Integumentary System I. Introduction A. Definition

1. Skin, Cutaneous Membrane, or Integument 2. Largest organ 7% of body weight 3. Divisions = Epidermis, Dermis, & Hypodermis 4. Thick vs. Thin skin

II. Functions

1. Protection from dehydration and mechanical damage 2. Sunscreen 3. Temperature Regulation 4. Waste Excretion 5. Produce Vitamin D 6. Sensory Reception

III. Parts A. Epidermis

1. Definition a. Stratified squamous epithelium “Keratinized” b. Basic cell type called a keratinocyte c. All intercellular junction present d. Avascular and not innervated

2. Strata “Layers” a. Basal, Spinosum, Granulosum, Lucidium, & Corneum Figure 4.3Figure 4.4

3. Associated Cells a. Melanocytesb. Langerhans cellsc. Merkel cells

4. Epidermal Derivatives a. Hairi. Partsii. Types Figure 4.7

b. Naili. Parts Figure 4.9

c. Sweat Glandsi. Types

B. Dermis

1. Definition a. Dense Irregular Connective Tissue b. Basic cell type = fibroblast (all others present) c. Collagen bundles thicken and increase in number with depth (Papillary versus Reticular) d. Highly vascularized and innervated

2. Strata & Function

C. Hypodermis

1. Definition a. Loose Connective Tissue b. Basic cell type = adipocyte (all others present) c. Fat layer (subcutaneous layer) d. Highly vascularized and innervated

IV. Problems A. Infections

B. Tumors

C. Wound Healing

D. Burns

Figure 4.11

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