neuro exam

33. What occurs when a stimulus shifts the local membrane potential of a neuron from the resting potential to a slightly less negative potential? a. hyperpolarization b. depolarization c. an action potential d. decreased neurotransmitter synthesis e. decreased neurotransmitter release > b. This is a depolarization, because the difference between the inside and outside of the neuron is reduced. The neuron is LESS polarized than it is at rest. However, the change is not necessarily enough to initiate an action potential. 34. If a drop of dye is placed into a beaker of water, the movement of the molecules illustrates __________. If a spoon of NaCl is placed into a beaker of water, the movement of the molecules illustrates __________. a. diffusion; electrostatic forces b. electrostatic forces; diffusion c. dispersion; diffusion d. diffusion; dispersion e. mass action; electrostatic repulsion > a. Dye molecules will diffuse according to their concentration gradient. NaCl molecules will dissociate, and the Na+ and Cl- molecules will each repel according to their ionic charges. 35. Where are the ions concentrated across the membrane of a neuron? a. Na+ is concentrated internally; Cl- is concentrated externally; K+ is concentrated externally. b. Na+ is concentrated internally; Cl- is concentrated externally; K+ is concentrated internally. c. Na+ is concentrated externally; Cl- is concentrated internally; K+ is concentrated internally. d. Na+ is concentrated internally; Cl- is concentrated internally; K+ is concentrated internally. e. Na+ is concentrated externally; Cl- is concentrated externally; K+ is concentrated internally. > e. Sodium is more than 10x more concentrated externally than internally. Potassium is more than 20x more concentrated internally than externally. Chloride is more concentrated externally than internally. 36. When a neuron is at resting potential, what forces act upon potassium (K+) ions? a. K+ is in equilibrium when the neuron is at rest, so there are no forces acting on it. b. The electrical gradient pulls K+ into the cell, and the concentration gradient pushes K+ out. c. The electrical gradient pushes K+ out of the cell, and the concentration gradient pulls K+ in. d. The electrical gradient pushes K+ out of the cell, and the concentration gradient pushes K+ out. e. The electrical gradient pulls K+ into the cell, and the concentration keeps K+ in the cell. > b. Potassium is more concentrated inside than outside, and it is a positive ion (cation). The neuron has a negative charge inside relative to the outside when the neuron is at rest. Therefore, the membrane potential keeps these positive ions inside, but the concentration gradient pushes potassium out. 37. A strange alien species is discovered that has the following Nernst potentials: Na+ = +50mV; K+ = -100mV If the membrane potential is +20mV, and Na+ and K+ ion channels open, what happens to these ions? a. Na+ = influx; K+ = influx b. Na+ = no net exchange; K+ = efflux c. Na+ = efflux; K+ = no net exchange d. Na+ = influx; K+ = efflux e. Na+ = efflux; K+ = efflux > d. The Nernst potential is the equilibrium or reversal potential for an ion. If the membrane potential is equal to the Nernst potential, the forces of diffusion and electrostatic potential are in balance, and there is no net exchange of ions. If the membrane potential is more negative than the Nernst potential for a cation, the cation will be attracted into the cell. If the membrane potential is more positive than the Nernst potential for a cation, the cation will be pushed out of the cell. Conversely, if the membrane potential is more negative than the Nernst potential for an anion, the anion will be pushed out of the cell, and if the membrane potential is more positive than the Nernst potential for an anion, the anion will be attracted into the cell. 38. The sodium channels in the axon hillock of a neuron control how many sodium ions cross the membrane. What most strongly controls the sodium channels? a. the concentration of sodium outside the cell b. the concentration of sodium inside the cell c. the voltage difference across the membrane d. the length of the axon e. the presence or absence of thiamine > c. These channels are voltage-gated. They open and close at specific voltages (differences in the electrical potential across the membrane). 39. In the graph of the action potential, __________ corresponds to the absolute refractory period. a. #1 only. b. #2 only. c. #3 only. d. #1 and #2. e. #2 and #3. > b. The refractory period is composed of the absolute refractory period (#2) and the relative refractory period (#3). 40. Which of the following statements is FALSE? a. Myelinated axons propagate action potentials more rapidly than unmyelinated axons do. b. Thin axons propagate action potentials more quickly than thick axons do. c. Saltatory conduction is a process that occurs only in myelinated axons. d. Rebound of action potentials is prevented by the absolute refractory period. e. Artificial stimulation of the distal end of an axon can produce an action potential that travels in the retrograde direction. > b. Thin axons exert more axial resistance than thick axons do. Therefore, the thick axons propagate an action potential more quickly.

