THE SKIN AND ITS ACCESSORY STRUCTURES THE INTEGUMENTARY SYSTEM

VIDEO: SKIN Incredible Human Machine – SKIN 10:08 mins

BODY MEMBRANES Function of body membranes Cover body surfaces Line body cavities Form protective sheets around organs Classified according to tissue types

CLASSIFICATION OF BODY MEMBRANES Epithelial membranes Also called covering and lining membranes Cutaneous membranes Mucous membranes Serous membranes Connective tissue membranes Synovial membranes

BEGIN NOTES HERE... CUTANEOUS MEMBRANE Cutaneous membrane = skin Composed of keratinized stratified squamous epithelium Underlying dermis is mostly dense connective tissue Dry membrane

Cutaneous membrane (skin) (a) Cutaneous membrane (the skin) covers the body surface. Figure 4.1a

MUCOUS MEMBRANES Mucosa Composed of Stratified squamous epithelium (mouth, esophagus) OR Simple columnar epithelium (rest of digestive tract) Underlying dermis = loose connective tissue (lamina propria) “Wet” or moist membranes Lines all body cavities that open to the exterior body surface Often adapted for absorption or secretion

Figure 4.1b Mucosa of nasal cavity Mucosa of mouth Esophagus lining Mucosa of lung bronchi (b) Mucous membranes line body cavities open to the exterior.

SEROUS MEMBRANES Serosa Composed of: Simple squamous epithelium (surface) Underlying dermis = thin layer of areolar connective tissue Lines body cavities that are closed to the exterior of the body Occur in pairs Visceral layer covers the outside of the organ Parietal layer lines a portion of the wall of ventral body cavity

Figure 4.1d Outer balloon wall (comparable to parietal serosa) Air (comparable to serous cavity) Inner balloon wall (comparable to visceral serosa) (d) A fist thrust into a flaccid balloon demonstrates the relationship between the parietal and visceral serous membrane layers. Layers separated by serous fluid secreted by both membranes Serous fluid allows organs to slide around.

SEROUS MEMBRANES Specific serous membranes Peritoneum Abdominal cavity Pleura Around the lungs Pericardium Around the heart

Parietal peritoneum Visceral peritoneum (c) Serous membranes line body cavities closed to the exterior. Parietal pericardium Visceral pericardium Parietal pleura Visceral pleura Figure 4.1c

CONNECTIVE TISSUE MEMBRANE Synovial membrane Composed of connective tissue only Line the fibrous capsules surrounding joints where they provide a smooth suface and secrete a lubricating fluid. Also lie small sacs called bursa and tendons Both cushion organs moving against each other

Figure 4.2 Ligament Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Fibrous capsule Synovial membrane Articular capsule

INTEGUMENTARY SYSTEM Skin (cutaneous membrane) Skin derivatives Sweat glands Oil glands Hair Nails

SKIN FUNCTIONS Protects deeper tissues from: 1.Mechanical damage (bumps) 2.Chemical damage (acids and bases) 3.Bacterial damage 4.Ultraviolet radiation (sunlight) 5.Thermal damage (heat or cold) 6.Dessication (drying out)

SKIN FUNCTIONS 7. Aids in body heat loss or heat retention as controlled by the nervous system 8. Aids in excretion of urea and uric acid 9. Synthesizes vitamin D

SKIN STRUCTURE Epidermis—outer layer Stratified squamous epithelium Cornified or keratinized (hardened by keratin) to prevent water loss Avascular Most cells are keratinocytes Dermis Dense connective tissue

FUNCTIONS OF THE INTEGUMENTARY SYSTEM Protection Regulate body temperature Cutaneous sensation Synthesize Vitamin D Blood storage Excretion of wastes (sweat)

THE SKIN A large organ composed of all 4 tissue types 22 square feet 1-2 mm thick Weight 10 lbs. dfasdjsdj fkjdfljlfjldf jlsdjlsflksd jsjfklsjfjdfjs dlfjsdfdlsf asdjlsflsdf ljdlfsdfjsd kljdfasdkl sdjsjfldjfla sfjsfljjflasjll djfla dfjkjklsjfksjfljd ljdlfjklfj

VIDEO Incredible Human Machine - SKIN

LAYERS OF SKIN Epidermis The superficial portion of the skin Composed of epithelial tissue Dermis The deeper layer of the skin Primarily composed of connective tissue Hypodermis (subcutaneous layer) Deep to the dermis Not a part of the skin Consists of areolar and adipose tissue Fat storage, area for blood vessel passage, and an area of pressure sensing nerve endings

OVERVIEW OF EPIDERMIS Stratified squamous epithelium avascular (contains no blood vessels) 4 types of cells 5 distinct strata (layers) of cells EPIDERMIS DERMIS

FOUR PRINCIPLE CELLS OF EPIDERMIS Keratinocytes Produce keratin KERATIN protects skin and underlying tissue from heat, microbes, chemicals  Release lamellar granules which release a lipid waterproof sealant Melanocytes Produce pigment melanin melanin contributes to skin color and absorbs damaging ultraviolet rays (UV rays) Langerhans cells Phagocyte cells that participate in immune response Merkel cells Sensory cells Function in the sensation of touch

5 LAYERS OF THE EPIDERMIS From deepest to most superficial (bottom to top)  Stratum basale (also called stratum germinativum)  Stratum spinosum  Stratum granulosum  Stratum lucidum (only in palms and soles)  Stratum corneum

STRATUM BASALE Deepest single layer of epidermis Include all 4 cell types: merkel cells, melanocytes, keratinocytes & stem cells Cells divide repeatedly (MITOSIS) When this portion of the epidermis is destroyed, new skin cannot regenerate (even with a skin graft).

