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85 Cards in this Set
- Front
- Back
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Functions of Muscle |
- Movement - Maintain body posture - Control of body openings & passageways - Communication (speech, facial expression) - Stabalizes joints - Protects internal organs - Heat production |
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Properties of Muscle |
- Excitability (responsiveness) - Conductivity (response) - Extensibility (ability to stretch) - Elasticity (ability to recoil after stretching) - Contractility (able to forcibly contract when stimulated) |
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Skeletal Muscle Tissue |
- Attachews to bone, skin - Striated muscle cells - Voluntary muscle subject to conscious control |
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Cardiac Muscle Tissue |
- Exclusive to heart - Striated muscle cells - Involuntary control |
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Smooth Muscle Tissue |
- In walls of hollow visceral organs - No striated muscle cells - Involuntary control |
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Superficial Fascia |
Loose connective tissue & fat underlying skin |
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Deep Fascia |
Dense irregular connective tissue around muscle organ |
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Epimysium |
Dense irregular connective tissue that surrounds the whole muscle |
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Perimysium |
Fibrous connective tissue that surrounds fascicles (groups of muscle fibers) |
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Endomysium |
FIne areolar connective tissue that surrounds each muscle fiber individually |
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Muscle |
Consists of hundreds to thousands of muscle cells, plus blood vessels and nerve fibers |
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Fascicle |
A portion of muscle. A discrete bundle of muscle cells |
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Muscle Fiber |
A portion of fascicle. An elongated multinucleate cell, has a striated appearance |
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Myofibril |
A portion of muscle fiber. Contractile organelle. Rodlike elements that occupy most of muscle cell volume. Composed of sarcomeres. |
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Sarcomere |
A segment of myofibril. The contractile unit, composed of myofilaments |
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Myofilament |
A segment of sarcomere. Contractile myofilaments are of 2 types: thick and thin that produce muscle shortening |
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Myoblast |
Muscle tissue develops from these embryonic mesoderm cells |
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Satellite Cells |
AKA: Stem cells Some myoblasts remain as these cells to aid in muscle repair |
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Sarcolemma |
The plasma membrane of a muscle fiber |
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Sarcoplasm |
The cytoplasm of a muscle fiber |
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Sarcoplasmic Reticulum |
Encircles the myofibril |
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Myoglobin |
A red pigment in the sarcoplasm that stores oxygen |
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Transverse (T) Tubules |
Encircle each sarcomere and filled with extracellular fluid; carries muscle action potentials into deepest regions of muscle cell |
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Terminal Cisterns |
The "end sacs" that releases calcium which causes muscle contractions |
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Myofibril Striations |
Perfectly aligned repeating series of dark A bands and light I bands |
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H Zone |
Of the myofibril striations: The lighter region in the dark A Band midsection |
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M Line |
Of the myofibril striation, in the dark A band, bisects the H zone |
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Z Disc |
Of the myofibril striation, interrupts I band midline |
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Myosin (thick) Filaments |
Extends the length of A band, connected at M line |
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Actin (thin) Filaments |
Extends across I band and part in A band, anchored to Z discs |
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Tropomyosin |
A regulatory protein that binds to actin filaments, blocks myosin-binding sites |
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Troponin |
A regulatory protein that binds to actin filaments, interacts with calcium ions |
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Myosin Heads |
Form thick filament; contains binding sites for actin and ATP |
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Cross Bridges |
During muscle contraction, myosin heads link thick and thin filaments together |
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Sliding Filament Model of Contraction |
Relaxed: thin and thick filaments overlap only at A band ends Contracted: muscle cell shortens, I bands shorten, H zones disappear |
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ATP Hydrolysis |
ATP molecule is split into an ADP and an inorganic phosphate |
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Neuromuscular Junction (NMJ) |
Where the somatic motor neuron synapses on the muscle cell |
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Synapse |
Point of close contact between a neuron and a muscle cell |
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Axon Terminal |
AKA: Synaptic End Bulb
Distal (end) part of the somatic motor neuron |
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Synaptic Vesicles |
Small membraneous sacs that contain the neurotransmitter |
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Motor End Plate |
The middle of a skeletal muscle cell, contains ACh receptors |
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Action Potential |
An electrical current that travels to axon terminal-- this nerve AP will cause a muscle AP |
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Acetylcholine (ACh) |
The neurotransmitter that initiates muscle contraction |
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Acetylcholinesterase (AChE) |
An enzyme that breaks down ACh to its building blocks-- prevents continuous muscle contraction |
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Calcium Release Channels |
Calcium enters the axon terminal, which causes ACh to be released by exocytosis |
