Chapter 39

Chapter 39 - BiologyNotes CHAPTER38&39...

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Biology Notes 10/03/2009 16:17:00     Protection, Support, and Movement Epithelial Tissue In both invertebrates and vertebrates  o Protects underlying tissues o Specialized to receive sensory signals, for gas exchange or respiratory  functions Outer epithelium specialized to secrete o Cuticle for protection o Lubricants or adhesives o Odorous or poisonous substances Integumentary System of Vertebrates Skin and structures that develop from it o Fishes and reptiles have scales o Amphibians with smooth skins and poison mucus o Feathers of birds insulate, maintain temperature o Colored for communication Mammalian skin includes o Hair, claws or nails, sweat glands, oil glands (sebum that empties into  hair follicle and acts as an antibiotic), sensory receptors, mammary  glands
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Epidermis 1 Protects body from outer environment Stratum corneum  o Most superficial layer o Consists of dead cells filled with keratin Diffusion barrier and most external layer Cells flake off and must be continuously  replaced  Keratin o Insoluble protein o Gives mechanical strength o Prevents water loss Stratum bassale o Cells divide, are pushed up to skin surface o Cells mature, flatten, produce keratin o Eventually die and slough off o Contains melanocytes; cells that produce melanin (sequestered in  melanosomes) Pigments acts as a UV protector, around nucleus Fair skinned people- more susceptible to malignant  transformation to melanoma  Dermis Underneath epidermis 
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Consists of: o Dense, fibrous connective tissue, collagen, and blood vessels o Hair follicles, sensory cells, muscle and sweat (sebaceous) gland Rests on layer of subcutaneous tissue o Composed largely of insulating fat 3/10/09 3:55pm Key Concepts     Epithelial coverings protect underlying tissues and may be specialized for  sensory, respiratory, or other functions The Skeletal System     o Supports and protects the body o Transmits mechanical forces generated by muscles o The Hydrostatic Skeleton (Fig 39-2) Hydra (diploblastic cnidarian): Longitudal epidermal fibers contract (shorten and  thicken) while inner (circular) fibers contract (elongate  and stretch) Fluid in the closed body compartment then transmits the  antagonistic forces generated by contractile cells or  muscle so that when the hydra shortens, it also thickens Also found in soft-bodied invertebrates Flatworms, annelids (triploblasts) More flexible than hydra; isolated septa allow segment  independence  o Exoskeletons  Non-living skeleton
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Characteristic of mollusks and arthropods Provides protection and cover
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Chapter 39 - BiologyNotes CHAPTER38&39...

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