1. When Sherrington pinched a dog’s paw and observed the reflexive withdrawal of that paw, he made three major conclusions. Which of the following is one of those conclusions? a. Communication between neurons is produced by chemical signaling. b. Communication between neurons is slowed at synapses. c. Sensory input is processed by the brain. d. Dog’s reflexes are very slow, compared to human reflexes. e. Neurons use action potentials to communicate. > b. Sherrington observed that the reflex was too slow to result from simple conduction of a neural impulse down an axon. He also observed temporal summation and contralateral inhibition. These observations formed our first knowledge of synaptic function: It is slower than axonal conduction, multiple inputs can summate, and inhibitory synaptic input exists. 2. After one frog's heart was stimulated, an extract of fluid from that heart made a second frog's heart beat slower. What conclusion did Otto Loewi draw from these results? a. Transmission at synapses is a chemical event. b. The sympathetic and parasympathetic nervous systems are antagonistic. c. Transmission at heart muscle synapses is electrical. d. Hormones facilitate the actions of the nervous system. e. Absence makes the heart grow fonder! > a. I hope nobody selected choice "e". Loewi identified that the chemical he extracted from one frog's heart increased neurotransmission in the second frog's heart. This was the first demonstration that synaptic neurotransmission is mediated by chemicals. 3. Which of the following synapses does not contribute to regulation of the firing rate of a neuron? a. axosomatic b. axoaxonic c. axodendritic d. Type I synapses e. Type II synapses > b. Axoaxonic synapses do not contribute to spatial or temporal summation, and do not contribute to the integration of inputs to determine the firing of the action potential. Rather, they simply exert effects on the amount of neurotransmitter release through presynaptic facilitation or inhibition. 4. Which of the following describes a synapse that produces an inhibitory postsynaptic potential? a. round vesicles, thick postsynaptic density (asymmetric) b. round vesicles, thin postsynaptic density (symmetric) c. flattened vesicles, thick postsynaptic density (asymmetric) d. flattened vesicles, thin postsynaptic density (symmetric) e. no vesicles, thin postsynaptic density > d. Gray’s Type I synapses or asymmetric synapses provide mostly distal inputs, and have a thick postsynaptic density, where the receptors are coupled to a thick protein matrix and they exert excitatory actions. Gray’s Type II synapses or symmetric synapses provide mostly proximal inputs, and have a thin postsynaptic density, where the receptors exert inhibitory actions. 5. How do metabotropic effects compare to ionotropic effects? a. Ionotropic effects produce EPSPs and metabotropic effects produce IPSPs. b. Ionotropic effects produce IPSPs and metabotropic effects produce EPSPs. c. Ionotropic effects produce action potentials and metabotropic effects produce graded potentials. d. Ionotropic effects have more rapid onset and briefer duration than metabotropic effects. e. Ionotropic effects have slower onset and longer duration than metabotropic effects. > d. Ionotropic receptors are associated with membrane ion channels. Opening these channels causes rapid exchange of ions across the membrane, producing changes in the postsynaptic potential. These effects are rapid and short-lived. Metabotropic receptors are coupled to intracellular cascades of chemicals. These cascades of chemical reactions are slower than ionotropic effects, but the changes endure as long as the chemical events continue. 6. Which of the following events could initiate an excitatory postsynaptic potential (EPSP)? a. Sodium (Na+) enters the cell through neurotransmitter-gated channels. b. Chloride (Cl- ) enters the cell through neurotransmitter-gated channels. c. Potassium (K+) exits the cell through neurotransmitter-gated channels. d. Magnesium (Mg2+) blocks a neurotransmitter-gated channel. e. Potassium (K+) exits the cell through voltage-gated channels. > a. EPSPs and IPSPs are very small local changes in membrane potential when ions are exchanged in response to neurotransmitter actions at receptors (directly through actions at ionotropic receptors, and indirectly through actions at metabotropic receptors). 