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 B
Explanation
A. a membrane that lines body cavities: While membranes are made of tissues, this describes a specific structure (like a serous membrane), not the definition of tissue itself.
B. a group of similar cells that perform a common function: This is the standard biological definition of a tissue, which sits between the cellular and organ levels of organization.
C. a thin sheet of cells embedded in a matrix: This describes specific types of connective or epithelial tissues, but is too narrow to define all tissues.
D. the most complex organizational unit of the body: This is incorrect; the "organism" is the most complex unit, followed by organ systems and then organs.
Correct Answer is D
Explanation
A. Environment: Factors like pollution, climate, or radiation exposure are known risk factors for various diseases.
B. Stress: Chronic stress weakens the immune system and contributes to cardiovascular and mental health issues.
C. Lifestyle: Choices regarding diet, exercise, and tobacco use directly impact the risk of developing chronic illnesses.
D. All of the above: Since environment, stress, and lifestyle are all recognized as significant risk factors for disease, "All of the above" is correct.
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