ch. 6 | the muscular system

• skeletal muscle tissue is attached to the bones

-striated, voluntary

-produces body movements

-stabilizes the skeleton

-produces heat/maintains body temperature

• cardiac muscle tissue is found only in the heart

-striated, intercalated discs, involuntary 

-makes up walls of heart

-generates force to pump blood

• smooth muscle tissue is found in most body organs

-not striated, involuntary 

-forms walls of hollow organs 

-stores and moves substances w/in body

-regulates organ volume

• sarcomere: contractile unit/building block of a muscle fiber 
• plasma membrane--> sarcolemma 
• cytoplasm--> sarcoplasm
• endoplasmic reticulum--> sarcoplasmic reticulum: transport system 

• myosin makes up thick filaments 
• actin makes up thin filaments 

• nerve signals initiate the contraction of skeletal muscle
• muscle & nerves DO NOT touch, they meet at a neuromuscular junction: synapse btwn the axon terminals of a motor neuron & the sarcolemma of a muscle fiber 

• peristalsis: wave-like contraction of muscles 
• muscles can only contract- not extend

sources that provide ATP:

1. creatine-phosphate: transfers phosphate from ADP to make ATP
2. anaerobic respiration (glycolysis): does not require oxygen
3. aerobic respiration: requires oxygen from myoglobin; provides more ATP than the others 

skeletal muscles work in groups:

• origin: where a muscle attaches to a stationary bone
• insertion: other end of muscle is attached to movable bone 
• belly: fleshy portion of the muscle

skeletal muscles of the body:

-masseter: elevates mandible (closing mouth)

-rectus abdominis: compresses abdomen to aid in defecation, urination, forced exhalation, childbirth

-internal & external oblique: compresses abdomen, bends vertebral column laterally & rotates it 

-transverse abdominis: compresses abdomen

-diaphragm: contracts to inhale & exhale