Test: Integumentary System - 1 - MCAT MCQ

The epidermis is the outermost layer of the skin and is responsible for producing new skin cells. It is composed of several layers, including the basal layer, which contains cells called keratinocytes. These keratinocytes continuously divide and produce new cells that move towards the surface of the epidermis, eventually replacing the old cells that are shed from the skin.

Sebaceous glands are responsible for producing sebum, an oily substance that lubricates and moisturizes the skin. Sebum helps to keep the skin soft and supple and also plays a role in protecting the skin from external factors, such as bacteria and moisture loss. Sweat glands, on the other hand, are responsible for producing sweat, which helps regulate body temperature.

The skin does not play a role in the production of red blood cells. Red blood cells are produced in the bone marrow. However, the skin does have important functions such as protecting against pathogens, regulating body temperature through sweating and blood flow control, and participating in the synthesis of vitamin D when exposed to sunlight.

Melanin is the pigment responsible for the color of the skin and hair. It is produced by melanocytes, which are specialized cells located in the epidermis. The amount and type of melanin produced determine the individual's skin and hair color. Melanin acts as a natural sunscreen, protecting the skin from the harmful effects of UV radiation.

The dermis is the second layer of the skin, located beneath the epidermis. It is composed of connective tissue and contains blood vessels, nerves, hair follicles, sweat glands, and sebaceous glands. The dermis provides structural support to the skin and is responsible for its elasticity and strength.

Sweat glands, also known as sudoriferous glands, play a crucial role in the regulation of body temperature. They produce sweat, which is composed of water, salts, and small amounts of other substances. When sweat evaporates from the skin surface, it helps to cool down the body and maintain a stable internal temperature. Sweat glands are most abundant in areas such as the armpits and forehead.

The hypodermis, also known as the subcutaneous layer or superficial fascia, is the deepest layer of the skin. It is primarily composed of adipose tissue, which serves as insulation and energy storage. The hypodermis also connects the skin to underlying structures, such as muscles and bones.

The arrector pili muscles are small muscles attached to hair follicles in the skin. When these muscles contract, they cause the hair to stand up, resulting in the formation of "goosebumps." This response is often triggered by cold temperatures or emotional stimuli and is a vestige of our evolutionary ancestors' response to threat or cold conditions.

The stratum corneum is the outermost layer of the epidermis and is composed of dead, flattened cells filled with keratin. Its primary function is to act as a physical barrier, protecting the underlying layers of the skin from environmental factors, pathogens, and water loss. It helps prevent the entry of harmful substances and microorganisms into the body.

The nail matrix, located at the base of the nail beneath the cuticle, is responsible for nail growth. It contains specialized cells that divide and produce new nail cells. As these cells are pushed forward, they harden and form the nail plate. The nail bed is the area of skin beneath the nail plate, and the lunula is the whitish, crescent-shaped area at the base of the nail. The eponychium, also known as the cuticle, is the layer of skin that overlaps and protects the base of the nail.