Chapter 32

I. Types of Signaling A. intracellular – within a cell 1. CDKs 2. cAMP B. Intercellular – between cells 1. growth factors (PDGF) 2. neurotransmitters 3. hormones C. Between organisms

II. Types of Signaling Molecules: A. Local signaling Molecules 1. Secreted into extracellular fluid 2. Travel by diffusion 3. Short lived 4. Very local effects 5. Histamine, neurotransmitters B. Pheromones 1. Signal other individuals 2. Molecules travel by air 3. Sensed by vomeronasal organ C. Hormones 1. transported around body by blood

III. Hormones A. Produced by endocrine system Endocrine glands/cells Some neurons B. Delivered by blood & interstitial fluid C. Received by target cells 1. Cells with receptors for that specific hormone 2. Peptide/protein hormone bind membrane receptors 3. Lipid hormones diffuse through cell membrane (they are non-polar) to Intracellular receptors

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

Intracellular Receptor https://www.youtube.com/watch?v=c6s6SZ9Vnbk

Neg. Feedback: Anterior Pituitary hormones Anterior Pituitary regulated by Hypothalamus Hypothalamus monitors hormone blood levels Low levels cause hypothalamus to signal Anterior Pituitary via secretory neurons Neurons make releasing hormones (_RH) that signal the anterior pituitary to begin secreting stimulating hormones (_SH) Stimulating hormones also called Tropins are hormones that travel to an organ

Thyroid function Negative Feed back example Hypothalamus monitors blood levels of thyroid hormones (T3/T4) Low levels of T3/T4 cause hypothalamus to make releasing hormones (TRH) that signal the anterior pituitary to begin secreting (TSH ) thyroid stimulating Hormone TSH binds to receptors in thyroid gland causing it to produce T3 & T4 T3/T4 feed back to shut down hypothal. & pit .

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

Glucagon induced cascade

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

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

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

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

Hormone Regulation 1)Antagonistic pairs (opposing functions) 2) Negative Feedback – increasing end-product shuts down system 3) Positive Feedback – increasing end-product encourages more production

Positive Feedback example posterior pituitary Oxytocin triggers uterine contractions And uterine contractions signal hypothalamus to make MORE oxytocin Oxytocin produced in neuron cell bodies within the hypothalamus It is then sent down axon to posterior pituitary where it is released and diffuses into blood Blood carries oxytocin to uterus