Integumentary System

• integumentary system includes: skin, hair, footpads, and claws
• skin is the largest organ of the body
• sebaceous glands secrete an antiseptic sebum onto the surface of the skin
• melanin is the pigment of skin and different from melanocytes
• function of skin: protection, sensory, secretion, production, storage, thermoregulation and communication
• the skin acts as a waterproof barrier since it's almost impermeable to water which prevents the body from drying out or waterlogged
• the pigmented area of the skin protects the body from uv radiation
• the surface of skin is packed with many types of sensory nerve endings that detect temperature, pain, touch, and pressure
• what does sebaceous glands secrete?

  sebum
• where does cats and dogs sweat?

  foot pads
• the specialized skin glands produced?

  pheromones
• UV light from the sun converts 7-dihydrocholesterol present in the sebum into vitamin D. This is activated in the kidney and liver which increases the uptake and dietary calcium
• fat that is stored under the skin is known as an adipose tissue or subcutaneous fat
• fat is an energy store and acts as a thermal insulating layer
• how does body losses heat?

  sweat
• how does dogs and cats dissipate excess body heat?

  panting
• the skin prevents heat loss by diverting blood away from the surface by vasoconstrictions, erecting hairs to trap a layer insulating air, and by having a layer of insulating fat
• pheromones - a natural scents used for intraspecific communication
• how does integument provides visual communication?

  hackles
• hackles is a sign or warning for possible aggression
• other glands that provide scents for communication: circumanal glands and glands of anal sacs
• skin provides a means of visual communication
• hypodermis lies beneath the skin but is not part of the skin
• skin is composed of two layers: epidermis or superficial layer

  and dermis, the underlying layer
• dermis is also called as?

  corium
• epidermis is composed of stratified squamous epithelium and has multiple layers that are continually renewed
• melanocytes contain granules of pigment melanin
• layers of epidermis from within to out:

  1. stratum basale,
  2. stratum spinosum,
  3. stratum granulosum,
  4. stratum lucidum,
  5. stratum corneum
• what is the first layer of epidermis from within?

  stratum basale
• what is the second layer of epidermis from within?

  stratum spinosum
• what is the third layer of epidermis from within?

  stratum granulosum
• what is the fourth layer of epidermis from within?

  stratum lucidum
• what is the last layer of epidermis from within?

  stratum corneum
• the new cells produced in the deepest layer of the epidermis and pushed upward to the surface is because of mitosis
• the dead skin cells are also called squames
• stratum basale is same as?

  germinativum
• this is where the cells are manufactured

  stratum basale
• stratum basale or germinativum - consists of single layer of dividing cells and where melanocytes may also be present
• stratum spinosum - the spinous or prickle cell layer which is composed of polyhedral keratinocytes and are joined together with desmosomes
• this is the prickle cell layer of the epidermis?

  stratum spinosum