7. Which of the following would produce depolarizing temporal summation? a. Present weak excitatory stimuli at two or more synapses at the same time. b. Present weak inhibitory stimuli at two or more synapses at the same time. c. Present an excitatory and an inhibitory stimulus at the same time. d. Present a rapid sequence of weak excitatory stimuli. e. Do not allow a flexor muscle to relax before stimulating the extensor muscle. > d. Two or more weak stimuli at the same time would produce spatial summation. A rapid sequence of weak stimuli will produce temporal summation as each stimulus adds to the depolarizing effect of the previous stimulus before that previous stimulus decays across the postsynaptic membrane. 8. What will occur if a hormone binds to a cytosolic or nuclear receptor? a. an ionotropic action b. a metabotropic action c. an ionotropic action or a metabotropic action depending upon the receptor that the hormone binds d. an action potential e. an attenuation of EPSPs > b. All cytosolic and nuclear receptors are metabotropic – Since they are inside the neuron, they cannot be directly associated with ion channels. 9. Which of the following statements is FALSE? a. When an action potential reaches the axon terminal, neurotransmitter vesicles migrate toward the presynaptic membrane and fuse with it. b. When an action potential reaches the axon terminal, calcium enters the presynaptic terminal and causes fusion pores to open. c. When an action potential reaches the axon terminal, neurotransmitters are actively transported into the synaptic cleft. d. When an action potential reaches the axon terminal, released neurotransmitter molecules may bind to specific postsynaptic receptors. e. When an action potential reaches the axon terminal, released neurotransmitter molecules may bind to specific presynaptic autoreceptors. > c. Neurotransmitter molecules diffuse passively out of the ruptured vesicle. There is a high concentration in the vesicle, and a lower concentration in the synaptic cleft. The molecules are not actively transported. 10. After dopamine is released, which of the following may happen to the transmitter molecules? a. They remain on the receptor until they are metabolized. b. They are absorbed into the postsynaptic neuron. c. They catalyze chemical reactions in the extracellular fluid. d. The presynaptic cell reuptakes them intact. e. They are converted to cocaine molecules. > d. Released neurotransmitters can be cleaned up by metabolizing enzymes or by reuptake and recycling in the presynaptic neuron. 11. The study of what happens to a drug when it is consumed (pharmacokinetics) is known by what acronym? a. ASAP b. DAME c. NASA d. IMAX e. ADME > e. Pharmacokinetics is described as the absorption, distribution, metabolism, and excretion of a drug, leading to the acronym ADME. 12. An antagonist drug will have __________ affinity and __________ efficacy for a postsynaptic receptor. a. high;.high b. low; low c. high; low d. low; high e. high; either low or high, depending upon whether the receptor produces an IPSP or EPSP > c. Since it has high affinity, it will bind to a receptor. Since it has low efficacy, it will not trigger a response from the receptor (neither an IPSP or an EPSP). Therefore, it binds to the receptor and blocks it - antagonizing (preventing) the action of the neurotransmitter that usually acts upon the receptor. 13. Which of the following routes of administration will produce the most rapid effects of a psychotropic drug on brain function? a. oral b. suppository c. inhaled d. intramuscular e. intraperitoneal > c. The inhaled route allows more rapid circulation of the drug than the other routes because those other routes require absorption through tissues, and eventual circulation in the blood. Inhalation is the most rapid route of administration, since the drug is absorbed directly from the lungs into the blood, and flows fairly directly to the brain. 14. A certain type of receptor in the brain allows an influx of chloride (Cl-) when activated by its endogenous neurotransmitter. You conduct an experiment with a new drug and find that the drug causes a depolarization through actions at that specific receptor. What kind of drug is it? a. It is an agonist. b. It is an antagonist. c. It is a partial agonist. d. It is an inverse agonist. e. It is a calcium chelator. > d. An inverse agonist binds to the receptor and initiates an effect that is opposite to the normal function of the receptor. 15. The relationship between the dose of drug that will cause damage or death, and the dose that will produce beneficial effects is known as the __________. a. margin of safety b. dose-response curve c. LD50 d. sensitization index e. addiction liability > a. The relationship describes the margin of safety, or the lethal dose for 50% of subjects divided by the effective dose for 50% of the subjects. 