Ch 5 quiz questions plain text.txt

• - largest organ in the body
• - 16% of body weight

• - avascular
• - composed of keratinized stratified squamous epithelium
• - contains 4 layers (thin skin) or 5 (thick skin)

• stratum basale: deepest layer, where mitosis occurs, sites of Merkel cells and melanocytes (this layer also called stratum germinativum)
• stratum spinosum: 8-10 layers of keratinocytes (site of Langerhans cells)
• stratum granulosum: transition to dead keratinocytes (cells undergo apoptosis), lamellar granules form, which are lipid secretions that help fill the space in this and the remaining layers, also acts as a water repellant
• strata lucidum (only in thick skin): dead cells in palms and soles)
• stratum cortex: outer surface - contains flat dead keratinocytes (callus forms with constant friction)

• - keratinocytes
• - melanocytes
• - merkel cells
• - Langerhans cells

• makes keratin, which is a fibrous protein that provides PROTECTION
• about 90% of the cells in the epidermis

makes melanin, which acts to protect the nucleus of keratinocytes against UV radiation

involved in immune response (ie: with HPV or gonorrhea, pus comes out of genitals due to langerhans cells immune response). cells come from RED bone marrow

involved in sensation of touch - have nerve structures that they are in contact with (deep in the epidermis)

process of keratin accumulation as going from the stratum basale to the stratum cortex

dead keratinized cells shedding from the scalp

• vascular
• elastic, resulting in the cause of stretch marks and wrinkles due to too much stretching
• composed of connective tissue containing collagen and elastic fibers

• papillary region: superficial region that is 1/5 of the dermis, has nerve endings and areolar connective tissue containing collagen and elastic fibers
• reticular region: deeper region, has dense irregular connective tissue containing collagen and elastic fibers, adipose cells, hair follicles, nerves, sebaceous glands (oil) and sudoriferous glands (sweat)

• different amounts of 3 pigments
• 1. melanin
• 2. carotene
• 3. hemoglobin

yellow-red or brown-black pigment produced by melanocytes. People have similar amount of melanocytes, but differences in production of melanin determine skin color

a mole (nevus) forms from a localized overgrowth of melanocytes

yellow-orange pigment found in stratum corteum, subcutaneous layer and dermis

red color pigment from erythrocytes (RBCs) flowing in dermal capillaries

below the dermis, not actually part of the skin. Attaches to underlying tissue and organs. contains LAMELLATED Corpuscles that detect external pressure applied to skin

• composed of dead keratinized cells
• shaft: projects above the surface of the skin (composed of medulla, cortex and cuticle)
• root: penetrates into dermis (more layers, same as above but after cuticle there is an inner, external and dermal root sheath (furthest out)
• epithelial root sheath: consists of inner and external roof sheaths

muscle around hair that makes it stand up when cold, for example

sebaceous glands: connected to hair follicles, secrete sebum - oil that prevents dehydration of hair and skin and kills some bacteria

• sudoriferous glands - there are two types
• eccrine: helps to cool the body by evaporating, also eliminates waste (ions such as salt, ammonia and urea)
• apocrine: located mainly in the skin of axilla and groin, secretes when physical, emotional stress. hypohydrosis is excessive sweating (can be treated with bottom)

• thick skin: palms and digits and soles (contains stratum lucid)
• thin skin: other parts of the body (also called hairy)

• composed of keratinized cells, have 3 parts
• free edge
• transparent nail body
• nail root

• 1. protection
• 2. absorption and secretion
• 3. regulation of body temperature
• 4. blood reservoir
• 5. site of vitamin D synthesis
• 6. cutaneous sensations

• epidermal wound healing: basale epithelial cells migrate towards each other and fill the gaps
• deep wound healing: blood clots, then the SCAB forms as the new cells fill the gaps and push the blood clot to the surface.