Outline

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Outline
Chapter 20 page 402-415

• Diversity of Skeletons
• Hydrostatic Skeleton
• Exoskeletons
• Endoskeletons
• Human Skeletal System
• Axial Skeleton
• Appendicular Skeleton
• Human Muscular System
• The Muscles
• Muscle Contraction

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Hydrostatic Skeleton

• Functions
• Supports body form
• Provides resistance for the contraction of
  muscles to act against
• Source
• Some organisms use their fluid-filled
  gastrovascular cavity
• Others use their fluid-filled coelom

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Locomotion in an Earthworm
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Exoskeletons and Endoskeletons

• Exoskeleton - External Skeleton
• Molluscs - composed of calcium carbonate
• Arthropods - composed of chitin
• Endoskeleton - Internal Skeleton
• Echinoderms and vertebrates
• Mineralized bone and cartilage
• Grows as the animal grows
• Does not limit space for internal organs
• Supports greater weight

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Exoskeleton
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The Vertebrate Endoskeleton
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Human Skeletal System

• Functions
• Supports and protects the body
• Permits movement
• Provides resistive foundation for muscles to act
  against
• Bones store calcium and phosphate ions
• Certain bones produce red blood cells

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Bone Growth and Renewal

• Cartilage structures in early development act as
  models for future bones
• Calcium salts deposited in matrix by cartilage
  cells and later by osteoblasts
• Endochondral ossification
• Osteoclasts
• Break down bone
• Remove worn cells
• Deposit calcium in the blood
• Work with osteoblasts to heal broken bones

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Anatomy of a Long Bone

• Gross
• Main shank
• Thick outer cylinder of compact bone
• Medullary cavity in center
• Spongy bone at ends
• Details
• Compact bone
• Unit of structure called osteon
• Concentric lamellae arranged around central canal
• Osteocytes lie in lacunae at lamellar boundaries
• Spongy bone
• Numerous bars and plates separated by irregular
  spaces
• Spaces filled with red bone marrow

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The Human Skeleton
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The Axial Skeleton

• Lies in the midline of the body
• Consists of
• The skull
• The vertebral column
• The sternum, and
• The ribs

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The Skull

• Formed by cranium and facial bones
• Major bones are named after
• The lobes of the brain, and
• The facial bones
• Foramen magnum
• Opening at base of skull
• Where spinal cord connects to brain
• Bones of cranium surround sinuses

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The Skull
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Vertebral Column

• Vertebral column
• Supports the head and trunk
• Protects the spinal cord and roots of spinal
  nerves
• Segments (from superior to inferior)
• Cervical - Neck
• Thoracic - Thorax
• Lumbar - Small of back
• Sacral - Sacrum
• Coccyx - Tailbone
• Intervertebral disks of fibrocartilage act as
  padding

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Rib Cage

• Protects the heart and lungs, and assists
  breathing
• Support by the thoracic vertebrae
• Twelve pairs of ribs
• True ribs
• Connect directly to sternum
• Seven pairs
• False ribs
• Do not connect directly to sternum
• Five pairs

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The Rib Cage
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The Appendicular Skeleton

• Consists of
• The bones within the pectoral and pelvic girdles
• The attached limbs
• Pectoral girdle Bones of the shoulder
• Anterior
• Supports the arms and hands
• Pelvic girdle - Bones of the pelvis
• Posterior
• Supports the legs and feet

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Bones of the Pectoral Girdle,the Arm, and the
Hand
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Bones of the Pelvic Girdle,the leg, and the Foot
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Classification of Joints

• Fibrous Joints
• Immovable
• Between cranial bones
• Cartilaginous Joints
• Slightly Movable
• Between vertebrae
• Synovial Joints
• Freely Movable
• Bones separated by a cavity
• Ligaments bind bones together at joint

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The Knee Joint
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Human Muscular System

• Skeletal muscles
• Attached to the skeleton by cable-like fibrous
  connective tissue called tendons
• Arranged in antagonistic pairs
• Can only contract, cannot push
• When one muscle contracts, it stretches its
  antagonistic partner
• A muscle at rest exhibits tone (minimal
  contraction)
• A muscle in tetany is at maximum sustained
  contraction

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Antagonistic Muscles