While walking in sunshine the face generally becomes reddish. This is due to-

Correct Answer: A

Rationale: The correct answer is A. When exposed to sunlight, the skin responds by widening the capillaries to allow more blood flow, leading to a reddish appearance. This process is known as vasodilation. Option B is incorrect as blood cells do not ooze out through skin pores. Option C is inaccurate as haemoglobin breakdown does not cause skin reddening. Option D is also incorrect since the spleen does not release more blood in response to sunlight.

Correct Answer: D

Rationale: The correct answer is D: Stratum lucidum. This layer of the epidermis is known for its clear, translucent appearance and plays a key role in forming a barrier that prevents the entry of water and other substances into the body. It is located between the stratum corneum and the stratum granulosum. The other choices are incorrect because: A: Stratum spongiosum is not a recognized layer of the epidermis. B: Stratum granulosum is involved in the production of keratin and the formation of the skin barrier, but it is not specifically responsible for preventing the entry of water and other substances. C: Stratum germinativum, also known as the stratum basale, is responsible for cell division and regeneration, not primarily for barrier function.

Correct Answer: B

Rationale: Correct Answer: B Rationale: 1. Melanin is produced from the amino acid tyrosine, making choice A true. 2. Melanin protects DNA from UV radiation, making choice C true. 3. Melanin is usually some shade of brown or black, making choice D true. 4. Melanin actually increases in concentration within cells during exposure to the sun to provide more protection, making choice B false. Summary: Choices A, C, and D are true statements about melanin. Choice B is incorrect as melanin increases in concentration during sun exposure.

Correct Answer: A

Rationale: The correct answer is A: Dermatitis. Dermatitis refers to skin inflammation, and when it primarily involves the papillary layer (located in the dermis), it is termed papillary dermatitis. This layer contains blood vessels, nerves, and collagen fibers, making it a common site for inflammation. The other choices are incorrect because: B: Papillitis specifically refers to inflammation of the papillae on the tongue or eye. C: Epidermatitis would suggest inflammation of the epidermis layer, not the papillary layer. D: Melanocytic relates to melanocytes, which are pigment-producing cells in the skin, not inflammation of the papillary layer.

Correct Answer: A

Rationale: The correct answer is A. Accessory structures of the integument, like hair and nails, do not provide direct protection to the skull. Skull protection primarily comes from the cranial bones and meninges. Hair and nails are involved in thermoregulation, sensation of touch, and production of skin pigments. Therefore, choice A is incorrect as the accessory structures do not directly protect the skull but serve other functions related to the integument system.