What is the first step in pulmonary circulation?

Correct Answer: B

Rationale: The correct answer is B: The pulmonary artery carries blood from the heart to the lungs. The first step in pulmonary circulation involves the right ventricle of the heart pumping deoxygenated blood into the pulmonary artery. The pulmonary artery then carries this deoxygenated blood from the heart to the lungs for oxygenation. This step is crucial for the exchange of carbon dioxide for oxygen to occur in the lungs, facilitating the oxygenation of blood. Choices A, C, and D are incorrect because they do not represent the initial step in pulmonary circulation. Option A refers to blood moving away from the heart, option C describes the gas exchange process that occurs in the lungs but not as the first step, and option D mentions oxygenated blood moving through the aorta, which happens after oxygenation in the lungs.

Correct Answer: C

Rationale: The skeletal system collaborates with the nervous system by providing protection and support for critical nervous system components. The vertebrae of the spine play a crucial role in safeguarding the spinal cord, a key component of the nervous system responsible for transmitting messages between the brain and the body. Protecting the spinal cord is essential to prevent neurological complications. Choices A, B, and D are incorrect because while bones do play a role in body position and can sense pain, the primary focus of the skeletal system's interaction with the nervous system is to protect vital components like the spinal cord, rather than generating nerve cells.

Correct Answer: D

Rationale: Melatonin is the hormone produced by the pineal gland. It plays a crucial role in regulating the sleep-wake cycle and is instrumental in maintaining the body's circadian rhythm. Melatonin production is triggered by darkness and inhibited by light, aiding in signaling the body when it is time to sleep. Corticosteroid, oxytocin, and prolactin are hormones produced by other glands in the body and are not associated with the pineal gland. Therefore, they are incorrect choices for this question.

Correct Answer: A

Rationale: The anterior chamber of the eye is the fluid-filled space located between the cornea and the iris in the front part of the eye. It contains aqueous humor and helps maintain intraocular pressure. The space between the iris and the lens is known as the anterior chamber, making option A, 'iris and lens,' the correct choice. Options B, C, and D are incorrect because they do not describe the correct anatomical location of the anterior chamber.

Correct Answer: D

Rationale: The average normal body temperature in degrees Celsius is 37°C. This temperature is considered the standard measurement for the human body under normal conditions. It is essential to know this baseline temperature for monitoring health and detecting abnormalities such as fever. Choice A, 30°C, is too low for the average normal body temperature. Choice B, 32°C, is also below the standard normal body temperature. Choice C, 35°C, is closer but still lower than the average normal body temperature of 37°C.