When the pulmonary valve and aortic valves are open, where can blood flow?

Correct Answer: C

Rationale: When the pulmonary valve and aortic valves are open, blood can flow between the heart and the rest of the body. The pulmonary valve allows blood to flow from the right ventricle to the lungs for oxygenation, while the aortic valve permits blood to flow from the left ventricle to the rest of the body for distribution of oxygen and nutrients. This circulation pathway ensures that oxygen-rich blood is pumped to the body tissues. Choices A, B, and D are incorrect because when the pulmonary valve and aortic valves are open, blood is not flowing between the ventricles, from atrium to ventricle, or between the atria; instead, it is being pumped out of the heart to the lungs and the rest of the body.

Correct Answer: B

Rationale: The correct answer is B: Approximately 30. The human skull is composed of 22 bones that are fused together. These 22 bones consist of 8 cranial bones and 14 facial bones, totaling approximately 30 bones in total. Choices A, C, and D are incorrect because the human skull does not have as few as 5 bones, as many as 60 bones, or as many as 210 bones. Understanding the basic anatomy of the skull helps in identifying the correct number of bones it comprises.

Correct Answer: D

Rationale: The correct answer is D, Cardiovascular system. Arteries are blood vessels that carry oxygen-rich blood away from the heart to various parts of the body. They are a key component of the cardiovascular system, which is responsible for transporting blood, nutrients, and oxygen throughout the body. The other options (A, B, and C) are incorrect because arteries are not part of the nervous system, endocrine system, or lymphatic system.

Correct Answer: C

Rationale: Inflammation is a secondary defense mechanism for the body against pathogens. When tissues are injured or infected, inflammation occurs as a protective response involving increased blood flow, white blood cell migration, and tissue repair. This process helps contain and eliminate pathogens, preventing them from spreading further in the body. Tears (Choice A) are a primary defense containing lysozyme and other antimicrobial agents. Urine (Choice B) is typically considered a non-specific defense mechanism due to its flushing action in the urinary tract. Mucus (Choice D) acts as a physical barrier and traps pathogens, also considered a primary defense mechanism.

Correct Answer: A

Rationale: The skeletal system is primarily responsible for storing minerals in the body. Bones serve as a storage site for essential minerals such as calcium and phosphorus, which are important for various bodily functions including bone strength, muscle contraction, and nerve signaling. The minerals stored in bones can be released into the bloodstream as needed to maintain optimal mineral levels in the body. The endocrine system is responsible for hormone regulation, not mineral storage. The lymphatic system is involved in immune function and fluid balance, not mineral storage. The cardiovascular system is responsible for circulating blood throughout the body, not storing minerals.