Muscle Anatomy and Contraction Muscle Music Muscle TermsAnatomy

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Muscle Anatomy and Contraction Muscle Music

Muscle Anatomy and Contraction Muscle Music

Muscle Terms---Anatomy • Fascia = fibrous connective tissue that separates individual skeletal muscle, connects

Muscle Terms---Anatomy • Fascia = fibrous connective tissue that separates individual skeletal muscle, connects to tendon then to periosteum of the bone. • Aponeuroses broad fibrous sheets that attach to bone or to coverings of other muscles. • Sarcoplasm cytoplasm of a muscle cell • Sarcolemma cell membrane of a muscle • Sarcomere 1 muscle unit of actin and myosin • I bands light bands (actin) attached to Z lines • A bands dark bands (myosin) thin filaments slide towards the thick

I. Nerve Stimulus and Action Potential A. One motor neuron can stimulate 1 or

I. Nerve Stimulus and Action Potential A. One motor neuron can stimulate 1 or 1000’s of muscle fibers • 1. One neuron + muscle cell = motor unit • 2. Neuromuscular junction = where nerve and muscle almost meet Draw a Neuromuscular Junction Fig. 8. 5 pg. 180

B. The start of a nerve impulse… Axon terminals of nerve release a “neurotransmitter”

B. The start of a nerve impulse… Axon terminals of nerve release a “neurotransmitter” called… Acetylcholine (ACH) which… • 1. Makes muscle temporarily permeable to Na+, creates an electrical current called an action potential which is unstoppable, runs the entire length of the muscle • 2. Then it returns to a resting stage (K+ out of cells)

II. The “Sliding Filament” theory A. Myosin heads attach and detach to actin repeatedly;

II. The “Sliding Filament” theory A. Myosin heads attach and detach to actin repeatedly; each time “pulling” on actin… muscle shortens/contracts • 1. Myosin heads “cock” forward and some are always in touch with actin … no backsliding • 2. Requires Ca+2, it moves proteins so binding sites are free • B. While action potential is occurring, the ACH is being broken down… prevents contraction in absence of impulse Sliding Filament Theory

III. Types of Contractions • Part 2 Sliding Filament Theory • A. Graded response

III. Types of Contractions • Part 2 Sliding Filament Theory • A. Graded response = “all or none” law to muscle cell not whole muscle; full contraction never partial • 1. Twitches (sometimes brief and jerky)= nerve impulses are rapid, contractions are summed up which creates a smooth sustained contraction • 2. Strongest contraction = all cells stimulated to fullest potential

B. Isotonic vs. Isometric • 1. Isotonic = “same tone/tension” ex. Smiling, bending knee

B. Isotonic vs. Isometric • 1. Isotonic = “same tone/tension” ex. Smiling, bending knee • 2. Isometric = “same measurement”, myosin heads are “spinning their wheels” Ex. Lifting 400 lbs. Or pushing a car • 3. Muscle tone = continuous partial contraction (even when relaxed) • 4. Opposite of muscle tone = Flaccid or flabby, muscles atrophy when not used

IV. Muscle Fatigue and O 2 debt AKA: Anaerobic Respiration * Can’t contract even

IV. Muscle Fatigue and O 2 debt AKA: Anaerobic Respiration * Can’t contract even if stimulated. Person can’t consume enough oxygen quick enough; lactic acid builds up, ATP runs low, rarely occurs to us. Afterwards, breathe deeply until enough O 2 is absorbed to remove lactic acid.