Week 4

Cards (90)

  • key features of animals
    • multicellular eukaryotes
    • cells without cell walls
    • heterotrophs: ingest food and digest it internally
    • generally mobile, able to respond rapidly to stimuli
    • most reproduce sexually
  • evolution of multicellularity through colonial flagellate hypothesis

    infolding of cells into the center of the spherical colonies formed tissue layers
  • different animal groups classified by
    • number of tissue layers
    • type of body symmetry
    • presence of body cavity
    • presence of segmentation
    • developmental paths
  • simplest animals
    don't have true specialized tissues
  • diploblastic animals
    two layers of tissues but no specialized organs
  • triploblastic animals
    three embryonic tissue layers
  • ectoderm
    skin and nervous system
  • endoderm
    digestive tract and derived organs
  • mesoderm
    muscles, reproductive system
  • tissues
    groups of cells that interact and perform specific functions
  • protostomes
    blastopore becomes mouth; mouth develops first
  • deuterostomes
    blastopore becomes anus; anus develops first
  • asymmetrical body
    no pattern to body plan
  • radial symmetry
    • several planes divide into mirror images
    • allows organism to extend in all directions from one central point
  • bilateral symmetry
    • only one plane produces mirror image
    • accompanied by cephalization
  • cephalization
    the concentration of sensory organs and a brain in a defined head region
  • segmentation
    • division of animal body into repeated sections, externally or internally
    • adds flexibility and potential for speciation
    • segments may be fused and modified for special functions
  • coelom
    fluid-filled cavity completely within the mesoderm that provides organs with flexibility and absorbs shock
  • acoelomate
    no body cavity
  • pseudocoelomate
    body cavity lined partly by mesoderm and endoderm
  • coelomate
    completely lined by mesoderm
  • porifera (sponges)
    • aquatic
    • asymmetrical or radially symmetrical
    • simple animals --> no tissues or organs
    • overall shape usually stiffened by mineral spine
    • adults are sessile (fixed in one place)
    • filter-feeders: depend on water flow, cells digest food intracellularly
  • cnidarians (jellies, corals, anemones)
    • aquatic (predominantly marine)
    • radially symmetrical
    • adults have two forms: polyp (sessile with tentacles), medusa (free-swimming)
    • some species go through both as stages
    • two tissue layers enclose a non-cellular jelly substance
    • incomplete digestive tract with tentacles around the mouth
    • predators: stinging cnidocytes help catch prey
    • hydrostatic skeletons (in some)
  • annelids (earthworms, leeches)
    • terrestrial and aquatic
    • bilateral symmetry
    • have repeated body segments
    • complete digestive tract; coelom
    • closed circulatory system, simple nervous and excretory system
    • detritivores, bloodsuckers, filter-feeders, predators
    • hydrostatic skeletons
  • mollusks (snails, clams, squid)
    • aquatic and terrestrial
    • unsegmented
    • bilaterally symmetrical and asymmetrical
    • hydrostatic skeleton, with supporting external or internal shell secreted by mantle tissue
    • complete digestive tract, coelom
    • muscular foot provides movement
    • filter-feeders, herbivores, and predators
  • arthropods (insects, spiders, crabs, prawns)
    • terrestrial, freshwater, marine
    • segmented body plan: major body regions - head, thorax, abdomen; jointed appendages
    • exoskeleton of chitin and protein: must molt to grow
    • open circulatory system, extensive respiratory system of tubes open to the outside
    • complete digestive tract, coelom
    • simple brain, well-developed nerves
  • echinodermata (starfish, sea cucumbers, sea urchins)
    • marine
    • five-part radial symmetry with bilaterally symmetrical larvae
    • complete digestive tract
    • water vascular system with tube feet act as gills, sense organs, perform circulatory and excretory functions
    • predators, detritivores
  • chordates (lancelets, tunicates, hagfish, and vertebrates)
    • vertebrates share this clade with some invertebrates
    • four distinguishing features of chordates at some point of development: notochord, dorsal + hollow nerve cord, pharyngeal pouches or slits, postanal tail
  • cells
    basic building blocks of the body
  • tissues
    cells that interact and provide specific functions
  • organs
    two or more interacting tissues
  • organ systems
    two or more organs joined physically or functionally
  • epithelial tissue
    • cover body's internal and external surfaces with one or more layers of tightly packed cells
    • one surface exposed either to the outside or to a space within the body
    • opposite surface anchored to other tissues by a basement membrane
    • functions: protection, nutrient absorption, gas diffusion, secretion
  • epithelial tissue layers
    simple, stratified, pseudostratified
  • epithelial tissue shapes
    squamous, cuboidal, columnar
  • connective tissue
    • most variable tissue type
    • functions: fill spaces, attach epithelium to other tissues, protect and cushion organs, provide mechanical support
  • types of connective tissue
    loose, dense, specialized (blood, cartilage, bone)
  • nervous tissue
    transmit information rapidly within an animal's body by electrical and chemical signals
  • neurons
    form communication networks that receive, process, and transmit information
  • neuroglia
    support cells that assist neurons in functioning