16. After repeated exposure to oxycontin, a rat exhibits a diminished analgesic response to an injection of fentanyl. This is known as __________. a. sensitization b. tolerance c. cross-sensitization d. cross-tolerance e. addiction > d. Sensitization is an increase in the response to a drug after repeated administration. Tolerance is a decrease in the response. Cross-sensitization is an increase in the response to a drug after repeated exposure to another similar drug, and cross-tolerance is a decrease to a drug after repeated exposure to another similar drug. 17. Which of the following statements is FALSE? a. Withdrawal effects can occur upon cessation of drug taking. b. Withdrawal effects occur because of sensitization to the drug. c. Withdrawal effects are generally opposite to the acute drug actions. d. Withdrawal effects can occur due to changes in receptor number or affinity. e. Withdrawal effects can occur due to changes in efficacy of coupling between receptors and downstream effectors. > b. Withdrawal effects occur due to tolerance, a homeostatic re-regulation of neurotransmitter function that is opposite to the acute actions of the drug. 18. Which of the following is an agonist action? a. blocking a postsynaptic ionotropic receptor that contains a chloride channel b. reversing a membrane transporter for a neurotransmitter c. increasing actions of a metabolizing enzyme d. activating an autoreceptor e. decreasing biosynthesis of a neurotransmitter > b. If a membrane transporter is reversed (e.g. amphetamine reverses monoamine transporters), there is an acute increase in the extracellular concentrations of the neurotransmitter, an agonist action. 19. Chemical substances released by neurons can be classified broadly as neurotransmitters or neuromodulators. According to this idea, __________ is a neurotransmitter; and __________ is a neuromodulator. a. dopamine; GABA. b. glycine; serotonin. c. glutamate; GABA. d. glycine; glutamate. e. dopamine; serotonin. > b. Glutamate, glycine, and GABA are principal effectors, and the other neurochemical substances (monoamines, peptides, soluble gases, etc.) perform broader functions like regulating arousal. 20. __________ is a soluble gas; and __________ is a peptide neurotransmitter. a. melatonin; glycine b. nitric oxide; dopamine c. nitric oxide; substance P d. acetylcholine; anadamide e. acetylcholine; GABA > c. Acetylcholine is a quaternary amine. Dopamine, norepinephrine and epinephrine are catecholamines. Serotonin and melatonin are indoleamines. Glutamate, GABA, and glycine are amino acids, Anandamide and 2-arachidonyl glycerol are lipid-derived endocannabinoids. Nitric oxide is a soluble gas. Enkephalin, endorphin, dynorphin are opioid peptides. Peptide YY, substance P, cholecystokinin, and many others are non-opioid peptides. 21. Which neurotransmitter binds to nicotinic and muscarinic receptors in the central nervous system? a. acetylcholine b. norepinephrine c. serotonin d. substance P e. GABA > a. Acetylcholine binds to nicotinic receptors at neuromuscular junctions in the PNS, and at axoaxonic synapses in the CNS. It binds predominantly to muscarinic receptors in prototypical axodendritic and axosomatic synapses in the CNS. 22. Cocaine alters neurotransmission by __________; and heroin alters neurotransmission by __________? a. reversing presynaptic dopamine transporters; activating postsynaptic GABA receptors b. reversing presynaptic dopamine transporters; blocking postsynaptic opioid receptors c. blocking presynaptic dopamine transporters; activating postsynaptic GABA receptors d. blocking postsynaptic serotonin receptors; blocking postsynaptic opioid receptors e. blocking presynaptic dopamine transporters; activating postsynaptic opioid receptors > e. When cocaine blocks the dopamine transporter, excess dopamine accumulates in the synapse. This increases activity of dopamine at postsynaptic dopamine receptors, an agonist action. Amphetamine reverses dopamine transporters, so is a much more powerful agonist. Morphine and heroin exert an agonist action by directly stimulating postsynaptic opioid (mostly mu) receptors. Valium enhances GABA binding at postsynaptic GABA-A receptors. 23. Which of the following statements is FALSE? a. Glutamate can exert either ionotropic or metabotropic postsynaptic actions. b. Activation of a GABA receptor requires coordinated GABA and glycine binding. c. GABA is enzymatically synthesized from glutamate. d. GABA is the principal neurotransmitter that participates in inhibitory neurotransmission in the forebrain. e. Imbalances in glutamate and GABA signaling are implicated in epilepsy. > b. Coordinated glutamate and glycine binding are required at NMDA receptors. GABA and glycine each have their own specialized types of receptors that mediate inhibitory actions in the brain and spinal cord respectively. 