TOPIC  5:    MUSCULO-­‐SKELETAL  SYSTEM  

Learning  outcomes  

1.  IdenAfy  types  of  muscle  Assues  

2.  Describe  types  of  skeletal  system  3.  IdenAfy  human  skeletal  system  

4.  IdenAfy  the  component  of    human  musculo-­‐skeletal  system  5.  Explain  how  muscle  contracts  

6.  Describe  muscle  and  bone  relaAonships  

topic  

1.  Muscle  bone  partnership  2.  Types  of  muscle  Assue  

3.  Muscle  contracAon  

4.  Skeletal  system  

5.  Musculo-­‐skeletal  system  

THE  MUSCLE–BONE  PARTNERSHIP  

The  muscle–bone  partnership  

•  Skeletal  muscles  are  bundles  of  muscle  fibers  that  interact  with  bones  and  with  one  another    

•  Tendons  aQach  skeletal  muscles  to  bones  

AcAon  of  muscle:  

Example:  Movement  of  the  forearm  at  the  elbow  joint  1.  When  muscle  contract  they  shorter  

2.  When  muscle  relaxed,  they  longer  

3.  Muscle  only  pull;  they  cannot  push.  

4.  Both  muscle  work  in  antagonisAc  pairs  

Synergy  Muscle  • Some cause movements by working as pairs or groups (synergy)

• Synergy muscle assist prime mover

Antagonist  Muscle  Others oppose or reverse the action of a partner muscle (antagonist)

TYPES  OF  MUSCLE  TISSUE  

Muscle  Tissues:  Move  the  Body  

•    Muscle  Assues  are  frequently  called  contracAle  Assues  because  they  contain  contracAle  protein  filaments  such  as  acAn  and  myosin.  

•  There  are  three  types  of  muscle  Assues.  1.  Skeletal  2.  Cardiac  3.  Smooth  

1.  Skeletal  Muscle  •  There  are  3  types  of  muscle  in  the  

human  body,  each  with  a  different  structure.  

1.  Cardiac  muscle,  found  in  the  heart,  consists  of  striated,  branched  cells  forming  a  la[ce.  

2.   Smooth  muscle  are  long,  spindle-­‐shaped  cells  that  are  formed  in  sheets.  

3.  Skeletal  muscle  cells  are  elongated  fibers  running  the  length  of  the  muscle.  

1.  Cardiac  muscle:  

•    Cardiac  muscle  is  involuntary  muscle.  

•  Cardiac  muscle  is  found  in  the  walls  of  the  heart.  

•  Cardiac  muscle  cells  are  highly  branched,  interconnected,  and  bounded  on  each  end  by  intercalated  disks.  

2.  Smooth  muscle:  

•    Smooth  muscle  is  involuntary  muscle  without  striaAons.  

•  Smooth  muscle  is  also  called  visceral  muscle  because  it  lines  the  walls  of  the  organs  and  blood  vessels.      

•  Skeletal  muscle  is  voluntary  muscle.  

•  Skeletal  muscle  is  aQached  to  bones  to  facilitate  movement.  

•  Skeletal  muscle  cells  are  called  fibers  and  are  striated  because  of  the  acAn  and  myosin  bands.        

3.  Skeletal  muscle:  

MUSCLE  CONTRACTION  

Pathway  of  Muscle  Control  

Skeletal  muscle:  AcAn  Filaments  •  Skeletal  muscle  cells  called  fibers  &  striated  because  of  acAn  and  

myosin  bands.  •  AcAn  filaments  consist  of  two  chains  of  globular  acAn  monomers  

intertwined  in  a  helix.  •  AcAn  filaments  support  the  cell  and  any  projecAons,  such  as  

microvilli.  •  AcAn,  and  another  molecule  called  myosin,  are  also  involved  in  

muscle  contracAon  and  cell  division.  

2  chains    of  globular  acAn  monomer  

Skeletal  Muscle  and  Physiology  

Skeletal  Muscle  ContracAon  •  In  the  presence  of  calcium,  myosin  

binds  to  the  acAn  filaments.  

•  The  myosin  head  flexes  inward  and  backward,  causing  the  acAn  filament  to  shorten.  

•  In  the  presence  of  ATP,  the  myosin  head  detaches  and  then  reaQaches  at  a  new  posiAon  on  the  acAn  filament.  

•  This  cycle  repeats  to  conAnue  the  shortening  of  the  muscle  (contracAon).  

Cross-­‐bridge  cycle  1.  Acetylcholine  (Ach)  from  a  

motor  neuron  axon  terminal  diffuse  to  the  muscle  fiber.  

2.  Calcium  is  transported  into  the  sarcoplasmic  reticulum  

3.  Presence  of  calcium  triggers  the  exposure  of  myosin  binding  sites.  

4.  Myosin  head  binds  to  actin  filaments  

Cross-­‐bridge  cycle  5.  The  power  stroke  occurs  

6.  ATP  binds  to  the  myosin  head  

7.  ATP  is  hydrolyzed  to  ADP  +P,  leading  to  the  reenergizing  and  repositioning  of  the  head  

SKELETAL  SYSTEM  

Skeletal  systems  •  ContracAle  force  exerted  against  

some  type  of  skeleton  moves  the  animal  body    

•  Many  invertebrates  have  a  hydrostaAc  skeleton,  which  is  a  fluid-­‐filled  body  cavity    

•  Others  have  an  exoskeleton  of  hardened  structures  at  the  body  surface    

•  Vertebrates  have  an  endoskeleton,  an  internal  skeleton  of  carAlage,  bone,  or  both  

1.  HydrostaAc  skeleton  – A  confined  fluid  accepts  the  force  of  muscle  contracAon    

2.  Exoskeleton    – Consists  of  hardened  parts  at  the  body  surface    

3.  Endoskeleton  – Consists  of  hardened  parts  inside  the  body  

Human  skeletal  system  

SKULL cranial bones facial bones

sternum RIB CAGE

ribs VERTEBRAL COLUMN

vertebrae

intervertebral disks

PECTORAL GIRDLES AND UPPER EXTREMITIES

clavicle

scapula humerus

radius ulna

carpals metacarpals

phalanges

pelvic girdle femur

patella tibia fibula

tarsals

metatarsals phalanges

PELVIC GIRDLE AND LOWER EXTREMITIES

MUSCULO-­‐SKELETAL  SYSTEM  Muscle-­‐  tendon-­‐bones  ligaments  

1.  Muscle    o  Long,  cylindrical  

cells  with  mulAple  nuclei  

o  Form  from  groups  of  embryonic  cells  that  fuse  before  they  differenAate  and  mature  

o  Bundled  inside  a  dense  connecAve  Assue  sheath  

2.  Tendons    o Extensions  of  connecAve  Assue  sheath  

o AQach  skeletal  muscles  to  bones  

3.  Joints  

•  Joints  – Regions  where  bones  meet  – Most  allow  bones  to  move  – Held  together  by  ligaments  

•  Types  of  joints  I.  Fibrous  joint  II.  CarAlaginous  joint  III.  Synovial  joint  

•  Muscles  generally  work  in  antagonisAc  pairs  to  provide  movement.  

•  Muscles  arAculate  movement  at  joints.  1.  Synovial  joints  have  a  fluid  filled  

cavity  that  ease  fricAon  as  the  bones  move.  

2.  Hinged  joints  move  only  in  one  direcAon.  

3.  Ball-­‐and-­‐socket  joints  allow  for  rotaAonal  movement.  

Types of joint

Types of synovial joint and location