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Powerstroke |
The energy from ADP released causes the myosin head to pivot towards the M line |
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Myasthenia Gravis |
An autoimmune disease: a shortage of ACh receptors causing general muscle weakness |
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Rigor Mortis |
ATP continues to be consumed after death, and cross bridge detachment is impossible |
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Prime Mover (agonist) |
A muscle that has the major responsibility for producing a specific movement |
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Antagonist |
A muscle that opposed or reverse a particular movement (located opposite to prime mover) |
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Synergists |
Help prime movers by adding a little extra force to same movement, stabilizes joints across which prime mover acts |
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Fixators |
A muscle that immobilizes one or more bones, allowing other muscles to act from a stable base |
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Isotonic Contraction |
"Same tension" Muscle tension developed and lifts load and muscle shortening occurs |
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Isometric Contraction |
"Same measure" Muscle tension develops but the load is not moved, muscle length remains the same Ex: Attempting to lift a piano |
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Concentric Contractions |
Those in which the muscle shortens and does work Ex: picking up a book |
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Eccentric Contractions |
Those in which the muscle generates force as it lengthens Ex: Occurs in calf muscle as you walk up a steep hill |
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Motor Units |
The motor neuron and all muscle fibers it innervates |
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Innervate |
Supply of nerves to a body part |
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Fine Movements |
Muscles that control the fingers, and eyes e.g. have small motor units |
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Powerful Movements |
Muscles that control hip muscles e.g. have large motor units |
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Twitch Contraction |
When muscle contracts faster than it relaxes, has 3 distinct phases |
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Latent Period |
Phase 1 of Twitch Contraction: Calcium being released from SR |
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Contraction Period |
Phase 2 of Twitch Contraction: Myosin binds to actin and muscles contract |
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Relaxation Period |
Phase 3 of Twitch of Contraction: Myosin heads detach, calcium is pumped back to SR and muscles relax |
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Wave Summation |
Primary function is to produce smooth, continuous muscle contractions. Rapidly stimulates a specific # of muscle cells |
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Incomplete (Unfused) Tetanus |
When a muscle fiber is stimulated at a rate of 20-30 times per second, it can only partially relax. This produces a "twitchy" contraction. |
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Complete (Fused) Tetanus |
When a muscle fiber is stimulated at a rate of 40-100x per second, it does not relax at all. This produces a strong contraction in which individual twitches cannot be detected * Happens infrequently i.e. superhuman strength |
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Recruitment |
AKA: Multiple Motor Unit Summation Controls the force of contraction, it recruits more muscle fibers to contract by delivering increasing voltage to muscle |
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Length-Tension Relationship |
In a sarcomere, the ideal relationship occurs when a muscle is slightly stretched and the thin and thick filaments overlap optimally. A severely stretched muscle cannot develop tension |
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Osteoarthritis |
The "wear and tear" that commonly occurs with age due to a degeneration of cartilage |
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Rheumatoid Arthritis |
An autoimmune disease in which the body's joints are attacked by its own immune system |
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Creatine Phosphate |
High energy molecules used for ATP regeneration, muscle cells store 2-3x more of this than ATP |
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Creatine Kinase |
Enzyme that catalyzes the transfer of phosphate from creatine phosphate to ADP, forming creatine and ATP; important in muscle contraction |
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Anaerobic Respiration |
After CP stores are exhausted, more ATP is generated by breaking down glucose- does not use oxygen |
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Glycolosis |
"Sugar splitting"- The initial phase of glucose breakdown, yields 2 pyruvic acid molecules and 2 ATP |
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Lactic Acid |
Formed from pyruvic acid during anaerobic glycolosis / partially responsible for muscle soreness during intense exercise |
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Aerobic Respiration |
Produces 95% of ATP used for muscle activity, occurs in mitochondria, requires oxygen. Yields water, carbon dioxide, and 32-36 ATP molecules |
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Slow Oxidative Fibers |
Cells that rely mostly on using aerobic pathways, contract slowly, resists fatigue and has high endurance |
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Fast Glycolytic Fibers |
Cells that rely on using anaerobic glycolosis, contracts rapidly, susceptible to fatigue |
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Tendon |
Attaches muscle to bone |
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Ligament |
Attaches bone to bone |
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Aponeurosis |
A sheet of fibrous tissue that takes the place of a tendon in sheetlike muscles having a wide area of attachment |
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Hypertrophy |
The increase in the volume of a tissue due to the enlargement of its component cells |
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Hyperplasia |
Increased cell production in a normal tissue |
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Myostatin |
A growth factor that regulates the size of muscles beginning in early embryonic development-- prevents muscles from growing too large |
