The mediastinum is located in which of the following cavities contains?

Correct Answer: B

Rationale: The correct answer is B: Thoracic. The mediastinum is a central compartment in the thoracic cavity that houses vital structures such as the heart, major blood vessels, esophagus, trachea, and thymus gland. It is located between the lungs and extends from the sternum to the vertebral column. The other choices are incorrect because: A: Dorsal refers to the back, C: Abdominal refers to the abdomen, and D: Cranial refers to the head. These locations do not accurately describe the position of the mediastinum.

Correct Answer: D

Rationale: The correct answer is D because the integumentary system has evolved various adaptations to help organisms survive in different environments. A is correct as thick fur or feathers help retain heat in cold climates. B is correct as thick skin helps prevent water loss in desert climates. C is correct as scales or fins protect aquatic animal skin. Therefore, D encompasses all these adaptations, making it the correct choice.

Correct Answer: C

Rationale: The correct answer is C: It is hypertension with no specific cause. Essential hypertension is the most common type of high blood pressure, where there is no identifiable underlying cause. This distinguishes it from secondary hypertension which is caused by another disease (eliminating option A). Option B is incorrect as the term 'essential' in essential hypertension does not imply the necessity of treatment, but rather the absence of a known cause. Option D is also incorrect as essential hypertension does not necessarily refer to severe or life-threatening hypertension, but rather indicates a primary form with no specific cause.

Correct Answer: A

Rationale: The correct answer is A: Skin. The integumentary system consists of the skin, which includes the epidermis, dermis, and hypodermis. The epidermis is the outermost layer of the skin, providing protection and regulating temperature. Choice B (Skin and skin derivatives) is incorrect as the epidermis itself is considered part of the skin, not a derivative. Choice C (Skin and cutaneous gland) and choice D (Skin and hairs) are also incorrect as they are specific structures or components of the skin, not the entire integumentary system. The term "skin" encompasses all layers and structures that make up the integumentary system, making choice A the most appropriate answer.

Correct Answer: B

Rationale: The correct answer is B: Stratum granulosum. This layer of the epidermis contains granules of keratohyaline protein, which play a crucial role in the formation of keratin. Keratohyaline granules help bind keratin filaments together, leading to the development of a tough, protective barrier in the skin. A: Stratum malpighi is not the correct choice as it refers to the combination of the stratum basale and stratum spinosum layers of the epidermis, which do not contain keratohyaline granules. C: Stratum lucidum is not the correct choice as it is a thin, translucent layer found only in certain areas of the skin, such as the palms and soles, and does not contain keratohyaline granules. D: Stratum corneum is not the correct choice as it is the outermost layer of the epidermis composed of dead, ker