Integumentary System - Basics & Layers

Skin (Cutaneous Membrane)

Our first line of defense; major part of the immune system.

3 Main Layers (Superficial to Deep)

Epidermis, Dermis, Hypodermis (Subcutaneous)

Epidermis Characteristics

Outer layer; Avascular (no blood); hardened by keratin.

Epidermis Renewal

Completely renews itself every 45 days.

Dermis Characteristics

Middle layer; mainly strong, flexible connective tissue; contains blood/nerves.

Hypodermis (Subcutaneous

Anchors skin to organs; provides shock absorption and insulation.

Adipose Tissue

The fatty tissue that makes up most of the Hypodermis.

Keratinocyte

Cell that produces Keratin (hardens and waterproofs the skin).

Melanocyte

Cell that produces Melanin (pigment)

Melanin Function

Prevents DNA mutation from UV radiation.

Melanocyte Count

Everyone has the same number; the amount of pigment produced differs.

Freckles/Moles

Caused by a localized accumulation of melanin

Dermal Papillae

Indentations that form fingerprints and improve grip.

Meissner’s Corpuscles

Nerve receptors for light touch; found in the papillary layer.

Pacinian Corpuscles

Nerve endings for deep pressure; found in the reticular layer.

Collagen

Protein in the dermis that provides toughness and hydrates skin

Elastin

Provides skin elasticity; tearing leads to stretch marks