POINTS TO REMEMBER : 20. Lcmtin and Mvement Types f Mvement : Amebid mvement: This mvement takes place in phagcytes where leuccytes and macrphages migrate thrugh tissue. It is affected by pseudpdia frmed by the streaming f prtplasm (as in ameba) Ciliary mvement: These mvements ccur in internal rgans which are lined by ciliary epithelium. Muscular Mvement: This mvement invlves the muscle fibers, which have the ability t cntract and relax. MUSCLES : Prperties f Muscle : Excitability Cntractility Extensibility Elasticity Types f Muscles : Skeletal muscles r striated muscles Clsely assciated with skeletn. They are striped appearance under the micrscpe and called Striated muscles. They are under vluntary cntrl f nervus system, hence called vluntary muscles. These invlved in lcmtin and change f bdy pstures. Unbranched and multinucleated. Visceral muscles r smth muscles These are lcated in inner wall f hllw visceral rgan. Spindle shaped and uni-nucleated. They d nt exhibit any striatin and are smth in appearance. They are called smth muscles r nn-striated muscles. Their activities are nt under vluntary cntrl f nervus system hence called as invluntary muscles. They assist in transprt f fd thrugh digestive tract and gametes thrugh the genital tract. Cardiac muscles The muscles f heart, invluntary in nature. Cardiac muscle cells assemble in a branching pattern t frm a cardiac muscle. These are uni-nucleated with characteristic intercalated disc. Structure f skeletal muscle : Each rganized skeletal muscle in ur bdy is made f a number f muscle bundles called fascicles held tgether by cmmn fibrus cvering called fascia. Each fascicle cnsists f a number f muscle fibres (cell) cvered by a cmmn fibrus perimysium. Each muscle fibre is lined by the plasma membrane called sarclemma, enclsing cytplasm called sarcplasm. The sarcplasm cntain endplasmic reticulum, called sarcplasmic reticulum is the stre huse f calcium in.
Muscle fibre is a syncitium as the sarcplasm cntain many nuclei. Muscle fibres cntain a large number f parallelly arranged filaments in the sarcplasm called myfilaments rmyfibrils. There are tw types f myfibrils are present in the sarcplasm Thin filament Actin Thick filament Mysin. The arrangement f thick and thin filament gives the characteristic striated appearance. The light bands cntain nly actin filaments and are called I-band r istrpic band. The dark band called A r anistrpic band cntains bth actin and mysin. In the centre f each I band is an elastic fibre called Z line which bisects it. The thin filaments r actin are firmly attached with the Z line. The thick filaments r mysin in the A band are als held tgether in the middle by a thin fibrus membrane called M line. The prtin between tw successive Z lines is cnsidered as the functinal unit f the muscle called sarcmere. Each A band cntains tw verlap zne f thick and thin filament called O band. The central part f thick filament, nt verlapped by thin filament is called H band. A band = 2(O) + H. Structure f Cntractile prteins : Thin filament r Actin : Each actin filament is made f tw F actins helically wund t each ther. Each F actin is made f plymer f mnmeric G (Glbular) actin. Each F actin assciated with anther prtein, trpmysin als run thrughut its length. Anther cmplex prtein, Trpnin is distributed at regular intervals n the trpmysin. Each trpnin has three cmpnent Trpnin-C binds with calcium. Trpnin-M, binds with the trpmysin. Trpnin T, masks the active site n the G actin (thin filament) In the resting state a sub-unit f Trpnin (Tn-T), masks the active binding sites n the thin filaments fr mysin. Thick filament : Each mysin (thick) filament is cnsists f many mnmeric prtein called Mermysins. Each mermysin has tw parts Heavy mermysin (HMM) - A glbular head with a shrt arm. Light mermysin (LMM) a tail. The HMM cmpnent, i.e. the head and shrt arm prjects utwards at regular distance and angle frm each ther frm the surface f a plymerized mysin filament and is knwn as crss arm. The glbular head is an active ATPase enzyme and has binding sites fr ATP and active sites fr actin.
