unit 3 integumentary and skeletal systems part 1: integumentary system
TRANSCRIPT
The integumentary system consists of the skin, hair, nails, and glands.
Functions: 1.protection of internal structures (from abrasion & UV
light)2.prevention of infectious agent entry 3.regulation of temperature 4.production of vitamin D 5.prevention of water loss 6.detection of stimuli such as touch, pain, and
temperature
Integumentary System
Integumentary System Hypodermis:
also called subcutaneous tissue or superficial fascia
It is not part of the skin, but usually is considered with it because it attaches the skin to underlying muscle, bone, or other connective tissue
loose connective tissue that contains collagen and elastic fibers
contains about half of the body's stored fat
important for padding and insulation
responsible for some of the differences in appearance between men & women & between individuals of the same sex.
Integumentary System (Skin)
Skin Two major tissue layers:
Epidermis (stratified squamous
epithelium)
Dermis (dense connective tissue)
Dermis (dense connective tissue)
Epidermis (stratified squamous epithelium)
Dermis
dense, irregular connective tissue responsible for most of the structural strength of the skin Common use of the dermis: leather (tanned animal dermis) consists of collagen and elastic fibers contains fibroblasts, fat cells, and macrophages On the upper part, has dermal papillae (projections which
extend toward the epidermis) Contains many blood vessels that supply the epidermis with
nutrients, removes waste products, & aids in regulating body temperature
The dermal papillae in the palms of the hands, soles of the feet, & tips of the fingers are in parallel, curving ridges that shape the overlying epidermis into fingerprints & footprints. (The ridges increase friction & improve the grip of the hands & feet.
Integumentary System (Dermis)
There are two layers of the dermis:
The reticular layer is the main fibrous layer and consists mostly of collagen. It is the deeper layer and blends into the hypodermis.
The papillary layer is well supplied with capillaries. It is the more superficial layer and derives its name from projections called dermal papillae that extend into the epidermis.
If the skin is overstretched for any reason, the dermis can be damaged, leaving lines that are visible through the epidermis. These lines, called striae or stretch marks.
Integumentary System (Dermis)
Characteristics of the Epidermis (“upon + skin”):
stratified squamous epithelium separated from the dermis by a basement membrane
It is avascular - contains no blood vessels and derives nourishment by diffusion from capillaries of the papillary layer
cells are produced in the deepest layers by mitosis (FYI: your skin is replaced approximately every 40-56 days!)
as new cells are formed, they push older cells to the surface, where they slough (flake) off - did you know that you will lose approximately 8 pounds just in dead skin cells in one year?
during migration from “deep” to “superficial” cells change in shape and chemical composition
thick skin is found on the palms of the hands, souls of the feet, and tips of the digits
Integumentary System (Epidermis)
Integumentary System (Epidermis)
Keratinization: process that epidermal cells undergo as
they move to the surface produces cells filled with protein (keratin) gives the stratum corneum its structural
strength produces an outer layer of epidermal cells
that resist abrasion & acts as a permeability barrier
Epidermis divided into regions or strata (from deep to superficial):
stratum basale or germinativum (SG) stratum spinosum (SS) stratum granulosum (SGR) stratum lucidum (absent in thin skin) stratum corneum (SC)
"Before Signing, Get Legal Counsel" (Mnemonics to learn deep to superficial)
The cell type that makes up the majority of the epidermis is a KERATINOCYTE
Produces the protein keratin which is waterproof & strong.
MERKEL CELLS: used as sensory receptors for the sense of light touch.
LANGERHANS CELLS: star-shaped cells arising from bone marrow that migrate to epidermis (macrophages) that aid in immune response in the skin
MELANOCYTES produce MELANIN (dark brown pigment)
Cells Types of the Epidermis
STRATUM BASALE• The deepest layer of the epidermis where cells
rapidly divide to create the upper layers (mitosis) – only at this layer
• Because of the rapid division, this layer is also called the Stratum Germinativum
• One layer of cuboidal or columnar cells (80-85% keratinocytes, with other 15% made up of melanocytes, Merkel disks, and Langerhans cells).
STRATUM SPINOSUM • “spiny layer”• - 8-10 rows of many sided cells with the
appearance of prickly spines• - melanin granules and Langerhans’ cell
predominate
Layers of the Epidermis
Layers of the Epidermis (continued)
STRATUM GRANULOSUM• 3-5 rows of flattened cells• nuclei of cells flatten out• organelles disintegrate & cells eventually die as
they are now too far from the needed nutrients found in the dermis.
STRATUM LUCIDUM • 3-5 layers of clear, flat cells found only in the
thickest skin (soles of feet, palms, & fingertips)
Layers of the Epidermis (continued)
STRATUM CORNEUM• Layer has many rows of dead cells filled with
keratin• Continuously shed and replaced• Acts as an effective barrier against light, heat
and bacteria• 20-30 cell layers thick• Dandruff and flakes• 40 lbs. of skin flakes in a lifetime (dust mites!)
