1. Producing body movement
2. Stabalizing body positions
3. Moving substances within the body
4. Generating heat
5. Regulating organ volume

• Most move bones
• Strated
• Voluntary control
• Each muscle is an organ

• Located in the heart
• Striated
• Voluntary control

• Located in the heart
• Striated
• Voluntary control

• Located in walls of hollow internal structures
• Nonstriated
• Involuntary control

Component surrounding individual fibers/sarcomeres

Made up of reticular fibers

Components surround fascicles

Made up of dense irregular connective tissue

Surround entire muscle

Made up of densce irregular connective tissue

Myoblasts form muscle fibers.

Multinucleated with poor regerneation (Born with fixed number of muscle fibers in body, only grow through enlargement of existing fibers.)

Muscle fiber cytoplasm

-Contains Glycogen and Myoglobin

• Invaginators on sarcolemma
• Form tunnel from surface to fiber center
• Filled with extracellular fluid
• Help spread electrical current through cell

• Fluid filled sacs surrounding myofibrils
• Store calcium
• Terminal cisterns

• Thick filaments
• Contractile protein
• Approximately 300 molecules of myosin form thick filaments
• Tail points toward M LINE

• Thin Filaments
• Contractile protein

• Thin Filaments
• Contractile protein

Keeps actin from binding to myosin in a relaxed muscle

REGULATORY protein

Hold tropomyosin in place

REGULATORY Protein

• Anchor thick filaments to Z dick and M line
• Keeps thick and thin filaments arranged
• Elastic and extensible
• Structural protein

Thin filaments move toward M line

Meet at center of sarcomere

Z disc come close together

Thick and thin filaments overlap

Sarcomere shortens

• Membrance enclosed sacs on synaptic end bulbs of motor neuron
• Store Acetylcholine molecules

• Region of sarcolemma adjacent to synaptic end bulb
• Houses ACh receptors

Muscle contraction cycle

BEFORE CYCLE

Step 1

BEFORE CYCLE

Nerve sends a motor action potential thourh a motor neuron (either from the brain or spinal cord) to neuromuscular junction

Action potential arrices at synaptic end bulbs stimulating the release of ACh via exoytosis from the synaptic vesicles into the synaptic cleft.

ACh bings to ACh receptors on the motor end plate, triggering muscle action potential.

Muscle Contraction Cycle

BEFORE CYCLE

Step 2

Muscle Contraction Cycle

BEFORE CYCLE

Step 3

Muscle contraction cycle

BEFORE CYCLE

Step 4

Muscle contraction cycle

BEFORE CYCLE

Step 5

1. ATP Hydrolysis
2. Myosin heads attaches to actin
3. Power stroke
4. Myosin detached from actin

Muscle Contraction Cycle

Step 1

ATP Hydrolysis

Energize myosin head to attach to actin

Muscle Contraction Cycle

Step 2

Myosin head attaches to actin

at myosin binding site forming cross bridges

Muscle Contraction Cycle

STEP 3

Power stroke

Myosin head rotates, releasing ADP and P.

Move thin filament along thick filament toward M line.

Muscle Contraction Cycle

STEP 4

Myosin detached from actin

ATP bound to myosin head again

Myosin head detached from actin

REDUCTIONS in

Calcium

Creatine Phosphate

Oxygen

Glycogen and other nutrients

ACh

BUILDUP of

Lactic Acid and ADP

Slow twitch

Small diameter fibers

Large amounts of myoglobin and capillaries

Slow due to Slow rate of ATPase in myosin heads

Intermediate diameter fibers

Large amounts of myoglobin, capillaries

Generate ATP through aerobic or anaerobic cellular respiration

FAST becasue ATPase hydrolyzes ATP in myosin FASTER than SO

Fast twitch

Largest diameter

Low myoglobin content, few capilaries

ATP throuh glycolysis

Hydrolyze ATP rapidly

STRONG, RAPID muscle contractions, fatique quickly