Chapter 45: Hormones & the Endocrine System Regulatory systems Nervous system Nervous system High speed messages High speed messages Endocrine system Endocrine system Slower; longer lasting Slower; longer lasting Result of hormone secretion Result of hormone secretion Connections between Nervous & endocrine systems Neurosecretory cells Neurosecretory cells Nerve cells that release hormones Nerve cells that release hormones Concentrated in hypothalamus Concentrated in hypothalamus Some hormones act as neurotransmitters Some hormones act as neurotransmitters Ex: epinephrine Ex: epinephrine

Hormones Hormones Chemical signal secreted into circulatory system through ductless glands Chemical signal secreted into circulatory system through ductless glands Action of hormones Action of hormones Operate at all levels of organization Operate at all levels of organization Intracellular, cell to cell, organ to organ, organism to organism (pheromones) Intracellular, cell to cell, organ to organ, organism to organism (pheromones) Produce developmental change Produce developmental change Ex. puberty Ex. puberty Metamorphosis (insects & amphibians) Metamorphosis (insects & amphibians) Incomplete Incomplete Egg  nymph  adult (grasshoppers) Egg  nymph  adult (grasshoppers) Complete Complete Egg  larva  pupa  adult (butterfly) Egg  larva  pupa  adult (butterfly)

Regulation of hormones Regulation of hormones Negative feedback Negative feedback Increase in substance inhibits its own production Increase in substance inhibits its own production Ex. Metabolic control Ex. Metabolic control Positive feedback Positive feedback Increase in substance increases its own production Increase in substance increases its own production Ex. Release of milk in nursing mother Ex. Release of milk in nursing mother Local regulators Local regulators Histamines Histamines Chemical from local cell for antigen-antibody response (allergies) Chemical from local cell for antigen-antibody response (allergies) Interleukins Interleukins Cytokine acting as communicator between immune cells Cytokine acting as communicator between immune cells Prostaglandins Prostaglandins Modified fatty acid which stimulates contraction of smooth muscles, induces fever & blood flow to infection sites Modified fatty acid which stimulates contraction of smooth muscles, induces fever & blood flow to infection sites

Classes of molecules acting as hormones Classes of molecules acting as hormones Proteins & peptides; H 2 O soluble Proteins & peptides; H 2 O soluble Amines (derived from amino acids); H 2 O soluble Amines (derived from amino acids); H 2 O soluble Steroids; non- H 2 O soluble Steroids; non- H 2 O soluble Events of hormone action Events of hormone action Reception (signal binds to receptor protein in or on target cell) Reception (signal binds to receptor protein in or on target cell) Water soluble hormones bind to surface receptor triggering activation of internal proteins in transduction pathway Water soluble hormones bind to surface receptor triggering activation of internal proteins in transduction pathway Steroid hormones enter cell & bind to internal receptor which enters nucleus to activate genes Steroid hormones enter cell & bind to internal receptor which enters nucleus to activate genes Signal transduction Signal transduction response response

Endocrine Gland Hormone Effect on target tissue Anterior pituitary (adenohypophysis) FSH Stimulate growth of ovarian follicle & sperm production LH Stimulate ovulation; secretion of sex hormones by ovaries/testes Prolactin Induces milk secretion in mammary glands TSH Stimulate throxin production by thyroid ACTH Stimulate adrenal cortex to produce cortisone GH Stimulate growth MSH Regulation of pigment in skin cells; inhibits hunger Beta endorphin Dull pain perception

Endocrine Gland Hormone Effect on Target tissue Posterior pituitary (neurohypophysis) ADH Stimulate increased H 2 O absorption by kidneys; constrict blood vessels Oxytocin Stimulate uterine contractions & release of milk Thyroid gland Thyroxin (T4) & Triiodothyronine (T3) Stimulate oxidative metabolism Calcitonin Regulation of calcium & phosphate blood levels Parathyroid gland Parathormone (PTH) Controls abosorption of Ca & P from blood; stimulates release of Ca from bone ThymusThymosin Stimulates production of T lymphocytes Adrenal cortex Cortisone* Regulate H2O reabsorption, electrolyte balance, protein & carbohydrate metabolism

Endocrine gland Hormone Effect on target tissue Adrenal medulla Epinephrine & norepinephrine Raises blood glucose levels; increases metabolic activity; constricts blood vessels Pancreas (islet of Langerhans) Insulin (beta cells) Stimulates uptake of glucose by cells Glucagon (alpha cells) Converts glycogen into glucose OvariesEstrogen* Stimulate female secondary sex characteristics; build uterine lining Progesterone* Maintain pregnancy TestesTestosterone* Stimulate male secondary sex characteristics PinealMelatonin Biological rhythms *denotes steroid hormone

Endocrine Disorders Thyroid Thyroid Cretinism Cretinism Under secretion of thyroxin in utero Under secretion of thyroxin in utero Goiter Goiter Enlarged gland usually related to hypothyroidism Enlarged gland usually related to hypothyroidism Graves disease Graves disease Most common form of hyperthyroidism Most common form of hyperthyroidism Autoimmune Autoimmune Hashimoto’s disease Hashimoto’s disease Most common form of hypothyroidism Most common form of hypothyroidism autoimmune autoimmune Pituitary Pituitary Dwarfism Dwarfism Under secretion of GH in child Under secretion of GH in child Giantism Giantism Over secretion of GH in child Over secretion of GH in child Acromegaly Acromegaly Over secretion of GH in adult Over secretion of GH in adult

Pancreas Pancreas Diabetes mellitus Diabetes mellitus Type I (insulin dependant) Type I (insulin dependant) Autoimmune Autoimmune Beta cells destroyed; little to no insulin production Beta cells destroyed; little to no insulin production Type II Type II Reduced responsiveness of target cells to insulin Reduced responsiveness of target cells to insulin Controlled through diet & exercise Controlled through diet & exercise Accounts for >90% of diabetes cases Accounts for >90% of diabetes cases Adrenal gland Adrenal gland Addison’s disease Addison’s disease Under-secretion of ACTH Under-secretion of ACTH