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UI BIOL 1140 - The Endocrine System
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BIOL 1140 1st Edition Lecture 18Outline of Last LectureI. Three Key Concepts of evolutionII. Evolution involves descent over time III. Evidence for EvolutionIV. Fossil RecordV. BiogeographyVI. Comparative AnatomyVII. Comparative BiochemistryVIII. Comparative GeneticsIX. Mutation and Natural Selection Drives EvolutionX. Genetic Drift and Gene FlowXI. Mass Extinctions XII. Young Earth: too hot for lifeXIII. Photosynthesis Revolutionized EvolutionXIV. Humans are PrimatesXV. Differences within the human speciesOutline of Current LectureI. The Endocrine SystemII. The Endocrine vs. the Nervous SystemIII. Hormone ReceptorsIV. Steroid vs. Non-steroid HormonesV. Steroid HormonesVI. Non-steroid HormonesVII. Negative Feedback LoopsVIII. Regulation of Blood GlucoseIX. The PancreasX. InsulinXI. GlucagonXII. Disorders of Glucose RegulationXIII. The Type 2 Diabetes EpidemicCurrent LectureI. The endocrine systemThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Makes hormones that are used for communication between cells in distant parts of the bodyb. Hormonesi. Chemical messengers made by endocrine glandsii. Circulate in the bloodsteamiii. Act on specific cells in the body ('target cells') that have a receptor for that particular hormonec. Endocrine glandsi. Ductles organs that secrete hormones into the blood1. Pituitary gland, testes and ovaries, thyroid gland, adrenal glands, and many othersd. Endocrine system has important role in 2 basic humnan functionsi. Development1. Growth and cell division stimulated by cehmical signals caled mitogens2. Differentiation of a cell depends on what chemical signals it receive3. Maturation and pubery are regulated by hormones 4. Reproduction - production of gametes and sexual behavior are hormonally regulatedii. Homeostatsis1. Mainenance of constant, optimal internal enviornmentII. The endocrine vs. nervous systema. Both systems use chemical signals to communicate in the bodyb. Both types of chemical signals must be received by receptors with a specific shapei. Like a lock and keyc. There is interaction between endocrine and nervous systemsd. Endocrine systemi. Chemical signal = hormoneii. Relatively slow actingiii. Travels through the blood and can reach all parts of the bodyiv. Diffuses out of blood into tissue fluids at some distance location e. Nervous systemi. Chemical signal = neurotransmitterii. Very fast actingiii. Released at point of contact between two nerve cells called the synapse (not into blood)iv. Cant signal over a long distanceIII. Hormone Receptorsa. Hormones have access to every cell in the body via bloodstream, but can only act on target cellsi. Target cell must have a receptor for that hormone ii. Hormone can bind to receptor if they fit together like lock and keyb. A cell can respond to a particular hormone if and only if it has a receptor for that hormoneIV. Steroid vs. non-steroid hormonesa. Steroid hormonesi. Steroids are a type of lipidii. Therefore lipid soluble (nonpolar) and able to cross cell membranesiii. Examples are testosterone, estrogen and progestogen, aldosteroneb. Non-steroid hormonesi. Structurally related to proteinsii. Lipid insoluble and not able to cross cell membranesiii. Examples are ADH, growth hormone, and most other hormonesV. Steroid Hormones a. Because they’re lipid soluble, can cross cell membrane to enter target cellb. Receptors are located in the cytoplasm of target cellc. Receptor-hormone complex enters the nucleus, binds to DNA, and activates transcription of specific genesd. Slower acting takes minutes to hours to have an effectVI. Non-steroid hormonesa. Because they are not lipid soluble, they cannot cross a membrane or enter target cellb. Receptors are located on the cell membranec. Binding of hormone to receptor begins a signal cascade inside the celli. Often involves a secondary messenger, such as cyclic AMPd. Faster acting takes seconds to minutes to have an effectVII. Negative Feedback Loopsa. Many (but not all) hormones maintain homeostasis using negative feedback loopsi. Controlled variable1. Factor in the body that is normally maintained at some set point, i.e. blood sugar levelsii. Sensor1. Gland or part of nervous system that sense changes in the variableiii. Control center1. An endocrine gland, such as the pancreas or pituitary glanda. Hormones allow signaling between control center and effectoriv. Effectors1. Target tissues or organs that respond VIII. Regulation of blood glucosea. Blood glucose levels in the blood must be kept at optimum level of 90mg/100 mli. We alternate between eating and not eating throughout the day, which influences blood glucose levelsb. Maintained by a simple network where the endocrine gland involved (the pancreas) acts as both the sensor and control centerc. Symptoms of low blood glucosei. Impairment of mental functionii. Hallucinations, seizures, comaiii. Deathd. Symptoms of high blood glucosei. Frequent urination and sugar in urineii. Excessive hunger and thirstiii. Weight lossiv. Irritabilityv. Blurry vision vi. Low energy, tiredness, fatiguevii. Numbness or tingling in arms and legsviii. Slow would healing, high frequency of infectionse. In a typical day, we oscillate between 2 statesi. Absorptive state = the time when digested nutrients are entering the blood1. Lasts about 4 hours after eating a meal2. Glucose is used to meet immediate energy needs; excess is stored as glycogen or fat ii. Post-absorptive state = the digestive tract is empty so no new nutrients enter bloodstream1. Energy stores (glycogen or fat) are broken down and used to maintain blood glucose at its optimum leveliii. The oscillation between these two states is regulated by the hormones insulin and glucagon 1. Both made by the same endocrine gland, the pancreasIX. The pancreasa. Both an endocrine gland and an exocrine glandi. The region of the pancreas called the islets of Langerhans contain the endocrine cells that make the insulin and glucagon hormones1. Alpha cells make glucagon2. Beta cells make insulin X. Insulin a. Insulin is a peptide hormone secreted by beta cells of the pancreasi. Causes increased uptake of glucose from blood into all cells1. Immediate increase in metabolism ii. Causes liver and skeletal muscle to increase uptake of glucose1. Converted into glycogen or fat and stored until neededb. Results in decreased blood glucosec. Insulin would be released


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UI BIOL 1140 - The Endocrine System

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