endocrine system

• Hormone Pathways:

  A) Prolactin

  B) Breast

  C) Many Tissues

  D) TRH

  E) Dopamine

  F) CRH

  G) GHRH

  H) GNRH

  I) LH

  J) FSH

  K) Liver

  L) GH

  M) ACTH

  N) TSH

  O) Cortisol

  P) Androgens

  Q) T3/T4

  R) IGFs

  S) Estrogen, progesterone

  T) germ cells

  U) somatostatin

  
• 3 classes of hormones are steroid, peptide, and amine
• amine hormones are made from tryptophan and tyrosine
• peptide hormones are made from linking amino acids
• steroid hormones are made from cholesterol
• primary pathway steroid hormones are sourced from the endocrine gland
• Most hormones are peptide hormones. They are made in advance and released from exocytosis (active transport) in the blood
• steroid hormones move with simple diffusion and need a carrier plasma protein. They have a longer half life
• insulin and parathyroid hormone are peptide hormones
• estrogen, androgens, and cortisol are steroid hormones
• Synergism is when the effect of 2 or more hormones on parameter is greater than addative
• Permissiveness is when one hormone is needed for the other to extert its full effect. ex: thyroid hormone and GH
• Antagonism is when hormones have the opposite effect. ex: glucagon and insulin
• Vasopressin is a hormone that is released by the posterior pituitary gland that can compress blood vessels and regulates water in urine
• Oxytocin triggers the mammary glands when a baby is breastfeeding to get milk
• oxytocin is a neural hormone that is efferent because it is released by the brain
• ACTH stimulates adrenal cortex to release cortisol
• The anterior pituitary is a endocrine gland that has vascular connection to the hypothalamus
• in the anterior pituitary there is a portal system where two capillaries are connected to each other (one in hypothalamus and one in the kidney)
• there is a one to one correspondence (in the endocrine system) because there is a signal for each receptor
• Dopamine regulates prolactin. If dopamine is high then prolactin will be low
• TRH comes from the hypothalamus and triggers an increase of TSH to then T3/T4. It also triggers prolactin to release
• GnRH comes from the hypothalamus and triggers LH and FSH to release
• corticotrophin releasing hormone (CRH) comes from the hypothalamus and triggers ACTH to release
• growth hormone releasing hormone (GHRH) comes from the hypothalamus and triggers GH to release
• growth hormone is regulated by GHRH and somatostatin
• somatostatin inhibits growth hormone secretion
• gonadotropins are sex hormones
• FSH are male androgens and LH are female estrogen and progesterone
• Trophic hormones function to trigger another hormone's release. Their concentration is regulated through negative feedback. ex: ACTH and CRH
• long loop negative feedback is the main feedback maintaining homeostasis
• primary pathology begins in the endocrine gland. secondary pathology begins in tissue producing trophic hormone.
• the hypothalamus is the first integrating center
• the first efferent is TRH
• the final integrating center is the thyroid gland
• The final efferent is T4
• TSH stimulates synthesis and secretion of T4 and T3 by thyroid gland
• T3 and T4 leave the thyroid cell by simple diffusion
• the thyroid binding globulin acts as a carrier protein
• T3/T4 have a nuclear receptor because they can stimulate protein synthesis