Physiology

33. Inhibition of pain signals by tactile stimulation of a skin surface involves which of the following selections? A) Type A alpha fibers in peripheral nerves B) Type A beta fibers in peripheral nerves C) Type A delta fibers in peripheral nerves D) Type C fibers in peripheral nerves

32.The highest degree of pain localization comes from : A) simultaneous stimulation of free nerve endings and tactile fibers B) stimulation of free nerve endings by bradykinin C) nerve fibers traveling to the thalamus by way of the paleospinothalamic tract D) stimulation of type A delta fibers

31.Which of the following is a type of interneuron in this region that utilizes enkephalin to inhibit pain transmission? A) Nucleus raphe magnus B) Postcentral gyrus C) Dorsal horn of spinal cord D) Type C sensory fiber

24.Which of the following structures carries axons from neurons in the ventral posterolateral nucleus of the thalamus to the primary somatosensory cortex? A) Medial lemniscus B) External capsule C) Internal capsule D) Extreme capsule

23.Which of the following represents the basis for transduction of a sensory stimulus into nerve impulses? A) Change in the ion permeability of the receptor membrane B) Generation of an action potential C) Inactivation of a G-protein–mediated response D) Protein synthesis

22.Which of the following structures carries axons from the nucleus gracilis to the thalamus? A) Fasciculus gracilis B) Fasciculus lemniscus C) Lateral spinothalamic tract D) Medial lemniscus

21.The first-order (primary afferent) cell bodies of the dorsal column–medial lemniscal system are found in which of the following structures? A) Spinal cord dorsal horn B) Spinal cord ventral horn C) Dorsal root ganglia D) Nucleus cuneatus

20.Which of the following explains why individuals in severe pain have difficulty sleeping without sedative medication? A) The somatosensory cortical area for pain perception blocks the sleep- generating circuits B) Pain fibers entering the dorsal horn and the ascending pain pathways block the sleep-generating circuits C) Ascending pain pathways provide excitatory input to brainstem reticular formation areas that are involved in maintenance of the alert, waking state D) The neurotransmitters used in the slow pain pathway diffuse to neighboring cell groups and generally raise the excitability of the brain

19.Which of the following systems conveys information concerning highly localized touch sensation and body position (proprioceptive) sensation? A) Anterolateral system B) Dorsal column–medial lemniscal system C) Corticospinal D) Spinocerebellar

18. Neurons located in which of the following areas release serotonin as their neurotransmitter? A) Periaqueductal gray area B) Interneurons of the spinal cord C) Periventricular area D) Nucleus raphe magnus

17. In chemical synapses that involve a so-called second messenger, typically a G- protein linked to the postsynaptic receptor is activated when neurotransmitter binds to that receptor.Which of the following represents an activity performed by the activated second messenger? A) Closure of a membrane channel for sodium or potassium. B) Activation of cyclic AMP or cyclic GMP. C) Inactivation of enzymes that initiate biochemical reactions in the postsynaptic neuron. D) Inactivation of gene transcription in the postsynaptic neuron.

16.Which of the following statements concerning the mechanoreceptive receptor potential is/are true? A) Increase in stimulus energy results in an increase in receptor potential. B) When receptor potential rises above a certain threshold action potentials will appear in the neuron attached the receptor. C) Number of action potentials generated in the neuron attached to the receptor is proportional to receptor potential. D) All of the above are correct.

15.Which of the following pathways crosses in the ventral white commissure of the spinal cord within a few segments of entry and then courses to the thalamus contralateral to the side of the body from which the signal originated? A) Anterolateral system B) Dorsal column–medial lemniscal system C) Corticospinal system D) Spinocerebellar system

14.Which of the following is the system that transmits somatosensory information with the highest degree of temporal and spatial fidelity? A) Anterolateral system B) Dorsal column–medial lemniscal system C) Corticospinal system D) Spinocerebellar system

13.Which of the following statements concerning the transmission of pain signals into the central nervous system is correct? A) The “fast” pain fibers that conduct at about 6 to 30 m/sec are classified as type C fibers. B) Type A-delta pain fibers are responsible for the localization of a pain stimulus. C) Upon entering the spinal cord dorsal horn, the fast and slow pain fibers synapse with the same populations of neurons. D) The paleospinothalamic tract is specialized to rapidly conduct pain signals to the thalamus.

12.The excitatory or inhibitory action of a neurotransmitter is determined by which of the following? A) Function of its postsynaptic receptor B) Molecular composition C) Shape of the synaptic vesicle in which it is contained D) Distance between the pre- and post-synaptic membranes

11.Which of the following is an important functional parameter of pain receptors? A) Exhibit little or no adaptation B) Not affected by muscle tension C) Signal only flexion at joint capsules D) Can voluntarily be inhibited

10.Which of the following substances enhances the sensitivity of pain receptors but does not directly excite them? A) Bradykinin B) Serotonin C) Potassium ions D) Prostaglandins

9.Which of the following is an encapsulated receptor found deep in the skin throughout the body as well as in fascial layers where they detect indentation of the skin (pressure) and movement across the surface (vibration)? A) Pacinian corpuscle B) Meissner’s corpuscle C) Free nerve endings D) Ruffini’s endings

8.Which of the following best describes the concept of specificity in sensory nerve fibers that transmit only one modality of sensation? A) Frequency coding principle B) Concept of specific nerve energy C) Singularity principle D) Labeled line principle