Chapter 37 The Skeletal and Muscular System: 3.5 Learning Objectives 3.5. Respnses in the human 1. Descriptin f the structure and functins f the skeletn. 2. Label the cmpnent parts f the axial and appendicular skeletn. 3. Detail the cmpnent parts f the axial skeletn. 4. Give the psitin and functin f discs in relatin t vertebrae. 5. Detail the cmpnent parts f the appendicular skeletn. 6. Describe the macrscpic anatmy f a lng bne. 7. Give the functin f the fllwing: cartilage, cmpact bne, spngy bne (red and yellw). 8. Classify and give lcatin and functin f jints. 9. Discuss ne disrder f the musculskeletal system: ne pssible cause, preventin, and treatment. 10. Explain the rle f cartilage, ligaments and tendns. 11. Give the general relatinship f muscles t the skeletn. 12. Name and detail ne example f antagnistic muscle pairs. 13. *Describe the Osteblast rle in: bne grwth, bne cell replacement, bne renewal. 14. *Discuss the rle f calcium in bne. The Skeletal and muscular systems wrk tgether t frm the musculskeletal system. It is cntrlled by the nervus system. 5 Key functins f the skeletn are: - 1. Supprt: The bnes frm the rigid system that keeps the bdy upright. - 2. Prtectin: Different bnes prtect different delicate rgans. The skull prtects the brain. Ribs prtect heart and lungs. - 3. Mvement: Bnes act as levers against which muscles can pull t cause mvement. - 4. Shape: The size f the bnes in the skeletn determines ur verall shape and size. The length f bnes determines ur height. - 5. Making f Bld Cmpnents: The Red Bld Cells, White Bld Cells and Platelets are all prduced in the bne marrw. The 206 bnes f the skeletn are divided int the Appendicular and Axial Skeletn. - The Axial Skeletn cnsists f the Skull, Spine, Ribs and Sternum. - The Appendicular Skeletn is cmpsed f the limbs (appendages), pectral girdle and pelvic girdle.
THE AXIAL SKELETON - THE SKULL (Cranium) Cnsists f 20 bnes, all fused tgether, prtects the brain. - THE RIBCAGE Cnsists f the Sternum and 12 pairs f ribs. All ribs are attached t the vertebrae f the spine. The tp 7 pairs are attached t the sternum, they are true ribs. The next three are attached t each ther at the frnt by cartilage, they are false ribs. The bttm tw pairs are nt attached at the frnt, they are flating ribs. - THE SPINE Cnsists f 33 Bnes called vertebrae. The tp 24 are jined by ligaments and enable mvement. The bttm 9 are fused tgether, thus d nt mve. The tp 24 vertebrae mve, thus they need t be separated by discs, t ease the mvement. Discs have a hard uter layer, which surrunds a jelly-like inner layer. They reduce frictin, act as shck absrbers and prtect the vertebrae.
THE APPENDICULAR SKELETON - PECTORAL GIRDLE Cnsists f the cllarbne (clavicle) and shulder blade (scapula). It cnnects with the vertebral clumn and the arms. - PELVIC GIRDLE Cnsists f the hip bnes and the sacrum. The sacrum is the area where it is fused t the spine. The hip bnes are cmpsed f tw halves, jined at the frnt by cartilage. - LIMBS The arms and legs make up yur limbs, they have very similar structures. Phalanges are the individual bnes in the fingers and tes (Digits). Each finger and te has 3 phalanges, except the thumb and big te, which cnsist f 2. Macrscpic Anatmy f a Lng Bne Lng bnes such as the femur and radius are enclsed by a membrane called the Peristeum. It cntains bld vessels and nerves.
Three types f bne: 1. Cmpact Bne, 2. Spngy Bne, 3. Bne Marrw. Cmpact Bne Lcatin: Diaphysis f bne Cmpsitin: Made f Osteblasts (Bne Cells) embedded in a matrix f in-rganic salts such as calcium and cllagen prtein. Bld vessels and nerve cells run thrugh the cmpact bne. Functin: Calcium gives the bne strength, prtein gives flexibility. Spngy Bne Lcatin: Epiphysis f bne Cmpsitin: Similar t cmpact bne but cntains many mre hllws. Hllws are filled with bne marrw which prduces bld cells. Functin: Gives strength and rigidity. Bne Marrw Lcatin: Within spngy bne and medullary cavity. Cmpsitin: Red marrw, fund in yung peple, prduces bld cmpnents. Hllws are filled with bne marrw which prduces bld cells. Functin: Gives strength and rigidity. CARTILAGE Cartilage is made f cllagen (a firm, flexible prtein). It has n bld vessels r nerves, thus is slw t heal. It is fund in the pinna f the ear, the nse, the trachea and vertebrae discs. Functin: On the ends f bnes, acts as a shck absrber allwing frictin free mvement. BONE GROWTH (H.L.) During embrynic develpment, cartilage begins t be replaced by bnes at week 8. Osteblast cells prduce cllagen prtein. Calcium phsphate and ther salts frm arund the steblasts and cllagen, making them drmant bne cells. In rder fr bnes t grw they require a grwth plate. The plate is made f cartilage and lcated between the Epiphysis and Diaphysis.
