Human Anatomy and Physiology II
Exam 1, Version 2 - Feb. 24, 1993
Dr. Chabot
Multiple Choice (@2 points): Circle the letter of the one best answer. GOOD LUCK!
Answer only 30 out of 33! The first 30 answered will be graded.
1. Assume that an axon is artificially stimulated about halfway along its length. All of the following will occur EXCEPT:
A. negative organic (A-) ions move out of the cytoplasm to the outside of the axon.
B. the impulse may travel both up the axon toward the cell body and down the axon toward the synapse.
C. sodium ions cross the membrane into the cytoplasm; potassium ions move across the membrane from the cytoplasm to the outside of the axon.
D. potassium ions cross the membrane into the cytoplasm; sodium ions move across the membrane from the cytoplasm to the outside of the axon.
2. Which of the following mechanism(s) ensures that nerve impulses only travel in one direction?
A. After excitation, a brief refractory period occurs during which that portion of the membrane cannot be excited again.
B. The released chemical neurotransmitters are degraded immediately by specific chemical enzymes.
C. Such a large number of Na+ and K+ ions move across the membrane that it requires a long period of time for the sodium-potassium pump to restore a resting potential.
D. Statements a and b above
3. Postsynaptic potentials:
I. can be summed.
II. are graded.
III. are conducted decrementally (decrease in amplitude with distance).
IV. usually last much longer than action potentials.
A. I and III only
B. II and IV only
C. I, II, and III only
D. I, II, III, and IV
4. An action potential in a human nerve cell:
A. is normally caused by a sudden increase in sodium-potassium pump activity.
B. is associated with a sudden increase in sodium permeability (gates open) and a somewhat slower increase in potassium permeability (gates open).
C. is associated with a sudden decrease in sodium permeability (gates close) and a rapid increase in potassium permeability (gates open).
D. varies in amplitude with the strength of the stimulus used to trigger it.
5. When a stimulatory (excitatory) neurotransmitter combines with a receptor site on a postsynaptic membrane, the first event that is triggered is an:
A. influx of potassium ions.
B. influx of sodium ions.
C. influx of chloride ions.
D. efflux of potassium ions.
6. If a stimulus to a nerve is great enough to surpass the threshold level, the strength of the action potential generated will be:
A. zero.
B. proportional to the strength of the stimulus.
C. inversely proportional to the strength of the stimulus.
D. the same, no matter what the strength of the stimulus.
7. The very first thing that happens at the membrane of an axon transmitting a nerve impulse is:
A. a rapid movement of sodium ions into the cell.
B. a rapid movement of potassium ions into the cell.
C. the membrane becomes completely impermeable to all ions.
D. the membrane becomes completely permeable to all ions.
8. If a chemical transmitter substance is produced in the cell body and transported to the treminal ends, where is it stored until it is released?
