Week 4b-Ch. 45 Hormones and the Endocrine System45.1- Hormones and other signaling molecules bind to target receptors, triggering specific response pathways 45.2 - Feedback regulation and antagonistic hormones pairs are common in endocrine system 45.3 - The hypothalamus and pituitary are central to endocrine regulation 45.4 - Endocrine glands respond to diverse stimuli in regulating homeostasis, development and behavior45.1- Hormones and other signaling molecules bind to target receptors, triggering specific response pathways Hormones – Body’s long-distance regulators Animal hormones are chemical signalsoSecreted into circulatory system – hemolymph or blood oCommunicate regulatory messages throughout the bodyFunction of hormones is to: oMaintain homeostasis oRespond to stimuli oRegulate growth and development **Hormones reach all parts of the body but only target cells with receptors specific for a particular hormone will respond cells lacking receptors for a particular hormone will be unaffected Two systems coordinate communicate communication throughout body: 1.Endocrine system[stimulus, signal travels everywhere via bloodstream, response limited to cells that have receptor for the signal] a.Hormones secreted by endocrine cells regulate reproduction, development, energy metabolism, growth and behavior 2.Nervous system[stimulus, travels along axon to a specific location, response limited to cells that connect by specialized junctions to an axon that transmits an impulse] a.Regulate neurons, muscle cells, endocrine cells Endocrine tissues and organs Endocrine glands:endocrine cells grouped together in ductless organs, have ducts and secrete onto body surfaces or into cavities oEndocrine system cells also found in organs that belong to other organ systemsoEndocrine glands secrete hormones directly into surrounding fluidMajor endocrine glands: Hypothalamus Pineal gland Pituitary gland Thyroid gland Parathyroid gland Adrenal glands Ovaries/testes
Organs containing endocrine cells: oThymusoHeartoLiveroStomach oKidneysoSmall intestine Example:Vasculature of the Thyroid gland Hormones synthesized within endocrine cells of the thyroidglandthey are then diffused into the interstitial fluid of thethyroid gland which then goes into the surrounding bloodvessels Hormone cells bind to target receptors and trigger a responseIntercellular CommunicationThings to consider in intercellular communication (howchemical signals are transmitted between animal cells): 1.Type of secreting cell 2.Route taken by signal in reaching its target (5) ways of achieving intercellular communication 1. Endocrine signaling 2. Paracrine signaling3. Autocrine signaling 4. Synaptic signaling 5. Neuroendocrine signaling Endocrine Signaling Endocrine cellsrelease hormones into extracellular spaceoHormone travels via bloodstream (or hemolymph) toreach targets cells oLong distance travelledParacrine and Autocrine Signaling Can be any type of cell in the body (not necessarily an
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- Fall '17
- Endocrine System, endocrine cells