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. The thoracic cavity lies _____________ the abdominopelvic cavity.

A. dorsal (posterior) to
B. ventral (anterior) to
C. superior to
D. inferior to

Correct answer: C

Rationale: The correct answer is 'superior to.' The thoracic cavity is located above the abdominopelvic cavity, making it superior. The term 'dorsal (posterior) to' refers to the back side, 'ventral (anterior) to' indicates the front side, and 'inferior to' means below. In the context of body cavities, the thoracic cavity is positioned higher than the abdominopelvic cavity, making 'superior to' the most appropriate choice.

3. 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.

4. 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.

5. Which of the following lists best illustrates the idea of increasing levels of complexity?

A. Cells, tissues, organelles, organs, organ systems
B. Tissues, cells, organs, organelles, organ systems
C. Organs, organelles, organ systems, cells, tissues
D. Organelles, cells, tissues, organs, organ systems

Correct answer: D

Rationale: The correct answer is D: Organelles, cells, tissues, organs, organ systems. This list correctly depicts the increasing levels of complexity in biological organization. It starts with organelles, which are subunits within cells, followed by cells, then tissues (groups of cells working together), organs (comprised of different tissues), and finally organ systems (multiple organs working together). Choices A, B, and C are incorrect as they do not follow the logical progression of complexity from smaller units to larger, more complex structures.