Mechanism f muscle cntractin : Mechanism f muscle cntractin is explained by sliding filament thery which states that cntractin f a muscle fibre takes place by the sliding f the thin filaments ver the thick filaments. Muscle cntractin is initiated by a signal sent by the central nervus system via a mtr neurn. A mtr neurn alng with the muscle fibres cnnected t it cnstitutes a mtr unit. The junctin between a mtr neurn and the sarclemma f the muscle fibre is called neurmuscular junctin rmtr-end plate. Neurtransmitter releases here which generates an actin ptential in sarclemma. These causes release f Ca++ int sarcplasm. These Ca++ binds with trpnin, thereby remve masking f active site. Mysin head binds t expsed active site n actin t frm a crss bridge, utilizing energy frm ATP hydrlysis. This pulls the actin filament twards the centre f A band. Z lines als pulled inward thereby causing a shrtening f sarcmere i.e. cntractin. I band get reduced, whereas the A band retain the length. During relaxatin, the crss bridge between the actin and mysin break. Ca++pumped back t sarcplasmic cisternae. Actin filament slide ut f A band and length f I band increases. This returns the muscle t its riginal state. Repeated muscle cntractin causes accumulatin f lactic acid, prduced frm anaerbic breakdwn f glycgen leads t muscle fatigue. Muscle cntains red clured xygen string pigment called myglbin. Muscle with myglbin called red muscle fibres, they are als cntain large number f mitchndria which can utilize large amunt f xygen stred in them fr ATP prductin als called aerbic muscle. Sme muscles pssess very less quantity f myglbin and less mitchndrin hence called white fibres. Amunt f sarcplasmic reticulum is high in these muscles. They depend n anaerbic prcess fr energy. SKELETAL SYSTEM : Human skeletn cnsists f 206 bnes in adult. Axial skeletn 80 bnes Appendicular skeletn 126 bnes. Axial skeletn : Skull 29 bnes. Cranium 8 bnes frms the brain bx. Facial 14 bnes frms the frnt part f the face. Hyid a single U-shaped bne at the base f the buccal cavity. Ear ssicles 6 bnes- 3 n either side (Malleus, Incus and stapes) The skull regin articulates with the superir regin f the vertebral clumn with the help f tw ccipital cndyles hence called dicndylic skull. Vertebral clumn 26 bnes Cervical 7 vertebrae.
Thracic 12 vertebrae. Lumber 5 vertebrae. Sacral 1 vertebra. (fused five bne) Caudal 1 vertebra (fused fur bnes) Sternum r breast bne 1 bne in the middle line f the thrax. Ribs 12 pairs (24 bnes) 1-7 are true ribs (cnnected t the sternum directly) 8 th, 9 th, 10 th pairs are called false ribs they attached t the 7th ribs. 11th and 12th nt cnnected ventrally hence called flating ribs. Ribs attaché drsally t the vertebra and ventrally with the sternum by hyaline cartilage. Thracic vertebrae, ribs and sternum tgether frm the rib cage. Appendicular skeletn: 126 bnes Fre limb 60 ( 30 in each) Humerus 1 bne Radius and ulna 2 bnes Carpals (wrist bnes) 8 in numbers. Metacarpals (palm bnes) 5 in numbers Phalanges (digits) 14 in number. Hind limb 60 (30 in each) Femur (thigh bne- the lngest and heaviest bne) 1 number. Tibia and fibula 2 bnes. Tarsals (ankle bne) 7 bnes. Metatarsals 5 in numbers. Phalanges (digits) 14 in numbers. Patella (knee cap) 1 bne. Pectral girdles: cnsists f 2 bnes each = 4 bnes. Helps in articulatin f fre limb with the axial skeletn. Each pectral girdle made f tw half. Each half made f tw bne the clavicle and scapula. Scapula is a large triangular flat bne situated in the drsal part f the thrax between the secnd and the seventh ribs. Scapula is characterized by spine with acrmin prcess. Belw acrmin, is glenid cavity t which head f humerus fits. Clavicle is cmmnly called cllar bne. Pelvic girdle: 2 bnes. Pelvic girdle cnsists f tw cxal bnes.
Each cxal bne is frmed f fusin f three bnes Ilium Ischium Pubis. At the pint f fusin f the three bnes is a cavity called acetabulum t which the femur articulates. Tw halves f the pelvic girdle meets ventrally t frm the pubic symphysis cntaining fibrus cartilage. JOINTS : Jints are the pints f cntact between bnes, r between bnes and cartilages. Frce generated by the muscles is used t carry ut mvement thrugh jints, where jint acts as a fulcrum. Jints are classified int three types: Fibrus jint Cartilaginus jint Synvial jint Fibrus jints : D nt allw any mvements. Fund in flat bnes which fuse end-t-end with the help f dense fibrus cnnective tissues in the frm f sutures. These types f jints are fund in the bnes f cranium. Cartilaginus jints : The bnes invlved are jined tgether with the help f cartilages. Permits very little mvements. Jint between the vertebral clumn are the example f such jints. Synvial jints : Characterized by the presence f a fluid filled synvial cavity between the articulating surfaces f the tw bnes. Allw free mvement between tw bnes. The fluid inside it called synvial fluid cvered by synvial membrane. Ball and scket jint - between humerus and pectral girdle Hinge jint knee jint Pivt jint between atlas and axis. Gliding jint between carpals. Saddle jint between carpals and metacarpals f thumb. DISORDERS OF MUSCULAR AND SKELETAL SYSTEM : Myasthenia gravis : It is an aut-immun disrder. Affects the neurmuscular junctin leads t fatigue. Caused weakening and paralysis f skeletal muscle. Muscular dystrphy : Prgressive degeneratin f skeletal muscle mstly due t genetic disrder. Tetany: rapid spasms (wild cntractins) in muscle due t lw Ca++ in bdy fluid.
Arthritis : inflammatin f jints. Osteprsis : age related disrder characterized by decreased bne mass and increased chances f fractures. Decrease levels f estrgen are a cmmn cause. Gut : inflammatin f jints due t accumulatin f uric acid crystals.