We are fearfully and wonderfully made!

         The spine is a wonderful creation of Almighty G-D.

How many bones are in the human body?
An average adult has 206 bones. Some people have an extra rib or two and may have more bones in their hands and feet.

How many bones are in the spine?
There are 33. The bones in the spine are called vertebrae . Beginning at the neck, there are 7 vertebrae in cervical 

spine - 12 thoracic  - 5 or 6 lumbar (lum-bar) - 5 sacrum - 3 coccyx .The coccyx is the tailbone.

 Thoracic Vertebra

How much do all the bones in the body weigh?
Total bone weight depends on how much the person's entire body weighs.

Bones make up about 15% of

a person's total body weight. For example, the bones of a person weighing

100 pounds would weigh about 15 pounds.

Are bones alive?
Yes! In fact bones contain thousands of living cells that are replaced as they die.

 Like other organs in the body, blood

brings food and oxygen to bones. The blood also removes waste - you

might say that blood takes out the garbage!

What is bone?
Bone is dense and hard yet, slightly elastic. It is made up of different layers of

bone tissue, cartilage, blood vessels, and other tissue.

 The outer layer is compact bone. It is very hard and strong.

The inside layer is called spongy bone and it does look something like

a kitchen sponge! In the center of the bone is marrow.

Within the bone marrow the body makes red blood cells.

What is bone marrow?
In the center of bone is a jelly like matter called bone marrow.

Bone marrow is the heart of the body's blood factory.

Not only does bone marrow make red blood cells, but it also makes

different types of white blood cells. How do

bones get blood? The outer layer of bone cells form rings around

 spaces called Haversian (have-er-shan) canals.

 The canals are connected to each other. Each canal is tiny and long.

 A blood vessel runs through each little canal.

Do bones have skin?
Bones have an outer layer that is like a thin skin or membrane (mem-brain).

This membrane is called the periosteum .

 The periosteum can be thick and is filled with blood vessels that help feed the bone.

 Many nerves also fill the periosteum.                                                                          

  How does the human heart beat?                       

     Heart cell beating

             We may not immediately think of our heart as a collection of individual cells.

But it is the complex interaction

of numerous cell types that give the heart its ability to pump blood.

 Some cells form heart connective tissue, other

cells grow into heart valves. And muscle cells give the heart its ability

 to beat and pump blood throughout the body.

Beating in Unison

As long as the beating cells do not touch one another, their beats are independent -

some are faster, some

are slower. But after two or three days, the myocytes form interconnected

 sheets of cells (monolayers, shown above )

that beat in unison. Pores (gap junctions) open between adjacent

touching cells, making their cytoplasms interconnected.

 It is these gap junctions that ensure that the connected cells work as one.

If the cells of the adult don't beat in unison, heart arrythmias can occur.

Electronic pacemakers may sometimes be used

 in a patient whose heart doesn't beat in rhythm.