ATI RN
ATI Anatomy and Physiology
1. Lowering the hand by straightening the elbow affects which of the following muscles?
- A. biceps brachii
- B. triceps brachii
- C. brachialis
- D. brachioradialis
Correct answer: B
Rationale: Lowering the hand by straightening the elbow is the action of extending the forearm, which is primarily done by the triceps brachii muscle. The triceps brachii is the main extensor muscle of the elbow joint. The biceps brachii is responsible for flexing the elbow, not extending it, making it an incorrect choice. Brachialis is a strong elbow flexor, and brachioradialis helps in flexing the elbow and pronating the forearm, so they are not the primary muscles involved in straightening the elbow.
2. What is homeostasis?
- A. The inability to keep body weight within normal limits.
- B. Room temperature decreasing because a window is open.
- C. Ingestion of more food than needed.
- D. The tendency of the body to maintain a stable internal environment.
Correct answer: D
Rationale: The correct answer is D: Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes. Choices A, B, and C are incorrect. Choice A describes obesity, choice B describes a specific scenario with room temperature, and choice C refers to overeating, which is not related to homeostasis.
3. Calcium concentration in the blood is controlled by which of the following glands?
- A. Hypothalamus gland
- B. Thyroid gland
- C. Pituitary gland
- D. Parathyroid glands
Correct answer: D
Rationale: The correct answer is Parathyroid glands. The parathyroid glands are responsible for regulating calcium levels in the blood by secreting parathyroid hormone (PTH). PTH helps increase calcium levels in the blood when they are too low. The other glands listed, such as the Hypothalamus, Thyroid, and Pituitary glands, do not directly control calcium concentration in the blood.
4. In negative feedback mechanisms, changes away from the normal state
- A. stimulate changes in the same direction
- B. inhibit all body reactions
- C. stimulate changes in the opposite direction
- D. stimulate a reduction in all body requirements
Correct answer: C
Rationale: In negative feedback mechanisms, changes away from the normal state stimulate changes in the opposite direction. This is a fundamental concept in biological systems where the response to a stimulus opposes the initial change, helping to maintain homeostasis. Choice A is incorrect because negative feedback does not stimulate changes in the same direction. Choice B is incorrect because negative feedback does not inhibit all body reactions, but rather specific responses. Choice D is incorrect because negative feedback does not stimulate a reduction in all body requirements, but rather adjusts specific functions to restore balance.
5. What do positive feedback mechanisms do?
- A. Cause long-term changes.
- B. Move conditions away from the normal state.
- C. Bring conditions back to the normal state.
- D. Usually produce stable conditions.
Correct answer: B
Rationale: Positive feedback mechanisms amplify or increase changes in a system, moving conditions away from the normal state. This makes choice B the correct answer. Choice A is incorrect as positive feedback does not cause long-term changes but rather accelerates deviations from the norm. Choice C is incorrect because positive feedback does not bring conditions back to normal; instead, it amplifies deviations. Choice D is incorrect as positive feedback does not usually lead to stable conditions but rather to further deviations from the normal state.
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