Which lymphatic organ is poorly developed at birth and develops postnatally when invaded by immunocompetent lymphocytes?
A. Thymus
B. Spleen
C. Bone marrow
D. Tonsil
E. Lymph node
B. Spleen
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Once a motor neuron has fired, all the muscle fibers in a muscle contract
Indicate whether the statement is true or false
All of the following are spinal plexuses EXCEPT ________
A) cervical plexus B) thoracic plexus C) brachial D) lumbar plexus
Sympathetic responses generally are widespread because ________
A) preganglionic fibers are short B) inactivation of ACh is fairly slow C) NE and epinephrine are secreted into the blood as part of the sympathetic response D) preganglionic fibers are long
Which of the following statements about the resting membrane potential is TRUE?
A) It results, in part, from the concentration gradients for Na+ and K+. B) It is due in part to the presence of extracellular proteins. C) It is normally equal to zero volts. D) The inside of the membrane is positively charged compared to the outside.