BISC 307L 1st Edition Exam 2 Study Guide I Autonomic Nervous System 1 What is the difference between the efferent and afferent pathways and what to each consist of o A Afferent carrying toward CNS Sensory system 1 Somatosensory touch 2 Visceral organs o B Efferent carry away from CNS 1 Sympathetic fight or flight 2 Parasympathetic rest and digest 3 Enteric nerves in digestive tract 2 What are the differences that define the sympathetic and parasympathetic divisions o 1 Sympathetic increase respiratory rate increase heart rate vasodilation in limb muscles and brain vasoconstriction in viscera intestines skin dilation of lung airways decrease secretion in mouth and gut increase general alertness open iris for more light fright o 2 Parasympathetic decrease respiration to resting decrease heart rate to resting vasoconstriction in limb muscles vasodilation in viscera constriction of lung airways secretion returns to normal alertness returns to normal 3 What is the job of the hypothalamus o Ultimate control of eating water balance thirst control temperature appetitive behavior sex salt o If damaged your behavior will be damaged 4 Please describe the general pathway for the autonomic nervous system o 1 Activity from brainstem from sensory information sent to preganglionic neurons at brainstem or spinal cord o 2 Synapse on autonomic ganglion between the preganglion and the postganglion which makes a synapse onto target tissue 5 What is the synthetic pathway for postganglionic sympathetic synapses o Tyrosine DPA Dopamine norepinephrine epinephrine 6 Describe the action of norepinephrine o 1 Action potential causes influx of calcium through Ca2 channels fusion of vesicles to membrane and exocytosis of NE NE released into synaptic cleft binds to adrenergic receptors on the effector cell usually G protein coupled Respons Terminated by usual mechanisms see below 7 What are the ways in which norepinephrine action can be terminated o 1 Carried away by blood vessels o 2 Degraded by enzymes in extracellular space o 3 Active transport reuptake of NE into presynaptic membrane can be repackaged or digested by mitochondrial monoamine oxidase 8 What are the structural differences between the sympathetic and parasympathetic pathways o 1 Sympathetic Thoracolumbar middle 1 Cervical ganglia neck 2 Prevertebral sympathetic ganglia chain preganglionic neurons make synapses onto postganglionic neurons 3 Adrenal medulla o 2 Parasympathetic Craniosacral at top and bottom Preganglionic axons are very long and usually there is no ganglion or it is embedded into organ 9 What was the traditional view as to how the autonomic nervous system worked o Parasympathetic preganglion uses ACh and binds nicotinic receptors on postganglion causes fast EPSP and action potential postganglion releases ACh which binds to muscarinic metabotropic receptors on target tissues o Sympathetic Same as parasympathetic except postganglion releases norepinephrine which binds to alpha1 2 and beta 1 2 and ARs adrenergic 10 What is the new and more accurate view of this pathway o 1 At ganglion for both sympathetic and parasympathetic pathways ACh from preganglion is released to bind BOTH nicotinic and muscarinic receptors on postganglion muscarinic receptors generate slow EPSP modulation of K o 2 Also peptides are released in addition to ACh at preganglion cotransmitters o Parasympathetic postganglions VIP vasoactive intestinal peptide salivary AND ACh released o Sympathetic postganglion norepinephrine AND ACh which co release ATP binds to ATP receptors or hydrolyzed to adenosine and binds to purinergic sweating receptors II Skeletal Muscle Learn general structure on your own 1 What is the rate determining step for cross bridge cycling o ATP hydrolysis ATPase activity determines how fast the muscle contracts 2 Describe the 6 steps of the cross bridge cycling o 1 RIGOR STATE Myosin head with nothing bound to it with NO ATP bound has a HIGH affinity for binding ACTIN o 2 DETACHEMNT Myosin head binds ATP lowers affinity for actin and head detaches o 3 ATPase activity of head hydrolyzes ATP to ADP this energy causes a conformation change in myosin changes from 45 degrees to 90 ADP and phosphate still attached o 4 REATTACHMENT ADP inhibits myosin to bind actin but less so so head attaches weakly since at 90 degrees attaches at second molecule myosin loses affinity for phosphate and it comes off o 5 Phosphate detachment changes angle from 90 to 45 again pulling thin filament along o 6 Now myosin has low affinity for ADP and so ADP comes off 3 What is an important and unique trait of the neuromuscular junction o ACh opens a non specific cation channel causing a large EPSP bringing it to threshold generating a postsymaptic action potential Reliable and effective There is a high density of Na channels at the T Tubule so the whole T Tubule system is depolarized 4 What are the two types of receptors for the T Tubule system o 1 Dyhydropyridine receptor voltage sensing protein o 2 Ryanodine receptor Ca2 channel pump which takes Ca2 out of the cytoplasm and pumps it into the SR lumen This lowers the concentration of Ca2 inside cell at rest but when channel opens Ca2 is released from SR causing contractions 5 Explain the pathway of the T tubule system o T Tubule membrane depolarized conformational change in dihydropyrindine receptor pulls links to Ca2 channels opening them contraction Ca2 sequestered back into the SR and contraction terminates 6 Describe the relaxed and cycling state in relation to how Ca2 triggers contraction o Relaxed low Ca2 so Ca2 is not bound to most of the troponin so tropomyosin is bound to binding site for myosin head for actin cant bind o Cycling Calcium rises 10 fold bind troponin causing conformational change tropomyosin moves aside so myosin can bind to actin binding site until Ca2 resequestered o Fall off due to how fast Ca2 can be resequestered 7 Explain the difference between isometric recording and isotonic recording o Isometric Force length relationship fix muscles at various lengths and measure the force produced maximum when optimal overlap between thin and thick filaments o Isotonic Fixed load on muscle and measure rate of change in length measure speed for which it shortens when load minimal has fastest velocity 8 What is the difference between a concentric and eccentric contraction o 1 Concentric When a muscle is active and it shortens lifting a small weight o 2 Eccentric When a muscle lengthens as it contracts