24. Why does caffeine exert stimulant actions? a. Caffeine blocks dopamine receptors. b. Caffeine blocks acetylcholine receptors. c. Caffeine blocks adenosine receptors. d. Caffeine blocks nitric oxide receptors. e. Caffeine blocks serotonin receptors. > c. Caffeine is an antagonist at adenosine receptors. Adenosinergic neurotransmission produces neuromodulatory actions on dopaminergic neurons, generally increasing the actions of dopamine. Thus, caffeine has psychomotor stimulant effects similar to amphetamine or cocaine, but not nearly as potent. 25. Chemical communication that affects nearby target cells is __________. a. intracrine communication b. autocrine communication c. paracrine communication d. endocrine communication e. ectocrine communication > c. Intracrine communication occurs when various cells synthesize chemicals that function within the cell to regulate internal cellular activity. Autocrine communication occurs when endocrine or neural cells release a hormone or neurotransmitter that exerts a direct feedback effect on the cell that released it. Endocrine communication occurs when endocrine or neuroendocrine cells release hormones into the bloodstream and the hormones travel through the circulation to distant target cells. Paracrine communication occurs when endocrine cells release hormones that act upon adjacent cells. Ectocrine communication occurs when ectocrine cells release chemicals (e.g. pheromones) into the environment, inducing a physiological response in other individuals. 26. Which of the following statements is FALSE? a. Steroid hormones are synthesized in glands. b. Steroid hormones are derived from modifications of cholesterol. c. Steroid hormones are stored in vesicles. d. Steroid hormones are carried through the circulation by attaching to proteins. e. Steroid hormones can cross the blood-brain barrier. > c. Steroid hormones are lipophilic (hydrophobic). They are synthesized on demand, and released immediately, because they cannot be contained within lipid membranes. 27. How do peptide hormones usually affect a cell? a. by attaching to receptors on the membrane of a cell b. by attaching to the DNA and altering the expression of genes c. by increasing the insulation provided by the myelin sheath d. by entering the cell and being metabolized as a source of energy e. by attaching to receptors in the cytoplasm > a. Proteins and peptides are lipophobic (hydrophilic). They cannot cross cell membranes, so they do not enter the cells. 28. Estrogens and androgens are classified as what kind of hormones? a. steroid b. peptide c. amino acid d. thyroid e. pituitary > a. Estrogens and androgens are the gonadal steroid that are synthesized from cholesterol. Additional steroid hormones are synthesized by the adrenal gland. 29. Which of the following hormones is a peptide? a. estradiol b. testosterone c. cortisol d. progesterone e. beta-endorphin > e. Estrogens, androgens, cortisol, and aldosterone are steroid hormones that are lipophillic. Opioid peptides (like beta-endorphin), adrenocorticotropic hormone (ACTH), oxytocin, vasopressin, substance P, and many others are hydrophilic peptide hormone. 30. Which endocrine gland releases the hormones thyroid stimulating hormone, luteinizing hormone, follicle stimulating hormone, adrenocorticotropic hormone (ACTH), and prolactin? a. posterior pituitary b. anterior pituitary c. pineal gland d. thyroid gland e. hypothalamus > b. The pituitary gland is the “Master gland”. It releases hormones that regulate the actions of glands all over the body. The anterior gland releases TSH, LH, FSH, ACTH, GH, β-endorphin and MSH (among others). 31. Which of the following hormones is released by the hypothalamus? a. estradiol b. oxytocin c. cortisol d. melatonin e. corticotropin releasing hormone > e. The pituitary gland is the “Master gland”. It releases hormones that regulate the actions of glands all over the body. The anterior pituitary gland releases TSH, LH, FSH, ACTH, GH, Bendorphin and MSH (among others). The hypothalamus releases “releasing hormones” and “inhibiting hormones” into the hypophyseal portal circulation to activate or inhibit release of hormones from the anterior pituitary. 32. Why are some neurohormones released in a pulsatile manner? a. One pulse signals the onset, and another signals the offset of a circadian rhythm. b. Specific environmental cues determine the rhythm of release. c. Changes in the patterns of small pulses signal the onset of puberty. d. Pulsatile release prevents tolerance to the cellular action. e. Patterns of pulses produce differing effects in males and females. > d. Constant exposure could cause desensitization of pituitary cells to the releasing hormone and inhibiting hormone inputs. Pulses and surges of hormones helps to optimize the efficiency of signaling by preventing desensitization. 