Integumentary System (Skin Color)
Skin Color determined by: pigments in the skin:
Melanin, a brown-to-black pigment, is produced by melanocytes in the stratum basale
Carotene – yellow pigment found in plants; it is lipid soluble, & when consumed, it accumulates in the stratum corneum & the fat cells of the dermis & hypodermis. This gives the skin a slight yellowish tint.
by blood circulating through the skin
by the thickness of the stratum corneum
melanin is transferred to other cells by melanocytes
melanin is present in large quantities in moles, freckles, the genitalia, and nipples
melanin production is genetically determined, but can be influenced by hormones and ultraviolet light
albinism a recessive genetic trait that causes a deficiency or absence of melanin
albinos have fair skin, white hair, and unpigmented irises in the eyes
Integumentary System (Skin Color)
Melanin Transfer from Melanocyte to Epithelial Cells
Melanocytes make melanin, which is packaged into melanosomes & transferred to many epithelial cells.
Redness of the skin can occur from: the inflammatory response anger or blushing exposure to heat exposure to cold
Skin Conditions: decreased blood flow causes a pale skin (shock) decreased oxygen content in the blood results in a bluish
color called cyanosis a yellowish skin color, jaundice, can occur when the liver
is damaged by a disease such as viral hepatitis the disease scarlet fever results from a bacterial infection
in the throat the condition of age spots are caused by increased
melanocytes
Integumentary System (Skin Color)
IV. Accessory Skin StructuresA. Hair
1. Characteristic of all mammalsa. Thick hair = fur
2. Hair anatomy:a. Hair shaft = portion of hair above skin surfaceb. Hair root = portion of hair below skin surfacec. Hair bulb = base of hair rootd. Medulla= center of haire. Cortex (bark) = surrounds the medullaf. Cuticle (skin) = single layer of overlapping cells
holding hair follicleg. Hair follicle = extension of epidermis deep into
dermisi. Plays role in tissue repair
3. Hair growth:a. Cyclic: growth stage + resting stage
i. Hair bulb produces hair; nourished by blood vessels
ii. Epithelial cells undergo keratinization in hair bulb; cells are added to base of hair – hair “growth”
iii. Growth stops during resting stage
iv. Next growth stage causes hair to fall out
v. Pattern baldness – permanent loss of hair
4. Hair color determined by varying amounts & types of melanin
a. Melanin production decreases with age = gray/white
Hair Type Growth Stage Resting Stage
Eyelash 30 days 105 days
Scalp 3 years 1-2 years
B. Muscles1. Arrector pili (that which
raises, hair) = contraction of these muscles cause hair to “stand on end”… goosebumps
a. Composed of smooth muscle
b. Evolutionary advantage in mammals – traps air (heat) for insulation, also look larger - intimidation
C. Glands (Exocrine – secrete onto a suface)
1. Sebaceous glandsa. Simple, branched acinar/alveolarb. Produce sebum – an oily white substance that lubricates
hair & skin surface, preventing drying out & protection against some bacteria
C. Glands, continued…2. Sweat glands (two types):
a. Merocrine sweat glandsi. Simple, coiled tubular w/ ducts opening to skin surfaceii. Every part of skin, most abundant in palms/solesiii. Produces sweat: slightly salty water-based secretion
• Evaporative cooling• Emotional stress produces sweat in palms, soles, axillae (used in lie
detector tests!)
b. Apocrine sweat glandsi. Simple, coiled tubular gland with ducts opening into hair follicles of
the axillae & pubic region• Become active at puberty due to sex hormone influence
ii. Secretes thick organic substances• Broken down by bacteria = body odor
Sensory Receptors of the Skin
Perceive Touch: Merkel’s Discs Meissner’s
Corpuscles Root Hair Plexus
Perceive Pressure: Pacinian
Corpuscle Krause’s
Corpuscle (also heat)
Ruffini Corpuscle (also cold)
D. Nails1. Nail = thin, horny plate at end of fingers and toes,
consisting of several layers of dead epithelial cells (stratum corneum) containing a hard keratin
2. Nail anatomy:a. Nail body = visible part of nailb. Nail root = part of nail covered by skinc. Eponychium or cuticle (upon + nail) = stratum
corneum extending onto nail bodyd. Nail bed = nail root and nail body attach to thise. Nail matrix = proximal portion of nail bed w/o nail
root attachedi. Produces cells that result in nail growthii. Nails grow continuously
f. Lunula = whitish, crescent-shape at base of nail
A. Burns1. Partial-thickness burns – part of stratum basale viable
a. First-degree burns – involves epidermis, red, painful, edemai. Sunburn, quick exposure to hot/cold
ii. No scarring, heals quickly
b. Second-degree burns – destruction of epidermis and dermis, recovery happens from edge of burn
c. Full-thickness or third-degree burnsi. Painless b/c nervous tissue destroyed
ii. May appear white, tan, brown, black, or deep cherry red
iii. Scarring with disfiguration, extended healing time
iv. Skin grafts (self, cadavers, pigs, lab-grown?)
