10-25-2004, 07:46 AM
go=gi
Q. When a person has no sense of control over a highly stressful situation, which of the following physiologic reactions would be expected to occur?
A. Weaker corticosteroid elevations will develop
B. An endogenous opioid peptide will be released
C. Diminished suppression of the cytotoxicity of natural killer cells will occur
D. A stronger immune response to mitogen stimulation will develop
The answer is: B
Stress without the sense of control has been found to influence the release of endogenous opioid peptides, such as -endorphin. When one learns that one has no control over a stressful situation, an opiate-based analgesia occurs. Both uncontrollable and controllable stressors produce a brief poststressor analgesia, but only the opioid produced by inescapable stressors can be blocked by administering opiate antagonists. Both controllable and uncontrollable stress situations suppress the cytotoxicity of natural killer cells, but inescapable and uncontrollable stress results in greater suppression than does controllable and escapable stress. Corticosteroid release during uncontrollable or inescapable stress is somewhat greater than when the stress can be controlled or escaped. Corticosteroid levels also decline more slowly after uncontrollable stress.
Substances such as tritiated amino acids and phaseolus vulgaris agglutinin microinjected into specific regions of the brain have also been employed by many investigators for the study of the nervous system. These methods are specific in that they label which of the following?
A. Cell bodies
B. Glial cells
C. Sensory receptors
D. Motor end plates
E. Axons and axon preterminals
The answer is: E
The mapping of pathways utilizing anterograde tracing of fibers depends upon the process of axonal transport. For example, if a tritiated amino acid such as 3H-leucine is microinjected into a region of the brain, it gets synthesized into protein in the cell bodies and transported down the respective axons to their terminals. By utilizing autoradiographic methods, one can identify the loci of the label contained in the protein that has been transported to the axon terminals. The application of phaseolus vulgaris agglutinin also utilizes the principle of anterograde transport to map the distribution of pathways from cell bodies injected with this substance.
The output of the retina is mediated by which of the following?
A. Bipolar cells
B. Horizontal cells
C. Rods
D. Cones
E. Ganglion cells
The answer is: E
The output of the retina is mediated by the ganglion cells. Ganglion cells receive inputs from photoreceptor and bipolar cells. In turn, ganglion cells give rise to optic nerve fibers, which project through the optic chiasm and optic tracts to the lateral geniculate nucleus of the thalamus. Other cells mentioned in this question only produce local connections within the retina.
Q. Which of the following receptors requires the simultaneous binding of two different agonists for activation?
A. L-AP4 receptor
B. Kainate receptor
C. NMDA receptor
D. AMPA receptor
E. GABAA receptor
The answer is: C
NMDA receptors are unique among receptors in that they require the simultaneous binding of two different agonists for their activation. NMDA ion channels are opened after such compounds as glutamate and glycine are applied to the membranes that include NMDA receptors. Recent evidence has shown that a metabotropic glutamate receptor, L-AP4, is present in the retina. Activation of this receptor may serve to hyperpolarize bipolar neurons within the retina. Glutamate activation (of this receptor) constitutes an unusual action because most neurons in the CNS are depolarized by glutamate. AMPA is one of several classes of ionotropic glutamate receptors and functions as a synaptic receptor for fast excitatory synaptic transmission mediated through glutamate. The other choices, kainate and GABA receptors, do not have this property
Q. Which of the followin
Q. When a person has no sense of control over a highly stressful situation, which of the following physiologic reactions would be expected to occur?
A. Weaker corticosteroid elevations will develop
B. An endogenous opioid peptide will be released
C. Diminished suppression of the cytotoxicity of natural killer cells will occur
D. A stronger immune response to mitogen stimulation will develop
The answer is: B
Stress without the sense of control has been found to influence the release of endogenous opioid peptides, such as -endorphin. When one learns that one has no control over a stressful situation, an opiate-based analgesia occurs. Both uncontrollable and controllable stressors produce a brief poststressor analgesia, but only the opioid produced by inescapable stressors can be blocked by administering opiate antagonists. Both controllable and uncontrollable stress situations suppress the cytotoxicity of natural killer cells, but inescapable and uncontrollable stress results in greater suppression than does controllable and escapable stress. Corticosteroid release during uncontrollable or inescapable stress is somewhat greater than when the stress can be controlled or escaped. Corticosteroid levels also decline more slowly after uncontrollable stress.
Substances such as tritiated amino acids and phaseolus vulgaris agglutinin microinjected into specific regions of the brain have also been employed by many investigators for the study of the nervous system. These methods are specific in that they label which of the following?
A. Cell bodies
B. Glial cells
C. Sensory receptors
D. Motor end plates
E. Axons and axon preterminals
The answer is: E
The mapping of pathways utilizing anterograde tracing of fibers depends upon the process of axonal transport. For example, if a tritiated amino acid such as 3H-leucine is microinjected into a region of the brain, it gets synthesized into protein in the cell bodies and transported down the respective axons to their terminals. By utilizing autoradiographic methods, one can identify the loci of the label contained in the protein that has been transported to the axon terminals. The application of phaseolus vulgaris agglutinin also utilizes the principle of anterograde transport to map the distribution of pathways from cell bodies injected with this substance.
The output of the retina is mediated by which of the following?
A. Bipolar cells
B. Horizontal cells
C. Rods
D. Cones
E. Ganglion cells
The answer is: E
The output of the retina is mediated by the ganglion cells. Ganglion cells receive inputs from photoreceptor and bipolar cells. In turn, ganglion cells give rise to optic nerve fibers, which project through the optic chiasm and optic tracts to the lateral geniculate nucleus of the thalamus. Other cells mentioned in this question only produce local connections within the retina.
Q. Which of the following receptors requires the simultaneous binding of two different agonists for activation?
A. L-AP4 receptor
B. Kainate receptor
C. NMDA receptor
D. AMPA receptor
E. GABAA receptor
The answer is: C
NMDA receptors are unique among receptors in that they require the simultaneous binding of two different agonists for their activation. NMDA ion channels are opened after such compounds as glutamate and glycine are applied to the membranes that include NMDA receptors. Recent evidence has shown that a metabotropic glutamate receptor, L-AP4, is present in the retina. Activation of this receptor may serve to hyperpolarize bipolar neurons within the retina. Glutamate activation (of this receptor) constitutes an unusual action because most neurons in the CNS are depolarized by glutamate. AMPA is one of several classes of ionotropic glutamate receptors and functions as a synaptic receptor for fast excitatory synaptic transmission mediated through glutamate. The other choices, kainate and GABA receptors, do not have this property
Q. Which of the followin