BIOL 141 Study Guide - Midterm Guide: Inhibitory Postsynaptic Potential, Neuromuscular Junction, Plantar Reflex

Santiago Ramon y Cajal’s theory of dynamic polarization refers to the:

(a)membrane potential of a neuron at rest.

(b)membrane potential of a neuron firing action potentials.

(c)opening and closing of gated channels in the membrane.

(d)one way flow of information in neurons from dendrites to axon terminals.

(e)one way flow of information in neurons from axon terminals to dendrites.

Over the course of scientific history, there are many examples of scientists reaching the right conclusion for the wrong reasons. When Schwann first proposed that the nervous system was made of individual cells, he based it on observations of:

(a)synapses.

(b)dendrites

(c)axon terminals.

(d)astrocytes.

(e)Nodes of Ranvier.

The synaptic cleft was finally seen in the 1950s. What prevented scientists from seeing it earlier?

(a)The resolution of the light microscope.

(b)They were looking in the wrong place.

(c)Their tissue was not appropriately stained.

(d)Myelination of the axons.

(e)all of the above

The resting membrane potential of a neuron is approximately:

(a) +65 V

(b) +65 mV

(c) -65 V

(d) -65 mV

What is largely responsible for the resting membrane potential in a neuron?

(a)Axonal insulation by myelin

(b)Voltage-Gated Sodium Channels

(c)The Action Potential

(d)Potassium Leak Channels

Which of the following would DECREASE the propagation velocity of an action potential down an axon?

(a)Increase in axon diameter

(b)Increase myelination between nodes of Ranvier

(c)Remove myelination between nodes of Ranvier

(d)Decrease density of voltage-gated Na+ channels except at the Nodes of Ranvier

The resting membrane potential of a neuron can be estimated using the:

(a)Nernst equation

(b)Goldman equation

(c)Hodgkin and Huxley equation

(d)Ohm’s law

18. What would happen to the resting membrane potential of a neuron if you added K+ to the extracellular fluid?

(a)Resting membrane potential would increase (become more positive)

(b)Resting membrane potential would decrease (become more negative)

(c)Resting membrane potential would not change

(d)Resting membrane potential would be abolished

. Which of the following statements is FALSE for Graded Potentials

(a)Magnitude changes with magnitude of triggering stimulus

(b)Magnitude decreases with distance from initial site

(c)Cannot be summed

(d)No refractory period

In the nervous system, the strength of the stimulus is coded into:

(a)The frequency of action potentials generated

(b)The amplitude of action potentials generated

(c)Both the frequency and amplitude of action potentials generated

(d)The duration of individual action potentials generated

Ion movement during both the depolarization and repolarization phases of an action potential are the result of:

(a)active transport pumps along the neuron membrane.

(b)diffusion of ions down their electrochemical concentration gradients.

(c)negative feedback loops.

(d)All of the above

At the peak of the action potential, the membrane potential is:

(a)Exactly at the Na+ equilibrium potential

(b)Greater (more positive) than the Na+ equilibrium potential

(c)Above 0 mV but less positive than the Na+ equilibrium potential

(d)0 mV

A needle is inserted into the right somatosensory nucleus of the thalamus in the central nervous system and the area is injected with GABA.

A. Define the term “nucleus” as it relates to the statement above.

B. What is GABA and what effect would GABA have on the membrane potentials of neurons in this area? Explain

C. Describe how/why GABA released from axon terminals in the following neural arrangements would alter impulse transmission:

i) an axoaxonal synapse

ii) an axodendritic synapse

D. If information relayed to this area carries precise touch, what specific somatosensensory pathway would be affected by this injection?

E. Which side of the body would be affected? Why?

F. What fiber type is associated with neurons in this pathway and what does this mean?

G. Through what structure does a primary sensory neuron from the hand enter the central nervous system?

H. Where does the first synapse for this somatosensory pathway occur?

I. Describe the type(s) of sensory information carried by this pathway.

J. Name and describe two different classes of primary sensory receptors that are associated with this pathway.

K. Discuss the common features that all primary sensory receptors possess.

L. If an adrenergic substance had been injected instead of GABA, how would this have altered neural transmission? Explain.

A needle is inserted into the right somatosensory nucleus of the thalamus in the central nervous system and the area is injected with GABA.

A. Define the term “nucleus” as it relates to the statement above.

B. What is GABA and what effect would GABA have on the membrane potentials of neurons in this area? Explain

C. Describe how/why GABA released from axon terminals in the following neural arrangements would alter impulse transmission:

i) an axoaxonal synapse

ii) an axodendritic synapse

D. If information relayed to this area carries precise touch, what specific somatosensensory pathway would be affected by this injection?

E. Which side of the body would be affected? Why?

F. What fiber type is associated with neurons in this pathway and what does this mean?

G. Through what structure does a primary sensory neuron from the hand enter the central nervous system?

H. Where does the first synapse for this somatosensory pathway occur?

I. Describe the type(s) of sensory information carried by this pathway.

J. Name and describe two different classes of primary sensory receptors that are associated with this pathway.

K. Discuss the common features that all primary sensory receptors possess.

L. If an adrenergic substance had been injected instead of GABA, how would this have altered neural transmission? Explain.