Muscle Physiology

What are the functions of muscle tissue?

1. produce body movements

2. stabilise body positions

3. storing and moving substances within the body

4. generating heat

what neurons stimulate skeletal muscles to contract?

somatic motor neurons

In somatic motor neurons where do the axons extend from?

brain or spinal cord

What structure brings oxygen and nutrients and removes heat and waste products to muscles?

capillaries

what are four properties of muscle tissue that helps it to function and aids homeostasis?

1. Excitability

2. Contractibility

3. Extensibility

4. Elasticity

What is meant by excitability?

Ability of muscles fibres to generate electrical impulses called action potential influencing muscle contraction

What is meant by contractibility?

Ability for a muscle to contract when stimulated by a nerve

What is meant by extensibility?

Ability of muscle tissue to stretch without damage

What is meant by elasticity?

Ability of muscle tissue to return to its original length and shape after contraction or extension

What does skeletal muscle contain?

connective tissue, blood vessels and nerves

How many layers of connective tissue are there?

3 layers

What are the 3 layers of connective tissue?

1. epimysium

2. perimysium

3. endomysium

What are the components of skeletal muscle fibre?

• sarcolemma

• myofibrils

• sarcoplasm

• sarcoplasmic retinaculum

  

What are sarcomeres made up of?

thick filaments and thin filaments

what structure makes up thick filaments?

mysoin

what structures make up thin filaments?

actin and tropomyosin

Myofibril anatomy?

what are the types of proteins involved in muscle contraction called?

1. contractile proteins

2. regulatory proteins

what do contractile proteins do?

generate force during muscle contraction

what are types of contractile proteins?

• myosin

• actin

what do regulatory proteins do?

help switch muscle contraction processes on and off

what are types of regulatory proteins?

• tropomyosin

• troponin

What is the muscle contraction mechanism called?

sliding filament mechanism

Describe sliding filament mechanism?

muscles contract when myosin filaments pull actin filaments

Describe the process of muscle contraction

1. Action potential arrives at neuromuscular junction

2. causes calcium to be released from sarcoplasmic reticulum

3. Calcium binds to troponin which causes it to change shape

4. causes troponin and tropomyosin to change position on actin filaments

5. Myosin binding sites are exposed on actin molecules

6. Myosin heads bind to actin filaments, forming cross-bridges

7. Formation allows myosin heads to change shape and pull the actin filaments towards centre of the sarcomere, myosin releases ADP and Pi

8. ATP attaches to myosin head causing it to detach from actin

9. ATPase enzyme hydrolyses ATP into ADP and Pi allowing myosin heads to return to original position

10. myosin heads attach further along the actin filament and the process repeats

When does muscle contraction stop?

when muscles run out of ATP