Common Integument

• What is the common integument?

  The outer barrier of the organism
• How does the common integument reflect the health of an animal?

  It is often affected by underlying diseases
• What are the main components of the common integument?

  • Subcutis (hypodermis, superficial fascia)
  • Cutis (dermis and epidermis)
  • Modified skin structures (hair follicles, skin glands, foot pads, nails/claws/hooves, horns, antlers)
• What is the subcutis also known as?

  Hypodermis or superficial fascia
• What type of tissue is the subcutis composed of?

  Loose connective tissue
• What are the functions of white fat in the subcutis?

  Insulation, energy source, padding/protection
• How does the texture of the subcutis change?

  It depends on water content
• What can cause folds in the subcutaneous tissues?

  Regional variations in fat and thickness
• Why is understanding subcutaneous tissue important for injections?

  It is important for subcutaneous injection sites
• What does the subcutis attach to?

  Underlying cutaneous muscle
• What is the role of cutaneous muscles?

  They provide means for active movement of the skin
• What is the cutaneous muscle over the neck and face called?

  Platysma
• Which cutaneous muscle is absent in horses?

  Frontalis

  
• What covers the lateral sides of the trunk?

  Cutaneous trunci

  
• What is the composition of the cutis?

  Composed of dermis and epidermis
• How is the dermis attached to the epidermis?

  Via interlocking papillae and ridges

  
• What can disrupt the adhesion between dermis and epidermis?

  Repeated mechanical stress
• What type of tissue primarily composes the dermis?

  Connective tissue
• What types of collagen are found in the dermis?

  Collagen Types I & III
• What are the two regions of the dermis?

  Superficial papillary region and deeper reticular region

  
• What are tension lines or Langer’s lines?

  Collagen fibres oriented in particular ways
• What additional structures are found in the dermis?

  Blood vessels, lymphatic vessels, nerves, sensory receptors
• What type of epithelium is the epidermis composed of?

  Stratified squamous epithelium
• How many layers does the epidermis have?

  4-5 layers

  
• What is produced in the stratum basale?

  Skin cells (keratinocytes)
• How long does the complete cycle of keratinocyte turnover take?

  20-30 days, depending on species
• What are the layers of the epidermis?

  1. Stratum basale
  2. Stratum spinosum
  3. Stratum granulosum
  4. Stratum lucidum
  5. Stratum corneum

  
• What is the function of the stratum granulosum?

  Keratinocytes contain granules for keratinisation
• What characterizes the stratum corneum?

  Thick waterproof cell membrane with dead cells
• What are melanocytes responsible for?

  Producing melanin pigment
• Where do melanocytes primarily reside?

  In the stratum basale
• What do Langerhans cells do?

  Act as antigen presenting cells
• What is the blood supply to the skin primarily provided by?

  Dermis is well-vascularised
• How many plexuses are involved in the blood supply to the skin?

  Three plexuses
• What are the three plexuses in the skin's blood supply?

  Subcutaneous plexus, reticular vascular plexus, superficial papillary plexus

  
• What can the walls of arteries in the dermis do?

  Dilate or constrict to regulate blood supply
• What is the role of sensory nerves in the skin?

  Detect pressure, heat, and pain
• What do autonomic nerves supply in the dermis?

  Sweat glands, arrector pili muscles, blood vessels

  
• What is the function of cutaneous nerves?

  Supply particular regions of the body
• What are the functions of the common integument?

  1. Protection
  2. Immune defence
  3. Sensing environment
  4. Thermoregulation
  5. Storage and excretion
  6. Communication/camouflage
  7. Selective permeability