Physiology 206 1STedition Lecture 29 Outline of Last Lecture I Review for Exam 3 Outline of Current Lecture I Neural Communication II Hormones Current Lecture Neural Communication Instantaneous cut on Instantaneous cut of Endocrine System cell secrete messengers into blood stream Which then goes throughout the body to target Doesn t usually involve cells that are close to each Characteristics that differ from Neural Takes much longer to get to target When it gets there it doesn t get there abruptly Takes awhile to reach full amplitude When stop secreting it lasts in blood stream for awhile The message is difused some hormone acts on many diferent cells Hormones messenger chemicals secreted by endocrine system which is secreted straight into bloodstream therefore the Endocrine Glands are also called ductless glands there are instances when the Neural System releases into bloodstream instead of target cells and they are known as Neuroendocrine and the hormones that release are called Neurohormones Basic Principles Endocrine Physiology Topics 1 what controls secretion 2 what efects they have They are practically important in things that have to be maintained over long periods of time These 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 this is important because in Neural System receptors fatigues or adapts so they are not good choices for maintaining things Things that are under endocrine control total body water blood glucose level Things that make up endocrine system consists of glands that are not connected or anatomically disconnected but work as a group because they are held together by circulation there are hormones that are released just to control other secretion of other hormones are called Tropic Hormones Hormones that mainly on things outside endocrine system called Nontrophic Hormone some endocrine glands that have more than one cell in them so they secrete more than one type of hormone Very common for a hormone to have efect on more than one type of cell Hormone Classes Determined by Chemical Structure 1 Peptides 2 Steroids 3 Amines Useful grouping because each class have similarities in how a b c d e they are synthesized what its stored in if it is how they get secreted how they are transported what it does when it gets there Peptide Hormones basically small proteins synthesized for export from cell synthesis happens on ribosomes as in active precursors Get transported through cell in ER When arrive at Golgi they get enclosed in membrane and get stored When it is stimulated the packages get released somewhere between last one and here get turned into hormones All water soluble they dissolve in plasma with no trouble and that s how they travel in blood they do not get into cells because large water soluble When they get to target cell there have to be structures on the external surface of the target cells called receptors that the hormone can interact with it and cause cell to do its trick any cell that doesn t have receptor won t be efected If gave a peptide orally it would be destroyed in stomach meaning you can t use them orally as therapeutic devices Steroid Hormones Unlike peptides they are fat lipid fat soluble meaning they can get into cell can difuse right across There is no way for cell to synthesize and store them so there is not step of storage to wait for stimulus Instead when cell gets stimulated then it starts producing steroid and release them When they get to target cell the membrane doesn t stop them so they difuse in get to nucleus get to proteins that bind to steroids to steroid which get in DNA which activate genes Have specific carrier proteins in plasma which steroid bind tightly to them it behaves as if proteins didn t exist hormones would end up in the walls of gland used like taxies Remains tied to proteins until it encounters a place that causes them to release from protein Because steroid cross membrane easily and they are not destroyed in stomach they can be given orally Amines Fairly diverse group so not able to produce a list of properties Characteristics of all Hormones 1 Efective at very low concentrations 10 8 M to 10 12 M much more potent unlike other systems 10 3 to 10 1 Many times more potent Concentration of hormone in blood stream represents a balance in it bring added of subtracted to blood stream it almost never means that one is acting more than another one goes up the other goes up too