All the following statements regarding the action potential are true except:
1. Only a relatively small number of ${\mathrm{Na}}^{+}$ and ${\mathrm{K}}^{+}$ ions actually diffuse across the membrane.
2. This event includes both positive and negative feedback loops.
3. The ${\mathrm{Na}}^{+}$/${\mathrm{K}}^{+}$ pumps are directly involved in creating the action potential.
4. During an action potential, the ${\mathrm{Na}}^{+}$ and ${\mathrm{K}}^{+}$ total concentration are not significantly changed.

A local anesthetic is a medication that causes reversible absence of pain sensation. They:
1. block the closure of voltage regulated potassium ion channels
2. stimulate the opening of voltage regulated potassium ion channels
3. block the opening of the voltage regulated sodium ion channels
4. stimulate the opening of voltage regulated sodium ion channels

What will respectively happen to the synaptic vesicles undergoing exocytosis and the amount of neurotransmitter release as the action potential frequency in a presynaptic neuron increases?

1. increases; increases
2. increases; decreases
3. decreases; increases
4. decreases; decreases

When an excitatory neurotransmitter is released and binds to a receptor on the postsynaptic membrane, the neurotransmitter:

1. stimulates the flow of K+ ions out of the cell
2. produces an EPSP
3. produces an IPSP
4. stimulates the flow of Cl- ions into the cell

When a receptor loses its sensitivity, they are said to be:

1. Summated

2. Transduced

3. Ablated

4. Adaptation

What would be true for the nociceptors?

1. Nociceptors respond to extreme stimuli

2. All nociceptors are located in the skin

3. Nociceptors are involved in noise perception

4. Nociceptor pathways of conduction cannot be inhibited

During accommodation reflex for near vision in the eye there is:
1. increased sympathetic stimulation of iris smooth muscle
2. relaxation of ciliary muscles and lens becomes more spherical
3. increased parasympathetic stimulation leading to relaxation of the ciliary muscles
4. increased parasympathetic stimulation leading to contraction of ciliary muscles

Cataract:
1. is abnormal curvature of cornea
2. is loss of elasticity of the lens
3. occurs often in children
4. involves increased opacity of the lens

A condition in which close objects appear clearly, but far ones don't is called as:
1. Hyperopia
2. Myopia
3. Presbyopia
4. Glaucoma

Identify the incorrect statement regarding rods and cones:
1. Rods are more sensitive to light than cones
2. There are more rods than cones in the retina
3. Cone vision provides higher acuity than rod vision
4. Rods are found primarily in the fovea while cones are more scattered throughout the retina