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64 Cards in this Set
- Front
- Back
- 3rd side (hint)
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MUSCULAR SYSTEM DEFINITION |
• Muscles are responsible for all types of body movement –they contract or shorten • “machines” of the body
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MUSCULAR SYSTEM TERMINOLOGIES |
• sarco= flesh • myo= muscle • my/s=muscle
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3 MUSCLE TYPES |
• Cardiac Muscle • Skeletal Muscle • Smooth Muscle
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CARDIAC MUSCLES CHARACTERISTICS |
• Has striations • Single nucleus • Branching cells joined by special junctions called Intercalated discs • Involuntary • Arranged in spiral figure 8-shaped bundles • Closely coordinated contraction & steady pace
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SKELETAL MUSCLES CHARACTERISTICS |
• Most are attached by tendons to bones • Cells are multinucleate • Striated–have visible banding • Voluntary–subject to conscious control • Reflexes -without command • Cells are surrounded and bundled by connective tissue
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SMOOTH MUSCLE CHARACTERISTICS |
• No striations • Spindle-shaped cells • Single nucleus • Involuntary • Mainly in the walls of hollow visceralorgans • Contraction -slow, sustained and tireless
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CONNECTIVE TISSUE WRAPPINGS OF SKELETAL MUSCLES |
• Endomysium • Perimysium • Epimysium • Fascia |
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around single muscle fiber |
Endomysium |
connective tissue wrapping of skeletal muscle |
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around a fascicle (bundle) of fibers |
Perimysium |
connective tissue wrapping of skeletal muscle |
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covers the entire skeletal muscle |
Epimysium |
connective tissue wrapping of skeletal system |
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on the outside of perimysium |
Fascia |
connective tissue wrapping of skeletal muscle |
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IMPORTANCE OF CONNECTIVE TISSUE |
• Help support & bind muscle fibers • Increase muscle strength • Provides a route (entry & exit) nerves & blood vessels |
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SKELETAL MUSCLE ATTACHMENTS |
• Tendon - cord-like structure (collagen fibers) • Aponeuroses - sheet-like structure |
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FUNCTION OF MUSCLES |
• Produce movement • Maintain posture • Stabilize joints • Generate heat
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MICROSCOPIC ANATOMY OF SKELETAL MUSCLE |
• Multiple nucleus beneath the sarcolemma • Sarcolemma • Myofibril • Sacromere • Myosin Filament |
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specialized plasma membrane of the muscle fiber |
Sarcolemma |
segment of skeletal muscle (muscle fiber) |
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complex organelle composed of bundles of myofilaments |
Myofibril |
segment of skeletal muscle (muscle fiber) |
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myofibril are aligned to give distinct bonds (the 2 bands) |
• I band = Light band • A band = Dark band |
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contractile unit of a muscle fiber |
Sacromere |
segment of skeletal muscle (muscle fiber) |
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organization of the sacromere |
• Thick Filaments - myosin filaments • Thin Filaments - actin filaments |
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MECHANISM OF MUSCLE CONTRACTION: THE SLIDING FILAMENT THEORY |
• Activation by nerve causes myosin heads (crossbridges) to attach to binding sites of the thin filament • Myosin heads then bind to the next site of the thin filament • This continued action causes a sliding of the myosin along the actin • The result is that the muscle is shortened (contracted) |
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MUSCLE CONTRACTION |
• Sarcoplasmic Reticulum |
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store calcium; release it on demand when the muscle fiber is stimulated to contract and known as a specialized smooth ER. |
Sarcoplasmic Reticulum |
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NERVE STIMULUS TO MUSCLES |
• Motor Unit • Skeletal muscles must be stimulated by a nerve cell (motor neuron) to contract • Neuromuscular Junction • Synaptic Cleft |
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one neuron & all the muscle cell it stimulates |
Motor Unit |
nerve stimuli |
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association site of nerve and muscle |
Neuromuscular Junction |
nerve stimuli |
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gap between nerve & muscle |
Synaptic Cleft |
nerve stimuli |
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TRANSMITION OF NERVE IMPULSE TO MUSCLE |
• Neurotransmitter • Acetylcholine (ACh) |
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chemical release by nerve upon arrival of nerve impulse |
Neurotransmitter |
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PROPERTIES OF SKELETAL MUSCLE ACTIVITY |
• Contractility • Excitability (Irritability) • Extensibility • Elasticity |
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ability to shorten when an adequate stimulus is received |
Contractility |
properties of skeletal muscle |
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ability to receive and respond to a stimulus |
Excitability |
properties of skeletal muscle |
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ability to be stretched |
Extensibility |
properties of skeletal muscle |
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ability to recoil and resume resting length after stretched |
Elasticity |
