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Integumentary Sytem
Doc. Milliem Reyes|1st^ Semester | BSMLS-1K
INTEGUMENTARY SYSTEM contributes to homeostasis by protecting the body and helping regulate body temperature. It also allows you to sense pleasurable, painful stimuli in your external environment. ● skin, hair, oil and sweat glands, nails, and sensory receptors ● Skin Accessory structure SKIN The skin (also known as the cutaneous membrane or integu ment) covers the body's external surface and is the body's largest organ in both surface area and weight. Protection from outside, regulation of body temperature, stores blood, cutaneous sensation, Vit D synthesis ● 16% of weight ● 1.5m^ ● Largest organ in the body ➢ EPIDERMIS - avascular ➢ Dermis - thicker, connective tissue (vascular) ➢ Hypodermis- Subcutaneous tissue (Fat tissue) The hypodermis is not part of the integumentary system or considered a true skin layer because it is anatomically distinct, composed primarily of connective and adipose tissue, and serves different functions. It lies beneath the dermis and acts mainly as an insulating and cushioning layer. SKIN SENSES Hair roots plexus, transmit info to the central nervous system. They all have their own receptive Meissner’s corpuscle -Light touch (low frequency) specific receptive -Two point discrimination Merkel cell -Continuos touch (tells you the texture) specific receptive -Two point discrimination Pacinian Corpuscle -Lamellated -fast vibration + deep pressure Wide receptive Ruffini endings -Steady pressure Wide receptive EPIDERMIS The superficial, thinner portion which is composed of epithelial tissue ➢ stratified squamous keratinizing ➢ 4 principal layer ( continues layer)( BS CLG) ➢ four principal types of cells: ker atinocytes, melanocytes, Langerhans cells, and Merkel cells ➢ Thick skin 5 layer - Palm, soles, hairless (ecrine sweat glands) ➢ Thin Skin 4 layer - Everywhere else, has hair Vitamin D (bones) is essential for the bones and teeth, the immune system, brain health, and inflammation regulation. Osteomalacia - “bone softening” in adults that is usually due to prolonged deficiency of vitamin D and Rickets for baby
Integumentary Sytem
Doc. Milliem Reyes|1st^ Semester | BSMLS-1K
PARTS OF EPIDERMIS ● keratinocytes ○ 90% of epidermal cells , which are arranged in four or five layers and produce the protein keratin ○ Produce lamellar granules (water repellant) ● melanocytes ○ 8% of the epidermal cells ○ produce melanin which develop from the ectoderm of a developing embryo and produce the pigment melanin ○ Melanin is a yellow-red or brown-black pigment that contributes to skin color and absorbs damaging ultraviolet (UV) light ● Langerhans cells ○ arise from red bone mar row and migrate to the epidermis ○ Immune response to help other cells of the immune system rec ognize an invading microbe and destroy it. ● Merkell ○ least numerous of the epidermal cells. ○ Deepest layer of the epidermis, where they contact the flattened process of a sensory neuron (nerve cell), a structure called a Merkel (tactile) disc
Integumentary Sytem
Doc. Milliem Reyes|1st^ Semester | BSMLS-1K
DERMIS ● Dense Irregular connective tissue containing collagen and elastic fibers. ● The few cells present in the dermis include predominantly fibroblasts, with some macrophages, and a few adipocytes near its boundary with the subcutaneous layer ● Blood vessels, nerves, glands, and hair follicles (epithelial invagina tions of the epidermis) are embedded in the dermal layer DERMIS TISSUE STRUCTURE PAPILLARY REGION ● Loose aerolar connective tissue ● Dermal papillae ○ Finger like projections into the undersurface of the epidermis. Some of these nipple-shaped structures contain capillary loops (blood vessels). ● Contain fibroblast, adipocytes ● Rete ridges ● Increase surface area by dermal papillae ● Dermal papillae also contain tactile receptors called Meissner corpus cles orcorpuscles of touch, nerve endings that are sensitive to touch,and freenerve endings,dendrites that lack any apparent structural specialization. ● Finger print (papillae and ridges) for grip and traction RETICULAR REGION ● Dense irregular connective tissue ● The collagen fibers in the reticular region interlace in a netlike manner. ● Deepest layer of the skin ● Lameltar corpuscle ● No reticular fiber ● Extreme stretching may produce small tears in the dermis, causing striae or stretch marks,visible as red or silvery white streaks on the skin surface HYPODERMIS ● The subcutaneous layer or superficial fascia ● Loose areolar connective tissue ● Well vascularize ● Contain adipose tissue STRUCTURAL BASIS OF SKIN COLOR SKIN PIGMENTS Melanin, hemoglobin, and carotene are three pigments that impart a wide variety of colors to skin. MELANIN ● Produce by melanocytes ● Causes the skin’s color to vary from pale yellow to reddish brown to black. ● Protects the DNA from damage caused by UV rays ● UV exposure = more melanin produced ● Too much sun exposure - destructure of cell (skin cancer) ● Melanocytes , ○ the melanin producing cells,are most plentiful in the epidermis of the penis, nipples of the breasts, area just around the nipples (areolae), face, and limbs ● Tranfered to keratin via melanosomes ● Eumelanis (brown to black) ● Phenomelnanin (yellow to red) ● ALBINISM ○ They have melanocytes but no melanin ● VIRTILIGO ○ partial or complete loss of melanocytes from patches of skin produces irregular white spots. ● FRECKLES ○ Not permanent The study of the pattern of epidermal ridges is called dermatoglyphics.
