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ATI Anatomy and Physiology Online Practice
1. Which of the following is not an example of a homeostatic mechanism in the human body?
- A. Shivering when the body temperature falls below normal.
- B. Increasing heart rate and force of contraction when blood pressure falls.
- C. Retaining fluid excessively.
- D. Secreting insulin after a meal to return blood sugar concentration toward normal.
Correct answer: C
Rationale: The correct answer is C. Homeostatic mechanisms aim to maintain internal stability within the body. Choices A, B, and D all represent examples of homeostatic mechanisms. Shivering helps generate heat to raise body temperature back to normal levels. Increasing heart rate and force of contraction work to restore blood pressure. Insulin secretion after a meal helps regulate blood sugar levels. On the other hand, retaining fluid excessively can lead to fluid imbalance rather than maintaining internal stability, making it the incorrect choice.
2. Organ systems consist of organs, which consist of tissues.
- A. True
- B. False
- C. Not Sure
- D. None of the above
Correct answer: A
Rationale: The statement is true. Organ systems are made up of organs, which in turn are composed of tissues. Organs are structures made up of two or more types of tissues that work together to perform specific functions. Tissues, on the other hand, are groups of cells that work together to perform a specific function. Therefore, organs are made up of tissues, and organ systems consist of organs.
3. Which of the following is the measurement of the percentage of red blood cells in whole blood?
- A. Hematocrit
- B. Hemoglobin
- C. Mean corpuscular volume
- D. Reticulocyte count
Correct answer: A
Rationale: The correct answer is 'Hematocrit.' Hematocrit is the measurement of the percentage of red blood cells in whole blood. It is used to diagnose conditions such as anemia and dehydration. Choice B, 'Hemoglobin,' measures the amount of hemoglobin in the blood, not the percentage of red blood cells. Choice C, 'Mean corpuscular volume,' measures the average volume of a red blood cell, not the percentage of red blood cells. Choice D, 'Reticulocyte count,' measures the percentage of young red blood cells in the blood, not the percentage of red blood cells.
4. What function is associated with the dermal layer of the skin?
- A. Sensory perception
- B. To provide support and structure to the skin
- C. Protection from UV rays
- D. Insulation
Correct answer: B
Rationale: The correct function associated with the dermal layer of the skin is to provide support and structure to the skin. The dermis is the thickest layer of the skin and is responsible for maintaining the skin's integrity and firmness. Choices A, C, and D are incorrect as sensory perception, protection from UV rays, and insulation are functions associated with other layers of the skin, such as the epidermis and subcutaneous tissue.
5. 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.
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