“Boning up” on the Skeletal System

We sure have lots of bones! We sure have lots of bones! A newborn baby has more bones than an adult. A baby is born with 300 bones. An adult only has 206. This Powerpoint is hosted on www.worldofteaching.com Please visit for 100’s more free powerpoints

Your hand has 27 bones.

Your face has 14 bones.

Smallest and The Longest: The longest bone in your body is your thigh bone, the femur it is about 1/4 of your height. The smallest bone in your body is the stirrup bone in your ear which can measure only 1/10 of an inch.

Did You Know? Humans and giraffes have the same number of bones in their necks? A Giraffe’s neck vertebrae are just much, much longer!

Your Femur (thigh bone) is stronger than concrete. Bone is stronger, inch for inch than the steel used in skyscrapers.

without the patella (knee bone) Babies are born without the patella (knee bone) it develops between ages 2 and 5.

One fourth of your bones are located in your feet.

Your backbone is really thirty-three bones that run down the middle of your body.

The jawbone is the hardest in the human body.

The only bone not broken so far during any ski accident is one located in your inner ear.

If you break your wrist as an adult it will take you 8 weeks to heal. A five year old child who breaks their wrist only takes 3 weeks to heal.

Your big toes have 2 bones in them, while all your other toes have 3 bones in them.

What is the Skeletal System? it is made up of cartilage and bone, with extra support coming from ligaments and tendons Shown here is the nose which is made of cartilage and bone

Purpose? protect and support muscles and organs (i.e.. the brain is protected by the surrounding skull as the heart and lungs are encased by the sternum and rib cage withstand tremendous forces that affect an organism • remain strong under the stresses of movement ( ex. walking) provide sites of attachment of tendons and muscles, essential for locomotion

What would happen if humans didn't have bones? You'd be floppy like a beanbag. Could you stand up? Forget it. Could you walk? No way. Without bones you'd be just a puddle of skin and guts on the floor.

What are bones? Hard, solid organs that form the skeleton help with support, protection, movement, storage and the production of blood cells ( in bone marrow) Have blood vessels and nerves supplying them nutrients and information Within the "alive bone" are blood vessels, nerves, collagen, and living cells including: osteoblasts, osteocytes and osteoclasts The nonliving, but very important, substances in bone are the minerals and salts. These help makes bones strong! Bones are not dead, or finished structures. They are a living and growing part of any animal. All bones have blood vessels and nerves supplying them nutrients and information. Bone tissue contains three different types of specialised generative cells called 'Osteoblasts', 'Osteocytes' and 'Osteoclasts'. Osteoblasts are the most common, they form the bone matrix around themselves by laying down collagen fibres and depositing the crystals of mineral material. They are the real bone builders. Osteocytes are branched cells. They lie embedded in the bone matrix where they monitor and help control the mineral balance of the body. Osteoclasts break down the matrix during normal bone renewal and growth, they are also important in the healing of fractures.

The Team Osteoblasts : bone builders, ( # decreases with age= brittle bones) Osteocytes help control the mineral balance of the body Osteoclasts : are mature osteoblasts that have ended their bone-forming careers. These cells break down bone during normal bone renewal and growth, they are also important in the healing of fractures Osteoblasts are cells which originate in the bone marrow and contribute to the production of new bone. These cells build up the matrix of the bone structure and also play a role in the mineralization of the bone matrix. Bone is constantly being built up and broken down by the body, making osteoblasts rather critical. The counterpart to the osteoblast is the osteoclast, a cell which is responsible for breaking down bone. As people get older, their production of osteoblasts decreases. This is why older people tend to have more brittle bones which are at risk of fracture, and why it takes longer for them to heal after breaks, because they have fewer cells to rebuild the damaged bone. Bone health can also be influenced by the amount of available calcium in the diet, as osteoblasts need calcium to work with in the process of building up bone. As people get older, their production of osteoblasts decreases. This is why older people tend to have more brittle bones which are at risk of fracture, and why it takes longer for them to heal after breaks, because they have fewer cells to rebuild the damaged bone. Bone health can also be influenced by the amount of available calcium in the diet, as osteoblasts need calcium to work with in the process of building up bone

There are two types of bone tissue: 1.Compact bone tissue : the hard outer layer of bones is composed of this Its name comes from the fact that is has a small amount of gaps and spaces ( is very dense ) gives bones their smooth, white, and solid appearance, and accounts for 80% of the total bone mass of an adult skeleton

Compact Bone tissue

Spongy bone tissue the spongy interior layer of bone that protects the bone marrow Cancellous bone may also be called a spongy bone or trabecular bone structurally resembles honeycomb and accounts for about 20% of bone matter in the human body ,but has nearly ten times the surface area of compact bone

What is bone marrow? Many bones are hollow. Their hollowness makes bones strong and light. It's in the center of many bones that bone marrow makes new red and white blood cells. Red blood cells ensure that oxygen is distributed to all parts of your body and white blood cells ensure you are able to fight germs and disease. Who would have thought that bones make blood!?!