33. Which hormone is most likely to complex with a receptor and then function as a transcription factor? a. cortisol b. luteinizing hormone c. alpha-fetoprotein d. melatonin e. somatostatin > a. Steroid hormones pass through lipid membranes to bind to cytosolic receptors. These hormone-receptor complexes often dimerized, and can then be chaperoned into the nucleus of the cell to bind to specific sites on the DNA and either activate or repress expression of specific genes. This has important impacts upon development, and activation of systems of cells. 34. Which of the following is the most important evolutionary advantage that is ONLY found in vertebrate species? a. nerve net b. homeobox genes c. ganglia d. segmented portions of the nervous system e. myelinated neurons > e. Vertebrates are defined as animals with a true brain and spinal cord. Nerve nets, ganglia, segmentation, and homeobox genes can all be found among invertebrate (and vertebrate) species. 35. Which of the following statements is FALSE? a. Chimpanzee bodies are very different from humans, but their brains are very similar. b. Humans have fewer chromosomes than other great apes do. c. In some ways chimpanzees are more similar to humans than bonobos are, and in some ways, bonobos are more similar to humans than chimpanzees are. d. Although chimpanzees and bonobos have a very similar genome, their behaviors are quite different. e. The ASPM gene contributes to cortical size, and the FOXP2 gene contributes to language ability in humans. > a. Chimpanzee and bonobo bodies may look a little different from humans, but they are actually highly similar. A chimpanzee kidney could even (at least briefly) be transplanted into a human. However, the genes that are used by the brain differ in important ways between humans and all the other apes. 36. Which of the following is NOT one of Darwin's" Principles of Evolution"? a. Pairs of genes determine the phenotype of the organism. b. Organisms produce more progeny than can survive. c. Sexual reproduction causes variation in traits. d. Different traits cause differential reproduction. e. The environment selects for specific traits. > a. Darwin identified that distinct units of heredity are inherited, but he did not know what genes were, or that it was a choice of 2 units of heredity for a particular monovalent trait. Those findings come from the work of Gregor Mendel. 37. The fact that humans evolved a large brain is an example of __________. a. monovalent selection b. convergent selection c. bidirectional selection d. stabilizing selection e. directional selection > e. Directional selection selects for those members of the population that have an extreme of a characteristic that promotes reproductive success. 38. Which of the following statements is FALSE concerning human evolution? a. Primate lifestyle (e.g. fruit eating, socialization) probably contributed to the evolution of a large brain. b. Our intellect is at least partially due to the process of neoteny in our evolution. c. Enlarged human brains required greater cooling than smaller primate brains. d. We cannot differentiate human brain cells from brain cells of other mammalian species. e. Evolutionary adaptations in the body are coordinated with evolutionary adaptations in the brain. > d. We can clearly see that species with larger and more complex brains also have larger and more extensively branched neurons. 39. In a study, different species of primates were taught a discrimination task. Then a second discrimination task (a reversal) was presented. What did the researchers find? a. Within a species family, the brain-to-body mass ratio was unrelated to learning. b. The first task always facilitated learning, but to different degrees. c. Ease of learning the second task was related to estimates of brain complexity. d. The greater the brain complexity, the more a species stuck with the first discrimination. e. Larger brains facilitated learning. > c. All the primates did fairly well on the first task. Those species that had less complex brains exhibited an impairment in learning the second task. Those primates with more complex brains showed enhanced learning of the second task after learning the first task. 40. Which statement best describes the “radiator hypothesis”? a. The brain functions to cool the blood. b. Evolution of the brain and the body are interactive processes. c. The skulls of recent hominids are more porous than the skulls of older Australopithecus. d. Hominid species migrated out of Africa and radiated out to populate the world. e. Humans and chimpanzees share 98.5% of their DNA. > c. Heat production is related to the mass of the brain and the amount of energy used by the brain. Hominids evolved a more porous skull, with more blood flow through it. This dissipates the heat, and allowed hominids to evolve a more massive brain.