Endocrine System Activity Controlling Mechanisms Endocrine system Nervous system Glands Exocrine Glands Exocrine Endocrine Neuroendocrine Link Chemical Messengers Hormones Autocrines Paracrines Pheromones Hormone Classifications Amino acid based Hormone Classifications Amino acid based Steroid Hormone Classifications Amino acid based Steroid Eicosanoid Anatomy Joke of the Day Hormone Action Target cells Hormone Actions Open or close ion channels Hormone Actions Open or close ion channels Stimulate protein synthesis Hormone Actions Open or close ion channels Stimulate protein synthesis Activate or deactivate enzymes Hormone Actions Open or close ion channels Stimulate protein synthesis Activate or deactivate enzymes Promote secretion Hormone Actions Open or close ion channels Stimulate protein synthesis Activate or deactivate enzymes Promote secretion Stimulate mitosis Hormonal Mechanisms Steroid Amino acid based Receptors on plasma membrane cell Receptors inside Direct activation Involves G proteins and secondary messengers Steroid Action Steroid Action Hormone diffuses through plasma membrane Binds with intracellular receptor Activated complex binds to receptor protein on DNA Transcription initiated mRNA translated Proteins produced Non steroid Action Non steroid Action Cyclic AMP mechanism PIP calcium mechanism Cyclic AMP Mechanism Hormone binds to membrane receptor Modified receptor binds with G protein G protein is activated Activated G protein activates adenylate cyclase Adenylate cyclase generates cAMP from ATP cAMP stimulates protein kinase reactions Proteins are phosphorylated Phosphodiesterase degrades cAMP PIP calcium Mechanism Hormone binds to membrane receptor Modified receptor binds with G protein G protein is activated Activated G protein activates phospholipase Phospholipase splits PIP2 into DAG and IP3 DAG activates protein kinases IP3 triggers release of calcium from ER Calcium acts as additional second messenger Factors Affecting Hormone Action Hormone level in bloodstream receptors in on target cells Receptor affinity Hormone Interactions Permissiveness Synergism Antagonism Modes of Endocrine Gland Stimulation Humoral Neural Hormonal Modified by nervous system Inhibited by negative feedback Endocrine Glands Pituitary Thyroid Parathyroids Adrenals Pancreas Gonads Pineal Thymus Pituitary Gland Hypophysis Posterior pituitary Anterior pituitary Infundibulum Adenohypophysis Neurohypophysis Neurohypophyseal Hormones Oxytocin Antidiuretic hormone ADH Oxytocin Stimulates smooth muscle contraction Childbirth Milk ejection Anatomy Joke of the Day ADH Regulates water balance Prevents urine formation Adenohypophyseal Hormones Growth hormone GH Thyroid stimulating hormone TSH Adenocorticotropic hormone ACTH Gonadotropins Prolactin Pro opiomelanocortin POMC Tropic Hormones Greek trephein GH Stimulates cell growth and division protein synthesis fat metabolism and glucose conservation GH Cascade Hypothalamus secretes GHRH Somatotropic cells of anterior pituitary begin GH synthesis GH has both direct and indirect effects on tissues Circulating GH triggers production of GHIH Production of GH stops Direct Actions of GH Increases blood levels of fatty acids Fats from fat stores Decreases glucose uptake and metabolism Encourages breakdown and release of glucose from glycogen in liver Called diabetogenic effect Indirect Actions of GH Operate through IGFs Stimulate uptake of amino acids from blood into cellular proteins Stimulate uptake of sulfur into matrix of cartilage TSH Stimulates development of and secretion from thyroid gland TSH Cascade Hypothalamus secretes TRH TRH causes thyrotrope cells of anterior pituitary to produce TSH Increased levels of TSH inhibit both pituitary gland and hypothalamus Also stimulate production of GHIH ACTH Stimulates adrenal cortex to release corticosteroid hormones Especially glucocorticoids ACTH Cascade Hypothalamus secretes CRH corticode releasing hormones CRH stimulates corticotrope cells to release ACTH Increased levels of glucocorticoids stop CRH ACTH secretion stops Fever hypoglycemia and stressors promote CRH release Gonadotropins Regulate functions of gonads testes or ovaries Includes both FSH and LH FSH stimulates gamete production also stimulates sperm production in males LH promotes production of gonadal hormones Male FSH stimulates sperm production LH stimulates interstitial cells of testes to produce testosterone Female FSH stimulates ova production FSH and LH cause maturation of follicle that FSH caused to be released LH triggers ovulation and promotes synthesis of ovarian hormones ex estrogen Gonadotropin Cascade At puberty hypothalamus secretes GnRH GnRH stimulates gonadotrope cells to secrete gonadotropins Gonadotropins cause gonads to mature and begin producing hormones Increased levels of gonad hormones suppress FSH and LH Prolactin Stimulates milk production by breasts May enhance testosterone production in males Prolactin Cascade Cycling not prego High estrogen levels stimulates release of prolactin Estrogen stimulates lactotropes to secrete prolactin by suppressing PIH production Prolactin production brief due to ovarian hormone cycling so brief no milk is produced Decreased estrogen stimulates production of PIH from hypothalamus Prolactin production stops Prolactin Cascade Pregnant High estrogen effects same PRL triggered near end of pregnancy Suckling maintains PRL production prehibits PIH Lack of suckling and return of normal hormonal cycles brings about PIH production