Skeletal systemSkeletal system

Benefits of skeletonsBenefits of skeletons• Skeletons provide Skeletons provide

support for the body for the body• Muscles and bones work Muscles and bones work

together for together for movement of the animalof the animal

• Some skeletons provide Some skeletons provide protection for the animal for the animal

A turtle’s skeleton plates provides protection

Arthropods vs. Arthropods vs. Vertebrates Vertebrates

Vertebrates have a backboneArthropods have an exoskeleton

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ExoskeletonExoskeleton• An exoskeleton is a An exoskeleton is a hard, waxy

covering on the outside of the body on the outside of the body that provides a framework for that provides a framework for support and support and protects the epidermal the epidermal cells. The waxy exterior protects cells. The waxy exterior protects against water loss in terrestrial against water loss in terrestrial (land) animals.(land) animals.

• Exoskeletons are composed of Exoskeletons are composed of protein and and chitin (polysaccharide) (polysaccharide)

• The exoskeleton is divided into soft The exoskeleton is divided into soft flexible joints that allow for flexible joints that allow for movementmovement

• Exoskeletons are often found on Exoskeletons are often found on invertebrates, which are animals invertebrates, which are animals which do which do not have a backbone

Disadvantages of an Disadvantages of an exoskeletonexoskeleton

• An exoskeleton An exoskeleton limits the size. Since they are very Since they are very heavy, land animals can heavy, land animals can not have a large not have a large exoskeleton.exoskeleton.

• It It limits the movement of of an animal especially if an animal especially if they are large heavy they are large heavy exoskeletonsexoskeletons

• Growth is also limited in in arthropods. Since it is arthropods. Since it is hard its size can not be hard its size can not be changed. The immature, changed. The immature, growing animals have to growing animals have to molt their old ones and molt their old ones and grow a new exoskeleton.grow a new exoskeleton.

A crab moltingOnce molted it has less protection since thenew shell is soft and they also can lose water quickly

EndoskeletonEndoskeleton

• Unlike an exoskeleton which Unlike an exoskeleton which covers the animal in one covers the animal in one continuous unit, the continuous unit, the endoskeleton is divided into endoskeleton is divided into many specialized parts (many specialized parts (bones))

• Some bones are used for Some bones are used for protection (skull, ribs and (skull, ribs and breastbone, vertebrae)breastbone, vertebrae)

• Bones also function in support. Bones also function in support. The long dense bones support The long dense bones support the weight of the body and aid in the weight of the body and aid in strength and speed of the animalstrength and speed of the animal

• Vertebrates are animals which Vertebrates are animals which have a backbone or have a backbone or vertebrae

EndoskeletonEndoskeleton

• Internal skeletons Internal skeletons protect internal protect internal organs but provide organs but provide very little protection very little protection for the outside. for the outside. (except skull)(except skull)

• Some animals have Some animals have special parts that help special parts that help with protection. Ex with protection. Ex the turtle has a shell the turtle has a shell made of bony plates made of bony plates attached to the attached to the endoskeletonendoskeleton

Bone developmentBone development• When we are very young, we don’t When we are very young, we don’t

have any bones, only cartilage. The have any bones, only cartilage. The bone is slowly deposited until the bone is slowly deposited until the most of our skeletal system is made of most of our skeletal system is made of bones and we only find cartilage bones and we only find cartilage where we need flexibility (ex. tip of where we need flexibility (ex. tip of nose, ears, spaces between vertebrae nose, ears, spaces between vertebrae and movable joints.)and movable joints.)

--------- Cartilage

----------- Bone (femur)

Bone GrowthBone Growth

• Bones grow in both Bones grow in both length and diameter.length and diameter.

• At the end of bones At the end of bones there is a line called there is a line called the cartilage plate. the cartilage plate. This area is where This area is where new bone is laid and new bone is laid and bones grow in lengthbones grow in length

• Bones go in width at Bones go in width at the in the outer the in the outer surface of the bonessurface of the bones

Types of JointsTypes of JointsJoints are where bone and bone or bone cartilage comes together. All joints are not alike – some permit movement othersdo not. Ligaments are connective tissuethat will hold the bones together and Cartilage is another connective tissuethat is found at the end of bones and helps by not allowing the bones to tub together

Bone MarrowBone Marrow

• Bone marrow is in the Bone marrow is in the center of the bones. center of the bones. There is 2 types of There is 2 types of bone marrow- bone marrow- Red Red marrowmarrow and and Yellow Yellow Marrow. Marrow. Red bone Red bone marrow produces red marrow produces red blood cells, some blood cells, some white blood cells and white blood cells and platelets. Yellow bone platelets. Yellow bone marrow stores excess marrow stores excess fat.fat.

QuestionsQuestions

• What are the benefits, drawbacks of each of the What are the benefits, drawbacks of each of the types of skeletontypes of skeleton

• What type of skeleton would be best for animals What type of skeleton would be best for animals that 1) live in the sea 2) are very big 3) are very that 1) live in the sea 2) are very big 3) are very small 4) flysmall 4) fly

• Further research: What are bone plates, when Further research: What are bone plates, when do they close in humans, what are they used fordo they close in humans, what are they used for

• Please write a 250-500 word report on a bone Please write a 250-500 word report on a bone disease (Osteoporosis, Paget's disease, bone disease (Osteoporosis, Paget's disease, bone cancer, Osteonecrosis, Osteoarthritis, or other. )cancer, Osteonecrosis, Osteoarthritis, or other. )

• Please email your work to Please email your work to purdy@satitpatumwan.netpurdy@satitpatumwan.net