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Name: __________________________ Spring 2020 BIOS 3775 Human Physiology Quiz 2 – FORM A 1. Drug “X” inhibits acetylcholinesterase action within the neuromuscular junction. What would drug “X” do to the membrane potential of the muscle fiber? a) It would remain depolarized. b) It would repolarize more quickly than normal. c) It would hyperpolarize. d) Drug “X” would have no effect on the membrane potential.

2. Which neuron structure usually receives incoming signals? a) axon b) axon terminal c) dendrite d) soma e) all of the above 3. In what way does the interior of a resting (non-conducting) neuron differ from the external environment? The interior is: a) b) c) d)

positively charged and contains less sodium negatively charged and contains less sodium negatively charged and contains more sodium positively charged and contains more sodium

4. The falling phase of the action potential is due primarily to A) Na+ flow in the cell only. B) Na+ flow out of the cell only. C) K+ flow out of the cell only. D) K+ flow into the cell only. E) Na+ flow out of the cell and K+ flow into the cell. 5. The rearrangement of connections at synapses, which occurs throughout life, is termed A) elasticity. B) intelligence. C) plasticity. D) senility. E) synchronicity.

Name: __________________________ 6. When the neuron is at rest, which statement is true? A) The activation gate is closed. B) The inactivation gate is open. C) No Na+ crosses the membrane is the only observation. D) The activation gate is closed, and the inactivation gate is open. E) The activation gate is closed and no Na+ crosses the membrane. 7. Tetrodotoxin is a toxin that blocks voltage-gated sodium channels. What effect does this substance have on the function of neurons? A) Neurons depolarize more rapidly. B) Action potentials lack a repolarization phase. C) The absolute refractory period is shorter than normal. D) The neuron is not able to propagate action potentials. E) The toxin does not interfere with neuron function because the voltage-regulated sodium channels would still function. 8. The brain consumes about half of the ________ circulating in the body. A) oxygen B) glucose C) sodium D) potassium E) fatty acids

9. For astronauts in space, the otoliths (crystal like structure in your ear) in the macula would respond to A) head position only. B) linear acceleration only. C) rotational acceleration only. D) linear acceleration and head position. 10. After an injury, Paul has difficulty recognizing and interpreting certain sounds. These symptoms imply damage to the A) external ear. B) auditory cortex. C) middle ear. D) cochlea. 11. In order for a synapse to be an effective means of cellular communication, slow removal or inactivation of neurotransmitter molecules from the synapse is important. A) True B) False

Name: __________________________ 12. If the sodium pump in the membranes of the photoreceptors were completely blocked, the result would be A) bright white light as all cones would be activated. B) an increase in visual acuity. C) darkness (blindness). D) grey images as only rods would function. E) the cells would not be able to produce glutamate.

13. Which of the following is NOT involved in creating the resting potential of a neuron? A) diffusion of potassium ions out of the cell B) diffusion of sodium ions into the cell C) resting membrane permeability for sodium ions greater than potassium ions D) resting membrane permeability for potassium ions greater than sodium ions 14. A threshold stimulus applied to an excitable membrane is one that is just sufficient to A) trigger an excitatory postsynaptic potential. B) cause a change in membrane potential. C) trigger an action potential. D) be conducted to the axon hillock. E) depolarize a dendrite.

15. Your friend is poking your skin with two pins a few millimeters apart at the same time. Visually, you can see there are two pins, but you can only feel a single pen poke. This is probably because: A) both pens are activating the same receptor. B) both afferent neurons converge on the same interneuron. C) the receptors in both skin areas utilize the same afferent neuron. D) both sensations are grouped together in the somatosensory cortex. 16. If the lens flattened with age, what type of vision would become easier over time for this individual? A) Both near and distance vision are fine, but changing back and forth between them becomes difficult B) Near vision (e.g., reading a book) C) Distance vision (e.g., reading a street sign) D) Both near and distance vision are compromised E) No light will enter the eye and blindness will result

17. The incus, malleus, and stapes of the middle ear

Name: __________________________ A) serve to keep the pressure on the two sides of the tympanic membrane equal. B) are part of the vestibular apparatus. C) are in direct contact with both the tympanic membrane and the round window. D) serve to amplify the pressure of sound vibrations from the air in the outer ear to the fluid in the inner ear. E) are found inside the cochlear duct.

18. Syndrome R involves a genetic mutation that affects all chemoreceptors in the body. Which sensations are NOT affected in Syndrome R? A) Hearing B) Taste C) Pain D) Smell 19. Lateral Inhibition is important because it: A) Allows for the determination of the exact location of the stimulus B) Reduces the amount of afferent input to reduce the sensory arriving and processing time at the higher brain centers C) Prevents illusions D) Prevents the potential damage of sensory fibers due to overreaction

20. When you eat a spicy pepper, such as a jalepeño, why do you perceive heat in your mouth? A) A chemical within the jalepeño acts as a stimulus for thermoreceptors. B) The breakdown of chemicals within the pepper causes exothermic reactions in the mouth. C) Friction while chewing activates thermoreceptors. D) Chemoreceptors can activate heat sensing parts of the brain. E) All of the answer choices are correct.

Name: __________________________ 21. Describe the sequence of events responsible for conduction of an action potential along an axon. (5pt.)

22. Why are mitochondria necessary at axon terminals? (5pt.) Neurotransmitter release and uptake is energy dependent process. Requires ATP or any answer related to ATP and how mitochondria provides energy is correct. 23. Explain the “all or none law.” (5pt.)

The all-or-none law is the principle that the strength by which a nerve or muscle fiber responds to a stimulus is independent of the strength of the stimulus. If that stimulus exceeds the threshold potential, the nerve or muscle fiber will give a complete response; otherwise, there is no response. 24. In the movie (or CBS series) “Limitless”, Bradley Cooper takes a mysterious nootropic drug called NZT and gains extraordinary cognitive power. He was able to remember every single life event that ever happened to him. Knowing what you have learned about plasticity, give some of the hypotheses to explain this. (5pt.)

This is an open-ended question so be flexible. Any answer explaining synaptic plasticity increase in synapse formation, enhancing neuronal stem cells to make more neurons, efficient any of forming action potential, any process explaining memory formation will be correct.

Name: __________________________ --------------------------------------------------------------------------------------------------------------------(Extra Credit: 3 pt. each) 1. The minimum amount of stimulus required to depolarize an excitable membrane and generate an action potential is known as the _____________.

threshold

2. If, during awake brain surgery, a doctor accidentally depolarized a neuron within the somatosensory cortex, which of these is most likely? A) The patient would perceive a specific, localized sensation in one body area. B) The patient would perceive a general sensation all over the body. C) The patient would perceive a general sensation over one side of the body. D) The patient would perceive nothing....