Integument pt. 2

• Integument


  External protective covering of the body
• Structures associated with the skin

  • Hair
  • Scales
  • Feathers
  • Horns
• Functions of Integumentary/Skin


  • Protection from mechanical & chemical injury, and invasion by microorganisms
  • Regulation of body temperature
  • Excretion of waste materials
  • Vitamin D production
  • Reception of environmental stimuli
  • Locomotion/movement
  • Movement of nutrient and gases
• Amoeba


  • Singled-celled protozoa and 1 plasma membrane for external covering
• Paramecium


  • Pellicle- a protozoa have thick protein outside the plasma membrane
• Nematodes & Annelids


  • Multicellular invertebrates that have single-layered epidermis covering the body
• Crustaceans, Arachnids, & Insects


  • Have added secreted non-cellular cuticle over the epidermis for additional protection
  • Molting: old cuticles need to be shed periodically by this process to permit growth
• Molluscs


  • They have delicate epidermis
  • Shells provide protection
• Cephalopods


  • More complex epidermis with a cuticle, simple epidermis layer of connective tissue, layer of iridocytes
  • Iridocytes - a guanine-containing cell in the skin of fish and some cephalopods, giving these animals their iridescence
• Arthropods


  • Complex integument that provides protection and skeletal support
  • Cuticles are thick and rigid
  • Hypodermis - single layered epidermis which secretes a complex cuticle
  • Procuticle - layers of chitin & protein
  • Epicuticle - moisture proofing barrier
  • Arthropods may remain tough, but flexible as in many small crustaceans and insect larvae, or it may become hardened
• Decapod Crustaceans


  • They have a cuticle stiffened by calcification
  • Calcification - deposition of calcium carbonate in the procuticle
• Insects


  • Hardening occurs by sclerotization
  • Sclerotization - protein molecules bond together producing the insoluble protein sclerotin
• Rotifers


  • Cuticles are thin and elastic
• Cnidarians


  • Hydra - epidermis is only a few cells layers thick
  • Corals - contains mucous glands that secrete calcium carbonate shells
• Platyhelminthes


  • The covering is a tegument (functions for nutrient ingestion and for protection)
• Nematodes & Annelids


  • Have an epidermis that is one cell thick and secretes a multilayered cuticle
• Echinoderms


  • Integument consists of a thin, ciliated epidermis & an underlying connective tissue dermis that contains calcium carbonate
• Epidermis


  • A thin outer stratified epithelial layer, derived from ectoderm
  • A stratified squamous epithelium
  • The cells in the basal part undergo frequent mitosis
  • As cells are displaced upward, cytoplasm is replaced by keratin
• Keratin


  • A tough protein that is also light and flexible
  • Composed of keratins in reptiles' scales, birds' feathers, beaks, & claws, and mammals' hair, hooves, claws, & nails
• Dermis


  • A thick inner layer, derived from mesoderm
  • A dense connective tissue layer: contains blood vessels, collagenous fibers, nerves, pigment cells, fat cells, and fibroblasts
  • This layer serves to support, nourish, and cushion the epidermis
  • The dermis may contain bony structures of dermal origin
• Ostracoderms & Placoderms


  • Had heavy bony plates
• Scales (fishes)


  • Are bony dermal structures that evolved from the armor of Paleozoic fishes
• Dermal Bone contribution to vertebrate animals

  • Reptiles: armor of crocodilians, the beaded skin of some lizards, and portions of a turtle's shell (carapace & plastron)
  • Mammals: their antlers
  • Claws, beaks, nails, and horns are composed of a combination of epidermal (keratinized) and dermal components
• Agnathans (jawless fishes)


  • Several types of glandular cells may be present; Multicellular slime glands produce large amounts of slime that covers the body
• Chondrichthyes (cartilaginous fishes)


  • Skin is multilayered and with mucous and sensory cells; Dermis has bones in the form of denticles
• Reptiles


  • Stratum corneum is very thick and modified into keratinized scales
  • Functions: Resist abrasion, Inhibit dehydration, Acts as a "suit of armor" for protection
• Osteichthyes (bony fishes)


  • The skin has scales; The skin is permeable and functions in gaseous exchange; Epidermis may also contain mucous cells; Dermis is richly supplied with capillary beds to facilitate its use in respiration
• Functions of Mucus


  • Prevents bacterial and fungal infections
  • Reduces friction as the fish swims
• Amphibians


  • Stratified epidermis and a dermis containing mucous, serous glands and with pigmentation
  • Keratin: protects the skin against UV and physical abrasions
  • Mucus: helps prevent desiccation and facilitates gaseous exchange
  • Poison glands: produce an unpleasant-tasting or toxic fluid that acts as a predator deterrent
  • Epidermis: over most of the body is thin and only 2 or 3 cell layers thick
  • Outer keratinized layer is soft and feathers are the most prominent parts of the epidermis
• Birds


  • Shows many reptilian features
  • Dermis: with blood, lymphatic vessels, nerves, sensory bodies
  • Arrector Plumose: dermal smooth muscle associated with feathers (control the position of the feathers)
  • Aquatic Birds may also have fat deposits in the hypodermal layer that store energy & help insulate the body
• Mammalian Skin (Human Skin)


  • A highly stratified, cornified epidermis
  • A dermis with blood and lymphatic vessels, nerve endings, small muscles, glands, hair follicles
  • A hypodermis composed of loose connective tissue, adipose tissue and skeletal muscles – the hypodermis attaches the skin to the underlying muscles
• Sweat Glands


  • Eccrine Sweat Glands – palms, soles of feet, forehead
  • Apocrine Sweat Glands – axillary and anogenital areas
  • Ceruminous Glands – modified apocrine glands in external ear canal that secrete cerumen
  • Mammary Glands – specialized sweat glands that secrete milk
• Sebaceous Glands


  • Simple alveolar glands found all over the body
  • It softens skin when stimulated by hormones
  • Secrete an oily secretion called sebum
• Skin Receptors


  • Meissner Corpuscles – touch
  • Pacinian Corpuscles – pain
  • Ruffini Corpuscles – heat
  • End Bulbs of Krause – cold
  • Merkel Disk – texture and touch
• Functions of the Skeleton

  • Supports the body
  • Framework of the body
  • Protects vital organs of the body
  • Blood cell formation/hematopoiesis
  • Site for the attachment of muscles
  • Accessory to movement
  • Storage of minerals
• Hydrostatic Skeletons (earthworm)


  • Muscles in the body wall develop force by contracting against incompressible coelomic fluids
  • Alternate contractions of circular and longitudinal muscles of the body wall enable a worm to move forward
• Rigid Skeletons (exo & endoskeleton)


  • Contains some kind of rigid elements
  • Provide anchor points for pairs of opposing muscles
• Exoskeleton


  Found in molluscs, arthropods, some vertebrates and invertebrates
• Endoskeleton


  Found in echinoderms, sponges, and chordates
• Vertebrate Endoskeleton


  Composed of bones & cartilages which is types of connective tissues