________ is a small connective tissue peg that contains nerve endings and blood vessels.

Correct Answer: D

Rationale: The correct answer is D: Hair papilla. The hair papilla is a small connective tissue peg located at the base of the hair follicle and contains nerve endings and blood vessels. It supplies nutrients to the hair bulb and helps in hair growth. The other choices are incorrect because: A) Hair cuticle is the outermost layer of the hair shaft. B) Hair bulb is the rounded, enlarged area at the base of the hair follicle where hair growth occurs. C) Hair matrix is the actively dividing part of the hair follicle responsible for producing new hair cells.

Correct Answer: D

Rationale: The correct answer is D, all of the choices. UV radiation damages collagen and elastin fibers, leading to skin wrinkling. Aging causes a decrease in collagen production and skin elasticity, contributing to sagging. Hormonal changes, like decreased estrogen levels, also impact collagen production and skin thickness. Therefore, all three factors (UV radiation, aging, hormonal changes) play significant roles in causing skin wrinkle and sagging. Other choices are incorrect as they do not encompass the comprehensive factors that contribute to these skin conditions.

Correct Answer: D

Rationale: The correct answer is D, stratum corneum. Insensible perspiration involves the constant evaporation of water through the skin to maintain body temperature. The stratum corneum is the outermost layer of the epidermis, consisting of dead cells that are continuously shed and replaced. This layer provides a barrier function and regulates the loss of water from the body. The other choices (A: stratum granulosum, B: stratum basale, C: stratum spinosum) are not involved in insensible perspiration as they are deeper layers of the epidermis responsible for cell division, keratin production, and structural support.

Correct Answer: C

Rationale: The correct answer is C: Vellus hairs. Vellus hairs are fine, unpigmented hairs that cover most of the body surface. They are short, thin, and barely noticeable. Velvet hairs (A) and follicular hairs (B) are not specific types of hairs. Terminal hairs (D) are thicker, coarser, and darker hairs found on the scalp, armpits, and pubic region, not fine and lacking pigment like vellus hairs. Therefore, vellus hairs are the correct choice for fine, pigmentless hairs covering much of the body surface.

Correct Answer: C

Rationale: The correct answer is C: fissure. A fissure is a groove or crack-like break in the skin. The term accurately describes the characteristic mentioned in the question. Exudate (A) refers to fluid discharge, hidrosis (B) refers to sweating, and heparin (D) is a medication used as a blood thinner. These choices are unrelated to the description of a groove or crack-like break in the skin, making them incorrect in this context.