propeties of skeletal muscle |
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CONTRACTION OF A SKELETAL MUSCLE |
• Muscle fiber contraction is “all or none” •A muscle cell will contract to its fullest extent when it is stimulated adequately; it never partially contracts • Graded responses –different degrees of skeletal muscle shortening • By changing the frequency of muscle stimulation • By changing the number of muscle cells being stimulated
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MUSCLE RESPONSE TO INCREASINGLY RAPID STIMULATION
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• Twitch-single > brief, jerky contractions • Tetanic Contraction > muscles are stimulated so rapidly that no evidence of relaxation is seen > completely smooth contractions & sustained |
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MUSCLE FATIGUE AND OXYGEN DEBT |
• Oxygen - get rid of lactic acid • Fatigued muscle - unable to contract |
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TYPES OF MUSCLE CONTRACTIONS |
• Isotonic Contractions • Isometric Contractions |
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myofilaments are able to slide past each other during contractionsand the muscle shortens, movement occurs
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Isotonic Contractions |
muscle contractions |
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muscle filaments are trying to slide, but the muscle is pitted against an immovable object and tension in the muscles increases, but do not shorten
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Isometric Contractions |
muscle contractions |
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MUSCLE TONE |
• State of continuous partial contractions • Some fibers are contracted even in a relaxed muscle • Result of different motor units being stimulated in a systemic way • Muscle remains firm, healthy, and constantly ready for action |
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EFFECTS OF EXERCISE ON MUSCLE |
• Results of increased muscle use > Increase in muscle size > Increase in muscle strength > Increase in muscle efficiency > Muscle becomes more fatigue resistant
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MUSCLES AND BODY MOVEMENTS |
• Movement is attained due to a muscle moving an attached bone • Muscle are attached to at least two points: > Origin > Insertion
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attachment to an immovable bone |
Origin |
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attachment to an movable bone
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Insertion |
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TYPES OF ORDINARY BODY MOVEMENTS |
• Flexion • Extension • Rotation • Abduction • Adduction • Circumduction |
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decreases angle of joint and brings two bones closer together |
Flexion |
body movements |
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opposite of flexion |
Extension |
body movements |
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movement of a bone in longitudinal axis (shaking head “no”) |
Rotation |
body movements |
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moving the limb away from the midline |
Abduction |
body movements |
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moving toward the midline |
Adduction |
body movements |
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cone-shaped movement, proximal end doesn’t move, while distal end moves in a circle. |
Circumduction |
body movements |
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TYPES OF MUSCLES |
• Prime Mover • Antagonist • Synergist • Fixators |
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muscle with the major responsibility for producing a certain movement |
Prime Mover |
type of muscle |
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muscle that opposes or reverses a prime mover |
Antagonist |
type of muscle |
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muscle that aids the action of the prime moveror by reducing undesirable movements |
Synergist |
type of muscle |
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hold a bone still or stabilizes the origin of a prime mover |
Fixators |
type of muscle |
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NAMING OF SKELETAL MUSCLES |
• Direction of muscle fibers > named in reference to some imaginary line; usually the midline of the body or the long axis of a limb bone > example: rectus(straight); transversus • Relative size of the muscle > example: maximus(largest); longus (long) • Location of the muscle > named for the bone with which they are associated > example: frontalis, temporalis, occipitalis • Number of origins > example: triceps(three heads) • Location of the muscles origin and insertion > example: sterno(on the sternum) • Shape of the muscle > example: deltoid(triangular) • Action of the muscle > example: flexorand extensor (flexes or extends a bone) |
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ARRANGEMENT OF FASCICLES |
• Circular • Convergent • Parallel • Fusiform • Pennate |
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concentric rings; close by contracting; sphincters(orbicularis muscles) |
Circular |
arrangement of fascicle |
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converge toward a single insertion tendon; triangular or fan-shaped (pectoralis major) |
Convergent |
arrangement of fascicle |
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parallel to the long axis of the muscle; straplike. |
Parallel |
arrangement of fascicle |
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spindle-shaped with an expanded belly (biceps brachii) |
Fusiform |
arrangement of fascicle |
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(“feather”); a short fascicle attach obliquely to a central tendon |
Pennate |
arrangement of fascicle |
