API Chapter 5 The Integumentary System

I.Integument

A.Skin

1.covering, encloses tissues and organs of body

2.16% of total body weight

B.Functions

1.control water loss and absorption

2.temperature regulation

3.barrier

a.UV light

b.microbes

4.Vitamin D synthesis role

5.nerve sensations

6.blood reservoir

7.excretion via sweat

a.drugs

b.poisons

c.nitrogenous metabolites

II.Anatomy

A.Epidermis

1.stratified squamous epithelial cells

a.4 cell types

(1)keratinocytes

(a)most

(b)produce keratin

(c)water proofing protein

(2)melanocytes

(a)melanin

(b)pigment

(c)protects from UV light

(3)Merkel cells

(a)sensory

(b)at epidermal/dermal junction

(c)touch receptors

(4)Langerhans cells

(a)migrate from bone marrow

(b)macrophages for immune response

b.5 layers of cells

(1)Stratum Basale

(a)single columnar layer on thin BM on dermis

(b)undergo mitosis

(c)keratinocytes

(d)melanocytes

(2)Stratum Spinosum

(a)spiny cells

(b)several layers

(c)most mitosis here

(d)flattened kertinocytes

(e)Langerhans cells

(f)nutrients diffuse up via intracellular spaces

(3)Stratum Granulosum

(a)1-5 layers

(b)squamous epithelium

(c)deratinization

(d)begins with keratin granules

(e)water proofing protein

(4)Stratum Lucidum

(a)clear layer

(b)flat squamous cells

(c)only in thick skinned areas

(d)palms of hands, soles of feet

(5)Stratum Corneum

(a)abundant in keratin

(b)protects deeper cells

(c)structureless, dehydrated dead cells

(d)

(6)most superficial layer

2.cells renewed every 28 days

B.Dermis

1.CT

2.rich vascular bed

3.cells

a.fibroblasts

b.macrophages

4.collagen, elastin fibers

5.nerves

6.blood vessels

7.lymphatic vessels

8.hair follicles

9.oil and sweat glands

10. regions

a.Papillary layer

(1)loose CT

(2)Meissner's corpuscles

(a)light touch receptors

(3)epidermal ridges with papilla

(a)fingerprints

b.Reticular layer

(1)dense CT

(2)high in collagen

(3)stretch marks due to ruptured collagen

11.Pacinian corpuscles

a.may extend into hypodermis

b.deep pressure sensations

C.Hypodermis

1.loose CT

2.superficial fascia (areola CT)

3.adipose tissue

4.deep fascia

D.Coloring

1.melanin

a.yellow to brown to black

2.carotene

a.yellow to orange

3.hemoglobin

a.pinkish in fair skined

b.low gives blue color (cyanosis)

4.jaundice

a.bilirubin

b.excess bile pigments

c.liver or kidney disfunction

5.hematomas

a.blood under skin

III.Appendages of the Skin

A.Hair

1.produced by a hair follicle

2.fused, keratinized cell

3.root, shaft

4.three concentric layers of keratinized cells

5.cuticle

a.outer layer

b.shingle like arrangement

6.melanocytes at base of hair follicle

7.Hair follicles

a.from epidermis through dermis

b.hair root plexus

(1)sensory nerve endings

c.arrector pili muscle

(1)smooth muscle

(a)contract pulls up hair- goose bumps

8.100,000 hairs on scalp

9.Baldness

a.alopecia

b.male pattern baldness

B.Nails

1.lunula

a.white crescent

2.cuticle

a.proximal end

3.lateral nail fold

a.along sides

C.Sudoriferous glands

1.sweat

a.eccrine

(1)merocrine gland

(2)secretory part in dermis

(3)duct opens to pore on skin surface

(4)secretes sweat

(a)hypotonic solution

(b)water

(c)salts

(d)metabolic wastes

(5)pH 4-6

b.apocrine glands

(1)axillary and anogenital areas

(2)ducts open in hair follicles

(3)function at puberty

D.Ceruminous glands

1.cerumen secretion: wax

2.modified apocrine glands in ears

E.Sebaceous glands

1.sebum (oil)

2.not on palms or soles

3.duct into hair shaft

4.holocrine glands

5.softens hair

6.secretion is stimulated at puberty

F.Mammary glands

1.specialized suderiferous glands for milk production

IV.Homeostatic Imbalances of the Skin

A.Burns

1.First-degree burns

a.only epidermis damage

b.redness, swelling,pain

2.Second-degree burns

a.injury to epidermis and upper dermis

b.blisters

c.little scarring

3.Third-degree burns

a.full-thickness burns

b.little or no edema or pain

c.fluid loss

B.Cancers

1.many of epithelial origin

2.benign

3.malignant

4.metastasize

5.Basal cell carcinoma

a.most common skin cancer

(1)from stratum basale

(a)do nto form keratin

(b)invade dermis and hypodermis

b.nodule appearance with ulcerated center

6.malignant melanoma

a.melanocytes - 5% of skin cancers

b.spontaneously appear or from mole

c.ABCD rule

(1)A asymmetry

(2)B border irregularity

(3)C color (different colors)

(4)D diameter (6 mm -Pencil eraser)

V.Developmental Aspects of Integumentary system

A.Lanugo coat - delicate hairs on fetus

B.Vernix caseosa -white cheesy covering of newborn

C.Aging -less collagen and elastin