All flashcards
Flashcard 1: What is the primary effect of cutaneous vasodilation on body temperature?
Answer: Increases heat loss by raising skin blood flow. By expanding vessels, it enhances convective and radiative heat transfer from blood to the environment.
Flashcard 2: What are the three major layers of the skin from superficial to deep?
Answer: Epidermis, dermis, hypodermis (subcutaneous tissue). These layers form the skin's structure, with the epidermis as the protective outer barrier, dermis providing support and elasticity, and hypodermis offering insulation and anchorage.
Flashcard 3: What type of epithelium composes the epidermis?
Answer: Keratinized stratified squamous epithelium. This epithelial type provides a tough, waterproof barrier due to multiple layers of flattened cells filled with keratin, ideal for protection against environmental stressors.
Flashcard 4: What is the primary barrier function of the stratum corneum?
Answer: Limits water loss and blocks pathogen/chemical entry. As the outermost layer of dead, keratinized cells, it forms an impermeable shield that prevents dehydration and invasion by external threats.
Flashcard 5: Which epidermal layer contains actively dividing keratinocytes?
Answer: Stratum basale (germinativum). This deepest layer houses mitotic stem cells that continuously generate new keratinocytes to replace those shed from the surface.
Flashcard 6: Which epidermal layer is present only in thick skin (palms and soles)?
Answer: Stratum lucidum. Present in areas of high friction, this translucent layer of dead cells adds extra protection and thickness to withstand mechanical stress.
Flashcard 7: What is the main structural protein produced by keratinocytes?
Answer: Keratin. This fibrous protein forms intermediate filaments in keratinocytes, conferring mechanical strength and water resistance to the epidermis.
Flashcard 8: What is the primary function of melanocytes in the epidermis?
Answer: Produce melanin to protect against ultraviolet radiation. These cells synthesize pigment that absorbs harmful UV rays, shielding DNA in keratinocytes from mutations and damage.
Flashcard 9: Identify the epidermal cell type that provides immune surveillance via antigen presentation.
Answer: Langerhans cells (dendritic cells). Derived from bone marrow, these immune cells capture skin antigens and migrate to lymph nodes to activate T-cell responses.
Flashcard 10: Which epidermal cell type functions as a mechanoreceptor for light touch?
Answer: Merkel cells. Associated with sensory nerve endings, these cells transduce mechanical stimuli into neural signals for tactile discrimination.
Flashcard 11: What is the primary tissue type of the dermis?
Answer: Dense irregular connective tissue. With collagen and elastin fibers oriented randomly, this tissue resists multidirectional stresses while providing flexibility and strength.
Flashcard 12: Which dermal layer contains most hair follicles, glands, and blood vessels?
Answer: Reticular dermis. As the deeper, denser layer, it supports skin appendages and vasculature crucial for nutrient delivery and sensory functions.
Flashcard 13: What is the main composition and role of the hypodermis (subcutaneous tissue)?
Answer: Adipose and areolar CT; insulation, cushioning, energy storage. These loose connective tissues store fat for thermal regulation, absorb shocks, and serve as an energy reserve.
Flashcard 14: Which skin appendage produces sebum, and what is its primary effect on skin?
Answer: Sebaceous gland; lubricates and provides antimicrobial barrier. Associated with hair follicles, it secretes oily sebum that moisturizes skin and inhibits microbial growth via fatty acids.
Flashcard 15: What type of sweat gland is most important for thermoregulation?
Answer: Eccrine sweat gland. Widely distributed, these glands produce watery sweat that evaporates to dissipate heat and maintain core temperature.
Flashcard 16: Which sweat gland is associated with hair follicles and activates at puberty?
Answer: Apocrine sweat gland. Located in axillary and anogenital regions, these glands secrete viscous fluid influenced by hormones, contributing to scent signaling.
Flashcard 17: Which autonomic division primarily controls eccrine sweating?
Answer: Sympathetic nervous system (cholinergic fibers). These fibers release acetylcholine to stimulate sweat secretion, enabling rapid cooling responses to heat or stress.
Flashcard 18: What is piloerection, and which muscle causes it?
Answer: Hair standing; contraction of arrector pili muscle. Sympathetic activation causes this smooth muscle to contract, erecting hairs to trap insulating air in cold conditions.
Flashcard 19: Which hypothalamic region is the primary thermostat for heat dissipation responses?
Answer: Anterior hypothalamus (preoptic area). This region senses elevated core temperature and initiates sweating and vasodilation to promote heat loss.
Flashcard 20: Which hypothalamic region is most associated with heat conservation and generation responses?
Answer: Posterior hypothalamus. This area detects hypothermia and activates shivering and vasoconstriction to generate and conserve body heat.
Flashcard 21: What is the most effective mechanism of heat loss during vigorous exercise in humans?
Answer: Evaporation of sweat. As sweat vaporizes, it absorbs latent heat from the skin, providing efficient cooling when other mechanisms are insufficient.
Flashcard 22: What is the primary effect of cutaneous vasoconstriction on body temperature?
Answer: Decreases heat loss by reducing skin blood flow. By narrowing vessels, it limits warm blood exposure to cold skin, minimizing heat dissipation to maintain core warmth.
Flashcard 23: Identify the heat transfer mechanism: heat loss to moving air or water across skin.
Answer: Convection. This process involves heat transfer from the body to surrounding fluid in motion, enhanced by wind or water flow.
Flashcard 24: Identify the heat transfer mechanism: heat exchange by direct physical contact with a surface.
Answer: Conduction. This direct transfer occurs when the skin touches a cooler object, allowing heat to flow down the temperature gradient.
Flashcard 25: What is the formula for body mass index (BMI) in SI units?
Answer: BMI=h2m. Using mass in kilograms and height in meters squared, it quantifies adiposity for assessing health risks.