WEEK 10

• Animals


  • Can look unique
  • Can do unique things
  • Can sense the world around them
  • Most have sensory organs
  • Able to hear, smell, touch, and taste
  • Can move around to search for food
• Characteristics most animals share

  • Sensory organs
  • Movement
  • Internal digestion
• Body symmetry


  The arrangement of body parts around a central axis
• Types of body symmetry

  • Radially symmetrical
  • Bilaterally symmetrical
  • Asymmetrical
• Radial symmetry


  • Arrangement of body parts around a central axis, like rays on a sun or pieces in a pie
  • Have top and bottom surfaces, but no left and right sides, or front and back
  • Two halves may be described as the side with a mouth ("oral side") and the side without a mouth ("aboral side")
• Radially symmetrical organisms


  • Sea anemones (phylum Cnidaria)
• Bilateral symmetry


  • Division of the animal through a sagittal plane, resulting in two mirror-image, right and left halves
  • Have a "head" and "tail" (anterior vs. posterior), front and back (dorsal vs. ventral), and right and left sides
  • Promotes active mobility and increased sophistication of resource-seeking and predator-prey relationships
• Bilaterally symmetrical organism


  • Monarch butterfly
• Asymmetry


  • No body plan symmetry
  • Only found in phylum Porifera (sponges)
  • Some fish species, such as flounder, lack symmetry as adults, but larval fish are bilaterally symmetrical
• Major animal phyla


  • Porifera (sponges)
  • Annelida (segmented worms)
  • Mollusca (mollusks)
  • Arthropoda (arthropods)
  • Echinodermata (echinoderms)
  • Chordata (chordates)
• Muscular system

  A set of tissues in the body with the ability to change shape
• Functions of the muscular system

  • Movement
  • Circulation
  • Digestion
• Skeletal muscle


  Attached to bones, responsible for skeletal movements, under conscious/voluntary control, striated (having transverse streaks), each muscle fiber acts independently
• Smooth muscle


  Found in walls of hollow internal organs, under control of the autonomic nervous system, non-striated, contracts slowly and rhythmically
• Cardiac muscle

  Found in the walls of the heart, under control of the autonomic nervous system, striated like skeletal muscle, rectangular in shape, contraction is involuntary, strong, and rhythmical
• Vertebrates


  Animals having a vertebral column or backbone
• Skeletal system


  Consists of bones, cartilage, ligaments and tendons, accounts for about 20 percent of the body weight
• Bone development and growth

  1. Osteogenesis and ossification (bone formation)

  2. Skeletal pattern formed in cartilage and connective tissue membranes by end of 8th week after conception

  3. Ossification begins

  4. Bone development continues throughout adulthood for repair and remodeling

  5. Osteoblasts, osteocytes and osteoclasts involved in development, growth and remodeling
• Types of bones


  • Long bones
  • Short bones
  • Flat bones
  • Irregular bones
• Long bones


  • Longer than they are wide, consist of a long shaft with two bulky ends or extremities, primarily compact bone but may have spongy bone at the ends
• Short bones


  • Roughly cube shaped with vertical and horizontal dimensions approximately equal, primarily spongy bone covered by a thin layer of compact bone
• Flat bones


  • Thin, flattened, and usually curved, most of the bones of the cranium are flat bones
• Irregular bones


  • Bones that are not in any of the other three categories, primarily spongy bone covered with a thin layer of compact bone, include vertebrae and some bones in the skull
• All bones have surface markings and characteristics that make a specific bone unique, such as holes, depressions, smooth facets, lines, projections and other markings