Notes – Muscle Energy & Disorders

Review

Epimysium (outer covering of muscle)

Fascicle (bundle of muscle fibers)

Perimysium (covering fascicle)

Endomysium (covers each muscle fiber)

Myofibril (bundle in each muscle cell – made of actin & myosin)

H - zone

Z - line

sarcomere

A band

I band

Which band is the thin filament?

ACTIN

Which band is the thick filament?

MYOSIN

What are the 8 steps of muscle contraction?

Step 1: action potential to muscleStep 2: ACETYLCHOLINE released from neuronStep 3: acetylcholine binds to muscle cell membraneStep 4: Na+ diffuse into muscle, action potential startedStep 5: Calcium ions bind to actinStep 6: myosin attaches to actin, crossbridges formedStep 7: myosin pulls on the actin causing it to slide over myosinStep 8: ATP attaches to myosin to provide energy

Still More Interesting Muscle FactsHow many muscles does it take to produce human speech?

72 different muscles

How many muscles make up the human tongue?

16 separate muscles – most people think its just 1

• ENERGY REQUIREMENTS FOR MUSCLE CONTRACTION

• ATP (adenosine triphosphate)

• produced by aerobic respiration (with O2) or anaerobic respiration (without O2)

• Aerobic Respiration

• ATP used in long continuous exercise (EX: distance running)

• fat is used for the fuel to make ATP with oxygen

• Anaerobic Respiration

• typically occurs during short periods of intense exercise

• body uses CREATINE PHOSPHATE for energy (10-15 seconds)

• body then switches to GLUCOSE for fuel

• lactic acid is produced – fatigue & oxygen debt results

• Disorder of Muscle Tissue

• Cramps & Spasms

• an “over contraction” – can be due to electrolyte imbalance, fatigue, overuse

• Hernia • a tear in wall of muscle – can be congenital, or from severe strain

ABDOMINAL HERNIA

• Muscle Tear • aka: “pulled” muscle or strained muscle – caused by overstretching of muscle during activity

• muscle fibers actually tear apart

Torn Pectoralis Major

• Hamstring Muscle Tear

• Hypertrophy • increase in the size of muscle fibers

EX - Governor of California

• Atrophy • decrease in size of muscle fiber

• Types of Movements (terminology)• Origin • where a muscle begins

• Insertion • where a muscle ends

• Action • motion produced

• Flexion • joint angle gets smaller

• Extension • joint angle gets larger

• hyperextension • movement beyond 180o of joint motion

• abduction • movement away from midline of body

• adduction • movement toward midline of body