System Function: Integumentary - Massage and Bodywork Licensing Examination Mblex

What is the outermost layer of the epidermis in thick skin?

Stratum corneum. Consists of dead, keratin-filled cells that form a waterproof, protective barrier against abrasion and microbes.
Which dermal layer is superficial and contains dermal papillae and capillary loops?

Papillary layer of the dermis. Interfaces with epidermis via projections that enhance nutrient exchange and sensory function.
Which sweat glands are most associated with odor and become active at puberty?

Apocrine sweat glands. Secrete viscous fluid in axillary and genital areas, influenced by hormones, contributing to body odor via bacterial breakdown.
What is the main pigment responsible for most variation in human skin color?

Melanin. Produced by melanocytes in varying amounts and types, determining skin tone and UV protection levels.
Which skin receptors detect light touch and low-frequency vibration in glabrous skin?

Meissner (tactile) corpuscles. Located in dermal papillae, these encapsulated receptors adapt quickly to stimuli for precise sensation.
Which epidermal sensory cell is associated with light touch sensation?

Merkel cell (tactile epithelial cell). Associates with sensory neurons to detect fine touch and texture, contributing to tactile discrimination.
What is the main protein that hardens and waterproofs the epidermis?

Keratin. Forms a fibrous network that toughens cells, providing mechanical strength and impermeability to water.
What is the primary secretion of sebaceous glands called?

Sebum. Oily substance produced by holocrine secretion from glands associated with hair follicles.
What is the primary function of eccrine (merocrine) sweat glands?

Thermoregulation via watery sweat secretion. Cools the body through evaporative heat loss from widespread glands activated by heat or stress.
Which dermal layer contains dense irregular connective tissue and most skin appendages?

Reticular layer of the dermis. Offers tensile strength and houses blood vessels, nerves, and glands for nourishment and function.
Which epidermal cell produces melanin to help protect against ultraviolet radiation?

Melanocyte. Synthesizes melanin pigment that absorbs UV rays, shielding DNA in keratinocytes from damage.
What is the primary function of the hypodermis (subcutaneous layer)?

Anchors skin; insulation and energy storage (adipose). Secures dermis to muscles and bones while storing fat for cushioning, thermal insulation, and caloric reserve.
Which thermoregulatory response conserves heat by reducing blood flow to the skin?

Cutaneous vasoconstriction. Narrows vessels to minimize heat loss from blood to skin, preserving core temperature in cold conditions.
What is the main function of sebum on skin and hair?

Lubricates and provides antimicrobial protection. Coats hair and skin to maintain moisture, softness, and defense against bacteria and fungi.
What type of epithelium composes the epidermis?

Keratinized stratified squamous epithelium. Provides a tough, protective barrier that regenerates continuously and prevents water loss and pathogen entry.
Which epidermal layer is responsible for continuous mitosis and new keratinocyte production?

Stratum basale (stratum germinativum). Contains stem cells that divide to replenish keratinocytes, ensuring epidermal renewal every 25-45 days.
What is the primary cell type of the epidermis?

Keratinocyte. Produces keratin for structural integrity and forms the majority of epidermal cells, migrating upward as they mature.
What are the three main layers of the skin from superficial to deep?

Epidermis, dermis, hypodermis (subcutaneous layer). Forms the structural organization of skin, with epidermis as outer barrier, dermis providing support, and hypodermis anchoring to underlying tissues.
What is the major mechanism of heat loss when cutaneous blood vessels dilate?

Increased heat transfer from skin to environment. Vasodilation enhances blood flow to skin surface, promoting radiation and convection of excess body heat.
What is the primary overall function of the integumentary system in human physiology?

Protection and homeostasis via skin and its appendages. Acts as a barrier against environmental threats and maintains internal balance through temperature regulation, sensation, and vitamin synthesis.
What is the role of the integumentary system in vitamin $D$ production?

UV exposure enables vitamin $D_3$ synthesis in the epidermis. Converts 7-dehydrocholesterol to previtamin $D_3$ in keratinocytes, essential for calcium absorption and bone health.
Which skin receptors are free nerve endings primarily responsible for pain and temperature?

Free nerve endings (nociceptors and thermoreceptors). Unencapsulated dendrites throughout skin detect noxious stimuli, heat, and cold for protective responses.
Which skin receptors detect deep pressure and high-frequency vibration?

Pacinian (lamellated) corpuscles. Deep in dermis or hypodermis, these onion-like structures sense rapid changes in pressure and vibration.
Which epidermal immune cell provides phagocytosis and antigen presentation?

Langerhans cell (epidermal dendritic cell). Functions in immune surveillance by engulfing pathogens and presenting antigens to activate T-cells.
What is arrector pili, and what visible effect can it produce on the skin?

Smooth muscle that elevates hair; causes goosebumps. Contracts in response to cold or emotion, pulling hair upright to trap air for insulation.

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