Week 3
Body System composed of the skin, hair, oil, sweat glands , nails, sensory receptors
integumentary system
Functions of skin - TRPSAD
Sensation, body temperature, protects the body, blood reservoir, excretion & absorption, synthesizes vitamin D
Largest organ of the body
skin - 7% of total weight
sweat & blood flow to dermis
Themoregulation
Oval shaped vibration receptor in dermis/subcutaneous tissue, consisting of layers of connective tissue around dendrites of a sensory neuron
Lamellar corpuscles
Ecrine sweat gland
Thermal regulation
Apocrine sweat gland
Sexual arousal areas associated with hair
One of two main parts of the skin: thinner, superficial, made of epithelial tissue, avascular. Keratinized stratified epithelium
Epidermis
One of two main parts of skin: deeper, thicker, connective tissue, vascular, containing collagen & elastic fibers, stretching & tone of the skin
Dermis
Tissue type deep in dermis consisting of areolar & adipose tissue, fibers from dermis anchor skin to this tissue that attaches to fascia. Serves as storage for fat, passage for blood vessels to supply blood for skin, region for nerve endings
Hypodermic (subcutaneous)
True or false: All 4 tissue types are in this organ system
True
Tissue type in the hair, nails, epidermis
Epithelial tissue
Dermis contains _________ tissue
connective
Tissue type found attached to hair follicles, and in substance of arteries & veins
Muscle tissue
________ tissue provides an abundance of sensation
Nervous
Keratinized stratified epithelium
Epidermis
4 principal cells in epidermis
dendritic, keratinocytes, melanocytes, tactile epithelial
Most numerous cells (85%), produce keratin
keratinocytes
Pigment producing cells, transfer melanin, protects nucleus & keratinocytes to shield DNA from UV
Melanocytes
Cells arising from red bone marrow & migrate to epidermis, participate in immune responses & defend against invading microbes
Dendritic cells
Cells that are least numerous , detects touch sensations , makes contact with nerve cells
Tactile Epithelial
Stratum basale, spinosum, granulosum, stratum corneum
Thin skin
Stratum basale, spinosum, granulosum, lucidum, stratum corner
Thick skin
Deepest layer of epidermis with a single row of cuboidal or columnar keratinocytes, continuous mitosis leads to new cells & produces other layers, melanin is produced here
Stratum basale
Superficial to stratum basale with 8 - 10 layers of keratinocytes
Stratum spinosum
Middle layer, non-dividing, 3-5 layers of keratinocytes undergoing apoptosis. Prescense of keratohyalin (immediate form of keratin)
Stratum granulosum
Present only in thick skin (palms, soles, plantar surfaces) superficial to stratum granulosum. Contains dead keratinocytes with large amounts of keratin providing toughness.
Stratum lucidum
Most superficial layer, 25 to 30 layers of flattened keratinocytes. Constant friction stimulates cell & keratin production resulting in callus
Stratum Corner/ corneum
Region of dermis just below epidermis, contains areolar tissue with elastic/collagen fibers, dermal papillae (capillary loops), tactile corpuscles & free nerve endings
Papillary dermis
Region of dermis attached to subcutaneous layer, contains connective tissue with thick collagen elastic fibers, fibroblasts, adipose cells (fat), sebaceous & sudoriferous glands (sweat)
Reticular dermis
Benefits of epidermis
Resists damage & offers protection to underlying tissues
Benefits of dermis
Provides temperature stability & prevents dehydration, enhances healing
Benefits of hyperdermis
Insulates, stores fat, anchors skin to deeper layers of the body
Also known as subcutaneous layer, attaches to underlying tissues & organs, contains lamellated (pacinian) corpuscles that detects external pressure applied to the skin
Hypodermis
Accessory structures of the skin
Hair, glands, nails
Surrounds base of hair follicle, onion shaped structure that houses a nipple shaped indentation, papilla of the hair with areolar connective tissue & blood vessels & hair matrix (epidermal stem cells of stratum basale)
Hair bulb
The smooth muscle of the hair extending from the papillary dermis of the skin to the dermal root sheath around base of hair follicle
Arrector muscle
Oil glands, simple, branched & rounded, connected to hair follicles opening into neck of hair follicle. secretes sebum preventing dehydration of hair/skin & growth of bacteria, inflammation causes acne, present on face, neck, chest
Sebaceous glands
Sweat glands, Secretes sweat or perspiration into hair follicles or pores in the skin; includes eccrine & apocrine
Sudoriferous glands
Modified sweat glands in the external ears; secretes waxy lubricating substance. Lies deep to sebaceous glands in hypodermic opening directly into ear canal. Ear wax is combined secretion of sebaceous & _______ glands (cerumen)
Ceruminous glands
Occurs following superficial wounds affecting only epidermis (abrasion or first degree burn). Repaired by enlargement & migration of basale cells and division of migrating & stationary basale cells to replace the ones moved into the wound.
Epidermal wound healing
Occurs following injury that penetrates dermis, repair process is more complex & permanent scar formation can occur
Deep wound healing
First phase of deep wound dealing: blood clot unites the wound edges, epithelial cells migrate across the wound, blood vessels deliver phagocytes & fibroblasts form
Inflammatory phase
Second phase of deep wound healing, blood clot becomes a scab, epithelial cells beneath scab, fibroblasts produce scar tissue, damaged blood vessels begin to grow, tissue fills the wound (granulation tissue)
Migratory phase
Third phase of deep wound healing ; events of the migratory phase intensifies, growth of epithelial cells, fibroblasts, collagen, new blood vessels
Proliferative phase
The last phase of deep wound healing: the scab sloughs off once epidermis is restored to normal thickness, collagen fibers become organized, fibroblasts disapear, blood vessels restored to normal
Maturation phase
Warning signs of malignant melanoma: ABCDE
Asymmetry, boarder is regular, color is uneven, diameter over 6mm , evolving in size
Scar formation retained within the boundaries of original wound is called a _____ scar
Hypertrophic
Scar formation extends beyond boundaries of original wound is called a _____ scar
Keloid scar
How Skin Contributes to Homeostasis
Temperature regulation, protection, sensation, water balance, immune defense, vitamin D synthesis, excretion