Skeletal System

Your skeletal system gives your body shape and support, provides protection for vital organs, and produces blood cells.

What does the skeletal system do?

Without the skeletal system we would be shapeless blobs on the floor

What is a skeleton? A framework of bones that support the muscles

and organs and protect the inner organs Bones also serve as points to which the

muscles attach and create body movement Inside some bones, there is a soft tissue

that makes new blood cells

How do bones grow?

At birth, the skeletal system is soft and mostly made of cartilage

As a child grows, bone tissue begins to replace the cartilage

At the end of long bones is a band of cartilage called the growth plate (epiphysis) Cartilage that will be

replaced by bone is grown here

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Your skeleton is made up of 206

bones and has two main parts, the

axial skeleton and the appendicular

skeleton. The image to the right

shows some of the major bones.

Axial skeleton = central bones that work together to provide support and protect vital organs

Appendicular skeleton = made up of 126 bones that form the frame to which the muscles are attached and enable the body to move about

What are bones made up of? Outside layer of a bone is made up of a membrane called

the periosteum Contains blood vessels that supply nutrients to the bone and

nerves, which signal pain Under the periosteum is a hard material called compact bone

which provides support and is made up of living bone cells, minerals, protein fibers, blood vessels and nerves

Inside compact bone is a network of spongy bone which is a connective tissue that makes bones both light and strong

Many bones also contain a soft tissue called bone marrow which can be either yellow or red Long bones are filled with yellow marrow which is mostly made of fat

and stores energy Other bones contain red bone marrow in which the production of

blood cells begin

How are bones held together?

Muscles, tendons, and ligaments hold bones together

Two or more bones meet at places in the body called joints

Ligaments, which are tough bands of tissue, hold the ends of bones together at joints

Tendons are cords of connective tissue that attach muscles to bones.

Muscles and tendons attach to the bones on either side of a joint, holding the joint together tightly

OUCH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Is it bad to crack knuckles?

No, the popping or cracking sound made by some joints is very normal

Pulling on the joint creates a vacuum inside the joint

This vacuum causes tiny air bubbles in the joint fluid to burst. The result is a “pop” or “crack” that you can hear.

Popping joints is not clearly linked with arthritis which is a painful inflammation of the joints

Do all joints move?

No, some joints are fixed, such as the ones between the bones in the skull A fixed joint does not allow any

movement Other joints, such as semi movable

joints (most of the vertebrae in the spine) allow only a small amount of movement

Ball and socket joint

all major movement =

hips and shoulders

Bones attached at the hinge joint can simply move

back and forth (knees and

elbows) Movement in all ways

except rotation!

(Wrists and ankles)

Questions for you!

What are the four basic parts of the bone? Four layers

Periosteum = contains blood vessels that transport nutrients to the inner layers of the bone.

Compact bone = provides support Spongy bone = makes bones light and strong Bone marrow = yellow stores fat for energy

and red is a site of blood cell production

Questions for you!

How do most bones grow? The structures that will become bones

are initially made up of cartilage. New cartilage is produced as a child grows and increases bone size to mature length. Bone tissue replaces the cartilage as a person grows. Cartilage is retained at the ends of the longest bones in the body.

Questions for you!

List 3 types of joints Fixed joint, semimovable joint, hinge

joint, ball and socket joint, pivot joint, and/or ellipsoidal joint

Question for you!

Do you know what role bones play concerning calcium? Calcium is part of teeth and bones and is

used to regulate the function of the nerves and muscles. Sources = dark, leafy veggies, milk and dairy products and calcium fortified juices. If bone calcium becomes depleted, the bones become brittle and can fracture.

Skeletal Assignment

Page 529 Questions 1-4

Due tomorrow!