STRATUM SPINOSUM Provides strength and flexibility to the skin 8 to 10 cell layers

STRATUM GRANULOSUM Transition between the deeper, metabolically active strata and the dead cells of the more superficial strata 3-5 layers of flat dying cells that show nuclear degeneration Contain lamellar granules that release lipid that repels water Contain dark-staining keratohyalin granules  keratohyalin converts into keratin

STRATUM LUCIDUM Present only in the fingers tips, palms of the hands, and soles of the feet. 3 to 5layers of clear, flat, dead cells Contains precursor of keratin

STRATUM CORNEUM 25 to 30 layers of flat dead cells filled with keratin and surrounded by lipids Continuously shed Barrier to light, heat, water, chemicals & bacteria Lamellar granules in this layer make it water-repellent. Where callus, an abnormal thickening of the epidermis, is formed

MNEUMONIC DEVICE C L G S B Every Good Boy Does Fine. Please Excuse My Dear Aunt Sally. King Philip, Come Out For Goodness Sake!

SKIN STRUCTURE Figure 4.4

DIAGRAM LEFT SIDE Epidermis Dermis Hypodermis RIGHT SIDE Hair shaft Stratum corneum Stratum basale Sebaceous (oil) gland Arrector pili muscle Nerve fibers Hair follicle X Fat (adipose tissue) BOTTOM Sweat gland

MELANIN Pigment (melanin) produced by melanocytes Color is yellow to brown to black Melanocytes are mostly in the stratum basale Amount of melanin produced depends upon genetics and exposure to sunlight Skin with too much melanin is called hyperpigmented skin. Skin with too little melanin is called hypopigmented skin.

DERMIS Strong, flexible connective tissue Heavily embedded with collagen, elastin, reticular fibers Binds the entire body together like a body stocking. (Like an animal “hide”.) Richly supplied with nerve fibers, blood vessels, and lymphatic vessels. Contain: hair follicles, oil & sweat glands

DERMIS Two layers 1. Papillary layer (thin, superficial layer = 20%) Projections called dermal papillae Pain receptors Capillary loops EPIDERMAL RIDGES form on palms of hands and soles of feet increase friction and enhance gripping Form FINGERPRINTS

2. RETICULAR LAYER (80% thickness) Contain; blood vessels, glands, nerve receptors Bundles of collagen fibers form cleavage lines (Appear as fine lines on the skin.) Surgery: incisions parallel, not perpendicular No skin gapes; heals faster Collagen & Elastin: give skin resiliency, flexibility and bind to water to keep skin hydrated. Flexure lines (deep joints (wrists, fingers, soles, toes)

FINGERPRINTS There are three basic fingerprint patterns and seven subgroups. 1.Arch 2.Whorl 3.Loop

FINGERPRINTS A fingerprint is an impression of the friction ridges found on the inner surface of a finger or a thumb. Friction ridges are also found on the palms of the hands and on the soles and toes of your feet. Fingerprints are formed while a baby is still in the womb. You cannot get rid of your fingerprints – you also cannot change them, unless you do something drastic such as chopping off a finger.

FINGERPRINTS Every person’s fingerprint is unique. Not even identical twins have the same fingerprints. No two fingerprints have ever been found to be identical. Secretions from the eccrine (sweat) glands can leave impressions on smooth surfaces, such as glass, plastic, and polished wood. A special type of powder is used to ‘lift’ fingerprints from such surfaces for purposes of identification.

FINGERPRINTS A Frenchman, pioneered the use of physical evidence to solve crimes. The date was Fingerprinting is the most commonly used forensic evidence worldwide. It is claimed to do better than DNA testing to identify murderers, rapists and other serious offenders, especially in countries where DNA testing is not widely used.

TATTOOS

Tattooing is a permanent coloration of the skin in which a foreign pigment is injected into the dermis. When first injected into the skin, tattoo ink spreads from the puncture site to both the epidermis and the dermis. And as your tattoo heals, immune cells or phagocytes in the epidermis engulf the ink and epidermal cells flake off, carrying ink away. The dermis also contains cells involved in immune responses and that recognize the tattoo ink as foreign. Tattoo ink is trapped in the dermis in a meshwork of fibroblast cells and collagen that form granular tissue. If a tattoo is done properly, tattoo ink won't reach the hypodermis. As you get much older, the tattoo pigment may migrate deeper into the dermis (that's why your tattoo may fade a bit over time), but for the most part, it remains at the upper portion of the dermis, closer to the epidermis.

SKIN COLOR Melanin Yellow, brown or black pigments Carotene Orange-yellow pigment from some vegetables Hemoglobin Red coloring from blood cells in dermis capillaries Oxygen content determines the extent of red coloring

HOMEOSTATIC IMBALANCES Choose ONE homeostatic imbalance in chapter 4. Look for the balance icon and red heading. Read about it. Write a short summary in your notebook, identifying the name, cause, and appearance (if listed). Use heading: “HOMEOSTATIC IMBALANCE OF THE INTEGUMENTARY SYSTEM”