THE ENDOCRINE SYSTEM Chapter 16

OVERVIEW Group of unimpressive, discontinuous organs Group of unimpressive, discontinuous organs Coordinates and integrates body activity through the use of hormones produced in Coordinates and integrates body activity through the use of hormones produced in ductless glands

Differs from nervous system because its work is strictly chemical Differs from nervous system because its work is strictly chemical Exocrine glands use ducts to deliver their secretions Exocrine glands use ducts to deliver their secretions

Organs Pineal, hypothalamus, pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, testis, ovary, placenta, tumors, cells within the digestive tract, heart, kidney, etc. Pineal, hypothalamus, pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, testis, ovary, placenta, tumors, cells within the digestive tract, heart, kidney, etc.

Adrenal Pineal Pituitary Thyroid Ovaries Thymus Digestive hormones Testes Pancreas Hypothalamus Parathyroid

Thyroid gland hypothalamus anterior pituitary gonadotropic hormones: follicle- stimulating hormone (FSH) & luteinizing hormone (LH) Mammary glands in mammals Muscles of uterus Kidney tubules posterior pituitary thyroid-stimulating hormone (TSH) antidiuretic hormone (ADH) Adrenal cortex Bone and muscle Testis Ovary Melanocyte in amphibian adrenocorticotropic hormone (ACTH) melanocyte-stimulating hormone (MSH) oxytocin prolactin (PRL) growth hormone (GH) tropic hormones

Hormones Chemicals released into extracellular fluids that regulate metabolic functions of other cells Chemicals released into extracellular fluids that regulate metabolic functions of other cells Ex: growth, development, metabolism immune response, electrolyte & water balance, blood pressure, RBC production Ex: growth, development, metabolism immune response, electrolyte & water balance, blood pressure, RBC production

Hormones fall into one of 2 categories: Hormones fall into one of 2 categories: Amino-acid based – most hormones in this category; ex: thyroxine, insulin, melatonin, ADH, etc. Amino-acid based – most hormones in this category; ex: thyroxine, insulin, melatonin, ADH, etc. Steroid- (cholesterol based) ex: sex hormones (estrogen, FSH, LH, testosterone), aldosterone Steroid- (cholesterol based) ex: sex hormones (estrogen, FSH, LH, testosterone), aldosterone

Function by binding to and influencing activity of a target cell (cell containing receptors for that hormone); ex: most body cells have receptors for human growth hormone and thyroxine Function by binding to and influencing activity of a target cell (cell containing receptors for that hormone); ex: most body cells have receptors for human growth hormone and thyroxine Provoke a secondary messenger activity Provoke a secondary messenger activityOR Directly influence DNA activity of the cell Directly influence DNA activity of the cell

Once bound, hormones: Once bound, hormones: Change plasma membrane permeability Change plasma membrane permeability Promote production of regulatory molecules; enzymes Promote production of regulatory molecules; enzymes Activate or deactivate enzymes Activate or deactivate enzymes Induce secretory activity of the cell Induce secretory activity of the cell

Control is by feedback mechanism Control is by feedback mechanism Ex: Negative Feedback Ex: Negative Feedback Gland is stimulated due to low levels of hormone Gland is stimulated due to low levels of hormone Hormone is released Hormone is released Hormone levels increase in bloodstream Hormone levels increase in bloodstream Increased levels deactivate gland Increased levels deactivate gland

Maintaining homeostasis high low hormone 1 lowers body condition hormone 2 gland specific body condition raises body condition gland Negative Feedback Model

Controlling Body Temperature high low nerve signals sweat nerve signals brain body temperature shiver brain dilates surface blood vessels constricts surface blood vessels Nervous System Control Feedback

liver pancreas liver Regulation of Blood Sugar blood sugar level insulin body cells take up sugar from blood liver stores sugar reduces appetite glucagon pancreas liver releases sugar triggers hunger high low Feedback Endocrine System Control

nephron low Blood Osmolarity blood osmolarity blood pressure ADH increased water reabsorption increase thirst renin increased water & salt reabsorption high Feedback Endocrine System Control pituitary angiotensin nephron (JGA) adrenal gland aldosterone JuxtaGlomerular Apparatus

Regulation of Blood Calcium blood calcium level (10 mg/100mL) calcitonin PTH  Ca ++ uptake in intestines high low Feedback Endocrine System Control  kidney reabsorbs Ca ++ bones release Ca ++  kidney filters Ca ++ Ca ++ deposited in bones activated Vitamin D parathyroid

corpus luteum ovary Female reproductive cycle pregnancy maintains uterus lining no yes Feedback estrogen egg matures & is released (ovulation) builds up uterus lining FSH & LH progesterone fertilized egg HCG corpus luteum breaks down progesterone drops = menstruation maintains uterus lining GnRH hypothalamus

Control falls into one of 3 categories: Control falls into one of 3 categories: Hormonal stimuli – Ex: FSH from pituitary stimulates ovary to release progesterone and estrogen; this in turn shuts down FSH = rhythm Hormonal stimuli – Ex: FSH from pituitary stimulates ovary to release progesterone and estrogen; this in turn shuts down FSH = rhythm

Humoral stimuli – Ex: blood sugar levels stimulate pancreas to release insulin; this lowers sugar levels which in turn reduces insulin production Humoral stimuli – Ex: blood sugar levels stimulate pancreas to release insulin; this lowers sugar levels which in turn reduces insulin production

Neural stimuli – Ex: stress triggers adrenal gland to release adrenaline Neural stimuli – Ex: stress triggers adrenal gland to release adrenaline

Organs/Hormones Organs/Hormones Anterior Pituitary – HGH, TSH, ACTH, FSH, LH, PRL Anterior Pituitary – HGH, TSH, ACTH, FSH, LH, PRL Hypothalamus – oxytocin, ADH Hypothalamus – oxytocin, ADH Thyroid – thyroxine, calcitonin Thyroid – thyroxine, calcitonin Parathyroid – PTH Parathyroid – PTH

Adrenal – glucocorticoids, androgens, aldosterone, adrenaline Adrenal – glucocorticoids, androgens, aldosterone, adrenaline Pancreas – insulin, glucagon Pancreas – insulin, glucagon Gonads – testosterone, estrogen, progesterone Gonads – testosterone, estrogen, progesterone Pineal – melatonin Pineal – melatonin Thymus – thymopoietin, thymosin Thymus – thymopoietin, thymosin

Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine

Robert Wadlow ' 11" Excessive HGH

Graves - hyperthyroid hypothyroidism Hyperthyroidism

Cushing’s Disease