The skele­tal sys­tem

Jamaica Gleaner - - SPORTS -

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.

MOR­RI­SON

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