Bone marrow saves lives! Can be used to diagnose Stem cells in donor bone marrow can be used to restore harmed bone marrow cells in cancer patients which are required to produce blood cells

How many bones do humans have? When you were born you had over 300 bones. As you grew, some of these bones began to fuse together. The result? An adult has only 206 bones! But how? In the fetus, most of the skeleton is made up of cartilage, a tough, flexible connective tissue that has no minerals or salts. As the fetus grows, osteoblasts and osteoclasts slowly replace cartilage cells and ossification begins. Ossification is the formation of bone by the activity of osteoblasts and osteoclasts and the addition of minerals and salts. Calcium compounds must be present for ossification to take place. Osteoblasts do not make these minerals, but must take them from the blood and deposit them in the bone. By the time we are born, many of the bones have been at least partly ossified. In long bones, the growth and elongation (lengthening) continue from birth through adolescence. Elongation is achieved by the activity of two cartilage plates, called epiphyseal plates, located between the shaft (the diaphysis) and the heads (epiphyses) of the bones (Figure 5). These plates expand, forming new cells, and increasing the length of the shaft. In this manner, the length of the shaft increases at both ends, and each head of the bone moves progressively apart. As growth proceeds, the thickness of the epiphyseal plates gradually decreases and this bone lengthening process ends. In humans, different bones stop lengthening at different ages, but ossification is fully complete by about age 25. During this lengthening period, the stresses of physical activity result in the strengthening of bone tissue. Figure 5. Long bones continue to grow and elongate (lengthen) though adolescence. This process is called ossification. In contrast to the lengthening of bone, the thickness and strength of bone must continually be maintained by the body. That is, old bone must be replaced by new bone all the time. This is accomplished as bone is continually deposited by osteoblasts, while at the same time, it is continually being reabsorbed (broken down and digested by the body) by osteoclasts (Figure 5). Osteoblasts are found on the outer surfaces of the bones and in the bone cavities. A small amount of osteoblastic activity occurs continually in all living bones (on about 4% of all surfaces at any given time) so that at least some new bone is being formed constantly. Normally, in fact, except in growing bones, the rates of bone deposition and absorption are equal to each other so that the total mass of bone remains constant. Usually, osteoclasts exist in small but concentrated masses, and once a mass of osteoclasts begins to develop, it usually eats away at the bone for about three weeks, eating out a tunnel that may be as large as 1 millimeter in diameter and several millimeters in length. At the end of this time the osteoclasts disappear and the tunnel is invaded by osteoblasts instead; then new bone begins to develop, Bone deposition then continues for several months, the new bone being laid down in successive layers of concentric circles on the inner surfaces of the cavity until the tunnel is filled. Deposition of new bone ceases when the bone reaches the surface of the blood vessels supplying the area. The canal through which these blood vessels run, called the haversion canal (Figure 5), therefore, is all that remains of the original cavity. This process continues until about age 40, when the activity of osteoblasts slows and bones become more brittle. Let's look at some important factors that are necessary to produce healthy bone. Bone development is influenced by a number of factors, including nutrition, exposure to sunlight, hormonal secretions, and physical exercise. For example, exposure of skin to the ultraviolet portion of sunlight is favorable to bone development, because the skin can produce vitamin D when it is exposed to such radiation. Vitamin D is necessary for the proper absorption of calcium in the small intestine. In the absence of this vitamin, calcium is poorly absorbed, the bone matrix is deficient in calcium, and the bones are likely to be deformed or very weak. Vitamins A and C also are needed for normal bone growth and development.

From about 300- 206? As a fetus your skeleton is composed of mainly cartilage which calcifies into bone with the help of bone building cells and minerals (calcium and phosphate) and salt . When born you have about 300 bones, but as you grow some fuse thus by the time you hit 25 you are a fully grown adult with 206 bones. This means that nearly one-third of the bones in our human body will bond together during the period between infancy and adulthood.

Infant Male Female

Types of Bones Long bones- Short bones- Flat bones- Irregular Bones-

Fun movie clips! http://www.youtube.com/watch?v=7vLAE_P_ u_4&feature=related