Support Structures

Exoskeletons:  Provide support for bodies; Provide external attachment for muscles

Disadvantages: limits size and movement; limits growth

Advantages: protection from predators; prevents dehydration

Endoskeletons: Provide support and protection for internal organs; Provide attachment for muscles; Covered with soft body tissues

Disadvantages: External organs are not protected

Advantages: Size and growth are not limited; Internal organs protected

Bony Tissue

Periosteum: outer covering of bone.

Compact bone: main tissue in the shaft of long bones. Surrounds yellow marrow, which stores fat.

Spongy bone: tissue in the ends of long bones and in flat bones; filled with red marrow, which makes red blood cells.

Osteocyte: bone cell

Ossification

A cartilage model develops a periosteum.

The model enlarges to form a collar of bone deposited by osteoblasts.

The cartilage begins to calcify.

A blood vessel enters at the midpoint of the diaphysis and forms a primary ossification center.

Ossification continues toward the epiphyses and the bone grows in length.

Secondary ossification centers appear in the epiphyses.

Structure of a Long Bone

Joints

Immovable joints

Allow little to no movement

Example: sutures of skull

Gliding

Allow gliding movements

Example: vertebrae

Hinge Joints

Allow movement in one direction

Example: knee

Bones attached by ligaments

Ball and Socket

Allow movement in all directions

Example: hip

Bones attached by ligaments

Locomotion and Support

Porifera: sessile; spicules

Cnidaria: flip, float, false feet; no support

Platyhelminthes: mucous trail and cilia; hydroskeleton

Nematoda: longitudinal muscles; hydroskeleton

Annelida: setae, longitudinal and circular muscles; hydroskeleton

Gastropoda: mucous trail; shell secreted by mantle

Bivalvia: muscular foot used to burrow in sand; shell secreted by mantle

Cephalopoda: jet propulsion; internal pen

Echinodermata: tube feet; water vascular system

Crustacea: chelipeds, walking legs, swimmerets; chitinous exoskeleton

Arachnida: four pairs of walking legs; exoskeleton

Insecta: 3 pairs of walking legs, wings; chitinous exoskeleton

Chondrichthyes:fins, swimming; cartilaginous skeleton

Osteichthyes: fins, swimming; bony endoskeleton

Amphibia: muscles for walking, jumping; webbed feet for swimming; bony endoskeleton

Reptilia: ribs attached to scales; bony endoskeleton

Aves: feathers, wings; hollow bones, bony endoskeleton

Mammalia: muscles in appendages; bony endoskeleton

 

Muscles

Cardiac muscle: involuntary control; striated; located in the heart

Smooth muscle: involuntary control; not striated; located in hollow organs, such as the stomach

Skeletal muscle: voluntary control; striated; associated with bones, such as biceps brachii; attach to bones by tendons; usually work in pairs

flexor: bends joint

extensor: straightens joint

 

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