Exam 1: Chapter 5

Integument system

• The largest system of body

• Sixteen percent of body weight

Made up of two parts

Cutaneous membrane (skin)

• Outer epidermis (superficial epithelium)

• Inner dermis (connective tissue)

• Hypodermis (subcataneous layer)

Accessory structures (originate in the dermis)

• Extend through the epidermis to skin surface

• Hair

• Nails

• Multicellular exocrine glands

Functions of skin (100%)

• PROTECTION

• Production of keratin (make)

• Synthesis of vitamin D3

• Storage of lipids

• Detection of touch, pressure, pain and temperature (sensory)

Connections

Cardiovascular system

• Blood vessels in the dermis

Nervous

• Sensory receptors for pain, touch, and temperature

Cells of epidermis

Keratinocytes

• Contain large amounts of keratin

• Are the most abundant cells in the epidermis

Epidermis: Thin and Thick skin

Thin skin (missing stratum lucidum)

• Covers most of the body

• Has four layers of keratinocytes

Thick skin

• Covers the palms of the hands and soles of the feet

• Has five layers of keratinocytes

Epidermis: Stratum Basale (germanous) and cells

• The deepest layer, is attached to basement membrane by hemidesmosomes

• Forms a strong bond between epidermis and dermis

• Forms epidermal ridges (project downward towards dermis) (basis of fingerprints)

• Dermal papillae (project upward towards epidermis) (tiny mounds)

Cells

Merkel

• Found in hairless skin

• Respond to touch receptors (trigger nervous system)

Melanocytes

• Contain the pigment melanin

• Scattered throughout stratum basale

Epidermis: Stratum spinosum

• The “spiny layer”

• Produced by division of stratum basale

• Eight to ten layers of keratinocytes bound by desmosomes

• Cells shrinks until cytoskeletons stick out (spiny)

Epidermis: Stratum granulosum and cells

• The “grainy layer”

• Stops dividing, starts producing: Keratin

• A tough, fibrous protein

• Makes up hair and nails

• Mitosis starts here

Cells

• Produce protein fibers

• Where cells dehydrate and die

Epidermis: Stratum lucidum

• The “clear layer”

• Found only in thick skin

• Covers stratum granulosum

Epidermis: Stratum corneum

• The “horn layer”, most superficial layer

• Exposed surface of skin

• 15-30 layers of keratinized cells

• Water resistant, not water proof

• Shed and replaced every two weeks

Keratinization

• The formation of a layer of dead, protective cells filled with keratin

• Occurs on all exposed skin surfaces except eyes

• Skin life cycle

Perspiration (100%)

Insensible perspiration

• Interstitial fluid lost by evaporation through the stratum corneum. Not perceived by the body, submerged in salt water (hypertonic solution)

Sensible perspiration

• Water excreted by sweat glands

• Dehydration

• Perceived by the body, evidence by sweating

• If a person is this we want to give isotonic solution, will prevent water in and out (equilibrium) (never give hypertonic solution, 350 miliosmos)

Pigments for skin: Carotene

• Orange-yellow pigment

• Found in orange vegetables

• Accumulates in epidermal cells and fatty issues of the dermis

Pigments for skin: Melanin and functions

• Yellow-brown or black pigment

• Produced by melanocytes in stratum basale

Functions

• Melanin protects skin from sun damage

• Ultraviolet (UV) radiation

• Causes DNA mutations and burns that lead to cancer and wrinkles

How to determine cancer and the two types

• A - Asymmetry of border (is the border different?)

• B - Border (are there any irregulars?)

• C - Color (is the color even?)

• D - Diameter (is it larger than 6mm/quarter of an inch)

• E - Evolving (did it get bigger over time?)

Two types

• UVA causes cancer

• UVB burns, can cause cancer

Cancer: Basal cell carcinoma

• Most common type

• Looks benign but not

• Does not follow ABCDE

• Light pink, pearly bumps

• Found in sun exposed skin

• Treatment is Mohs surgery or cyro therapy

• Survival rate if caught early is 99%

Squamous cell carcinoma

• 2nd most common

• Follows ABCDE

• Has a different color and crusts over

• UV exposure and tanning beds

• Found in people with fair skin

• Treatment is Mohs surgery or cyro therapy

• Survival rate if caught early is 99%

Melanoma

• Follows ABCDE

• Tanning beds and UV radiation

• If caught before it metastasizes its a 99% survival rate, if not 5 year survivable rate only at 35%

• Hard to see in dark skin

Capillaries and skin color

• Oxygenated red blood contributes to skin color

• Blood vessels dilate from heat, skin reddens

• Blood flow decreases, skin pales

Cyanosis

• Blush skin tint

• Caused by severe reduction in blood flow or oxygenation

• Lack of oxygen to the skin

Illnesses and skin color

• Buildup of bile produced by liver

• Yellow color

• Pituitary tumor

• Excess MSH

Addison’s disease

• A disease of the pituitary gland

• Skin darkening

Vitiligo

• Loss of melanocytes

• Loss of color

• More noticeable on dark skin (assumed to be an autoimmune reaction)

