Lecture: Chapter 05 Flashcards
INTEGUMENTARY SYSTEM
Skin. Composed of TWO distinct regions: the dermis and epidermis.
EPIDERMIS
epithelial cells; outer covering of body; it is AVASCULAR and gets nutrients by way of diffusion.
DERMIS
fibrous co. annective tissue, leathery, vascularized; provides nutrients to epidermis by diffusion.
HYPODERMIS
a.k.a. “Superficial Fascia;” subcutaneous tissue just deep to the skin; mostly ADIPOSE tissue; anchors skin to underlying layer (usually muscle). The adipose (fat) acts as an insulator and shock absorber.
THE EPIDERMIS
keratinized stratified squamous epithelium. Consists of 4 types of cells: 1) Keratinocytes, 2) Melanocytes, 3) Langerhans’ cells, & 4) Merkel cells. (see following cards)
KERATINOCYTES
produce keratin, the fibrous protein that is responsible for toughening of the skin and gives the epidermis its protective properties. New cells continually produced which pushes older cells upward (superficially). They are DEAD when they reach the free surface of the skin. These cells SLOUGH OFF for totally new layer every 25-45 days. Persistent friction causes a thickening of the epidermis called a CALLUS.
MELANOCYTES
synthesize pigment melanin; melanin accumulates on the superficial side of the keratinocyte’s nucleus, protecting it from harmful UV radiation. (Melanin acts as an umbrella preventing modification of DNA in nuclei that would lead to abnormal (cancer) cells). Everyone has SAME # of melanocytes.
LANGERHANS’ CELLS
a.k.a. “Dendritic Cells;” Macrophages; work with immune system; these are phagocytic cells that arise from bone marrow & migrate to epidermis.
MERKEL CELLS
touch receptors; located at dermal-epidermal junctions.
LAYERS OF THE EPIDERMIS
Cornum, Lucidum, Granulosum, Spinosum, Basale.
Can Lucy Give Some Blood
STRATUM CORNUM
outermost layer, 20-30 cells thick; protects skin from abrasion, penetration, and wter loss; provides a durable overcoat.
STRATUM LUCIDUM
clear layer only visible in thick skin (on palms and soles); thin, translucent band.
STRATUM GRANULOSUM
granular layer; 3-5 layers; as cells move up they flatten, nuclei & organelles disintegrate, and they build up KERATOHYALINE granules & LAMELLATED granules, which PREVENT excessive WATER LOSS through the skin. The keratohyaline granules form keratin in the upper layers; the lamellated granules contain a water-proofing glycolipid and decrease water loss.
STRATUM SPINOSUM
prickly layer; the keratinocytes appear irregular and spiny (in tissue samples, not living cells); This layer contains melanin granules and Langerhans’ cells.
STRATUM BASALE
basal layer; the deepest epidermal layer; attached to dermis; single row of cells undergoing rapid mitotic division. This layer also contains melanocytes and a few Merkel cells.
THE DERMIS
strong and flexible (vascular also) connective tissue, similar to animal hides used for leather; contains nerve fibers, blood vessels, and lymphatic vessels; also parts of hair follicles and oil and sweat glands (derived from epidermal tissue but “live” in the dermis); Contains 3 Kinds of Cells: 1)Mast_Cells, 2)Macrophages, 3)Fibroblasts
LAYERS OF THE DERMIS
Papillary Layer and Reticular Layer (also, flexure lines)
PAPILLARY LAYER
80% of dermis; areolar connective tissue with many blood vessels; superior surface has dermal papillae that project into the epidermis. Many papllae contain free nerve endings (pain receptors) or Meissner’s corpuscles (touch receptors). On the palms and soles, the papillae lie on dermal ridges, which force the overlying epidermis to form epidermal ridges that increase gripping ability. These ridges are unique to each of us and give rise to fingerprints.
3 FUNCTIONS OF
PAPILLARY LAYER
1) Feed & oxygenate the dermis
2) Provide touch & pain receptors
3) Form ridges on palms and soles
RETICULAR LAYER
dense, irregular connective tissue; major portion of the dermis. The thick collagen fibers run in different planes but mostly parallel to the skin. These are separated b less dense regions which form cleavage or tension lines in skin. The tension lines are not visible but are important for surgery. The run up and down the limbs but around the head and trunk.
*Pacinian Corpuscle = pressure receptor
FLEXURE LINES
dermal folds occurring near joints where the dermis is secured to deeper structures, e.g. lines on the palms, fingers, and wrists.
SKIN COLOR
Determined by 3 pigments:
1) Melanin, 2) Carotene, & 3) Hemoglobin
(see following cards)
Can indicate a medical condition, a disease, or an emotion.
MELANIN
yellow to reddish-brown to black color. Local accumulations of melanin are freckles of pigmented moles. Long sun exposure causes a build-up of melanin - a tan which helps protect skin DNA from UV light damage.
CAROTENE
yellow to orange pigment, common in carrots. It tends to accumulate in the stratum corneum and fatty tissues of the hypodermic. Most obvious in palms and soles where stratum corneum is the thickest.
HEMOGLOBIN
in red blood cells (RBCs); gives fair-skinned people their pinkish tone.
CYANOSIS
BLUE - heart failure, respiratory distress
ERYTHEMA
RED - embarrassment, fever, hypertension, inflammation.
PALLOR
PALE - fear, anger, anemia.
JAUNDICE
YELLOW - liver condition (seen in eyes); yellow bile pigment accumulation.
BRONZING
Addison’s Disease - low adrenal function; adrenal correct/pituitary gland produce inadequate amounts of hormones.
