Download CHAPTER 11 HW KEY Multiple Choice: A 7) B (1) d, (2) b, (3) f, (4) c

CHAPTER 11 HW KEY
Multiple Choice:
1) A
2) (1) d, (2) b, (3) f, (4) c, (5) a,
3) B
4) C
5) A
6) C
7) B
8) D
9) C
10) C
11) A
12) (1) D, (2)A, (3) A, (4) C
Short Answer:
13) Anatomical division includes the CNS (brain and spinal cord) and the PNS (nerves and ganglia). Functional
division includes the somatic and autonomic motor divisions of the PNS. The autonomic division is further divided
into sympathetic and parasympathetic subdivisions.
14)
a) The cell body is the biosynthetic and metabolic center of the neuron. It contains the usual organelles, but
lacks centrioles.
b) Dendrites and axons both function to carry electrical current. Dendrites differ in that they are short,
transmit toward the body, and function as receptor sites. Axons are typically long, myelinated, and
transmit away from the body. Only axons can generate action potentials, the long distance signals.
15)
a) Myelin is a whitish, fatty, phospholipid insulating material. (The wrapped plasma membranes of the
oligodendrocites or Schwann cells)
b) CNS myelin sheaths are formed by flap-like extensions of oligodendrocites and lack a neurilemma. Each
oligodendrocite can help to myelinate several fibers. PNS myelin is formed by Schwann cells; the wrapping
of each Schwann cell forms the internode region. The sheaths have a neurilemma, and the fibers they
protect are capable of regeneration.
16) Multipolar neurons have many dendrites, one axon, and are found in the CNS and autonomic ganglia. Bipolar
neurons have one axon and one dendrite and are found in the receptor end organs of the special senses, such as the
retina and olfactory mucosa. Unipolar neurons have one process that divides into an axon and a dendrite and is a
sensory neuron with the cell body found in the dorsal root ganglion or cranial nerve ganglion.
17) A polarized membrane possesses a net positive charge outside, and a net negative charge inside with the
voltage across the membrane being -70mV. Diffusion of Na+ and K+ across the membrane establishes the resting
potential because the membrane is slightly more permeable to K+. The Na+/K+ pump, an active transport
mechanism, maintains this polarized state by maintaining the diffusion gradient for Na+ and K+.