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Integumentary System - Anatomy & Physiology

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  • What are the main components of the integumentary system?

    The integumentary system includes skin, hair, nails, sweat glands, sebaceous glands, and mammary glands.

  • What are the primary functions of the skin?

    Skin provides protection, temperature regulation, excretion, synthesis and storage of lipids and vitamin D3, immune response coordination, and sensation.

  • What are the layers of the cutaneous membrane?

    The cutaneous membrane consists of the epidermis (superficial epithelium) and the dermis (underlying connective tissue).

  • What is the hypodermis and is it part of the integument?

    The hypodermis (subcutaneous layer) lies deep to the dermis, contains adipose tissue and blood vessels, and is not normally considered part of the integument.

  • What are the functions of the epidermis?

    The epidermis protects the dermis, controls skin permeability, prevents water loss, blocks pathogen entry, synthesizes vitamin D3, and contains sensory receptors.

  • What are the two layers of the dermis and their functions?

    The papillary layer nourishes and supports the epidermis; the reticular layer restricts pathogen spread, stores lipids, attaches skin to deeper tissues, and contains sensory receptors and blood vessels.

  • Name the four cell types found in the epidermis.

    Keratinocytes (produce keratin), melanocytes (produce melanin), Merkel cells (sensory), and Langerhans cells (immune macrophages).

  • What are the layers of the epidermis from deepest to most superficial?

    Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (only in thick skin), and stratum corneum.

  • What is the function of the stratum basale?

    It contains basal stem cells for regeneration, melanocytes for pigment, and Merkel cells for touch sensation.

  • What distinguishes thick skin from thin skin?

    Thick skin has five epidermal layers including stratum lucidum and is found on palms and soles; thin skin lacks stratum lucidum and covers most of the body.

  • What causes fingerprints?

    Dermal papillae form ridges in the epidermis called epidermal ridges, creating unique fingerprint patterns.

  • What factors influence skin color?

    Skin color depends on dermal blood supply, stratum corneum thickness, and concentrations of carotene and melanin, all under genetic control.

  • How does melanin protect the skin?

    Melanin absorbs UV radiation, protecting skin cells from damage and contributing to natural skin color and tanning.

  • What is the role of vitamin D synthesis in the skin?

    UV light converts a cholesterol precursor to vitamin D3, which is then activated in the liver and kidneys to regulate calcium metabolism.

  • What are the main components of the dermis?

    The dermis contains the papillary layer (loose connective tissue, capillaries, neurons) and the reticular layer (dense irregular connective tissue, hair follicles, sweat and sebaceous glands).

  • What causes wrinkles and stretch marks in the dermis?

    Wrinkles result from aging, hormone changes, and UV damage; stretch marks occur when reticular fibers break due to excessive stretching.

  • What are tension lines (cleavage lines) in the skin?

    They are patterns of collagen and elastic fibers aligned parallel in the dermis, guiding surgical incisions to reduce scarring.

  • What is the function of the blood supply in the dermis?

    Blood vessels form the cutaneous and subpapillary plexuses, aiding in thermoregulation and maintaining blood flow to tissues.

  • What types of sensory receptors are found in the dermis?

    Tactile discs (light touch), Ruffini corpuscles (stretch), and lamellated corpuscles (deep pressure and vibration).

  • What are the main accessory structures of the integumentary system?

    Hair follicles, sebaceous glands, sweat glands, and nails.

  • Where is hair not found on the body?

    Hair is absent on the palms, soles, sides of fingers and toes, lips, and certain genital areas.

  • What are the parts of a hair follicle and hair shaft?

    Hair papilla, hair bulb, hair matrix (keratinized cells), medulla (soft keratin), cortex (hard keratin), cuticle, hair root, and hair shaft.

  • What are the functions of hair?

    Protection from UV light, insulation, guarding entrances (nose, ears), sensory input via root hair plexus, and goosebumps from arrector pili contraction.

  • What are the types of hair?

    Lanugo (embryonic, unpigmented), vellus (fine body hair), and terminal (head, eyebrows, eyelashes).

  • What determines hair color?

    Hair color depends on melanin production by melanocytes; more melanin means darker hair, less melanin causes gray or white hair.

  • Describe the hair growth cycle.

    Active growth phase lasts 2-5 years with ~0.33 mm/day growth; resting phase where hair detaches and becomes a club hair; replacement hair then grows.

  • What types of glands are found in the skin?

    Sebaceous glands (sebum), sweat glands (apocrine and eccrine), ceruminous glands (earwax), and mammary glands (milk production).

  • What is the function of sebaceous glands?

    They secrete oily sebum to lubricate skin and hair, inhibit bacterial growth, and are found everywhere except palms and soles.

  • What distinguishes apocrine and eccrine sweat glands?

    Apocrine glands produce odorous secretions in armpits and nipples; eccrine glands produce watery sweat for cooling and are widespread.

  • What is the structure and function of nails?

    Nails protect finger and toe tips; composed of nail body, root, lunula, eponychium, hyponychium, and nail folds.