Layers of the Skin and Types of Epithelium

Epidermis
- Protects the Dermis
- Prevents toxins and bacteria from entering the body
- Reduces friction
- Prevents fluid loss
- Provides skin flexibility and strength
- Develops new skin cells
Dermis
- Nourishes and supports the Epidermis
- Contains hair follicles and dermal papillae that generate hair shafts
- Houses sensory receptors including tactile and lamellated corpuscles
Hypodermis
- Provides insulation and structure to the skin

Stratum Corneum
- Outermost layer
- Composed of dead skin cells, providing a barrier against environmental damage
Stratum Lucidum
- Present in thick skin (palms, soles)
- Provides an additional layer of protection
Stratum Granulosum
- Contains keratinocytes that produce keratin
- Prevents fluid loss
Stratum Spinosum
- Provides strength and flexibility to the skin
- Contains keratinocytes and immune cells
Stratum Basale
- Deepest layer where new skin cells are generated
- Contains melanocytes (pigment production) and Merkel cells (touch sensation)

Sebaceous Gland
- Releases sebum (oil)
- Helps keep skin moisturized
Apocrine Sweat Gland
- Scent glands located in specific areas (e.g., armpits, groin)
- Associated with hair follicles
Eccrine (Merocrine) Sweat Gland
- Distributed widely across the skin
- Helps cool the surface of the skin through sweat secretion

Tactile Corpuscle
- Transmits touch vibrations
- Provides sensitivity to light touch
Lamellated (Pacinian) Corpuscle
- Sensitive to deep pressure and vibration

Thin Skin
- Lacks stratum lucidum
- Contains four layers of skin
Thick Skin
- Contains all five layers, including stratum lucidum
- Typically found on palms and soles

Stratified Squamous Epithelium
- Non-keratinized and keratinized forms
- Provides protection against pathogens (e.g., esophagus)
Simple Squamous Epithelium
- Reduces friction, found in alveoli of lungs
Simple Cuboidal Epithelium
- Secretion role, found in kidney tubules
Simple Columnar Epithelium
- Secretion and absorption, found in the lining of the stomach
Transitional Epithelium
- Permits stretching, found in the urinary bladder
Pseudostratified Ciliated Columnar Epithelium
- Moves mucus with cilia, found in the nasal cavity

Areolar Connective Tissue
- Surrounds nerves and organs
- Provides cushioning
Adipose Connective Tissue
- Stores fat
- Provides padding and insulation, particularly in the buttocks and deep skin
Dense Regular Connective Tissue
- Found between skeletal muscles, reduces friction
Dense Irregular Connective Tissue
- Found in the dermis of the skin, prevents overexpansion
Hyaline Cartilage
- Provides flexible support, found between tips of ribs
Bone Tissue (Osseous)
- Provides structure and support to the body
Blood Tissue
- Vascular tissue that circulates nutrients and gases

Skeletal Muscle Tissue
- Stabilizes the skeleton, voluntary control
Cardiac Muscle Tissue
- Circulates blood in the heart, involuntary control
Smooth Muscle Tissue
- Regulates diameter of blood vessels, involuntary control