A. in Schwann cells
B. in the synaptic cleft
C. in synaptic vessicles
D. in postsynaptic dendrites
9. The central nervous system is composed of the:
A. spinal cord and spinal nerves only.
B. brain and spinal nerves only.
C. brain and cranial nerves only.
D. brain and spinal cord only.
10. The depolarization of the neuronal membrane is produced by any factor that:
A. increases the membrane's permeability to sodium ions.
B. decreases the membrane's permeability to sodium ions.
C. stimulates the sodium-potassium pump.
D. increases the membrane's permeability to potassium ions.
11. Which of the following moves via a pump?
A. Na+ only
B. K+ only
C. Cl- only
D. Na+ and K+ only
12. Where would you look in the spinal cord for the cell bodies of the motor neurons that control skeletal muscles?
A. ventral gray horn
B. lateral gray horn
C. gray commissure
D. none of the above
13. The dorsal root of each spinal nerve:
I. carries sensory information from peripheral receptors.
II. contains the processes (axons/dendrites) of nerve cells located in ganglia.
III. contains motor neuron cell bodies.
A. I only
B. II only
C. III only
D. I and II only
14. In a reflex, the synapse between the sensory and motor neurons is located in the:
A. skin or sense organs.
B. dorsal root ganglia.
C. spinal cord.
D. thalamus.
15. Which of the following most accurately describes the meninges?
A. cover the brain and spinal cord
B. cover the brain only
C. are made up of two layers
D. function in increasing the rate of nerve conduction
16. Which of the following brain parts is incorrectly matched with a function it helps control?
A. frontal lobes of cerebrum-vision
B. reticular formation-arousal
C. cerebellum-coordination of skeletal muscle movement
D. medulla oblongata-coordination of heart and respiratory rates
17. All of the following are functions of the cerebellum EXCEPT:
A. balance.
B. initiation of body movements.
C. timing of body movements.
D. adjusting body positions.
18. Glial cells:
A. are found in low numbers in the central nervous system
B. such as Schwann cells provide a myelinated wrapping for axons in the periphery
C. are found only in the gray matter of spinal cords
D. are also known as "ghost" cells
19. In neurons, cellular transport down the long axons is effected primarily by:
A. facilitated diffusion
B. fast diffusion
C. microtubule transport
D. active transport
20. Tetrodotoxin, a poison from puffer fish, blocks:
A. the active transport pump which maintains ion gradients
B. K+ channels
C. Na+ channels
D. Cl- channels
21. Sodium and potassium ion channel selectivity appears to be based on:
A. different charges on the ions
B. channel recognition factor
C. the fact that one is a salt
D. size differences between the hydrated and non-hydrated (naked) ions
22. Action potentials travel faster in myelinated axons because:
A. myelin acts as a super conductor and speeds up the conduction
B. the action potentials jumps (travels very fast) between the nodes of Ranvier
C. the myelin greatly increases the resistence of the axonal cytoplasm
D. myelin acts as an enzyme which speeds up (catalyzes) the reaction
23. Electrical synapses are characterized by:
A. protein molecules in pre-and post-synaptic membranes which form channels through which electrical signals can pass directly
B. having electrical generators between the pre-and post-synaptic membranes
C. the lack of glial cells in the vicinity
D. tight junctions
24. Inhibitory post synaptic potentials (IPSPs) occur in neuronal post synaptic membranes when:
A. Na+ channel gates are opened in the post synaptic cell
B. K+ channel gates are opened in the post synaptic cell
C. Ca++ channel gates are opened in the post synaptic cell
D. Cl - is freely distributed across the membrane
25. Two neurons A and B have excitatory input onto neuron C. The terminal of neuron A is located 0.5 mm from the axon hillock of neuron C, while the terminal of neuron B is located 1.0 mm from the hillock. If, at different times, both A and B stimulate neuron C at the same rate and cause the same amount of post-synaptic depolarization at the terminals:
A. Neuron A will have a greater chance of causing neuron C to fire
B. Neuron B will have a greater chance of causing neuron C to fire
C. They will both cause neuron C to fire since action potentials are all-or-none
D. They both have an equal chance to cause neuron C to fire.
26. The effects that a neurotransmitter will have on the postsynaptic membrane is determined primarily by:
A. the chemical structure of the transmitter
B. the type of pre-synaptic cell
C. the types of enzymes located in the synapse
D. the structure of the post-synaptic receptor
27. Cerebrospinal fluid performs all of the following functions except:
A. helps to absorb impacts
B. helps to remove metabolic wastes
C. helps to buoy and support the brain
D. helps the brain to maintain its resting potential
29. The brain is dependent on a constant (on the order of minutes) supply of:
A. oxygen
B. glucose
C. protein
D. A and B
E. A, B, and C
30. The medulla oblongata serves all the following functions except:
A. regulates respiratory functions
B. regulates heart rate
C. regulates liver functions
D. regulates the diameter of arterioles
31. The cerebrum functions to:
A. serve as a site for memory storage
B. serve as a site for "higher thought" and analysis
C. process sensory information
D. process motor information
E. all of the above
32. Damage to the basal ganglia may lead to:
A. jerky motor movements
B. a change in personality
C. an increased sense of smell
D. an inability to recognize spices
33. The hypothalamus is important to normal functioning because:
A. it is located at the base of the brain
B. it contains receptors which monitor bodily functioning
C. it controls several bodily functins by sending information to the medulla oblongata
D. A and B
E. B and C
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Complete the following sentences with the most appropriate (one) word (@ 2 points).
Choose 10 out of 12 only.
1. Dendrites carry nerve impulses ______________ the cell body.
2. A collection of cell bodies of neurons of peripheral nerves is called a _______________.
3. Chemical messengers called ________________ communicate between two nerve cells.
4. The dorsal root of each spinal nerve receives sensory innervation from a segment of the skin known as a _________________.
5. A __________________ is a predictable involuntary response to a stimulus.
6. Information ascends and descends the spinal cord in organized (but not visibly distinguishable) _________________.
7. Proteins which span neuronal membranes and allow ions to pass through are called __________.
8. Proteins which allow ions to pass through membranes only only after they are stimulated by chemical messengers are called ________________.
9. The (specific) chemical messenger at the neuromuscular junction is known as a __________________.
10. The ionic basis for the resting and action potentials was first worked out in the _________ giant axon.
11. The additive effects of EPSPs caused by inputs from different axonal terminals is known as _________________ summation.
12. A bundle of axons surrounded by connective tissue and located in the periphery is called a ____________.
Essay/Short Answer (@ 10 pts). Answer only 2 of the following 3. The first 2 answered will be graded.
1) Draw and label a graph showing: A) the membrane voltage changes and B) the ionic currents underlying the action potential. Be as detailed as you can.
2) Draw and label a cross-section of the human spinal cord including any associated nerves.
3) Outline the events underlying synaptic transmission from: A) the action potential arriving at the terminal to B) the generation of an EPSP. Do not use complete sentences.