Vitamin D3 (100%)

• Epidermal cells produce cholecalciferol (vitamin D3)

• In the presence of UV radiation

• Liver and kidneys convert vitamin D3 into calcitriol

• Insufficient vitamin D3 → causes rickets

The dermis

• Located between epidermis and subcutaneous layer

• Anchors epidermal accessory structures (hair follicles, sweat glands)

Consist of two components

• Outer papillary layer (areolar tissue)

• Deep reticular layer

Layers of the dermis: Papillary and Reticular layer

Papillary

• Consists of areolar tissue

• Contains smaller capillaries, lymphatics, and sensory neurons

• Has dermal papillae projecting between epidermal ridges

Reticular

• The deeper layer of the dermis

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Dermatitis

• An inflammation of the papillary layer

• Caused by infection, radiation, mechanical irritation, or chemicals

• Atopic dermatitis (eczema) - IGE reaction (immune hypersensitivity)

• IGG reaction id delayed hypersensitivity

Skin damage: Sagging and wrinkles

• Sagging and wrinkles (reduced skin elasticity)

Caused by

• Dehydration

• Age

• Hormonal

• UV exposure

The Hypodermis

• The deepest layer

• Stabilizes the skin

• Made of elastic areolar and adipose tissues

• The site of subcutaneous injections using hypodermic needles

• Deposits of subcutaneous fat

• Distribution patterns determined by hormones

• Reduced by cosmetic liposuction

Hair in the human body

• Palms

• Soles

• Lips

• Portions of external genitalia

Functions of hair

• Protects and insulates

• Guards opening against particles and insects

• Is sensitive to very light touch

Structures of hair

Hair follicle

• Located deep in dermis

• Produces nonliving hairs

Arrector pili

• Always next to hair follicle

• Involuntary smooth muscle

• Causes hairs to stand up

• Produces “goosebumps”

Sebaceous glands

• Lubricate the hair

• Control bacteria

• Always next to a hair follicle

Regions of hair

Hair root

• Lower part of the hair

• Attached to the integument

Hair shaft

• Upper part of the hair

• Not attached to the integument

Bulb

• Where the arteries and veins are

Hair production and color

• Begins at the base of a hair follicle, deep in the dermis

• The hair papilla contains capillaries and nerves

• The hair bulb produces hair matrix

Color

• Produced by melanocytes at the hair papilla

• Determined by genes

Hair shaft structures

Medulla

• The central core (deepest part)

Cortex

• The middle layer (outer part)

Cuticle

• The surface layer

Keratin

• As hair is produced, it is keratinized

• Medulla contains flexible soft keratin

• Cortex and cuticle contain stiff hard keratin

Layers in the follicle

Internal root sheath

• The inner layer

• Contacts the cuticle in lower hair root

External root sheath

• Extends from skin surface to hair matrix

Glassy membrane

• A dense connective tissue sheath

• Contacts connective tissues of dermis

Hair growth cycle

Growing hair

• Firmly attached to matrix

Club hair

• Not growing

• Is attached to an inactive follicle

Vellus hairs

• Soft, fine

• Cover body surface

Terminal hairs

• Heavy pigmented

• Head, eyebrows, and eyelashes

• Other parts of body after puberty

Exocrine glands: Sebaceous glands

• Oil glands

• Its a holocrine gland

Types

• Simple branched alveolar glands - associated with hair follicles

• Sebaceous follicles - discharge directly onto skin

Sebum

• Contains lipids and other ingredients

• Lubricates and protects the epidermis

• Inhibits bacteria

Sweat glands: Apocrine glands

• Found in armpits, around nippl*s, and groin

• Secrete products into hair follicles

• Break down and causes odor, increase after puberty

Sweat glands: Merocrine (eccrine) glands

• Widely distributed on body surface

• Especially on palms and soles

• Discharge directly onto skin surface

• Sensible perspiration

Functions

• Cools skin

• Excretes water and electrolytes

• Flushes microorganisms and harmful chemicals from skin

Other integumentary glands

Mammary glands (over breast)

• Produce milk

Ceruminous glands

• Produce cerumen (earwax)

• Protect the eardrum

Nails and nail production

• Protects fingers and toes

• Made of dead cells packed with keratin

• Metabolic disorders can change nail structure

Nail production

• Occurs in a deep epidermal fold near the bone called the nail root

Structure of a nail

Nail body

• The visible portion of the nail

• Covers the nail bed

Lunula

• The pale crescent at the base of the nail

Sides of nails

• Lie in lateral nail grooves

• Surrounded by lateral nail folds

• Skin beneath the distal free edge of the nail

• Is the hyponychium (onyx=nail)

Visible nail emerges

• From the eponychium (cuticle)

• At the tip of the proximal nail fold

Repair of the skin

• Bleeding occurs

• Mast cells trigger inflammatory response

• A scab stabilizes and protects the area

• Germinative cells migrate around the wound

• Macrophages clean the area

• Fibroblasts produce scar tissue

• Inflammation decreases, clot disintegrates

• Fibroblasts strengthen scar tissue

• A raised keloid may form

The rules of the 9s