Ch 36 Musculoskeletal System

AP lecture

Three vertebrate muscles

• Skeletal – A.k.a striated – Voluntary movements

• Cardiac – Involuntary – Beating of the heart– Appears striated because of myosin

and actin – Smaller than skeletal – Cells attached by gap junctions

• Smooth – Involuntary –Movement of internal organs– Internal organs controlled by ANS – Smaller than skeletal –Do not appear striated because of

the actin and myosin arrangements

Muscle contraction

• Skeletal muscle cells and muscle fibers are bundled together by connective tissue

• Interactions between actin and myosin – Every muscle fiber is made of

myofibrils- actin and myosin in repeating segments called sarcomeres

Muscle

voluntary, striated

involuntary, striatedauto-rhythmic

involuntary, non-striatedevolved first

multi-nucleated

digestive systemarteries, veins

heartmoves bone

Actin

• Thin filaments • Long chains of actin monomers

twisted around each other. • Twisted around that chain is

tropomyosin and attached to that is troponin. – These control contractions and

relaxation

Myosin

• Two long polypeptide chains coiled together. Each ends in a large globular head.

• Myosin filaments have many myosin molecules

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__myofilament_contraction.html

ATP feeds the contractions

• Immediate system uses ATP • Glycolytic system metabolizes

carbohydrates to lactate and pyruvate

• Oxidative system metabolizes carbohydrates or fats into water and carbon dioxide

Where is ATP needed?

3

4

1 2

1

1

1

Cleaving ATP ADP allows myosin head to bind to actin filament

thin filament(actin)

thick filament(myosin)

ATP

myosin head

formcrossbridge

binding site

ADP

releasecrossbridge

shortensarcomere

1

Put it all together…1

ATP

2

3

4

5

7

6

ATP

Vertebrate skeleton

• 206 bones • Axial skeleton – Skull, vertebral column ,sternum

and ribs

• Appendicular skeleton – Pectoral girdle, pelvic girdle, arm,

leg, hands and feet bones

Important bones

http://www.google.com/url?sa=i&source=images&cd=&cad=rja&docid=9sc4GACO7tYhhM&tbnid=QIaoQVZLILafOM:&ved=0CAgQjRwwAA&url=http://www.buzzle.com/articles/labeled-skeletal-system-diagram.html&ei=GStiUeO_G8WHqwGiw4GQCw&psig=AFQjCNERabY25j7VfYnfCx_YfWItvi4Erg&ust=1365474457506258

Bone growth

Joints

• Two bones join and muscles work in antagonistic pairs – Flexor – Extensor

• Types of joints – Ball and socket – Pivot –Hinge

• Tendon • Ligament