Ch. 1 Sec. 2

The Skeletal System

(cranium)

Skeleton model

Functions of Skeletal System

1. Provides shape & support

2. Enables movement

3. Protects internal organs

4. Produces blood cells

5. Stores certain materials until body needs them

1. Provides shape & support

• vertebrae= 26 bones that make up backbone

(vertebra- singular)• Newborn- 275 bones• Adult- 206 bones

2. Enables you to move

• Muscles pull on bones

3. Protects internal organs• Skull protects brain

• Ribs protect heart & lungs

4. Produces blood cells

•made by bone marrow

5. Stores certain materials until your body needs them

• calcium & phosphorus

Bones- strong & living• Hard b/c made of Ca & P

• Contain cells & tissues

• Form new bone tissue as you grow

Structure of bones• outer membrane= covers

bone, except @ ends- cartilage (connective tissue-more flexible than bone)

• compact bone= hard & dense

• spongy bone= lightweight but strong

Structure of bones• marrow=

– soft, connective tissue– found in spaces in bone– 2 types:

1.1. red bone marrow-red bone marrow- produces most blood cells

2.2. yellow bone marrow-yellow bone marrow- energy reserve

Bone Structure

• infant- skeleton mostly cartilage

How Bones Change As We Grow

[04:43]

healthy bones

well balanced

dietexercise

wear safety

equipmentCa & P

osteoporosis• condition where

body’s bones become weak & break easily due to mineral loss

• more common in women than men

ACTIVITY "HOLLOW STRENGTH" 1) Students will roll up a sheet of paper (8 1/2 x 11) about 1 in wide into a cylinder.

They will make 3 of these (paper bones). 2) Students will stand the bones up on their ends, placing a paper plate on top of the

bones. 3) Teacher will ask students to tell what is happening - the hollow rolls will support

the plate. 4) Students will begin to add weights (wooden blocks) to the plate.5) Students will count how many blocks the plate can hold before it collapses the

bones.6) Students will roll 3 more sheets of paper as tightly as they can so that there is no

hollow section. 7) Students will stand these "bones" up as before placing the same plate on top of

them. 8) Students will place weights on top of the plate until they collapse. 9) Students will deduce what happened. Teacher will explain that hollow bones were

able to support more weight. Teacher will also explain that having a hollow center gave the bones a better design and made them stronger. Teacher will continue explaining that the large bones in our body are also hollow, which makes them strong so they can support more weight, but light, so it takes less energy to move them.

• place where 2 bones come together

joint

2 kinds of joints:

1. immovable joint- little or no movement

• eg: skull bones

2. movable joints

ball & socket joint–greatest range of motion

–shoulder & hips

hinge joint• forward or backward motion

• knee & elbow

pivot joint• bone rotates around another

• neck

gliding joint• 1 bone slides over another

• wrist, ankle, vertebra

Video-Bone Joints

Skills Activity-pg. 15Skills Activity-pg. 15Perform these activities.Perform these activities.

• Determine which type of movable joint or joints is involved in performing each activity. Give a reason to support your classifications.

1. Move your arm in a circle.2. Push open a door.3. Lift a book from a desk.4. Kneel down.5. Wave your hand.6. Twist your head from side to side.

gliding joint hinge joint

pivot joint

immovable joint

ball & socket joint

ligament

• tissue that holds bones in movable joints together

Bone

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Label your body’s framework with the scientific name for each bone.

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