Burns
First-degree(epidermis only; redness)
Third-degree(full thickness, destroying epidermis, dermis, often part of hypodermis)
Second-degree(epidermis and dermis,with blistering)
The estimated extend of burns may be calculated using the rule of nines.
Totals: Anterior & posterior head & neck = 9% Anterior & posterior upper limbs = 18% (9% per
arm) Anterior & posterior trunk = 36% Perineum = 1% Anterior & posterior lower limbs = 36% TOTAL 100%
Rule of Nines for Adults
33
Rule of Nines for AdultsCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Anteriortrunk18%
Posteriortrunk18%
Anterior upperextremities 9%
Posterior upperextremities 9%
Posterior lowerextremities 18%
Perineum 1%
Anterior andposterior upper
extremities18%
Anterior andposterior lower
extremities36%
100%
Anterior andposterior trunk
36%
Anterior and posterior head and neck9%
Anterior headand neck 41/2%
Posterior headand neck 41/2%
Anterior lowerextremities 18%
9% 9% 9% 9%
41/2%
41/2% 41/2% 41/2% 41/2%
41/2%
Skin Disorders Warts - nonmalignant epithelial growth caused by
a virus Cold sores (fever blisters)
small fluid-filled blisters around lips & mouth caused by a herpes simplex virus
Acne - inflammation of sebaceous glands Impetigo - inflamed lesions caused by
staphylococcus infection Decubitus ulcers (bed sores) caused by
irritation and inadequate circulation, especially in areas over bony projections such as hip bones, heels, etc. (occur most often in those who are bedridden or confined to a wheelchair.
Metastasize (Metastasis): Spreading of cancer
Benign: A non-cancerous tumor
Malignant: A cancerous tumor
Carcinoma: Cancer
Carcinogen: Cancer-causing agent
Causes for Skin Cancer
1. Overexposure to UV light 2. Frequent skin infections 3. Chemical exposure 4. Physical trauma
Basal Cell Carcinoma
Most common form of skin cancer
Least deadly Stratum Germinativum
cells are altered and the boundary between the dermis and epidermis is destroyed
Occurs most commonly on sun exposed areas (face)
24-38
Basal Cell Carcinoma (continued)
Signs and symptoms New growth or sore that will
not heal Waxy, smooth, red, pale, flat,
or lumpy May or may not bleed approx. 30% of caucasians
will develop this 99% cure rate
Squamous Cell Carcinoma Less common than basal
cell carcinoma Scaly keratinized
elevation that arises from Stratum Spinosum
Found most commonly on scalp, ears, back of hands, and lower lip.
Can metastasize to the lymph nodes
Believed to be sun induced
Good chance of complete cure
24-40
Malignant Melanoma From melanocytes,
usually in a pre-existing mole
Appear on trunk, head, neck of men
Appear on arms and legs of women
Itches or bleeds Metastasizes quickly to
lymph and blood vessels.
Treatment Surgery and biopsy Removal of lymph
nodes Chemotherapy and
radiation therapy Immunotherapy Survival is helped by
early detection
Malignant melanoma
Irregular growths with variety of pigmentation (brown, gray, black, or blue)
Occur in all age groups, usually in people who sunburn easily
More common in people who get short intense exposure to sunlight .
Survival rate is low.
Here are some ways to play it safe in the sun: Avoid the sun between 10 a.m. and 4 p.m. Seek shade: Look for shade, especially in the middle of the day when the sun’s
rays are strongest. Practice the shadow rule and teach it to children. If your shadow is shorter than you, the sun’s rays are at their strongest.
Slip on a shirt: Cover up with protective clothing to guard as much skin as possible when you are out in the sun. Choose comfortable clothes made of tightly woven fabrics that you cannot see through when held up to a light.
Slop on sunscreen: Use sunscreen and lip balm with a sun protection factor (SPF) of 30 or higher. Apply a generous amount of sunscreen (about a palmful) and reapply every 2 hours and after swimming, toweling dry, or sweating. Use sunscreen even on hazy or overcast days.
Slap on a hat: Cover your head with a wide-brimmed hat, shading your face, ears, and neck. If you choose a baseball cap, remember to protect your ears and neck with sunscreen.
Wrap on sunglasses: Wear sunglasses with 99% to 100% UV absorption to provide optimal protection for the eyes and the surrounding skin.
Follow these practices to protect your skin even on cloudy or overcast days. UV rays travel through clouds.
Avoid other sources of UV light. Tanning beds and sun lamps are dangerous. They also damage your skin in other ways.
Reduce your risk of skin cancer: