Skeletal SystemBones, joints, cartilages, and ligaments

FUN FACTS

When we were born we had over 300 bones. As we grew up, some of the bones fused together. As an adult we only have ____ bones!

97% of all the creatures do not have a backbone or spine.

The human hand has 27 bones and our face has 14!

The smallest bone in our body is the stirrup bone in our ear it measures 1/10 of an inch.

206

Overview and basic functions

Video introduction

Video

“The Skeletal System- Human Anatomy”

Functions of Bones

1. Support2. Protection3. Movement4. Storage5. Blood cell formation6. Homeostatic balance

Function #1: SUPPORT

• Our bones are an internal framework• Without bones to hold us up, we’d all

be gooey piles of mush flopping around on the floor • Bones are the ‘reinforced concrete’ of

the body

Function #2: PROTECTION

• Bones protect soft body organs• For example, what would happen to

our brain if we didn’t have a skull?? • Our vertebrae protect our spinal cord• Can you think of any other examples?

Function #3: MOVEMENT

• Skeletal muscles are attached to bones by tendons• These muscles use our bones as

levers to move the body and its parts

Function #4: STORAGE

• Fat is stored in the internal cavities of bones• Bones are a ‘storehouse’ for minerals,

including calcium and phosphorous• IMPORTANT: Ca2+ (calcium ion) must

be present in the blood at all times for 1. the nervous system to transmit messages2. for muscles to contract 3. for blood to clot

Function #5: BLOOD CELL FORMATION

• “Hematopoiesis” is blood cell formation• Hematopoiesis occurs within the

marrow cavities of certain bones

The 4 types of bone shapes

There are 4 Types of Bones (pg 131)

Long bones• Longer than they are

wide• They typically have a

long centerpiece with a head at both ends

• All the bones of the limbs (legs, arms) except the carpals and tarsals

Short bones

• Generally cube shaped• Contain mostly spongy

bone• Best known example is a

patella• Carpals, tarsals

Flat bones• Thin, flattened• Usually curved• Have two thin layers of

compact bone sandwiching a layer of spongy bone

• Most bones of the skull, the ribs, and the sternum

Irregular bones• Any bone that doesn’t fit into a previous category• Vertebrae of the spinal column, hip bones

How many neck vertebrae do giraffes have?HINT: Humans have 7.

7!! Both Humans and giraffes have the same amount of bones on their necks, just that the giraffes have a much longer vertebra.

The two types of bone tissueCompact and spongy

• Compact • Spongy

Compact vs Spongy (pg 130)

• COMPACT• Dense• Looks smooth and homogenous

• SPONGY• Composed of small needlelike

pieces of bone and lots of open space

Which of these is compact skeletal tissue?

Which makes this one spongy skeletal tissue.

Gross AnatomyYucky!General anatomy of our bones

Pg 133

Basic Structure• Diaphysis:

the shaft of a long bone, filled with compact bone

• Epiphysis: Rounded end of a long boneDistal

epiphysis

Proximal epiphysis

Diaphysis (shaft) Covering• Periosteum: Fibrous

connective tissue that covers and protects the diaphysis

• The periosteum contains the blood vessels and nerves that provide nourishment and sensation to the bone.

Epiphyses (ends) Covering

• Instead of periosteum, articular cartilage covers both epiphyses

• Glassy hyaline cartilage which makes it smooth and slippery

• Why do you think our bones are covered with glassy hyaline cartilage?

Epiphyseal Line• The epiphyseal line is a remnant of the

epiphyseal plate (a flat line of hyaline cartilage) seen in young, growing bone

• When the bones are done growing, the epiphyseal plate is completely replaced by bone

What’s in the

diaphysis?

Center of the diaphysis (pg 133)

• In adults, the cavity of the diaphysis is primarily a storage area for FAT (or ‘adipose’ tissue)

• This is called yellow marrow. • The cavity

where the yellow marrow is found is called the medullary cavity.

Let’s Review!

What kind of bones are your carpals?

Short bones!

What is an example of an irregular bone?

How many bones does a human body have?

206!

Exit Ticket:

1. What are the different functions of bones? Name as many of the six as you can.

2. What are the four types of bones?3. What are the ends of a long bone called? The

proximal and distal ____________?4. What is the inner cavity of the diaphysis called?5. Watch this video and reflect: “What properties of

the skeletal system make this man’s talent possible?”• A Man With No Bones