Chapter Questions
Summing incoming neural signals is part of (a) reception(b) transmission (c) integration (d) action by effectors(e) afferent neuron transmission
The myelin sheath is produced around axons in the PNS by (a) ganglia (b) neuron cell bodies (c) dendrites (d) Schwann cells (e) oligodendrocytes
Which of the following occurs first when voltage reaches the threshold level in a neuron plasma membrane? (a) voltageactivated Na $^{+}$ channels open (b) $\mathrm{K}^{+}$ channels open $(\mathrm{c})$ the membrane hyperpolarizes (d) neurotransmitter is released(e) $\mathrm{K}^{+}$ channels close
Saltatory conduction (a) requires more energy than continuous conduction (b) occurs in unmyelinated neurons(c) occurs when the action potential jumps from one node of Ranvier to the next (d) slows transmission of an impulse(e) depends on the action of GABA
Receptors for serotonin and many other neurotransmitters (a) are voltage-activated ion channels (b) permit influx of chloride ions, leading to depolarization (c) inhibit EPSPs(d) are ligand-gated channels(e) are passive ion channels
A presynaptic neuron in the cerebrum transmits information to hundreds of other neurons. This process is an example of (a) convergence (b) divergence (c) temporal summation(d) spatial summation (e) a graded potential
Describe the action taking place at each of the numbered steps in the figure.
Using the diagram in question $7,$ add several red spheres in the synaptic cleft to represent molecules of an antidepressant medication. Illustrate a potential mechanism of action for the antidepressant molecules. (Extend the diagram if you like.)
State whether each of the following would result in an EPSP or IPSP (explain your answer).$(a) \mathrm{Na}^{+}$enter postsynaptic neuron (b) $K^{+}$ diffuse out of postsynaptic neuron (c) $\mathrm{C}$ - enter postsynaptic neuron.
Develop a hypothesis to explain why acetylcholine has an excitatory effect on skeletal muscle but an inhibitory effect on cardiac muscle.
A test for risk of Alzheimer's disease is available. Based on gene markers that can be identified in a saliva sample, a healthy person can learn his or her approximate risk for AD. How might this information be useful to people? Would you be concerned about the psychological consequences of a person knowing that he or she has a high risk of AD? Would you want to know?
Investigators have genetically engineered cells to produce acetylcholine, dopamine, GABA, and other neurotransmitters. In what ways might these cells be useful in neurobiological research? How might they be useful in clinical medicine?
From the perspective of adaptation, hypothesize the advantages of neural circuits characterized by a great deal of convergence and divergence.