Integumentary Sytem
Doc. Milliem Reyes|1st^ Semester | BSMLS-1K
● MOLE
○ Accumulation of melanin HEMOGLOBIN ● Light skinned ○ found in blood depending on oxygen content ● The red color is due to hemoglobin, the oxygen-carrying pigment in red blood cells. CAROTENE ● Precursor of vitamin A ● Found in egg yolks, carrots ● Carotenemia (too much carrot) ACCESSORY STRUCTURES OF THE SKIN hair, skin glands, and nails—develop from the embryonic epidermis. They have a host of important functions. For example, hair and nails protect the body, and sweat glands help regulate body temperature. HAIR Dead keratinized cell. hair on the head guards the scalp from injury and the sun’s rays. It also decreases heat loss from the scalp. hairs also function in sensing light touch. Arrector pili muscle - causes hair to stand up PROTECTION ● Sensory input increases how sensitive you be ● Thermoregulation ● Communication HAIR FOLLICLE CYCLE ● Anagen (growth) - 2yrs ● Catagen(regression) - 2-3weeks ● Telogen(resting) - stop growing 2- months ● Alopecia - the partial or complete lack of hair, may result from genetic factors, aging, endocrine disorders, chemotherapy, or skin disease. ● Hair Grows 0.3mm/day ● 50-100 strands lost and replaced per day HAIR COLOR Influenced by the amount and type of melanin in the keratinized cells Grey hair loose melanocytes Aging reduce melanin TYPES OF HAIR ● lanugo ○ e fifth month of development, the follicles produce very fine, nonpigmented, downy hairs ● terminal hairs. ○ Prior to birth, the lanugo of the eyebrows, eyelashes and scalp are shed and re placed by long, coarse, heavily pigmented hairs ● vellus hairs ○ commonly called “peach fuzz,” which are short, fine, pale hairs that are barely visible to the naked eye. ANATOMY OF A HAIR HAIR FOLLICLE -dermis -external and internal root sheath (epithelial root sheath)
- Surrounding the root of the hair HAIR SHAFT -exposed part -Medulla central core surrounds medulla compressed lerain
- cortex forms the major part of the shaft and consists of elongated cells -cotide (outermost).
- medulla, cortex, and cuticle of the hair HAIR ROOT - the portion of the hair deep to the shaft that penetrates into the dermis, and sometimes into the subcutaneous layer.
- medulla, cortex, and cuticle of the hair
Integumentary Sytem
Doc. Milliem Reyes|1st^ Semester | BSMLS-1K
● Malignant tumor - cancerous, have cells that grow uncontrollably and spread locally and/or to distant sites Cancer UV rays ● Basal Cell Carcinoma ○ Basal cells ○ Most common in US ○ UV exposure ● Squamous Cell Carcinoma ○ Keratinocytes ○ Scalp, ears ○ 2nd most common, most aggressive ( fast level up) ● Melanoma ○ Affects melanocytes, ○ Develop from mole ○ Most fatal, highly metastatic ○ Asymmetry, Border, Color, Diameter, Evolving Burn Injuries Classified by depth, 1ST degree, 2ND degree, 3RD degree Bed Sores ● Decubitus ulcer ● Constant, long-term, unrelieved pressure ● In hospital, a patient with bed sore should turn every 2 hours Stretch Mark Streching of dermis beyond limits of elasticity No adverse Calluses Due o constant abrasive forces on skin Can be softened
