ATI RN
ATI Anatomy and Physiology
1. Which of the following ions is most abundant in extracellular fluid?
- A. Calcium
- B. Chloride
- C. Sodium
- D. Potassium
Correct answer: C
Rationale: Sodium is the most abundant ion in extracellular fluid. It plays a crucial role in maintaining fluid balance, nerve function, and muscle contraction. Calcium (Choice A) is mainly found in bones and teeth, Chloride (Choice B) is the major anion in extracellular fluid but not the most abundant ion, and Potassium (Choice D) is found predominantly inside cells.
2. Are the oral, nasal, orbital, and middle ear cavities in the dorsal cavity?
- A. TRUE
- B. FALSE
- C. Not Sure
- D. None of the above
Correct answer: B
Rationale: The correct answer is False. The oral, nasal, orbital, and middle ear cavities are actually part of the ventral cavity, not the dorsal cavity. The dorsal cavity contains the cranial and spinal cavities, while the ventral cavity includes the thoracic, abdominal, and pelvic cavities. Therefore, these structures are located in the ventral cavity, not the dorsal cavity. Choices A, C, and D are incorrect because these structures are not situated in the dorsal cavity.
3. Which of the following illustrates a positive feedback mechanism?
- A. Maintaining blood pressure
- B. Uterine contractions during childbirth
- C. Body temperature control
- D. Control of blood sugar
Correct answer: B
Rationale: The correct answer is uterine contractions during childbirth. This is an example of a positive feedback mechanism where the initial stimulus (contractions) leads to an increase in intensity and frequency, ultimately resulting in childbirth. In contrast, choices A, C, and D (maintaining blood pressure, body temperature control, and control of blood sugar) are examples of negative feedback mechanisms. These mechanisms work to maintain stability by counteracting any deviations from the set point, rather than amplifying the response like in a positive feedback mechanism.
4. Homeostasis exists if concentrations of water, nutrients, and oxygen in the body and heat and pressure __________.
- A. decrease steadily
- B. remain within certain limited ranges
- C. increase when the body is stressed
- D. fluctuate greatly between very high and low values
Correct answer: B
Rationale: Homeostasis is the body's ability to maintain stable internal conditions despite external changes. To achieve this balance, concentrations of essential substances must remain within specific ranges. Choice A is incorrect because decreasing concentrations would not maintain stability. Choice C is incorrect as increasing concentrations when the body is stressed would disrupt homeostasis. Choice D is incorrect as fluctuating greatly between high and low values would also not support the body's stability. Therefore, the correct answer is B, as it aligns with the concept of homeostasis by emphasizing the need for stability within certain limits.
5. Testosterone production is regulated by which of the following glands?
- A. Pineal
- B. Thymus
- C. Parathyroid
- D. Pituitary
Correct answer: D
Rationale: Testosterone production is regulated by the pituitary gland. The pituitary gland secretes luteinizing hormone (LH), which stimulates the Leydig cells in the testes to produce testosterone. This hormone is not regulated by the Pineal, Thymus, or Parathyroid glands. The Pineal gland is responsible for secreting melatonin, the Thymus gland is involved in immune function, and the Parathyroid glands regulate calcium levels in the blood.
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