In the grwth plate, cartilage is cntinually made and then ssified (turned t bne) by steblasts. When a persn reaches adulthd, the grwth plate stps functining, terminating the develpment f adult height. BONE DEVELOPMENT/CELL REPLACEMENT (H.L.) In life bne is cnstantly being disslved, thus it needs t be renewed. This ccurs ~ten times thrughut life. The restructuring prcess invlves the remval f bne material frm inside the medullary cavity, then extra bne material being depsited utside the bne. This exchange prevents bnes frm becming heavier as they grw lnger. The remval f bne material frm the medullary cavity is carried ut by Osteclast (bnedigesting) cells. They digest the bne that lines the cavity and depsit it int bld vessels. Osteblasts then frm new bne n the utside f the bne. Osteblasts and steclasts wrk ppsite each ther t enlarge the medullary cavity and thicken the cmpact bne lining it. BONE RENEWAL (H.L.) The cntinual renewal f bne is dependent n: Physical Activity, Hrmnes and Diet. When bnes are stressed by physical activity, they activate steblasts, which make them thicker and strnger( especially near where muscles attach). Lack f stress causes them t becme thin. The main hrmnes affecting bne develpment include; grwth hrmne, sex hrmnes and parathrmne. Grwth and sex hrmnes are active at puberty and increase bne mass rapidly. Parathrmne remves calcium frm bne, this allws a cnstant supply f calcium in the bld fr crrect nerve and muscle functin. ROLE OF CALCIUM (H.L.) Calcium is required in the diet fr a number f reasns: It frms the slid structure f bne, giving it its strength. It s essential fr bld cltting. It stabilizes bld pressure. It cntributes t nrmal brain functin.
It s critical fr cmmunicating essential infrmatin amng cells. RELATED DISEASES Osteprsis is the lss f cllagen prtein frm bnes. This results in a lss f flexibility and bnes becme brittle and easily brken. Ostemalacia is the lss f minerals including calcium frm the bnes, due t a lack f vitamin D in the diet. This causes bnes t lse rigidity and strength. JOINTS A Jint is where tw r mre bnes meet. They can be categrised as: 1. Immvable, 2. Slightly mvable, 3. Freely mvable (Synvial) Immvable Jints Are fixed f fused int psitin. Functin: prvide strength, supprt and prtectin. Examples: Skull and Pelvic Girdle. Slightly Mvable Jints Allw limited mvement. Example: The vertebrae f the spine, they are separated by discs f cartilage & held by ligaments. They prtect the spinal crd. Freely Mvable (Synvial) Jints Allw a range f mvements. The ends f the bnes are cvered with cartilage and separated by a small cavity. The bnes are held in place by ligaments t prevent ver mvement. Inside the cavity is a synvial membrane which cntains synvial fluid. This lubricates the jints reducing frictin. There are tw types f synvial jints: Ball and Scket and Hinge. Ball and Scket Jint All mvement in ALL directins, they cannt supprt high levels f weight. E.g.: Shulder jint, hip jint. Hinge Jint All mvement in nly ne directin, they can supprt high levels f weight. E.g.: Knee and Elbw Jint
LIGAMENTS & TENDONS Ligaments are strng, fibrus, slightly elastic tissues which cnnect bne t bne. They are mre flexible when warm, hence yu shuld warm up prir t exercise. Tendns are strng, flexible, inelastic fibres that cnnect muscle t bne. They cntain bld vessels and are made f cllagen. Synvial Jint MUSCULOSKELETAL SYSTEM DISORDER Arthritis is a skeletal disrder resulting frm inflammatin f a jint. There are ver 100 types. Tw mst cmmn: Ostearthritis & Rheumatid Arthritis. Ostearthritis Onsets at ~50 Caused by cartilage at jints wearing dwn. The bnes becme enlarged and synvial fluid prductin increase. Jints becme sre and stiff. Rheumatid Arthritis Mst severe frm. It is a genetic disrder, caused due t the immune system attacking the bdy (Aut-immune disease). The synvial membranes are attacked first, this causes jints t swell and becme damaged and defrmed. Preventin (Ostearthritis) Caused by wear and tear n the cartilage in jints, can be reduced by aviding wear and tear n jints (running n rads is a majr cause). Treatment N cure but treatment includes rest, exercise, weight lss, sterids, anti-inflammatry medicatins, immunsuppressant's and surgery t replace jints (hip replacement).
MUSCLES The bdy cntains three types f muscle: Skeletal, Smth, Cardiac. Skeletal Muscle Can be called striated, striped r vluntary muscle. There are ver 600 in the human bdy, making up 50% f bdy weight. Skeletal muscle is cncerned with bdy mvements and is under cnscius cntrl. Smth Muscle Can be called unstriped r invluntary muscle. It is fund in internal structures such as the digestive system, bld vessels, bladder and uterus. It is under uncnscius cntrl. Cardiac Muscle Is fund in the heart and is slw t tire. It is invluntary and has many, many mitchndria fr a high energy input. Antagnistic Pairs The cntractin f muscles requires use f large amunts f energy (ATP). Tendns cnnect muscles t bnes. When a muscle cntracts it pulls n the bne, causing mvement. Muscles can nly pull (cntract) s they need anther muscle ppsite t pull them back ut. An Antagnistic pair is a pair f muscles that have ppsing effects n each ther. E.g. Bicep and Tricep