Chapter 36

Signaling Molecules: 1) Neurotransmitters 2) Local signaling Molecules a)Secreted into extracellular fluid b)Short lived c)Very local effects 3) Pheromones a)Signal other individuals b)Sensed by vomeronasal organ 4) Hormones

Hormones Produced by endocrine system Produced by endocrine system –Endocrine glands/cells –Some neurons Delivered by blood & interstitial fluid Delivered by blood & interstitial fluid Received by target cells Received by target cells –Cells with membrane receptors for that specific hormone –Lipid hormones diffuse through cell membrane (they are non-polar)

Intracellular receptors Intracellular receptors Bind lipid Hormones like steroids Bind lipid Hormones like steroids Testosterone & thyroid hormones Testosterone & thyroid hormones Often affect promoters regulating transcription Often affect promoters regulating transcription Why do they need carrier proteins in blood? Why do they need carrier proteins in blood?

Intracellular Receptor

Membrane Receptors Membrane Receptors Bind peptide/protein hormones Bind peptide/protein hormones Binding produces 2 nd messenger mols. Like cAMP Binding produces 2 nd messenger mols. Like cAMP cAMP initiates chain reaction cAMP initiates chain reaction resulting series of chem. rxns is called a cascade resulting series of chem. rxns is called a cascade Example: Glucagon Example: Glucagon

Glucagon induced cascade

Anterior Pituitary Hormones Regulated by Hypothalamus Regulated by Hypothalamus Hypothalamus monitors blood levels of thyroid hormones (T3/T4) and cortisol Hypothalamus monitors blood levels of thyroid hormones (T3/T4) and cortisol Low levels of T3/T4 or cortisol cause hypothalamus to signal Anterior Pituitary Low levels of T3/T4 or cortisol cause hypothalamus to signal Anterior Pituitary Neurons in hypothal. make releasing hormones (_RH) that signal the anterior pituitary to begin secreting hormones Neurons in hypothal. make releasing hormones (_RH) that signal the anterior pituitary to begin secreting hormones

Releasing Hormones Produced by hypothalamus Produced by hypothalamus CRH = Corticotropin Releasing Hormone CRH = Corticotropin Releasing Hormone  In response to low cortisol levels  Coritsol helps maintain blood glucose levels  High cortisol levels may result from stress TRH = Thyrotropin Releasing Hormone TRH = Thyrotropin Releasing Hormone  In response to low thyroid hormone level in blood

Negative feedback loops Slow production of Releasing hormones by Hypothalamus Slow production of Releasing hormones by Hypothalamus High blood thyroid hormone levels = slow TRH production High blood thyroid hormone levels = slow TRH production High blood cortisol levels in blood = slow CRH production High blood cortisol levels in blood = slow CRH production

Transmission of ___RH Releasing hormones produced in hypothalamus neruons flow into hypothalamus capillary bed Releasing hormones produced in hypothalamus neruons flow into hypothalamus capillary bed Blood & hormones flow to 2 nd capillary bed in anterior pituitary where TRH and CRH bind to receptors Blood & hormones flow to 2 nd capillary bed in anterior pituitary where TRH and CRH bind to receptors

Anterior Pituitary Response RHs binding to receptors on Ant. Pituitary cells begin cascade of rxns leading to….. RHs binding to receptors on Ant. Pituitary cells begin cascade of rxns leading to….. Release of TSH (thyroid stimulating hormone) or ACTH (adreno corticotropin) Release of TSH (thyroid stimulating hormone) or ACTH (adreno corticotropin) TSH also called thyrotropin TSH also called thyrotropin -tropins stimulate other glands -tropins stimulate other glands These hormones travel through blood to their target endocrine glands These hormones travel through blood to their target endocrine glands

