Skeletal System

• Hydrostatic skeleton - supports body and structural form and provides resistance for the contraction of muscles to act against
• For the source of hydrostatic skeletons, some organisms use their fluid-filled gastrovascular cavity or others use their fluid-filled coelom (body cavity)
• Earthworm with fluid-filled coelom cavity, separated into pressurized compartments by structures called a septa

  
• What are the bristles of the earthworm to anchor it to the soil and to prevent backward sliding called?

  Setae
• During peristalsis of an earthworm, what contracts first, and last?

  Circular muscles contract first, longitudinal muscles contract last.
• Rigid skeletons - consist of rigid elements where skeletal system is

  usually jointed has muscle attachments.
• What are the 2 principle types of rigid skeletons?

  Exoskeletons, endoskeletons
• Exoskeleton - external skeleton of most invertebrates and must molt to grow developmentally and serves for protection and locomotion
• What is the exoskeleton composed of for molluscs and arthropods respectively?

  Molluscs: Calcium carbonate Arthropods: Chitin
• What animal phyllum contains a rigid endoskeleton?

  Chordata, Echinoderms
• Endoskeleton - Internal skeleton, mineralized bone and cartilage, support, protection, and reservoir of calcium and phosphorous, grows as the animal grows

  ✓does not limit space for internal organs

  ✓supports greater weight
• In echinoderms such as starfish, what are the endoskeleton plates enclosed by?

  Epidermis
• Notochord is made up of what kind of cartilage?

  Hyaline cartilage
• Notochord - semirigid supportive axial rod composed of large

  vacuolated cells surrounded by elastic and fibrous sheaths and is a stiffening device
• What type of endoskeleton is present in vertebrate during larvae and embryonic stages?

  Notochord
• The notochord is eventually replaced by backbone when transitioning

  into adult stages.
• Notochord and cartilage - Jawless vertebrates (i.e., hagfishes and

  lampreys) have both a notochord present and purely cartilaginous skeletons

  
• Cartilage skeleton - major skeletal element of some vertebrates and are soft, pliable tissue that resists compression (skeletal cartilage of adult

  sharks and rays)
• What are the two ends of a long bone called?

  Epiphysis
• Spongy bone - bone composed of thin intersecting lamellae, usually found internal to compact bone
• Bone marrow - is a spongy substance found in the center of the bones and It manufactures bone marrow stem cells and other substances, which in turn produce blood cells.
• Compact bone - Outer bone substance that is dense
• Label what is asked.

  A) Epiphysis

  B) Epiphysis

  C) Bone marrow

  D) Medullary cavity

  E) Endosteum

  F) Perosteum

  G) Perosteum

  
• Label the following in the osteon.

  A) Blood vessels

  B) Perosteum

  C) Nerve

  D) Osteon

  E) Osteocyte

  
• Bone - Living tissue having significant deposits of calcium salts in the extracellular matrix and density of this tissue form will vary.
• The long bone has what kind of bone development?

  Endochondral
• Endochondral ossification - any bone that develops in cartilage and eventually replaces cartilage
• bones in the face, cranium, and clavicle are made by what bone ossification?

  Intramembranous
• intramembranous ossification - any bone that develops without the presence of any associated cartilage
• Osteocytes - Involved in bone formation and reabsorption(bone turnover) and are made from osteoblasts
• Calcium salts are deposited in matrix by cartilage cells and later by osteoblasts
• Osteoclasts - break down bone to remove worn cells, deposit calcium in the blood and they work in tandem with osteoblasts to heal broken bones
• When endochondral ossification is completed, what cartilage remains at the epiphyseal plates?

  Hyaline cartilage, articular cartilages
• What are differentiated into osteoblasts during intramembranous ossification?

  Mesenchymal cells
• What do osteoblasts secrete?

  Osteoid (unmineralized bone)
• As the osteoid mineralizes, and random hardening of bone matrix

  results in the formation of what?

  Trabeculae
• Vascular tissue within trabecular spaces form what?

  red marrow
• What is the eventual fate of the mesenchyme during intramembranous ossification to give rise to a layer of connective tissue surrounding the bones?

  Periosteum
• What replaces woven bone at the outer edge?

  Lamellar bone