Integumentary System Review Sheet PDF

Integumentary System Review Sheet Overview Consists of one organ: the skin (cutaneous membrane), which is also the largest organ in the body Key functions include protection against external dangers (i.e. UV, pathogens), sensation (i.e. touch, temperature, pain) through receptors, te...

Integumentary System Review Sheet Overview Consists of one organ: the skin (cutaneous membrane), which is also the largest organ in the body Key functions include protection against external dangers (i.e. UV, pathogens), sensation (i.e. touch, temperature, pain) through receptors, temperature regulation (i.e. through vessel dilation, sweat), excretion of waste (i.e. through sweat), vitamin D synthesis (critical for bone health) Skin Structure (Two Main Layers) Epidermis: Thin outer layer (stratified squamous epithelium). The outermost layer is the stratum corneum (which consists of keratin and is waterproof). Contains melanocytes and keratinocytes. Dermis: Thick inner layer consisting mainly of connective tissue. Provides support and elasticity. Skin Color - Pigmentation Melanin: Pigment ranging from yellow to dark brown. Melanocytes in the base layer of the epidermis produce melanin granules which are packaged into melanosomes. They are released (and color is transferred) into skin epithelial cells (keratinocytes). ○ Two Types of Melanin: Eumelanin: brown-black. The more eumelanin, the darker the skin. Pheomelanin: red-yellow. More abundant in people with lighter skin Carotene: A yellowish pigment found in the stratum corneum and fatty layer under the skin. Together, carotene and melanin produce a yellowish hue. Skin Color and UV Radiation (see video from in-class case study at https://youtu.be/hFw8mMzH5YA) Highly energetic UV radiation, emitted by the sun, can cause cell damage and DNA mutations. It also breaks down folate, which is an essential nutrient for reproduction Melanin protects DNA by forming a cap around a cell’s nucleus and absorbing UV ○ UV radiation triggers melanocytes to produce more melanin as a threat mitigation response Geographic UV intensity is correlated with human skin color (stronger UV → darker skin) Humans do not all have darker skin because UV light is not “all bad;” a portion of it (UVB) is essential for vitamin D synthesis (needed for absorbing calcium from food to build strong bones and a healthy immune system). Humans have lighter skin (less melanin) in areas with weaker UV to absorb enough UVB. Skin Glands Sebaceous Glands: Secrete sebum, an oily substance that lubricates (prevents drying) and protects the skin and hair. Particularly active during puberty due to hormone production and can contribute to acne. Sweat Glands: ○ Eccrine Glands: Found all over the body. Primarily involved in temperature regulation by releasing sweat, which evaporates to cool the body. ○ Apocrine Glands: Located mainly in the armpits and groin. These glands secrete a thicker sweat, which, when broken down by bacteria, can lead to body odor. Other Integumentary System Components Hair: Grows in hair follicles in the dermis. Growth begins at the papilla (structure at follicle base) and is influenced by hormones and blood flow to the papilla. As new cells are formed, existing cells are pushed up and filled with keratin. The arrector pili muscle causes hair to stand up when the body is cold or stressed. Nails: Nails are formed from cells in the epidermis and are made of hard keratin. Key structures include the lunula (visible white part at the nail base) and the nail root (hidden under the skin where nail growth starts). Sensory Receptors: Various receptors in the skin allow us to experience temperature, touch, and pain Skin Conditions and Homeostasis Thermoregulation: The skin plays a critical role in maintaining homeostasis by regulating body temperature. Vasodilation (widening of blood vessels) helps release heat, while vasoconstriction (narrowing of vessels) helps conserve heat. Sweat glands also assist in cooling the body through evaporation.