1. Nervous, Muscle, CV System
AnSci 214 Exam 2 Review
Nervous, Muscle, CV System

2. What is temporal summation and how are EPSP’s/IPSP’s involved?
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, same at same time and postsynaptic neuron
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

3. Nervous System
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
Resting State: Membrane Potential at steady -70mV
Depolarization: Na+ channels open, quick influx of Na+, cause cell to become positive
Peak of AP: Na+ channels close quickly
Repolarization: K+ channels open, efflux K+, allows cell to become more negative (protein carries – charge)
Hyperpolarization: K+ channels slow to close, allows cell to become over negative, need Na/K pump to restore
Resting State: Membrane Potential at steady -70mV
Depolarization: Na+ channels open, quick influx of Na+, cause cell to become positive
Peak of AP: Na+ channels close quickly
Repolarization: K+ channels open, efflux K+, allows cell to become more negative (protein carries – charge)
Hyperpolarization: K+ channels slow to close, allows cell to become over negative, need Na/K pump to restore resting potential

4. Nervous System
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
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.

5. Nervous System
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
AP arrives at Axon Terminal
Stimulates (Voltage gated) Ca2+ channels open, Ca2+ influx
Ca2+ stimulates synaptic vesicles (containing neurotransmitter) to undergo exocytosis (fuse to synapse)
Neurotransmitter diffuse across to receptors on PSN
Binding leads to graded AP
Reuptake diminish signal

6. 3) Explain the role of myelination in signal conduction.
Nervous System
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
Distinguish between
CNS and PNS
Oligodendrocytes: CNS
Schwann Cells: PNS
Nodes of Ranvier: gaps
Between myelination
Conduct Impulse and
Channel openings.

7. Muscular System
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.
REDO Dr. Selsby Diagram
Ach is released, ligand gated channels, induce voltage gated Na+ channels open, AP to SR, signal Ca2+ release, Ca2+ flood into sarcomere, contraction is result

8. Explain Power Stroke Process Figure 9.12.
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 9.12.
Cross Bridge Detachment: Myosin bound to ATP–Myosin at low energy state (3)
Cocking of Myosin: ATP hydrolysis (ADP+P)–release energy free for myosin use (4)
Cross Bridge Formation: Myosin is in high energy state–attach to actin (1)
Power Stroke: Myosin and ADP+P dissociate–allow for ratcheting movement (2)
Note Low and High energy states of myosin

9. 4) Explain what is meant by the 'graded' nature of muscle response.
Muscular System
4) Explain what is meant by the 'graded' nature of muscle response.
Distinguish fused and unfused tetanus
Figure 9.15.
Observe:
Frequency of stimuli
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

10. 5) Explain the length-tension theory. Figure 9.22
Muscular System
5) Explain the length-tension theory.
Figure 9.22
Example with book or chair!
Actin is overlapped, cannot pull inward any further  sarcomere is too short
NO contact between Actin and Myosin  too much stretch in sarcomere

11. Cardiovascular System
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
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

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

13. Second-degree Heart Block Ventricular Fibrillation
Cardiovascular System
Normal Rhythm
Junctional Rhythm
SA node is nonfunctional
What wave is absent?
Second-degree Heart Block
Majority of P wave (impulse) is not sent to the AV node
Which wave is effected?
Ventricular Fibrillation
When is this case observed?

14. 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 18.12
Depolarization: Influx Na+ and rapid fire of AP
Plateau: Due to Ca2+ influx through slow opening Ca2+ channels–cell remains depolarized very few K+ channels open
Repolarization: Ca2+ channels deactivate, K+ channels open, allow K+ efflux to bring cell back to resting potential