Module 3 - Muscular System Anatomy

4 Properties

Contractility

Excitability

Extensibility

Elasticity

3 Coverings

Epimysium - surround muscle

Perimysium - surround fascicle

Endomysium - surround fibre

Sarcolemma

Plasma membrane

Carry electrical impulses

Transverse (T) Tubules

Folds of sarcolemma

Carry impulse deep into fibre

Simultaneous contraction

Sarcoplasmic Reticulum

Smooth ER

Store/release Ca

Terminal Cisternae

Enlarged sacs of SR

Triad

T tubule sandwiched between 2 terminal cisternae

G Actin

Single globular protein w/ binding site

F Actin

2 chains of G actin

Tropomyosin

Cover myosin binding sites

Troponin - 3 Subunits

1 - attach to actin

2 - attach to tropomyosin

3 - bind to Ca

Myosin Parts

Rod - 2 twisted chains

Heads - 2

Actin & Myosin Process

1. Ca binds

2. Troponin change shape

3. Move tropomyosin

4. Expose binding sites

5. Cross bridge - P released

6. Pull actin - ADP released

7. Myosin detach - ATP binds

8. ATPase break down into ADP + P

9. Resting

Z Disks

Sarcomere ends

I band

Actin only

A band

All myosin

H zone

Myosin only

M line - Function

Hold myosin

Titin - Function + Where

Large proteins that provide elasticity

Between Z disk & M line