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The Skeletal System

Chapter 14Section 2

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Key Concepts no cares about

What are the functions of the skeleton?What role do joints play in the body?What are the characteristics of bone, and how can you keep your bones strong and healthy?

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VocabularySkeleton Vertebrae

Joint Ligament

Cartilage Compact bone

Spongy bone Marrow

Osteoporosis

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What the Skeletal System Does

Can a building stand without a frame?

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Five major skeletal functions

Just as a building cannot stand without frame you would collapse without your skeletonFunctions

Provides shape and supportEnable you to moveProtects your organsProduces blood cellsStores mineral and other materials until your body needs them

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Shape and SupportThe skeleton provides a framework that supports and protects many other body partsThe backbone or vertebral column is the center of the skeletonThe bones in the skeleton are in some way connected to this columnYou can feel 26 small bones if your move your fingers down the center of your back

Bend forward at the waist and feel the bones adjust as you moveThink of each individual vertebra as a bead on a string it is flexible and able to bend

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Production and Storage of Substances

Some of your bones produce substances that your body needsThe long bones of your arms and legs can be thought of as factories that make certain blood cellsBones also store minerals such as calcium and phosphorusWhen the body needs these minerals the bones release small amounts of them into the blood

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Joints of the SkeletonJoints allow bones to move in different ways as they are the place in the body where two bones come together

There are two kinds of jointsMovable and immovable joints

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Immovable Movable

JointsSome joints in the body connect bones in a way that allows little or no movementBones of the skull are held together by immovable joints

Most joints in the body are movable they allow the body to make a wide range of movementsMovable joints are held together by connective tissues called ligamentsThey also have a second type of connective tissue called cartilage which is more flexible than bone

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Movable jointsHinge Joint-allows forward or backward motionYour knee is a hinge joint as well as your elbow

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Ball and Socket JointAllows the greatest range of motionThe ball and socket joint in your shoulder allows you to swing your arm freely in a circleHips also have ball and socket joints

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Pivot JointAllows one bone to rotate around anotherPivot joint in your neck allows you to turn your head from side to side

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Gliding JointAllows one bone to slide over anotherYour wrist or ankle enables you to bend and flex as well as make limited side to side motions

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CartilageCovers the ends of the bones and keeps them from rubbing against each other

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Bones-Strong and LivingBones are complex living structures that undergo growth and developments

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Bone Structure (1)Femur is the body’s longest bone and connects the pelvic bones to the lower leg bonesA thin tough membrane covers all of the bone except the endsBlood vessels and nerves enter and leave the bone through the membraneBeneath the bones outer membrane is a layer of compact bone which is hard and dense but not solid

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Bone Structure (2)Small canals run through the compact boneThese canals carry blood vessels and nerves from the bone’s surface to the living cells within the boneJust inside the compact bone is a layer of spongy bone

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Spongy BoneLike a SPONGE, spongy bone has many small spaces within itThis spongy structure makes spongy bone tissue lightweight but strongIt is also found at the ends of the boneSpaces in the bones contain a soft connective tissue called marrow

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Two types of MarrowRed and Yellow

Red bone marrow produces some of the body’s blood cellsAs a child most of your bones contain red bone marrowAs a teenager only the ends of your femurs, skull, hip and breastbone contain red marrow

Other bones contain yellow marrowThis marrow stores fat that can serve as an energy reserve

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Bone StrengthThe structure of bone makes it both strong and lightweightThey are so strong they absorb more force without breaking than can concrete or granite rockBones are hard because they contain minerals-phosphorus and calciumYou can jump up and down or turn cartwheels without breaking bones

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Bone DevelopmentThe tip of your nose contains cartilageAs an infant much of your skeleton was cartilageOver time the cartilage is replaced with hard bone tissueThis replacement of cartilage by bone tissue usually is complete by the time you stop growing

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Bone GrowthBones are alive-they contain cells and tissues such as blood and nervesThey also form new bone tissue as you grow as they are aliveEven after you are grown however, bone tissue continues to form within your bones

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Taking care of your bonesA combination of a balanced diet and regular exercise are important for a lifetime of healthy bones

Diet and exercise are some ways of taking care of your bones

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OsteoporosisAs people become older their bones begin to lose some of the minerals they containMineral loss can lead to osteoporosis a condition in which the body’s bones become weak and break easilyIt is more common in women than men

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1. What are five functions of the skeleton?

Provide shape and supportEnable you to moveProtect your organsProduce blood cellsStore minerals and other materials

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2. What are four types of movable joints?

Hinge Ball and socketPivotgliding

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3. What are three types of tissue in bone?

Compact boneSpongy boneMarrow

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4. Which function of the skeletal system gives you a clue that bones are not dead

or solid?

Bones make certain blood cells and release small amounts of minerals into the blood when needed.

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5. Where is marrow produced?

In the spaces in bone

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6. Does new bone tissue stop forming after you

stop growing?No, bones make new tissue when they absorb the force of your weight and when a bone has broken

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7. What do ligaments do?They hold together the bones in movable joints.

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8. What substance keeps bones from rubbing against each other?

cartilage

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9. What other functions does the skeletal system

perform besides providing support and protection?

Produces certain blood cellsStores minerals

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10. Why are vertebrae important?

The are the bones that make up your backbone, and all other bones are connected to the backbone.