Unit 2- Integumentary Study Guide REVISED PDF

Unit 2: Integumentary Study Guide Composition of the Integument Epidermis - Describe the five layers (strata) of the epidermis. Know these layers based on their characteristics and the order of the layers. 1. Stratum Basale (Basal Layer): Deepest layer, firmly attached to dermis, contains youn...

Unit 2: Integumentary Study Guide Composition of the Integument Epidermis - Describe the five layers (strata) of the epidermis. Know these layers based on their characteristics and the order of the layers. 1. Stratum Basale (Basal Layer): Deepest layer, firmly attached to dermis, contains young keratinocytes that undergo rapid division (germination). 2. Stratum Spinosum (Prickle Layer): Contains intermediate filaments attached to desmosomes, abundant in melanin granules and Langerhans cells. 3. Stratum Granulosum (Granular Layer): Thin layer (3-5 cell layers) with dramatic changes in keratinocyte phenotype. Contains keratohyaline and laminated granules. 4. Stratum Lucidum (Clear Layer): Thin, transparent band superficial to the stratum granulosum. Made of flat, dead keratinocytes, present only in thick skin. 5. Stratum Corneum (Horny Layer): Outermost layer, composed of keratinized cells. Accounts for 75% of the epidermis thickness. Differentiate between thick skin and thin skin. "Thick skin" refers to the skin found on the palms of the hands and soles of the feet, characterized by a thicker epidermis with an additional layer called the stratum lucidum. Thick skin also typically lacks hair follicles and sebaceous glands, which are present in thin skin. "Thin skin" is found on most other body areas and lacks the stratum lucidum layer, resulting in a thinner overall skin structure. Explain what causes differences in skin color Three pigments contribute to skin color: o The amount and kind (yellow, reddish brown, or black) of melanin in the epidermis. o The amount of carotene deposited in the stratum corneum and subcutaneous tissue. o The amount of oxygen-rich hemoglobin (pigment in red blood cells) in the dermal blood vessels. People that produce a lot of melanin have brown-toned skin. In light skinned people, who have less melanin, the crimson color of oxygen-rich hemoglobin in the dermal blood supply flushes through transparent layers and gives a rosy tone. DERMIS - Characterize the two layers of the dermis. Papillary Layer: The upper dermal region. Areolar connective tissue with collagen and elastic fibers. Contains papillary loops (which provide nutrients to the epidermis), Meissner's corpuscles (also known as tactile corpuscles, are specialized nerve endings located in the skin that are primarily responsible for detecting light touch and low-frequency vibrations), and free nerve endings for touch, pain, and other sensations; has ridges which press on the epidermis to produce fingerprints. Reticular Layer: Accounts for 80% of dermis thickness. Contains collagen fibers (strength, resiliency) and elastin fibers (stretch, recoil) as well as blood vessels, sweat and oil glands, deep pressure receptors called Lamellar corpuscles, and Phagocytes. Is the deepest skin layer. List the functions of the subcutaneous layer. Deep to the dermis, the subcutaneous, or hypodermis, layer anchors the skin to underlying organs and provides a site for nutrient (fat) storage. It also serves as a shock absorber and insulates the deeper tissue from extreme temperature changes occurring outside the body. It is also responsible for woman’s curves. Composed of adipose and areolar connective tissue. Be able to identify and know the function of sweat glands. Sweat Glands under the control of the nervous system, produce sweat, which is ducted to the epithelial surface. Functions: Prevent overheating. Types: Eccrine: Palms, soles, forehead – produce sweat; most numerous and are main thermoregulators Apocrine: Axillary (armpit), anogenital areas – larger than eccrine glands and secretions contain fatty acids and proteins as well as sweat but may have a milky or yellowish color. Ceruminous: External ear canal, secrete cerumen (earwax). Mammary: Specialized sweat glands that secrete milk. Describe the function of sebaceous glands. Sebaceous glands produce an oily product (sebum) usually ducted into a hair follicle. Sebum keeps the skin and hair soft and contains bacteria-killing chemicals. Key points about sebaceous glands: Location: Mostly found connected to hair follicles on the face and scalp. Mechanism: Sebum is released through the sebaceous duct that empties into the hair follicle. Benefits of sebum: Hydration: Helps maintain skin moisture and flexibility Protection: Creates a barrier against irritants and bacteria Lubrication: Keeps hair and skin smooth Epidermis Functions Name ways in which the epidermis protects the body and prevents water loss. Functions of the Integumentary System: 1. Protection from: a. Mechanical damage (bumps) – physical barrier contains keratin, which toughens cells; fat cells to cushion blows; and pressure receptors which alert the nervous system to possible damage. b. Chemical damage (acids and bases) – has a relatively impermeable keratinized cells; contains pain receptors, which alert the nervous system to possible damage. c. Bacterial damage – has an unbroken surface and “acid mantle” (skin secretions are acidic and thus inhibit bacteria). Phagocytes ingest foreign substances and pathogens, preventing them from penetrating into deeper body tissues. d. Ultraviolet radiation (damaging effects of sunlight) – Melanin produced by melanocytes offers protection from UV damage. e. Thermal (heat or cold) damage – Contains heat/cold/pain receptors. f. Desiccation (drying out) – Contain a water-resisting glycolipid and keratin. 