Which area of the retina has the highest concentration of cones?
A) optic disc (blind spot)
B) optic nerve
C) choroid
D) fovea centralis
E) ciliary body
D
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A person is unable to detect electromagnetic waves, except visible light, because of which of the following reasons?
A) The CNS might be unable to process a given stimulus. B) The stimulus might irritate or stimulate all the available receptors and make interpretation impossible. C) No receptors of a type necessary to register the stimuli exist in the body. D) The stimulus might be outside the range of sensitivity of the available receptors. E) All of the answers are correct.
Conduction by local current flow
a. occurs in unmyelinated fibers. b. is faster than propagation of an action potential in myelinated fibers because myelin acts as an insulator to slow down the impulse. c. involves current flowing locally between the active and adjacent inactive areas, thereby bringing the inactive areas to threshold so that they too become active (i.e., have an action potential). d. both (a) and (c) above. e. all of these answers.
The third stage of labor
a. involves dilation of the cervix to 10 cm. b. refers to the actual birth of the baby. c. occurs when the entire uterine contents shift downward and the fetus's head is positioned against the cervix. d. involves delivery of the placenta. e. is characterized by rupture of the membranes surrounding the amniotic sac.
Raising an arm to one side of the body to stop a taxi, is an example of ________ of the shoulder.
A. protraction B. abduction C. rotation D. adduction E. circumduction