Part 4 Physiology NotesNeural Communicationvery discrete-can stimulate/inhibit a single cell –local stimuliEndocrine System endocrine=ductless-secrete directly into circulation; exocrine=ducts/glandsCharacteristics that differ from NeuralBasic PrinciplesPeptide HormonesSteroid HormonesAminesEndocrine DisordersHypothalamusPosterior Pituitarysupraoptic and paraventricular nuclei make hormonesAnterior PituitaryMechanism of ControlHypothalamus HormonesGrowth HormoneGrowth Hormone DefiencyExcess Growth HormoneThyroidWays to make ATPInsulinRegulation of Blood Calcium LevelsDistribution of Calcium in BodyBoneKidneysAbsorption from GutCalcitoninVitamin DDisordersPhis 206 1nd EditionExam # 3 Study Guide Lectures: 29-37Part 4 Physiology NotesNeural Communication very discrete-can stimulate/inhibit a single cell –local stimuli- Instantaneous cut on; Instantaneous cut ofEndocrine System endocrine=ductless-secrete directly into circulation; exocrine=ducts/glands - cell secrete messengers into blood stream, which then goes throughout the body to target- Doesn’t usually involve cells that are close to each other –not anatomically connected - Long term regulation 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 –gradual increase/decrease in concentration - When stop secreting; it lasts in blood stream for awhile- The message is difused- some hormone acts on many diferent cells --global simuli Hormones- messenger chemicals secreted by endocrine system; which is secreted straight intobloodstream therefore, the Endocrine Glands are also called “ductless glands”- there are instances when the nervous system(neurons) releases hormones into bloodstreaminstead of target cells, and they are known as Neuroendocrine cells and the hormones that release are called Neurohormones.Basic Principles They are practically important in things that have to be maintained, over long periods of time. this is important because in Neural System receptor 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, and 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 act on things outside endocrine system, called Nontrophic Hormone some endocrine glands 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 cellHormone Classes: work at low concentrations - Determined by Chemical Structure1.) Peptides2.) Steroids 3.) Amines Useful grouping because, each class have similarities in how:a.) they are synthesizedb.) what its stored in, if it isc.) how they get secretedd.) how they are transportede.) what it does when it gets therePeptide Hormones - basically small proteins ;chains of amino acids; too big to cross cell membranes - 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 ( as vesicles) - 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; small enough to difuse in capillaries - 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 Secondary messenger carries message into cell  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.- Hormone and receptor is internalized by lysosome and degraded into amino acids 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.- 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)- When they get to target cell, receptors allow carrier proteins to release steroid then it difuses in, get to nucleus, get to proteins, that bind to steroids to steroid, which get in DNA, which activate genes.- 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 propertiesCharacteristics of all Hormones1.) Efective at very low concentrations(10-8M to 10-12M)-much more potent, unlike other systems(10-3 to 10-1)- 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 if a hormone concentration changes, it’s usually due to secretionOperate on negative feedback loops Endocrine Disorders- include situation in which blood concentrations are pathologically high-secrete too much-hypersecretion - Plasma levels are low- secrete too little—hyposecretion - Target cell responses abnormal- some efects are if concentrations were low.- When plasma level is too low, give them hormone- When too high, depends on reason why it is too high Tumor is not subject to same regulations as endocrine gland When gland secreting too much, have to find out why it is not regulatingDown regulation-with peptide hormones, they bind to surface receptors then they get internalized, broken down, then resynthesized. Down regulation is more are being internalized than being resynthesized. Causes desensitivity in target cells to hormone. Can be caused by chronic high levels of hormone. Hypothalamus-