2. Aids in body heat loss or heat retention (controlled by the nervous system) a. Heat loss – by activating sweat glands and by allowing blood to flush into skin capillary beds so that heat can radiate from the skin surface. b. Heat retention – By not allowing blood to flush into skin capillary beds. 3. Aids in excretion of urea and uric acid – Contained in perspiration produced by sweat glands. 4. Synthesizes vitamin D – Modified cholesterol molecules in skin converted to vitamin D by sunlight. Know the function of Merkel discs Merkel discs serve as touch receptors; they are composed of Merkel cells which are found at the epidermal-dermal junction and are associated with sensory nerve endings. Describe the integument’s role in secretion and absorption. The integument plays a crucial role in secretion by releasing substances like sweat through sweat glands to regulate body temperature, and in absorption by allowing certain substances like vitamin D from sunlight to permeate through its layers and into the bloodstream; essentially acting as a barrier that can selectively allow certain substances to pass through while preventing others. Identify the immune cells that reside in the integument and describe their actions. Epidermal dendritic cells are important in alerting and activating immune system cells to a threat such as bacterial or viral invasion and Phagocytes found in the reticular layer act to prevent bacteria that have managed to get through the epidermis from penetrating any deeper into the body. List some of the shared functions between the dermis and the epidermis. The dermis and epidermis both share functions related to sensation (feeling touch, pressure, pain, temperature), protecting the body, regulating body temperature through blood vessels and sweat glands, and contributing to overall skin barrier function; with the dermis primarily providing structural support and the epidermis acting as the outer protective layer. Explain how skin helps cool the body or retain warmth. 1. Skin helps cool the body by sweating. Sweat glands release moisture that evaporates from the skin surface, taking heat with it. 2. By dilating blood vessels near the skin surface, allowing more warm blood to circulate and release heat into the environment; conversely, to retain warmth, the skin constricts blood vessels, reducing blood flow to the skin and minimizing heat loss. Know all the structures and characteristics associated with the Dermis The dermis, the middle layer of skin, is primarily composed of dense irregular connective tissue containing collagen and elastin fibers, which provide strength and flexibility, and houses various structures including blood vessels, nerve endings, hair follicles, sweat glands, sebaceous glands, and lymphatic vessels; it is divided into a thin upper layer called the papillary dermis and a thicker deeper layer called the reticular dermis. Key structures within the dermis: Collagen fibers: The primary protein in the dermis, providing tensile strength and structure. Elastic fibers: Interwoven with collagen, allowing the skin to regain its shape after stretching. Papillary dermis: The upper layer of the dermis, containing finger-like projections that interlock with the epidermis. Reticular dermis: The deeper layer of the dermis, with thicker bundles of collagen fibers. Blood vessels: Supply nutrients to the dermis and epidermis. Nerve endings: Sensory receptors that detect touch, pressure, temperature, and pain. Hair follicles: Structures that produce hair, anchored in the dermis. Sweat glands: Produce sweat to regulate body temperature. Sebaceous glands: Produce sebum, an oily substance that lubricates the skin. Key characteristics of the dermis: Provides structural support for the skin: Due to its collagen and elastin network, the dermis gives the skin its shape and resilience. Sensory perception: Houses nerve endings that allow for the perception of touch, pressure, temperature, and pain. Thermoregulation: Plays a role in temperature control through sweat gland activity. Blood supply: Rich network of blood vessels that nourish the skin. Connective tissue composition: Primarily composed of dense irregular connective tissue Know all the structures and characteristics associated with the Hypodermis The hypodermis, also called the subcutaneous tissue, is the deepest layer of skin and is primarily characterized by the presence of adipose (fat) tissue, loose connective tissue, larger blood vessels, nerves, and occasional hair follicles, acting as a cushion and insulator for the body by storing fat and connecting the skin to underlying muscles and bones. Key structures and characteristics of the hypodermis: Adipose tissue: The primary cell type in the hypodermis, storing fat for energy and providing insulation. Connective tissue: Loose areolar connective tissue that allows for flexibility and movement of the skin. Blood vessels: Larger blood vessels compared to the dermis, supplying the hypodermis with nutrients and oxygen. Nerves: Sensory nerve endings that transmit touch sensations Hair follicles: Occasionally present, extending into the hypodermis where the hair root is located Functions of the hypodermis: Fat storage: Acts as a major site for fat storage in the body Cushioning: Protects underlying muscles and bones from impact due to its fat padding Thermoregulation: Helps regulate body temperature by insulating the body with stored fat Anchoring the skin: Connects the skin to deeper tissues like muscles and bones through connective tissue