Nursing Elites

1. Which of the following cardiac valves prevents blood from returning to the left ventricle of the heart?

• A. pulmonic
• B. mitral
• C. tricuspid
• D. aortic

Correct answer: D

Rationale: The correct answer is the aortic valve. The aortic valve is located between the left ventricle and the aorta, preventing the backflow of blood into the left ventricle once it has been pumped out during systole. Choice A, pulmonic, is incorrect as it is associated with the right side of the heart. Choice B, mitral, is incorrect as it is the valve between the left atrium and ventricle. Choice C, tricuspid, is incorrect as it is located between the right atrium and ventricle.

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. In a normally functioning cardiovascular system, where does the heartbeat originate?

• A. Atrioventricular nodes
• B. Bundle of His
• C. Purkinje fibers
• D. Sinoatrial node

Correct answer: D

Rationale: The correct answer is the Sinoatrial (SA) node. The SA node is known as the natural pacemaker of the heart as it initiates the electrical impulses responsible for the heartbeat. The other choices, such as the Atrioventricular (AV) nodes, Bundle of His, and Purkinje fibers, are involved in conducting the electrical signals generated by the SA node to coordinate the heart's contractions. Therefore, they do not serve as the primary origin of the heartbeat.

4. Cells do not aggregate into organelles based on similar functions.

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

Correct answer: B

Rationale: The statement is false. Cells with similar functions do not aggregate into organelles. Organelles are specialized structures within cells that perform specific functions, such as the nucleus, mitochondria, and endoplasmic reticulum. Cells themselves are the basic structural and functional units of organisms, and organelles are located within cells to carry out various tasks. Therefore, cells do not aggregate into organelles, but organelles are found within cells to support their functions. Choices A, C, and D are incorrect as cells do not form organelles by aggregating based on similar functions.

5. Living organisms use oxygen to __________________.

• A. reduce heat production
• B. accept electrons for cellular metabolism
• C. release energy stored in the molecules of food
• D. remove metabolic wastes

Correct answer: C

Rationale: The correct answer is C. Living organisms use oxygen to release energy stored in the molecules of food through a process called cellular respiration. This process involves breaking down glucose molecules in the presence of oxygen to produce energy in the form of ATP. Choice A is incorrect because oxygen does not directly reduce heat production in organisms. Choice B is incorrect because oxygen is involved in accepting electrons rather than donating them in cellular metabolism. Choice D is incorrect because the removal of metabolic wastes is not the primary role of oxygen in living organisms.

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