L1 | INTEGUMENTARY SYSTEM

• INTEGUMENT

  • "Protective covering"
• INTEGUMENTARY SYSTEM

  • Largest organ (15% of the body weight)

  1. EPIDERMIS
  2. DERMIS
  3. HYPODERMIS
• EPIDERMIS

  • Keratinized stratified squamous epithelium
  • Top layer of skin
  • Made of 4 individual stratum
• • KERATINIZED - Glowing of skin
  • STRATIFIED SQUAMOUS - Layers of flat cells
  • “Strata” – Layers
  • “Squamous” –Flat cells
• CELLS OF EPIDERMIS

  1. STEM CELLS
  2. KERATINOCYTES
  3. MELANOCYTES
  4. TACTILE (MERKEL) CELLS
  5. DENDRITIC (LANGHERHANS) CELLS
• STEM CELLS

  • Undifferentiated cells in deepest layers
• KERATINOCYTES

  • Most of the skin cells
• MELANOCYTES

  • Synthesize pigment that shield UV
• TACTILE (MERKEL) CELLS

  • Receptor cells associated with nerve fibers
• DENDRITIC (LANGERHANS) CELLS

  • Macrophages guard against pathogens
• STRATUM

  1. STRATUM BASALE
  2. STRATUM SPINOSUM
  3. STRATUM GRANULOSUM
  4. STRATUM LUCIDUM
  5. STRATUM CORNEUM
• STRATUM BASALE

  • Convoluted over time
  • Forms dermal papilla
  • Holds the epidermis on the dermis
  • Where mitosis occur (new cells)
• STRATUM BASALE CELL TYPES

  1. KERATINOCYTES
  2. MELANOCYTES
  3. MERKEL CELLS
• KERATINOCYTES

  • Undergo mitosis to replace epidermis
• MELANOCYTES

  • Distribute melanin through cell processes 
  • Melanin picked up by keratinocytes
• MERKEL CELLS

  • Touch receptors; from merkel disc
• STRATUM SPINOSUM

  • Layers of keratinocytes
  • Appear spiny due to shrinkage during histological preparation
  • Contains dendritic (langerhans) cell
  • Macrophages from bone marrow that migrate to the epidermis
• STRATUM GRANULOSUM

  • Appearance: Granular
  • 3 - 5 layers flat keratinocytes
  • Contain keratohyalin granules
  • Combine with filaments of cytoskeleton to form keratin
• STRATUM GRANULOSUM

  • Produces lipid filled vesicles that release a glycolipid by exocytosis to waterproof the skin
  • Forms barrier between surface cells and deeper layer of epidermis
  • Cuts off surface strata from nutrient supply
• STRATUM LUCIDUM

  • Thin translucent zone seen only in thick skin
  • Keratinocytes are packed with eleidin
  • Precursor to keratin
  • Does not stain well
  • Cells have no nucleus or organelles
• STRATUM CORNEUM

  • Up to 30 layers of dead, scaly, keratinized cells
  • Surface cells flake off (exfoliate)
• DERMIS

  • Connective tissue layer
  • Have vascular tissues capillaries, and nourishment
• SEBACEOUS GLAND

  • Release oil to keep our hair and skin waterproof
• TACTILE RECEPTORS

  • Near top: sensing light touch
  • Farther down: sensing deep touch
• PAIN RECEPTORS

  • Keeps us from damaging skin
• HYPODERMIS

  • Sometimes called “subcutaneous”
  • Thickness variable, normally 1-2 mm
  • Dermis may thicken, up to 6 mm
  • Stratum corneum layer increased
• APPENDAGES OF THE SKIN

  1. HAIR
  2. NAILS
  3. SWEAT GLANDS
  4. SEBACEOUS GLANDS
• HAIR

  • Hair follicles produce hair, which provides insulation and protection
  • Matrix
  • Layer of cells that makes new cells
  • Forms hair as they are pushed up
• NAILS

  • Protective plate 
  • Found at the tip of the digits (fingers and toes) of all primates, corresponding to the claws in other tetrapod animals.
  • Eponychium
  • Makes the cuticle
• SWEAT GLANDS

  • Produces sweat, which helps regulate body temperature
• SEBACEOUS GLANDS

  • Secrete sebum
  • Oily substance that lubricates the skin.
• SKIN CONDITIONS AND DISORDERS

  1. ECZEMA
  2. PSORIASIS
  3. ACNE
  4. RASHES
• ECZEMA

  • Chronic inflammatory skin condition
  • Characterized by dry, itchy, and inflamed skin
• PSORIASIS

  • Autoimmune disease causing scaly, red patches on the skin
• ACNE

  • Caused by clogged pores and inflammation
• RASHES

  • Temporary skin irritation
  • Caused by variety of factors, including allergies, infections, and exposure to irritants
• INTERNAL STRUCTURE OF SKIN

  A) HAIR SHAFT

  B) ARRECTOR PILI MUSCLE

  C) SEBACEOUS GLAND

  D) SWEAT GLAND

  E) HAIR FOLLICLE

  F) HAIR BULB

  G) ADIPOSE CELLS

  H) EPIDERMIS

  I) DERMIS

  J) HYPODERMIS

  
• EPIDERMIS SUBLAYERS

  A) CORNEUM

  B) LUCIDUM

  C) GRANULOSUM

  D) SPINOSUM

  E) BASALE