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membrane potential more negative than the threshold potentialMetabotropic receptorsi.1994 Nobel Prize: Gilman and Rodball for research on G-proteinsii.2012 Nobel Laureates: Lefkowitz and Kobilka for research on metabotropic receptor structure and functioniii. Single protein with 7 transmembrane helicesiv. Extracellular messenger binds to receptor, activating G-proteinCentral Nervous Systemi.a. Sensory (afferent) nerves bring information to CNSi.b. Motor (efferent) nerves bring information from CNSSomatic nervous system: skeletal musclei.b..a.α-motor neuroni.b..b.Cell bodies in spinal cordi.b..c.Nicotinic ACh receptorsi.b..d.Excite or not excite, inhibit in spinal cord (+,0)Autonomic nervous system: smooth muscle and cardiac musclei.b..a.Have inherent pacemakers but transmitters can either excite or inhibit neurons (+,-); regulate up or downi.b..b.Dual innervation of each organ by ANSi.b..b.i. Parasympathetic: long preganglionic fiber, short postganglionic fiberOriginate in cranial and sacral areas of CNS1st synapse: nicotinic ACh receptors; 2nd synapse: muscarinic ACh receptors (both cholinergic)i.b..b.ii.Sympathetic: short preganglionic fiber, long postganglionic fiberOriginate in thoracic and lumbar regions of spinal cord
1st synapse has nicotinic ACh receptors (cholinergic); 2nd has metabotropicnorepinephrine receptors (adrenergic) i.c. Norepinephrine receptor subtypesα and β receptorsβ1 – stimulate adenylyl cyclase; heart and kidneysi.c..a.Activates cAMP; excitatory i.c..b.β1 blocker – control blood pressure with selective Metoprolol (with a diuretic) and non-selective propranololi.c..c.Diuretic because kidneys also regulate blood pressure more water in blood, higher blood pressureF.Muscle Physiology3 types of muscleSkeletal: make up muscular systemVoluntary and striatedInnervated by somatic motor systemCardiac: found only in the heartInvoluntary and striatedModulated by autonomic nervous systemSmooth muscle: appears throughout the body systems as components of hollow organs and tubesUnstriated and involuntaryModulated by autonomic nervous systemRelationship of a whole muscle and muscle fiberTendons connect muscle to boneMuscle comprised of many muscle fibers (single muscle cell) bound together by connective tissueMuscle fiber comprised of many myofibrils bound togetheri.Multinucleated, 10-100 microns in diameter and 2.5 feet in lengthii.Myofibrils:ii.a.Contractile elements ofmuscle fiberii.b.Thick filaments: myosinii.c.Thin filaments: actinii.d.Alternating dark (A bands)and light (I bands) give appearance