Thyroid Gland Response TSH binds to thyroid receptors TSH binds to thyroid receptors Cascade of reactions results in release of T3 and T4 (thyroxins) Cascade of reactions results in release of T3 and T4 (thyroxins) High T3/T4 levels result in negative feedback to Hypothalamus and Anterior pituitary..stops TRH and TSH production High T3/T4 levels result in negative feedback to Hypothalamus and Anterior pituitary..stops TRH and TSH production T3/T4 regulate metabolism, growth & maturation T3/T4 regulate metabolism, growth & maturation

Adrenal Gland Response ACTH binds to adrenal cortex receptors ACTH binds to adrenal cortex receptors Cascade of reactions results in release of cortisol Cascade of reactions results in release of cortisol High cortisol levels in blood cause negative feedback to Hypothalamus and Anterior pituitary..stops CRH and ACTH production High cortisol levels in blood cause negative feedback to Hypothalamus and Anterior pituitary..stops CRH and ACTH production cortisol regulates blood glucose levels, stress response, excess = poor growth/imune system, cushings syndroms cortisol regulates blood glucose levels, stress response, excess = poor growth/imune system, cushings syndroms

Other Ant. Pit. Hormones FSH – Follicle-stimulating Hormone FSH – Follicle-stimulating Hormone  Stimulates follicle to release egg (see ch 44)  Stimulates sperm production in males LH – Luteininzing Hormone LH – Luteininzing Hormone  Stimulates gamete formation (see ch 44) Prolactin – Prolactin – causes lactation causes lactation Growth Hormone- duhh Growth Hormone- duhh

Posterior Pituitary Function Hormones produced in cell bodies in the hypothalamus Hormones produced in cell bodies in the hypothalamus Axons of hypothamamic nerves extend into the posterior pituitary Axons of hypothamamic nerves extend into the posterior pituitary Action potentials trigger the release of hormones into capillaries Action potentials trigger the release of hormones into capillaries Blood carries hormones to target organs Blood carries hormones to target organs

Posterior Pituitary Hormones ADH – AntiDiuretic Hormone ADH – AntiDiuretic Hormone * Controls water excretion by kidney * Controls water excretion by kidney Oxytocin – controls…. Oxytocin – controls…. * Uterine contractions/ lactation * Uterine contractions/ lactation

Pancreatic Hormones Hormones produced in Pancreatic Islets Hormones produced in Pancreatic Islets 2 types of cells in islets 2 types of cells in islets 1) alpha cells = glucagon 1) alpha cells = glucagon 2) beta cells = insulin 2) beta cells = insulin

Glucagon = peptide hormone Low blood glucose triggers alpha cells Low blood glucose triggers alpha cells Glucagon produced, binds to liver cells Glucagon produced, binds to liver cells Cascade causes breakdown of glycogen into glucose Cascade causes breakdown of glycogen into glucose High blood glucose levels = neg. feedback High blood glucose levels = neg. feedback

Insulin High blood glucose levels trigger beta cells High blood glucose levels trigger beta cells Produce insulin Produce insulin Insulin  cascade resulting in uptake of glucose Insulin  cascade resulting in uptake of glucose –(only hormone to do this) Targets skeletal muscle, fat & liver cells Targets skeletal muscle, fat & liver cells Promotes: Promotes: protein, fat & glycogen synthesis protein, fat & glycogen synthesis Low glucose levels = Neg. feedback Low glucose levels = Neg. feedback

Diabetes mellitus Cells do not take up glucose properly Cells do not take up glucose properly Type I = autoimmune attack on Type I = autoimmune attack on B cells (juvenile onset diabetes) B cells (juvenile onset diabetes) Type II = target cells ignore insulin Type II = target cells ignore insulin  Beta cells constant production of insulin  fail  Insulin shots required  Caused by genetics & obesity

Symptoms of Diabetes Sugar accumulated in blood/ urine upsets water-solute balance  kidney damage Sugar accumulated in blood/ urine upsets water-solute balance  kidney damage Cells burn protein/fats in absence of glucose Cells burn protein/fats in absence of glucose * Produces ketones  ketoacidosis * Affects brain, blood vessels & nerves * amputations