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AnSci 214 Exam 2 Review Nervous, Muscle, CV System
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Nervous System 1) Explain how summation, EPSPs and IPSPs work to influence events at the post-synaptic neuron. – What is an EPSP? IPSP? – What is temporal summation and how are EPSP’s/IPSP’s involved? – What is spatial summation and how are EPSP’s/IPSP’s involved? Figure 11.19. EPSP: Excitatory, stimulus leaves postsynaptic neuron at a more positive state (easier to reach threshold) IPSP: Inhibitory, stimulus leaves post synaptic neuron at a more negative state (harder to reach threshold) Temporal: At same location, different time/frequency of stimulus Spatial: At different location, at same time and postsynaptic neuron
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2) Trace the initiation and propagation of an action potential from a presynaptic neuron and the transfer of a signal to the postsynaptic neuron. Be sure to include refractory periods and neurotransmitters in your discussion. Figure 11.11. Nervous System 1)Resting State: Membrane Potential at steady -70mV 2)Depolarization: Na+ channels open, quick influx of Na+, cause cell to become positive 3)Peak of AP: Na+ channels close quickly 1)Repolarization: K+ channels open, efflux K+, allows cell to become more negative (protein carries – charge) 2)Hyperpolarization: K+ channels slow to close, allows cell to become over negative, need Na/K pump to restore
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2) Trace the initiation and propagation of an action potential from a presynaptic neuron and the transfer of a signal to the postsynaptic neuron. Be sure to include refractory periods and neurotransmitters in your discussion. Figure 11.14. Nervous System ARP: CANNOT produce another AP while currently firing–not dependent on strength of stimulus RRP: An AP has the potential to fire– depends heavily on strength of stimulus.
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2) Trace the initiation and propagation of an action potential from a presynaptic neuron and the transfer of a signal to the postsynaptic neuron. Be sure to include refractory periods and neurotransmitters in your discussion. Figure 11.17. Nervous System 1)AP arrives at Axon Terminal 2)Stimulates (Voltage gated) Ca2+ channels open, Ca2+ influx 3)Ca2+ stimulates synaptic vesicles (containing neurotransmitter) to undergo exocytosis (fuse to synapse) 4)Neurotransmitter diffuse across to receptors on PSN 5)Binding leads to graded AP 6)Reuptake diminish signal
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3) Explain the role of myelination in signal conduction. – What is the myelin sheath? What is it made of? – What are the nodes of Ranvier? Figure 11.15 Nervous System Distinguish between CNS and PNS Oligodendrocytes: CNS Schwann Cells: PNS Nodes of Ranvier: gaps Between myelination Conduct Impulse and Channel openings.
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1) Explain the events that take place at the neuromuscular junction that leads to an action potential. – Figure 9.8 and Figure 9.9. 2) Explain what is meant by excitation-contraction coupling and trace the events involved. – Figure 9.11. Muscular System
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3) Explain what events must occur on the myofibril level in order for a muscle contraction and relaxation to take place. – Explain Power Stroke Process Figure 9.12. Muscular System 1)Cross Bridge Detachment: Myosin bound to ATP–Myosin at low energy state (3) 1)Cocking of Myosin: ATP hydrolysis (ADP+P)–release energy free for myosin use (4) 1)Cross Bridge Formation: Myosin is in high energy state–attach to actin (1) 2)Power Stroke: Myosin and ADP+P dissociate–allow for ratcheting movement (2)
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4) Explain what is meant by the 'graded' nature of muscle response. – Distinguish fused and unfused tetanus Figure 9.15. Muscular System Observe: 1)Frequency of stimuli 2)Relaxation ability Unfused: temporal summation, high frequency of stimuli, allow for moderate relaxation but not complete Fused: even higher frequency of stimuli, do not allow for any relaxation of muscle
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5) Explain the length-tension theory. Figure 9.22 Muscular System NO contact between Actin and Myosin too much stretch in sarcomere Actin is overlapped, cannot pull inward any further sarcomere is too short
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1) Trace the electrical events involved in cardiac contraction. Be able to explain what would happen if one part was extracted. – What would happen if you had a defective SA node? – What would happen if you had a defective AV node? Figure 18.14. Cardiovascular System Defective SA node: Ectopic focus–AV takes over and leads to junctional rhythm Defective AV node: Partial to total heart block–few, if any SA impulses reach ventricles
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2) Explain electrocardiography by drawing a normal EKG and explaining its elements, and then giving examples of cardiac abnormalities that can be detected using this diagnostic tool. – What happens in Junctional Rhythm? Second-degree Heart Block? Ventricular Fibrillation? Figure 18.16/18.17 Figure 18.18 Cardiovascular System P Wave: Atrial depolarization (depolarization of SA node) QRS Complex: Ventricular Depolarization T Wave: Ventricular repolarization
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Normal RhythmJunctional Rhythm SA node is nonfunctional What wave is absent? Ventricular Fibrillation When is this case observed? Second-degree Heart Block Majority of P wave (impulse) is not sent to the AV node Which wave is effected? Cardiovascular System
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Compare the action potentials between the Nervous, Muscular, and Cardiovascular Systems. – What ions are moving and from where? – When are these ions moving? – What are the pre- and post-synaptic structures? – What are the resting membrane potentials? Be able to explain differences between Figures 11.11, 9.9/9.10, and 18.12 Cardiovascular System 1)Depolarization: Influx Na+ and rapid fire of AP 2)Plateau: Due to Ca2+ influx through slow opening Ca2+ channels–cell remains depolarized very few K+ channels open 3)Repolarization: Ca2+ channels deactivate, K+ channels open, allow K+ efflux to bring cell back to resting potential
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