ANSWERS

1. Define integument.
   The literal meaning of integument is the skin or a layer of tissue covering a part or organ of the body. With regard to the anatomy and physiology of animals, integument means the covering of the body and includes the skin, hair (or feathers), pads and claws.
2. List the 8 main functions of the skin.
   • Protection of the surface of the body.
   • Protection against invasion by microorganisms.
   • Temperature regulation.
   • Prevention of excessive water loss in land mammals (prevention of water uptake in aquatic mammals).
   • Manufacture of vitamin D.
   • Protection against ultraviolet radiation.
   • Sensory to pain, pressure and temperature.
   • Secretion via exocrine glands.
3. Name the 3 distinctive layers that comprise the skin.
   • Epidermis (the most superficial layer).
   • Dermis (the middle layer).
   • Hypodermis (the deepest layer).
4. The epidermis is made of stratified squamous epithelium and consists of 4 strata (layers). Name them.
   • Stratum germinativum.
   • Stratum granulosum.
   • Stratum lucidum.
   • Stratum corneum.
5. The epidermis is avascular; what does this mean?
   It does not contain any blood vessels.
6. What is another name for the stratum germinativum?
   Stratum basale.
7. What are melanocytes and where would you find them?
   Skin pigment cells. These are found between the rapidly dividing basal cells of the stratum germinativum.
8. Give an example of a part of the body where dermal papillae likely to be prevalent.
   The pads (and other areas of thick skin liable to trauma).
9. What is the name of the protein which forms the principle constituent of all horny tissues?
   Keratin.
10. List 6 structures located within the dermis.
    • Blood vessels.
    • Elastic fibres.
    • Nerve fibres and sensory nerve endings.
    • Hair follicles.
    • Sweat glands.
    • Sebaceous glands.
11. Which part of the skin consists of loose connective tissue that is often infiltrated by fat?
    The hypodermis.
12. Briefly describe how hair is formed.
    • Epidermal tissue extends down into the dermis.
    • A hair cone is formed over a piece of the dermis known as the dermal papilla (or hair papilla).
    • The epidermal cells surrounding the hair cone are destroyed allowing the hair to grow freely through an open channel known as the hair follicle.
    • The hair grows continually until it dies and becomes detached from the hair cone.
    • The dead hair is shed and either falls out of its own accord, or if it remains attached, is removed by combing.
13. What substance is secreted by the sebaceous glands?
    Sebum.
14. List the 4 main functions of sebum.
    • Lubrication.
    • Waterproofing.
    • Production of smells used for territorial marking.
    • Production of pheromones used to attract a mate.
15. What is the name given to the long hairs of the topcoat which are responsible for waterproofing?
    Guard hairs.
16. Which muscles are responsible for raising the hairs when the animal is cold or about to fight?
    The arrector pili.
17. What is the name given to the insulating layer of short, soft hairs found beneath the topcoat?
    Wool hairs.
18. What part of the dog's anatomy carries guard hairs but no undercoat?
    The scrotum.
19. What is another name for the tactile hairs?
    Vibrissae.
20. Why should the vibrissae not be cut without good reason?
    They possess nerve endings at their base that respond to the movements of the hair, and thus are important sensory organs.
21. What is the correct term for the seasonal shedding of hair?
    Moulting.
22. During what seasons do kennelled dogs moult most heavily?
    Spring and autumn.
23. Give 2 reasons why many household pets shed pretty much throughout the whole year?
    • Central heating.
    • Artificial lighting (this upsets the normal stimuli of seasonal increase or decrease of photoperiod).
24. What is the correct name for the nosepad?
    The rhinarium.
25. What is the name of the main pad on the forelimb of a dog or cat?
    The metacarpal pad.
26. What is the name of the main pad on the hindlimb of a dog or cat?
    The metatarsal pad.
27. Where are the digital pads located and how many are present in dogs and cats?
    These are located on the underside of each toe. There are 4 on each hindlimb, whilst there are 5 on each forelimb due to the presence of the dew claw.
28. What is another name for the carpal pad that covers the accessory carpal bone?
    The stopper pad.
29. Why are cats' claws sharper than dogs' claws?
    The main function of cat claws is the capture of prey, whilst dog claws are predominantly designed for digging.
30. What is the name of the specialised part of the epidermis from which the nail grows?
    Coronary band (or border).
31. What is the purpose of the dew claws?
    This is a trick question! These have no function and are merely remnants of digit I, which has become obsolete as the carnivore evolved from a plantigrade to a digitigrade posture.
32. What do the sudiferous glands secrete?
    Sweat.
33. In what part of the anatomy are the sudiferous glands found?
    Hairless epidermal areas (the rhinarium and footpads).
34. Name the 3 specialised sebaceous glands that play an important role in territorial marking.
    • Tail glands.
    • Circum-anal glands.
    • Glands of the anal sacs.