7. Pay attention to how many cells there are.

8. *BONUS* Name that cell…

8.

Functions of the Integumentary System

• Protection

• Body temperature regulation – Dilation – Constriction – Sweat gland secretions

• Cutaneous sensation

• Metabolism

Three major regions

Cells of the Epidermis

• Keratinocytes• Melanocytes • Langerhans’ cells • Merkel cells

TH

ICK

vs TH

IN skin

Epidermis

Five layers:•Stratum corneum: dead cells; keratin dominate cells; can become thick from irritation

•Stratum lucidum: Present in thick skin only, dead cells

•Stratum granulosum: cells dying; begin keratinization

•Stratum spinosum: living cells, keratin generation

•Stratum basale: youngest cells; specialized cells present

Dermis

• Strong, flexible connective tissue

• Cell types: fibroblasts

macrophages

mast cells

white blood cells

• Composed of two layers – papillary and reticular

Skin Color• Three pigments contribute to skin color

– Melanin• yellow to reddish-brown to black pigment• Freckles and pigmented moles

– Carotene • yellow to orange pigment

– Hemoglobin• reddish pigment

Fingerprint Characteristics

Integumentary Accessories

Sweat Glands– Eccrine sweat glands – Apocrine sweat glands – Ceruminous glands – Mammary glands

Sebaceous Glands

• Simple alveolar glands • Androgen• Sebum• Lubrication• Complications…

Nails• Consist of:

– free edge– Body– Root– Cuticle– Lunula– keratin

Growth- 0.5 mm/week fingernails faster than toe nails …why?

Hair• Filamentous strands

of dead keratinized cells

• Functions? – Hint…there are 6

• Location

Hair Follicle

Regions: shaft, root, medulla (inner), cortex (outer), cuticle (cover)

Hair Thinning and Baldness

• Alopecia – hair thinning in both sexes

• True, or frank, baldness – Genetically determined – Sex-influenced condition – Male pattern baldness

Rule of Nines

Figure 5.8a

Developmental Aspects of the Integument: Fetal

Lanugo

Vernix caseosa

• Oil, hair and acne…oh my!• Sweat!• Cumulative environmental assaults• Scaling• Dermatitis

Adolescent to Adult

• Replacement of cells slows and skin gets thinner

• Decreased lubrication

• Decreased elasticity

• Loss of subcutaneous tissue

• Decreased numbers of

Melanocytes

Langerhans’ cells

Developmental Aspects of the Integument: Old Age