The central nervous system consists of the:

Correct Answer: A

Rationale: The central nervous system, comprising brain and spinal cord, directs all bodily commands and responses. Unlike peripheral extensions, it's the control hub. Clinicians focus here for issues like strokes, safeguarding its role in coordinating life's processes.

Correct Answer: A

Rationale: Diffusion allows substances to move passively across membranes, driven by concentration gradients, not energy. Unlike active processes, it's effortless flow. Clinicians rely on it like in oxygen uptake ensuring vital exchanges occur naturally for cellular health.

Correct Answer: D

Rationale: This question's phrasing suggests a trick, but all listed epithelial, connective, muscle, nervous are core tissue types. The document's 'D' answer may be an error; all are fundamental. In practice, nurses recognize these as the body's building blocks, each vital for health.

Correct Answer: D

Rationale: Parathyroid hormone (PTH) adjusts blood calcium, mobilizing it from bones when low. Unlike metabolic or sex hormones, it's a calcium gatekeeper. Nurses monitor it in bone health like osteoporosis ensuring skeletal and systemic balance.

Correct Answer: D

Rationale: A tissue is a group of similar cells with a specific function, like muscle tissue contracting. An organism is a whole living entity, an organelle is a cell component (e.g., nucleus), and an organ combines tissues. Tissues are the second organizational level after cells, foundational in anatomy for understanding how specialized functions like epithelial tissue protecting skin build complex structures.