When current leaps across an insulating myelin sheath from node to node, the type of impulse conduction is called:
repolarization.
refraction.
saltatory conduction.
diffusion.
The Correct Answer is C
A. repolarization: This refers to the phase where a neuron returns to its resting state after firing.
B. refraction: In biology, this refers to the period during which a nerve cannot fire again (refractory period).
C. saltatory conduction: This is the correct term for an impulse "jumping" from one Node of Ranvier to the next along a myelinated axon, which significantly increases signal speed.
D. diffusion: This is the passive movement of molecules and does not describe the electrical leaping of a nerve impulse.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A. Sternocleidomastoid and abdominal muscles: The sternocleidomastoid is an accessory muscle for forced inspiration, not expiration.
B. Sternocleidomastoid and intercostals: Again, the sternocleidomastoid helps lift the ribcage for inhalation.
C. External intercostals and pectoralis muscles: Both of these are used to expand the chest cavity during inspiration.
D. Abdominal muscles and internal intercostals: Forced expiration is an active process where abdominal muscles push the diaphragm up and internal intercostals pull the ribs down to force air out.
Correct Answer is D
Explanation
A. Causes the pancreas to increase exocrine secretions high in enzyme content: CCK stimulates pancreatic acinar cells to release digestive enzymes.
B. Opposes the influence of gastrin on gastric parietal cells: CCK helps inhibit gastric emptying and acid secretion to allow the small intestine time to process fats.
C. Stimulates the contraction of the gallbladder: This is the most well-known function, which pushes bile into the duodenum to emulsify fats.
D. Does all of the above: All three statements accurately describe the multi-faceted role of CCK in digestion.
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