BRUISING
BLACK & BLUE - blood pools and clots below the skin.
SKIN APPENDAGES
Sweat glands, sebaceous glands, nails, hair & hair follicles. (see following cards)
SWEAT GLANDS
a.k.a. “Sudoriferous” glands; two types: Eccrine (most numerous) and Apocrine
ECCRINE
a.k.a. “Merocrine;” Function: thermoregulation; high concentration on palms, soles, & forehead; Each is a coiled tubular gland. THe coiled part lies in the dermis, and the duct extends to open in a funnel-shaped pore at the skin surface which produces sweat. Sweat is composed of mostly water with some salts, Vitamin C, antibodies, anti-microbial dermicidin, and traces of metabolic wastes (urea & uric acid). Composition depends on heredity and diet.
APOCRINE
Function: scent glands; mostly in axillary areas; ducts empty into hair follicles instead of onto skin; components mostly same as sweat plus fatty substances and protein. Can be yellowish or milky. Comes out odorless, but when decomposed by skin bacteria, puts off a generally unpleasant odor - body odor.
CERUMINOUS GLANDS
modified apocrine glands; secrete cerumen or EAR WAX
MAMMARY GLANDS
secret milk
SEBACIOUS GLANDS
(oil glands); located all over body except palms & soles; large on face, neck, and upper chest. Secret sebum into hair follicle which lubricates the hair, slows, water loss from skin, and has bacterial action. Secretion of sebum is stimulated by hormones.
- Acne is an inflammation of sebaceous glands.
- Seborrhea (a.k.a. “Cradle Cap”) seen in infants and is over-active sebaceous glands.
NAILS
scale-like; correspond to hooves or claws; made of hard keratin (soft keratin is skin); Each nail has a free edge, body, and root; deeper layers of epidermis below the nail make up the nail bed. Nail matrix at the proximal end is responsible for nail growth; white crescent at base of nail is called “lanula”
VITAMINS
A - helps w/ vision and hair/nail growth
D - produced in skin w/ exposure to UV light
C - aids in would healing by helping collagen synthesis
K - blood clotting
SICKLE CELL ANEMIA
due to abnormal hemoglobin
PERNICIOUS ANEMIA
due to B12 deficiency
HAIR & HAIR FOLLICLES
see following cards
FUNCTION OF HAIR
sense insects; on head, protects from trauma, heat loss, and sunlight; eyelashes & nose hair act as filters. Also made of hard keratin. Hair has three concentric layers of keratinized cells: the MEDULLA (central ring, only part containing soft keratin), the CORTEX, and the CUTICLE (outermost layer, provides strength). Hair follicles fold down from the epidermis into the dermis.
APOLECIA
hair thinning and loss; most common type is male pattern baldness; occurs because hair follicle is inactive.
VELLUS
fine, velvety hair (peach fuzz)
TERMINAL HAIR
coarser hair of the scalp, eyebrows, and axillary areas
ARRECTOR PILI
smooth muscle that contracts to form goosebumps; controlled by the sympathetic nervous system
FUNCTIONS OF
INTEGUMENTARY SYSTEM
Protection, Body Temperature Regulation, Cutaneous Sensation, and Metabolic Functions
(see following cards)
PROTECTION
- Chemical Barrier: skin secretions and melanin (shields skin cells from UV damage to DNA.
- Physical Barrier - continuity of skin and hardness or keratin; water-proofing glycolipids prevent water loss and water entry through skin.
- Biological Barrier - Langerhans’ cells (macrophages) in epidermis; in dermis macrophages; DNA can absorb UV radiation and dissipate it as heat.
BODY TEMPERATURE
REGULATION
Thermoregulates by use of 1) blood vessels (constrict in cold, dilate in heat) & 2) Sweat glands; When body temp. rises, sweat glands increase activity. Evaporation of sweat from skin dissipates excess heat.
CUTANEOUS SENSATION
Meisner’s corpuscles (dermal papillary) and Merkel cells (epidermis) are touch receptors. Pacinian receptors (reticular dermis) are deep pressure sensors, and free nerve endings are pain receptors.
METABOLIC FUNCTIONS
- Synthesizes Vit D (located under skin in inactive form, activated by UV rays, then travels to liver & kidneys for further activation)
- Deactivates cancer-causing chemicals
- Changes some chemicals into carcinogens
- Activates some steroid hormones
- Makes some proteins, e.g. collagenase (enzyme)
SKIN CANCER
see following cards
BASAL CELL CARCINOMA
a.k.a. “Rodent Ulcers;” 80% of skin cancer; most common skin cancer; LEAST malignant; shiny, dome-shaped nodule with pearly white edge.
SQUAMOUS CELL CARCINOMA
2nd most common; will metastasize if not removed; scaly, reddened, elevated patch; arises most often on head, scalp, ears, lower-lips, & hands.
MELANOMA
most malignant; highly metastic; usually brown to black; most dangerous; ABCDE
(A)symmetric; (B)order irregularity; (C)olor; (D)iameter bigger than eraser; (E)levanted.
BURNS
caused by heat, electricity, radiation, and some chemicals; all denature cellular proteins.
1º BURN
only epidermis is damaged, e.g. sunburn; partial thickness burns
2º BURN
epidermis and upper layer of dermis: blisters; partial thickness burns
3º BURN
full thickness burns; entire skin can be gray, bright red, or blackened; not painful b/c nerve endings are damaged/destroyed; epidermis, dermis, & hypodermis are damaged, necessitates skin graft.
