Integumentary system (structure-4, structure-2, subcutaneous-2)
Epidermis - outer, epithelial
Dermis - inside, connective tissue
3. Subcutaneous (hypodermis)
Not part of skin
connects skin to lower layers.
Muscle & nerve (feelling)
1. Avascular; nourished by diffusion from capillaries of the papillary layer of the dermis (stratified epithelial)
2. Composed of cells arranged into layers or strata.
3. Separated from dermis by basement membrane
Cells of epidermis
1. Keratinocytes - major portion, eventually protein keratin (a protein)
2. Melanocytes - pigment (melanin) cells, don't shed. if you have too many melanin it moves to keratinocytes. why your tan fades. everyone has the same # but different amt of melanin.
3. Langerhans cells - resident WBC in skin to take care of problems that arise
Layers of epidermis (5) on EXAM
skin grows from bottom up. not necessarily a single layer
1. Stratum basale (germinitivum) - bottom layer, single layer. sits on basement membrane (stimulate to grow=rubbing, irritation calacus, thus moves up faster)
a. Deepest portion of epidermis and single layer.
b. Mitosis - only layer
2. Stratum spinosum (a little bit of division)
a. Limited cell division.
3. Stratum granulosum
a. Contains keratohyalin.
b. In superficial layers nucleus and other organelles degenerate and cell dies
4. Stratum lucidum
a. Thin, clear zone. Found only in palms and soles (thick part of skin)
5. Stratum corneum
a. Most superficial and consists of cornified (dead, hard, dry) cells
1. True skin
2. Storage site for water and electrolytes
3. Sensory receptors for pain, pressure, touch and temperature
4. Hair follicles, sweat and sebaceous glands, blood vessels, muscle fibers.
5. Connective tissue (loose (top) connective & dense (bottom) irregular) bottom-can take a lot of compression & has a lot of fiber. Irregular=runs at all different angles
6. Dermal papilla (finger-like, nipple-like projections)
Every function you can think of happens here
LAB: If glands leads to skin then sweat. another name = suderificous gland??
LAB: If gland leads to hair = sebacious gland
1. Important in surgery
a. If incision parallel to lines, there is less gapping, faster healing, less scar tissue (dense irregular tissue)
2. If skin is overstretched, striae (stretch marks) occur
skin color (6)
1. Quantity of melanin (gives protection) in cells of epidermis
b. UV radiation (can increase melanin)
2. Carotene - especially in babies (ex. yellow=too many carrots. b/c skin thinner in kids)
3. Changes in blood flow to skin
a. Decrease blood flow - pale (ex. if you are cold)
b. Increased blood flow - flush.
a. Deoxyhemoglobin - cyanosis (low or no O2)
b. Carboxyhemoglobin - cherry red (carbonmonoxide=bonded w/hemoglobin & doesn't let go) blue on tips=lung or heart problems
5. Jaundice - yellow (can't get rid of bilirubin-killing of hemoglobin)
6. Vitilago - melanocytes. stops working in spots (M. Jackson)
physiological functions of the skin (EXAM) (6)
1. Protection - barrier, produces secretion (oil & sweat=antibacterial). you have bacteria on you (normal flora) & bacteria gets nutrition. bacteria protects you from other bacteria
3. Excretion - sweat
4. Vitamin D synthesis - unprotected sunlight & you get vit. D
5. Immune - fight infection. Langerus cells
6. Homeostasis of body temperature
homeostasis of body temperature (2)
1. Hyperthermia - abnormally high body temperature. sweating & vasodilation
2. Hypothermia - abnormally low body temperature. shiver, vasoconstriction (blood vessel get smaller to retain heat) & no sweating (just make you lose temp).
homeostasis (body temperature)
feedback is the corrective response
feedback= shut off deviation
shivering is homeostasis
the way the body responds to deviation is feedback
below skin, subcutaneous
1. Deep to skin
2. Consists of loose connective tissue with collagen and elastic fibers
3. Types of cells
b. Adipose cells
4. Also called
a. Subcutaneous tissue
b. Superficial fascia (connective tissue/skin on top of the muscle. ex. transparent material - like on a chicken)
5. Contains about one-half of body's fat. Functions as
a. Energy source
Glands - 3 types (EXAM)
1. Eccrine glands = sweat gland. function=from birth to death, sweat to cool you down all over body. Doesn't produce body odor.
2. Apocrine glands = sweat gland. starts working at puberty. arm pits, nipples & anus. body odor=you have to attract sexual mate (phermones). bacteria starts working on the apocrine glands.
3. Sebaceous glands - secrete sebum (oil). oil glands can be protective against bacteria.
4. Ceruminous glands - modified apocrine sweat glands. each air canal only. cerume=ear wax. keeps things from getting wet & from bugs crawling in.