Question 1

Which form of cell-to-cell communication allows for the direct transfer of electrical and chemical signals between adjacent cells?

Accepted Answer

Gap junction signaling

Question 2

What determines which cells act as targets for endocrine signals?

Accepted Answer

Those cells with receptors specific for the signaling molecule

Question 3

Which specific characteristic must a signaling molecule have in order to bind to a cytosolic or nuclear receptor?

Accepted Answer

It must be lipophilic.

Question 4

The binding of a single ligand to its receptor can activate many second messengers. Which characteristic of signal transduction systems is this?

Accepted Answer

Signal amplification

Question 5

Administration of ibuprofen can decrease pain. Why does this COX inhibitor have this effect?

Accepted Answer

It blocks production of prostaglandins.

Question 6

Which of the following best describes the role of an endocrine organ in a simple endocrine reflex pathway?

Accepted Answer

To function as a sensor and integrating center

Question 7

A patient is exposed to a bacterial infection that triggers antibodies against axonal gangliosides, resulting in paralysis but preserved sensation. Which condition is most likely?

Accepted Answer

Acute motor axonal polyneuropathy (AMAN)

Question 8

Which glial cells form myelin in the central nervous system?

Accepted Answer

Oligodendrocytes

Question 9

Where in the neuron is an action potential initially generated?

Accepted Answer

Axon hillock

Question 10

The depolarization phase of an action potential results from the opening of which channels?

Accepted Answer

Voltage-gated Na+ channels

Question 11

The velocity of the action potential is fastest in which of the following axons?

Accepted Answer

A myelinated axon with the largest diameter

Question 12

A neuron has a resting potential of $$-70\ \mathrm{mV}$$ and a threshold voltage of $$-50\ \mathrm{mV}. $$There are three active synapses on the neuron's dendrites, each located the same distance from the axon. The potential changes are $$+40\ \mathrm{mV} at $$synapse 1, $$+20\ \mathrm{mV} at $$synapse 2, and $$-10\ \mathrm{mV} at $$synapse 3. These synaptic potentials decrease by $$50\% by $$the time they reach the trigger zone. Will this neuron produce an action potential at this time?

Accepted Answer

Yes. At the trigger zone, all potentials have halved and will sum as follows: $$+20\ \mathrm{mV} ($$originated at synapse 1), $$+10\ \mathrm{mV} ($$originated at synapse 2), $$-5\ \mathrm{mV} ($$originated at synapse 3) sum to produce a total potential change of $$+25\ \mathrm{mV}. $$The neuron required a minimum change of $$+20\ \mathrm{mV}$$ ($$-70\ \mathrm{mV} + 20\ \mathrm{mV} = -50\ \mathrm{mV}$$), so it will fire an action potential.

Question 13

What triggers exocytosis of synaptic vesicle contents from an axon terminal?

Accepted Answer

The opening of voltage-gated Ca$$^{2+}$$ channels

Question 14

A ligand binds to a receptor-channel that stimulates a channel to open. This is a chloride channel. This will stimulate __________.

Accepted Answer

An inhibitory postsynaptic potential (IPSP)

Question 15

Which type of receptor would bind acetylcholine and be found in skeletal muscle?

Accepted Answer

Nicotinic cholinergic

Question 16

Which is a similarity between spatial summation and temporal summation?

Accepted Answer

Both occur when graded potentials overlap in time.

Question 17

What is the definition of an ionotropic receptor?

Accepted Answer

A receptor that alters ion flow when it binds with its ligand

Simple and Complex Reflex Pathways: Components and Sequence

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