Integument- Tetrapods

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  1. General characteristics
    There is keratinization of the epidermis (major feature of the tetrapod integument proper)
  2. General characteristics
    -Prominent stratum corneum, which is composed of dead cells filled with water-proofing protein, keratin

    -Prevents mechanical abrasion, invasion, etc
  3. General characteristics
    Whereas fish glands are in the epidermis, tetrapod glands are generally in the dermis
  4. Amphibian skin in general is different than all other vertebrate skin for what reason?
    because, although higher vertebrates do excrete a bit through their skin and use the urinary system, there is more excretion that goes on in the amphibian skin; and, the amphibian skin is also a major structure through which respiration occurs
  5. Explain amphibian skin
    the blood vessels supply, particulary the capillary beds, are very numerous  - the skin is slightly more complicated
  6. Amphibian epidermis
    - stratified and cornified in most amphibians; thse that spend most time in water have stratified epithelium with a mucous cuticle

    - scattered through the cells of the epidermis, you will find Leydig cells, which secrete substances that resist the entry of bacteria or viruses
  7. Amphibian dermis
    • -Stratum spongiosum and compactum
    • -Loose and dense irregular

    -Dermal scales are really absent, except there are vestiges of dermal scales in certain limbless amphibians

    -Contains multicellular glands and lots and lots and lots of blood vessels

    Nuptial pads
  8. Explain nuptial pads
    -In many amphibians, during the breeding season, there are nuptial pads that are found in some of the digits of the male; these are really cornified epithelium
  9. Function of nuptial pads
    -Function is to grasp on and hold on to the female because, in many amphibians during breeding, the male squeezes the eggs out of the female
  10. Reptilian integument characteristics
    • Reptiles have much more keratinization
    • There are very few glands in reptilian skin
  11. Reptilian epidermis
    Epidermis: there are three layers (in to out stratum basale (where cell division takes place), stratum granulosum, stratum corneum (upper layer))
  12. Reptilian dermis
    • Dermis: two regions—the spongiosum and the compactum
    • –Dermal bone is present in many reptilian dermises
    • –Glands that are present in the skin—roles not well understood; usually restricted to certain parts of the body
  13. True or False:

    Reptiles have no hypodermis
    False: Hypodermis is also present
  14. Bird epidermis
    Epidermis in birds has two layers—a basale and a corneum

    Sometimes, there is a transitional layer between the two where the cells are being transformed into keratinized packets
  15. Bird dermis
    • Dermis has two regions: spongiosum and compactum
    • –Rich blood supply; lots of sensory nerve endings; smooth muscle; there are also glands, but they are restricted to certain areas; and this is for flight and feathers (flight feathers)
  16. Mammalian epidermis
    Most developed--stratified squamous epithelium with many layers

    There are also Langerhans cells scattered throughout the stratified squamous; they function in cell-mediated immunity

    In some mammalian cells, you find sensory cells for pressure called Merkel cells, responding to pressure (mechanoreceptors)
  17. Explain the layers of the mammalian epidermis.
    Inner to outer: stratum basale (germanitium where mitosis is restricted to), stratum spinosum (nuclei start to enlarge; hypertrophy of the cell—dying process, stratum granulosum (where you see prekeratin fibers), stratum lucidum (layer of transparent cells located in soles of feet and palms of hands), stratum corneum
  18. Mammalian dermis
    –Dermis is also well developed with double layers, but this time, the dermis projects into the epidermis For that reason, the layer is referred to as the papillary layer= stratum spongiosum
  19. Explain the papillae of the dermis
    In these papillae is where you find capillaries—brings blood supply closer to epithelial tissue, which is avascular
  20. Deeper layer of the dermis is?
    Deeper layer is the reticular layer (stratum compactum—dense irregular CT and most of the structures of the dermis—blood vessel, nerves, hair, etc. are found here
  21. In terms of dermal bone in mammals?
    In terms of dermal bone, it usually contributes to parts of the skull; rarely are there dermal scales
  22. What is underneath the mammalian dermis?
  23. What are specialized hairs in mammals?
    There are specialized hair called vibrissae (whiskers) which surround the snout of many mammals
  24. Hair
    -epidermal derivative, meaning that it comes from the epithelium; you can see the epithelial layer found on the outside of the hair

    Even though it originates in the dermis, it is derived from the epidermis
  25. Explain the hair formation
    • -It reaches deep down into the dermis to form the hair follicle. At the very base of the follicles an invagination is a papillae; that is where capillaries and nerves are located to control the hair
    • -As division takes palce and the cells are pushed up through this hair follicle and pierce the epidermis and then reach the outside, what you are looking at is the shaft—dead keratinized epithelium. By the time the cells reafch the surface, they are dead epithelial tissue. The structure of the keratin in hair is  a little bit different than structure of keratin in skin and nails, resulting in a different texture
  26. Associated with hair follicles are __
    sebaceous glands and arrector pili muscle
  27. What do sebaceous glansd do
    keep hair moist and pliable because they have an oily secretion
  28. What does the arrector pilus do?
    • causes hair to stand up on 
    • -when it contracts, hair stands on end, a reaction to fright or cold
Card Set
Integument- Tetrapods
Test One
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