Growth And Development
Growing and developing is a big part of your life and your bodies job. Growing allows for your bones, muscles, and whole body to get bigger throughout your life. For female growing usually stops at the age of 18, and for male 21.
Fetal Development
A Zygote is created by a sperm and an egg. Sperm and egg alone have only one half of DNA, but when they come together they form a cell with one full DNA, and this creates the zygote. After it's created, the zygote then divides into different cells by mitosis. After sometime there are many cells in a ball. This is called a blastula, which is actually a hollow ball of cells. Inside is the inner cell mass, which is also known as stem cells. the blastula then folds inward in itself and creates a gastrula, wjhich has three different layers of cells called germ layers. These are the:
Ectoderm: Creates the nerves, sense organs and skin
Mesoderm: Creates middle muscles, cardions, reproduction and excretory organs
Endoderm: Creates the digestive tract and respiratory.
Ectoderm: Creates the nerves, sense organs and skin
Mesoderm: Creates middle muscles, cardions, reproduction and excretory organs
Endoderm: Creates the digestive tract and respiratory.
Bone Development
There are two different ways a bone develops. Intramembranous and Endochordral development.
Intramembranous
This type of development creates the flat bones in your bone, or the cranial bones, the ones in your skull. This type of bone is created from scratch.
|
Endochordral
This creates all the other bones and starts with a cartilage model.
|
Bone Growth
Bone growth is probably the most complex and important part of your body growth. Bones keep up standing up tall and strong, and if the grow improperly then there might be problems that your body will have to face. There are two different ways a bones grows, in length and width. Both ways of growing are very necessary, growing in length allows for your body to grow taller and longer, the bones then have to grow in width so that no strength is lost when the bone is stretching out.
Bone Growth In Length
A bone grows in width at the start of the growth plate. When a bone starts to grow there are three different zones. The growth, transformational and ossification zone.
|
Bone Growth In Width
Appositional Growth is the bone growing in width. In between the periosteum of the bone is a layer of osteoblasts, to grow new bone to the outside. Out side of the hollow cavity of the bone is the endosteum, and this has osteoclasts to break down bone.
The osteoclasts will break down bone on the inside to make the cavity larger on the inside. while this is happening, that means the sides are getting thinner, due to the grow in length and the bone being broken down on the inside, so osteoblasts on the outside create new bone to keep it's strength. When bone cells are broken down, it needs osteoclasts to do the job, and also enzymes that digest organic matter and acids that break down calcium salts. When bones are made you need osteoblasts, and also vitamins A,C and D, calcium and phosphorus. |
Muscle Development
Muscles develop from the mesoderm germ layer in the gastrula. Myoblasts are the cells that create muscles. Muscles develop first, and then the nerve endings attach into the muscles. Everyone is born with all muscle fibers, but some can and can't repair themselves. Muscles can change in size and health throughout the years and grow bigger and stronger if you excersize and take care of your body, which leads to the next page on how you can develop your muscles to the perfect size and strength for marching band.