The skeletal system
THE HUMAN skeleton is composed of 206 bones. The skeleton is the framework of the body. Without it, the body would be shapeless. The bones are shaped according to their function. Bones may be: I Long, as in the arm and legs I Flat, as the sternum and scapula I Short as in the ankles and wrist I Irregular, as in the vertebrae I Round, as in the patellae
The bones of the arms, legs, shoulders and pelvis make up the appendicular skeleton.
The bones of the skull and face and the auditory ossicle, vertebrae, ribs, and sternum make up the axial skeleton.
FUNCTIONS OF BONES
There are five principal functions of bones. They: support the body, enabling you to stand erect protect the internal organs and tissues assist movement by coordination with muscles and joints provide storage areas for minerals serve as sites for formation and development of blood cells in the bone marrow (haematopoiesis).
IIIIIBONE GROWTH
Bones develop in the growing foetus through a process called ossification. The skeleton is completely formed by the end of the third month of gestation (pregnancy). After birth, bone growth proceeds from the epiphyseal plates (growth plates). Growth proceeds from the end towards the centre of the bone. When the bone has reached its full size and growth ceases, the epiphyseal growth centres are replaced by bone cells.
Longitudinal (length) bone growth and ossification usually continue in girls until about age 15 and age 16 in boys.
However, bones continue to mature and develop their final shape until about 21 years of age.
The whole growth process is controlled by hormones. If there are too many growth hormones, the cartridge in the plates grows too fast and result in gigantism, while too little hormone leads to dwarfism.
Bone formation and resorption are caused by the actions of osteoblast and osteoclast. Osteoblast makes new bone, and at the same time, cells called osteoclast break it down. Exercise cause osteoblast to work harder. But, extreme training especially with weights at young age, can result in problem with bone deformity.
Bones get more fragile as you age and can get weak and break easily (osteoporosis), especially in women.
NUTRIENTS AND BONE GROWTH
The most important nutrients for growth are: proteins – build cells and repair damaged tissues. Found in milk, cheese, eggs, fish, pulses and nuts. vitamins – vitamin D helps with the
IIIabsorption of calcium and is found in milk, fish, liver and eggs. The body also makes it with sunshine. minerals – calcium, which give strong bones and teeth, is found in milk, cheese fish and green vegetables.
Morrison favoured for Liguanea Club Open
JOINTS
A joint is where two (2) or more bones meet (articulate). There are over 100 joints in the body. Joints are divided into three (3) types based on the amount of movement they allow.
FIXED OR IMMOVABLE JOINTS (FIBROUS)
In these, bones are fused together by tough fibres. These types of joints are found in areas requiring strength. Examples are the joint between the plates of the cranium (skull) and the fused joints in the sacrum.
SLIGHTLY MOVABLE JOINTS (CARTILAGINOUS)
In these, a small amount of movement can occur. The bones are linked by cartilage. Cartilage is a tough but flexible cushion of tissue that stops the bones from knocking together (friction) and can also compress a little to allow slight movement. Slightly movable joints are found between most of the vertebrae in the vertebral column and the joint between the ribs and sternum.
FREELY MOVABLE JOINTS (SYNOVIAL)
All freely movable joints share features which prevent friction between moving bones. One of the main features is the presence of synovial fluid between the moving bones. The bones are held together by slightly elastic fibres called ligaments, which allow the bones to move. Any damage to the ligament results in the joint losing some of its strength and stability.
Joints work smoothly together when we perform sporting activities. They must be capable of their full range of movement in order to work well. The demands of sport put severe stress on joints. Therefore, it is essential to warm up before an activity and cool down after the activity. Joints can be injured as a result of impact, internal forces or a mixture of both. Examples are sprains, torn ligament and dislocation.
That’s it for this week’s lesson. See you next week as we continue with the skeletal system. KINGSTON: RISING STAR Julian Morrison served off as the favourite as the 2016 Liguanea Club Open squash tournament, which got under way on Monday night. The former Caribbean junior champion is among 38 players vying for top honours in the week-long competition.
Although highly touted, Morrison can take nothing for granted as the tournament employs a handicap format which creates a level playing field regardless of the competitors’ experience and skill levels. In addition, male and female players are going head to head as the competition has a gender-neutral draw.
Facing stiff odds due to the handicaps, Morrison beat Roger Grant 21-19, 21-19 to start his campaign on the right note. The senior national team player has come into the competition razor-sharp, having played two highly competitive overseas tournaments within the last two months.
However, the wide open field of competitors includes senior national team member Nathlee Boreland, who beat Mark Haddad 21-19, 21-19 in first round action. Also in contention is the skilled and strategic Stewart Maxwell, who defeated Alan Johnston 21-19, 21-19. Other early winners include Dave Morrison, who beat Nicola Guy 9-21, 22-20, 21-18 and Andrew Shim, who stopped Stuart Reid 21-16, 21-13.
Tournament director David Harrison said the handicap format will keep spectators guessing right up until the final match.
“We’re talking about a situation where the most skilled and experienced players are on even footing with any other contender, so every match is unpredictable,” he explained.
“The Liguanea Club Open is always one of the most exciting tournaments on the squash calendar, and we anticipate that the 2016 competition will continue this tradition,” Harrison added.
The competition, which began on Monday night, will run until Saturday, October 1, at the Liguanea Club in New Kingston.
The early rounds will be played up to today and then the quarter-finals, semi-finals and finals will be held tomorrow, Friday and Saturday, respectively. Matches start at 5:30 p.m. each evening.
The 2016 Liguanea Club Open Squash Tournament is sponsored by Total, UHY Dawgen, Avis, Lifespan, KLAS ESPN Sports FM, Epic Technologies, Jamaica Biscuit Company and Cari-Med.