INTEGUMENTARY SYSTEM

• INTEGUMENTARY SYSTEM - consists of the skin, hair, nails, the subcutaneous tissue below the skin, and assorted glands.
• PRIMARY FUNCTIONS:

  • Protection
  • Sensory Perception
  • Thermoregulation
  • Excretion
  • Production of Vitamin D
  • Homeostasis
  • Storage and Insulation
• Protective - water resistant barrier that protects against DEHYDRATION, ABRASIONS, UV LIGHT and TOXINS.
• IMMUNOLOGICAL - serves as a passive barrier to pathogens but has antigen- presenting cells
• SENSORY - nerve receptors
• EXOCRINE - sweat glands
• ENDOCRINE - photolytic pathways for VITAMIN D (hormones)
• HOMEOSTASIS - thermoregulation, water conservation, gas exchange and excretion
• Communication - goosebumps
• LAYERS OF SKIN:

  EPIDERMIS - outer avascular epithelial

  DERMIS - inner layer consist of dense connective tissues

  A) apocrine

  B) hair bulb

  C) eccrine sweat gland

  D) sebaceous gland

  E) arrector pili muscle

  F) duct of eccrine

  G) pore of eccrine

  H) hair shaft

  I) hair root

  J) duct

  K) hair follicle

  
• EPIDERMIS LAYERS

  A) stratum corneum

  B) stratum basale

  C) stratum spinosum

  D) stratum granulosum

  E) stratum lucidum

  
• STRATUM CORNEUM (horny layer)

  • outermost layer
  • several layer of keratinized dead cells
  • appears clear and NO NUCLEI
  • varies in thickness

  
• STRATUM LUCIDUM (clear layer)

  • only found in specific areas of THICK SKIN or HAIRLESS regions
  • Thin,
  • Translucent
  • Homogenous Line

  
• STRATUM GRANULOSUM

  • flattened cells
  • contains: keratohyalin granules and lamellar granules

  
• STRATUM SPINOSUM

  • several layers of POLYHEDRAL CELLS
  • TONOFILAMENTS are more prominent than in STRATUM BASALE

  
• STRATUM BASALE (basal layer)

  • a.k.a STRATUM GERMINATIVUM
  • consists of single layer of CUBOIDAL cells

  
• DERMIS (corium) - true skin

  • lies beneath the membrane, extends to hypodermis
• 2 LAYERS OF DERMIS

  1. PAPILLARY LAYER - thinnest layer consist of connective tissue, in contact with epidermis
  2. RETICULAR LAYER - thicker layer, dense irregular CT, smooth muscle called ARRECTOR PILI MUSCLE near hair follicle
• SKIN APPENDAGES

  • mammals - skin w/ hair
  • birds - feathers
  • fish and reptiles - scales
• HAIR - a flexible keratinized structure produced by a hair follicle
• PARTS of HAIR:

  A) hair shaft

  B) hair root

  C) hair bulb

  D) medulla

  E) cortex

  F) cuticle

  
• SEBACEOUS GLAND - secrets oil into hair follicle (SEBUM- prevents growth of bacteria)

  
• SWEAT GLANDS - consists of coiled up tube on a duct onto the skin surface.

  • sweat contains salt and waste products like UREA
  • evaporation of sweat is MAJOR COOLING MECHANISM

  
• MAMMARY GLAND

  • only present in mammals
  • modified sebaceous glands present in both sexes (rarely in male)
• KERATINOCYTES (from stratum basale)---move up--- eventually becoming anucleated.

  
  

  • 95% of the epidermis
• HOOFS

  • found in sheep, cows, horses, etc.
  • UNGULATE MAMMALS
  • nails

  
• TRUE HORNS

  • made of keratin
  • never shed
  • consist of core bone arising from dermis
  • fused with skull
  • forms a hollow cone

  A) cornual diverticulum

  B) corium

  C) periosteum

  D) horn

  
• DEER HORNS

  • MALES differs in structures, don't consists of keratin.
  • sheds yearly
  • often branched
  • VELVET - skin covering of the antlers (sold in Asia for medicine)

  A) velvet

  B) bone

  
• FEATHERS

  • light fluffy down feathers are best natural insulator
  • CONTOUR feathers - large feathers that cover the body, wings and tail.
  • PREENING - bird usage of its beak to fix barbs and barbules

  A) vane

  B) shaft

  C) follicle

  D) quill

  E) barb

  F) barbules

  
• PREEN GLAND - situated near birds tail, produces oil
• MAMMARY GLAND

  A) teat orifices

  B) teat canal

  C) teat

  D) teat sinus

  E) gland sinus

  F) secretory tissue