Presentation on theme: "April 28, 2014 – Chemical signals and hormones II"— Presentation transcript:
1 April 28, 2014 – Chemical signals and hormones II Announcements:Lab this week will meet in the computer labsFinal Exam: May 15ICES evaluationPre-lecture quizReview of cell-to-cell signaling & thyroid hormones (T3 & T4)SpecificityLipid soluble hormones – SteroidsG-coupled protein receptors –Tyrosine kinase receptorsHormone-mediated physiological tradeoffs
2 Endocrine systems are regulated by negative feedback Endocrine pathwayNeuroendocrine pathwayNeuroendocrine-to-endocrine pathwayStimulusStimulusStimulusEndocrine cellEndocrinesignalSensor cellSensor cellFeedback inhibitionEffectorcellFeedback inhibitionFeedback inhibitionNeural signalNeural signalResponseCNSCNSNeuroendocrinesignalNeuroendocrinesignalEffectorcellEndocrine cellEndocrinesignalResponseEffectorcellResponse
3 Chemical characteristics of hormones – major classes Peptides and PolypeptidesAmino AcidDerivativesSteroidsSecretinEpinephrineCortisolReceptorReceptorNot lipid soluble;bind to receptors onsurface of target cellMost not lipid soluble;bind to receptors onsurface of target cellLipid soluble;bind to receptorsinside target cellReceptorTarget cell
5 Hydrophobic messengers pass into cell where they bind with transcription factors which affect gene expression.
6 Hydrophilic hormones bind to a receptor on the cell membrane which causes several reactions known as a signal transductionpathway. This can affect the properties of enzymes/proteins, etc. or it may affect gene expression.
7 Thyroid Hormone Thyroid hormone: - Actually two hormones (T3/T4) Mammals mainly secrete T4- but some T4 is converted under certaincircumstances- Same receptor binds both,but ↑affinity for T3T3/T4 are membrane soluble- ↑metabolism in muscles, heart, liver & kidneyT4T3
9 Figure 47-8 T3 T3 Juvenile frog (tadpole) Adult frog Locomotion Swim via movements of muscular tailLocomotionTailless; walk or hopRespirationGas exchange occurs in gills, across skin,and in lungsRespirationGas exchange occurs across skin, and inlungsNutritionMost are herbivorous; have a long gutspecialized for digesting algae and plantsNutritionMost are carnivorous; have a large mouthor long tongue for catching prey; short gutspecialized for digesting proteinsExcretionMost nitrogenous wastes excreted asammoniaExcretionMost nitrogenous wastes excreted as urea
11 Thyroid hormone levels go up as flat fish go through this metamorphosis.
12 Anadromous versus Resident Stream Sticklebacks Higher metabolic ratesMigrate from ocean to freshwater to breedBiggerLower metabolic ratesPermanent residents in freshwaterSmaller
13 Take home message: The same hormone can have multiple physiological effects How do we explain this?
14 Altering individual behaviors by altering overall thyroid levels seems like a pretty blunt way to go about changing specific phenotypes.How could this system be fine-tuned to optimize specific traits under different contexts?A.) changes in TRH expressionB.) changes in TSH expressionC.) alterations of TSH receptorsD.) alteration of T3/T4 receptors in specific cell types.
27 Some additional effects of the “fight or flight response 1.) Redirection of blood flow from the skin and digestive system toward heart, brain, and muscles.2.) Relaxation vascular smooth muscle to aid in vasodilationTake home message:1.) Short term stress responses are EXTREMELY beneficial over the short term.2.) Prolonged stress responses can be harmful.*Radio Lab episode on stress: