Which of the following best describes neurons and their processes?
The correct answer is A.
A. No matter its function, be it a sensory neuron, motor neuron, or interneuron, all neurons form synapses or contacts with target cells and signal or communicate with their targets. Depending on their function, different neurons can have very different types of morphologies, and not all have an axon or branched dendrites. Neuronal cell bodies can be present in the PNS (dorsal root ganglia and autonomic ganglia); not all axons are myelinated (about half are not) or branched; and not all dendrites are spiny.
A 48-year-old man goes to his physician because of pain and paresthesia along the lateral aspect of the leg and the dorsum of the foot. The patient's symptoms suggest impingement of the L5 spinal nerve resulting from a herniated intervertebral disc. The L5 spinal nerve most likely exits between which of the following vertebrae?
L3–L4 vertebrae
L4–L5 vertebrae
L5–S1 vertebrae
S1–S2 vertebrae
The correct answer is C. You answered C.
Spinal nerves in the thoracic and lumbar vertebral region exit the vertebral canal below their associated vertebra. Therefore, the L5 spinal nerve exits below L5, between L5 and S1.
A herpetologist is bitten by a poisonous snake and is taken to the emergency department with progressive muscle paralysis. The venom is probably incapacitating his
A. Na+ channels.
B. Ca2+ channels.
C. phospholipids.
D. acetylcholine receptors.
E. spectrin.
Answer
1. D. Snake venom usually blocks acetylcholine receptors, preventing depolarization of the muscle cell.
Review Material: Neuromuscular Junction