Which of the following situations stimulates the skin to produce Vitamin D?
Presence of calcium
Exposure to ultraviolet light
Exposure to cold temperature
Presence of parathyroid hormone
The Correct Answer is B
a. Presence of calcium: Calcium does not directly stimulate the production of Vitamin D in the skin.
b. Exposure to ultraviolet light: UVB rays from sunlight stimulate the skin to produce Vitamin D3 (cholecalciferol).
c. Exposure to cold temperature: Cold temperature does not affect Vitamin D production.
d. Presence of parathyroid hormone: Parathyroid hormone helps regulate calcium levels and can stimulate the conversion of Vitamin D to its active form in the kidneys, but it does not stimulate its production in the skin.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
a. Purkinje fibers: Purkinje fibers are the last structures to receive the signal within the ventricles, causing them to contract.
b. Bundle of His: The correct sequence of the cardiac conduction system is as follows: The electrical impulse originates in the sinoatrial (SA) node, then travels to the atrioventricular (AV) node. From the AV node, the impulse travels to the Bundle of His. After the Bundle of His, the impulse travels through the bundle branches and finally reaches the Purkinje fibers, which facilitate the contraction of the ventricles.
c. Bundle branches: The electrical impulse for heartbeat originates in the SA node (sinoatrial node). It then travels to the AV node (atrioventricular node), which delays the signal before sending it to the Bundle of His. The Bundle of His splits into right and left bundle branches, which distribute the electrical signal to the Purkinje fibers in the ventricles, causing them to contract in a coordinated fashion.
d. SA node: The SA node initiates the electrical impulse, not receive it after the AV node.
Correct Answer is B
Explanation
a. Stratum granulosum: This layer is composed of keratinocytes that are in the process of dying and forming a barrier of keratin.
b. Stratum basale: This is the deepest layer of the epidermis, where keratinocytes are actively dividing. This layer contains stem cells that produce new keratinocytes to replace those shed from the surface.
c. Stratum lucidum: This layer is only present in thick skin, such as on the palms and soles, and consists of dead keratinocytes that have a translucent appearance.
d. Stratum spinosum: This layer contains keratinocytes that are beginning to produce keratin and other proteins but are not rapidly dividing.
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