Bone growth
Parts of the skeleton form during the first few weeks of life; by week eight after conception, the skeletal pattern has formed in cartilage and connective tissue membranes and thus ossification begins. Ossification is the process in which bones are formed, connective tissues, such as cartilage is transformed to bone or bone-like tissue. The ossified tissue is joined with blood vessels. These blood vessels bring minerals like calcium and deposit it in the ossifying tissue. Bone formation is a dynamic process, with cells called Osteoblasts depositing minerals, and Osteoclasts removing bone. This process, termed bone remodeling continues throughout life.
There are two types of ossification these are;
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Endochondral ossification is one of two types of bone formation and is the process responsible for much of the bone growth in vertebrate skeletons, especially in long bones. Endochondral ossification occurs by replacement of hyaline cartilage.
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Intramembranous ossification is one of the different types of bone formation; it is the process behind the development and formation of flat bones, mainly those found in the skull and clavicles.
Bone development continues throughout life; even after adult structure is attained, bone development carries on for repair of injuries such as fractures and for remodeling to meet lifestyle changes such as weight. Osteoblasts, Osteocytes and Osteoclasts are the three cell types involved in the development, growth and remodeling of bones. Osteoblasts are bone-forming cells, Osteocytes are mature bone cells and Osteoclasts break down and reabsorb bone.
Effects of exercise on bones and joints
3 sporting Movements
Effects of exercise continued
The skeletal system is affected in a more than beneficial way due to exercise. However these changes are dependent on the type of exercise participated. The skeleton has both long term and short term changes through exercise and strenuous participation.
Short term changes include;
- An increase in the production of synovial fluid
Long term changes include;
- An increased thickness in hyaline cartilage
Joints
Joints require motion to stay healthy. Long periods of inactivity cause the arthritic joint to stiffen. Also when a person participates in exercise the body moves at different speeds meaning the joints have to work harder than they do when resting; this extra stress on the joints causes the release of a fluid called synovial fluid. This fluid travels around the joint and helps it move more accurately and easily. Through exercise cartilage called hyaline cartilage increases in its thickness around where the two bones meet, this helps prevent the surface of the bones softening and wearing away.
Bones
Strenuous exercise is very good for the bones, this is due to it building bone strength, flexibility, and increasing bone density. Regular exercise also prevents osteoporosis, which is a disease inside the bone which leads to a sharply increased risk of fractures through a high decrease in bone density.
The muscular system
The muscular system is the element of our body that enables us to move so freely and so quickly. There are major and minor muscles within our bodies the major ones are…
These muscles above are all voluntary muscles meaning they enable the body to move, not all muscles are there for movement…There are three different types of muscle;
Cardiac muscle
voluntary muscle
involuntary muscle
Cardiac muscle/heart muscle
heart muscle controls the beating of the heart is influenced by different factors of stress for example when running there is an increase of stress on the heart there for the muscle contract and relaxes at a faster rate to get the blood pumping quicker.
Involuntary muscle
This is muscle used for the bodily systems, for example it forces food through the digestive system and aids the blood flow away from the heart. These are controlled by the nervous system making them move without conscious thought. This muscle has the ability to stretch and maintain tension for long periods of time.
Voluntary(skeletal) muscle
This is the muscle attached to the skeletal system, and thus provides the body with movement through a series of contractions and relaxations. These are controlled by the nervous system and can be controlled when both conscious (running) and unconscious (sleep walking).
How muscles move?
Antagonist pairs
Skeletal muscles always work in groups, they never work on their own.
As one muscle contracts another one relaxes. For example, when the quadriceps in the front thigh straightens the leg, the hamstrings in the back of the thigh relax. When the hamstrings contract to bend the leg, the quadriceps relaxes.
Muscles which contract and relax in a co-ordinate movement are called antagonist pairs.
Muscle contraction
- Isometric contractions - when the muscle stays the same length
- Concentric contractions - where the muscle shortens throughout movement
- Eccentric movement – where the muscle lengthens throughout movement
Effects of exercise on muscles
Short-term
short term changes are usually described as the responses to exercise, for example the short terms effects are;
- An increase in blood flow due to the demand of oxygen needed y each muscle within and moving part of the body.
- An increase in the demand of energy needed by a working muscle to complete an activity.
- An increase in waste products due to the exercising of the muscles, E.g carbon dioxide, lactic acid.
- An increase in body temperature due to the continued stress upon the muscles.
Long-term
long term changes are describes as bodily adaptations to regular exercise, for example the long term changes are;
- Muscles adapt in both size and strength due to the consistent stress implied upon them.
- An increase in muscle mass thus allowing movement to be quicker and more effective.
Different types of activity using aerobic or anaerobic energy systems.
