which of the following ions is most abundant in extracellular fluid

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. 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.

3. Reproduction is the change in body characteristics over time.

A. TRUE
B. FALSE
C. Not Sure
D. None of the above

Correct answer: B

Rationale: Reproduction is the process by which living organisms produce offspring of the same kind. It is not related to changes in body characteristics over time. Therefore, the statement is false. Choices C and D are also incorrect as they do not align with the definition of reproduction.

4. Which of the following is a role of platelets in hemostasis?

A. formation of plugs
B. promotion of vasodilation
C. conversion of prothrombin to thrombin
D. activation of calcium

Correct answer: A

Rationale: Platelets play a crucial role in hemostasis by forming plugs to stop bleeding. Choice B is incorrect because platelets do not promote vasodilation; instead, they help in vasoconstriction. Choice C is incorrect as the conversion of prothrombin to thrombin is a function of the coagulation cascade involving various clotting factors, not platelets. Choice D is incorrect as platelets do not directly activate calcium; instead, they play a role in the activation of other clotting factors.

5. 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.