Which structure regulates the amount of light entering the eyeball through the pupil?
a) Retina
b) Cornea
c) Iris
d) Choroid
e) Ciliary muscle
Iris
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Pain that feels like it is coming from a part other than the part being stimulated is called ________ pain.
Fill in the blank(s) with the appropriate word(s).
What is the largest type of neuromodulator?
a. ATP b. nitric oxide c. serotonin d. dopamine e. neuropeptides
Which stage of the cell cycle immediately precedes the S phase?
A. G2 B. G1 C. M D. None of the choices are correct.
The plasma membrane of an excitable cell is more permeable to potassium ions because
A. of its positive electrical charge. B. there are more leak ion channels for K+ than Na+. C. protein molecules cannot exit through the cell membrane. D. calcium ions block Na+ and Cl- channels. E. there are more gated channels for K+.