AnSci 214 Exam 2 Review Nervous, Muscle, CV System

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 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

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 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

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 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.

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 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

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 Nervous System Distinguish between CNS and PNS Oligodendrocytes: CNS Schwann Cells: PNS Nodes of Ranvier: gaps Between myelination Conduct Impulse and Channel openings.

1) Explain the events that take place at the neuromuscular junction that leads to an action potential. – Figure 9.8 and Figure ) Explain what is meant by excitation-contraction coupling and trace the events involved. – Figure Muscular System

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 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)

4) Explain what is meant by the 'graded' nature of muscle response. – Distinguish fused and unfused tetanus Figure 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

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

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 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

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 Cardiovascular System P Wave: Atrial depolarization (depolarization of SA node) QRS Complex: Ventricular Depolarization T Wave: Ventricular repolarization

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

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 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