogens

  • produced by the inner-most cortex layer
  • function: development of female sexual characteristics, menstrual cycle regulation, reproductive function, bone health
• Epinephrine & Norepinephrine

  • collectively called Catecholamines
  • enhances and prolongs the effects of the sympathetic nervous system during fight or flight response
  • prepares the body to cope with short-term stressful situations
• Pancreatic islets

  • “ islets of Langerhans”
  • are little masses of endocrine tissue among the enzyme-producing tissue of the pancreas
  • Insulin
  • Glucagon