1 Skin and Underlying Structures

Hypothalamus

Stimulates sweat glands to produce sweat

Vasodilates blood vessels

Stratum Granulosum

3-5 layers of flattened keratinocytes undergoing transformation

Produces keratin for skin protection

Reticular Layer

Contains nerve endings, blood vessels, sebaceous glands, sweat glands

Provides structural support with thick collagen fibers

Monocytes

WBC

Break down bacteria and clean up damaged cells

Antimicrobial peptides

Provide resistance to pathogenic organisms to pathogenic organisms through bacterial influence

How many layers of skin?

2, epidermis and dermis

Layers of epidermis

Stratum corneum

Stratum Lucidum

Stratum Granulosm

Stratum Spinosum

Stratum Germinativum

(Corny Lucy Granulates Spiny Germs)

Stratum Corneum

Outer layer

Provides tough barrier against environmental damage

Keratinocytes turn into corneocytes

Skin cells continuously shed

Stratum Lucidum

Transparent layer of keratin found ONLY in thick skin (palms, heels)

Protects skin that experiences high levels of friction and mechanical stress

Langerhans cells

First line of defense against environmental antigens

Help initiate immune response

Types of WBC

Neurophils

Lymphocytes

Eosinophils

Basophils

Monocytes

Neutrophils

Most common WBC

Kill bacteria, fungi, foreign debris

Low= at risk for infection

Constitutive skin color

Genetically predetermined without environmental influence

Acid Mantle

Natural defense mechanism of skin

PH of skin (average)

5.5

Biomolecules

Help fight pathogens

How many microorganisms can be found on 1 sq. cm of skin?

1 billion

What is the normal water loss through skin per day?

500 mL

Xerosis

Dry flaky skin indicates excessive TEWL or insufficient sebum prodiction

Tx: moisturizers containing lipids to prevent water loss

Melanin production

Protection against UVB rays

Sun exposure increases melanin production

Vitamin D

Regulates calcium and phosphorus levels in bone and blood

Epidermis thickness

0.1 cm

*ALL open wounds are AT LEAST 0.1 cm deep

Stratum Spinosum

Helps make skin strong and flexible

Keratinocytes held together with desmomes

Langerhans cells, help immunity

Stratum Germinativum

Innermost layer

Helps produce new skin

Only layer where cell mitosis occurs

Cells of Epidermis

Keratinocytes

Langerhans cells

Melanocytes

Merkel Cells

Keratinocytes

Most abundant; 90% of cells

Produce keratin

Starts at the base; takes ~28 days to migrate up

New cells push old cells to surface; old cells die

Melanocytes

Pair with keratinocytes

Create and distribute melanin

Protect skin from UV radiation

Give skin color

Merkel Cells

Found in stratum germinativum

Sensory cells, nerve endings=

Epidermal Junction (BMZ)

Basement Membrane Zone

Seperates epidermis and dermis

Provides structural support and facilitates the exchange of fluids

Irregular surface (rete ridges) create interlocking bond

Dermis thickness

0.2 cm thick

How many layers of Dermis?

2

Papillary layer

Reticular layer

Papillary Layer

Loose connective tissue

Capillary loops, fibroblasts, EXTRACELLULAR MATRIX, vascular and lymphatic netowrks

Extracellular Matrix

Creates scaffolding for new cells to heal

Component of dermis

Made of sugars, protein, collagen, elastin

Transport system for nutrients and waste products

Fibroblasts

Cell of dermis

Produce collage (tensile strength)

Produce elastin (elastic coil)

Magrophages

Cell of dermis

Significant role in immune defense

Teams up with neutraphils (kill bacteria) and consume bacteria

Mast cells

Cell of dermis

White blood cell containing heparin and histamine

Involved in cascade of healing

Subcutaneous tissue

Connects skin to underlying fascia

YELLOW in color (if yellow = full thickness)

Subcutaneous tissue function

Thermoregulation

Insulation and protection for body

Attachment site for fascia and muscles

Energy reserve

Hormone production (leptin)

Fascia

Envelops and supports muscles, bones, organs

WHITE and shiny

Composed mainly of collagen

Provides frictionless surface

Muscle Tissue

Vascular, striated

Responds to stimulation by contracting

PINK to DARK RED if healthy

Tendons

Mostly made of collagen

Connect MUSCLE to BONE

WHITE cord or rope

Ligaments

Attach BONE to BONE

WHITE flat, ribbon

Bone

Provides structural support and protection of internal organs and mobility

WHITE and shiny

Periosteum

Layer of dense fibrous connective tissue covering the external surface of bone

Cartilage

Thin layer of tissue over end of bone

WHITE shiny

Vascular system

Delivers oxygen and nutrients to organs, tissues and wound sites

Good blood flow to damages tissues promotes faster healing

RBCs

40-45% of blood

Lifespan = 120 days

Gather O2 from lungs and deliver to tissues

Hemoglobin

Binds oxygen to deliver it to and remove carbon dioxide from cells

WBCs

Defend the body against microorganisms and fight infection

Lymphocytes

WBC

Consist of T and B cells; fight viruses and produce antibodies

Eosinophils

WBC

Kill parasites, fight cancer cells, help with allergic reactions

Basophils

WBC

Secrete histamine; help control body's immune response

Platelets

Sticky, irregular disc shape

Assist with blood clotting and forming a plug

Attract fibrin, which makes a net to trap RBCs

Facultative skin color

Results from exposure to sunlight

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