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BIOL 273 (91)
Lecture

Chapter 6 textbook material only Chapter 6 text material only

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Department
Biology
Course
BIOL 273
Professor
Katherine Wood
Semester
Winter

Description
Unit 1Introduction Chapter 6 Communication Integration and Homeostasis CELLTOCELL COMMUNICATION75 trillion cells in human bodyElectrical signalschanges in cells membrane potential Chemical signalsmolecules secreted by cells into ECF Gap Junctions Create Cytoplasmic Bridges ContactDependent Signals Require CelltoCell Contact Paracrine and Autocrine Signals Carry out Local Communication LongDistance Communication May Be Electrical of ChemicalCytokines May Act as both Local and LongDistance SignalsModulate immune responsesVarity of regulatory proteinsAll nucleated cells secrete cytokines in response to a stimuliControlso Cell developmentfunction as paracrine or autocrine o Cell differentiationfunction as paracrine or autocrine o Immune response o Stress and inflammationmaybe transported as hormones and affect distant targetsHow are cytokines different from hormoneso Cytokines act on a broad spectrum of target cells o Cytokines are not produced by specialized cells like hormones are o Cytokines are produced on demand o Hormones are produced and stored in endocrine cell unit until needed o Signal pathways are usually different o However line between is blurryEx erythropoietincontrols synthesis of red blood cells Traditionally considered a hormoneFunctionally fits the definition of a cytokine SIGNAL PATHWAYS Receptor Proteins Are Located Inside the Cell or on the Cell MembraneChemical signals either o Lipophilico LipophobicTargetreceptors found in nucleus cytosol or on the cell membrane as integral proteins o Where chemical signal binds depends on if the signal molecule can get into the cellLipophilic signal molecules o Diffuse through phospholipid membrane and bind to cytosolic receptors of nuclear receptors o Often turns on a gene and instructs DNA to make new mRNAtranscription o mRNA then provides a template for protein synthesistranslation o Slowresponse may not be noticed for an hour or longer o Can also turn off or repress gene activityEx hormonesLipophobic signal molecules o Unable to diffuse through phospholipid membrane o Remain in ECF o Bind to receptors proteins on cell membrane or cell membrane receptors o Fastwith in milliseconds to minutesProtein receptors for signal molecules play an important role in medicine o Half the drugs we use act on protein receptorsFour types of membrane receptors o ReceptorchannelsChemically gated ligandgatedLigand binding opens or closes channel o Receptorenzymessignal transduction SDsignal molecule passes information from one side of the membrane to another using membrane proteins
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