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Definition
| 40% of body weight, Almost 600 muscles (around 3 muscles per bone) |
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Term
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Definition
| 70% H2O, Mostly protein (actin & myosin), small amount of CHO( stored as glycogen), small amount of lipid(stored) |
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| Muscle excitability (or irritability) |
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Definition
| Muscle tissue contracts in response to nervous stimuli (electrical current is ion movement) |
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Definition
| Muscle tissues responds to electrical stimuli by contracting, muscles only pull they don't push. |
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Definition
| Once muscle fibers relax they can be stretched beyond their resting length by contraction of opposing muscle |
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Definition
| Muscle fibers recoil to original length after stretching |
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Definition
| Movement, thermogenesis, posture/support. |
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Definition
| Move the body (and/or parts of the body) |
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Definition
| Heat production, are in a continuous state of fiber activity. |
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| Function: Posture/Support |
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Definition
| Maintain posture, stabilize joints, support viscera, many times you don’t even notice that postural muscles are working. |
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Definition
| Twitching of muscle segments. |
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Definition
| Striated, voluntary, cells are called fibers |
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Definition
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Definition
| No striations, involuntary. cells are called fibers |
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Term
| What does muscle contraction depend on? |
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Definition
| Myofilaments(located in cytoplasm) |
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Definition
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Definition
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Term
| Skeletal Muscle CT: Endomysium |
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Definition
| Surrounds individual muscle cells, binds adjacent fibers together and supports capillaries and nerve endings that serve the muscle fibers |
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Term
| Skeletal muscle CT: Perimysium |
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Definition
| Binds group of muscle cells (fascicle), supports blood vessels and nerve fibers |
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Term
| Skeletal muscle CT: Epimysium |
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Definition
| Binds fascicles together (dense irregular CT) and surrounds entire muscle, is continuous with tendon. |
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Definition
| Smallest unit that can be seen with naked eye |
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Term
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Definition
| All 3 layers of CT are continuous with the tendons of mm |
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Term
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Definition
| Fibrous CT that covers muscle and attaches it to skin. |
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Term
| Blood vessels in Skeletal muscle |
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Definition
| Generally, each skeletal muscle is supplied by one nerve, one artery, and one or more veins |
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Term
| Nerves in Skeletal muscle |
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Definition
| Each muscle fiber is contracted by one nerve ending – Contact point is neuromuscular junction (aka motor endplate) |
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Term
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Definition
| one motor neuron and all the muscle fibers it stimulates. |
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Term
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Definition
LARGE ratio 1:1000 = strong motor unit (ex: quads)
SMALL ratio 1:10 = fine, precise control (ex: eyeball)
Within each muscle of the body there are MANY motor units, ranging from small to large ratios |
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Term
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Definition
| detects electrical currents of activation process |
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Term
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Definition
| Skeletal muscles cross at least one joint, extend from one bone to another, muscles attach to origins and insertions via CT that extends into periosteum. |
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Term
| Muscle attachments: Origin |
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Definition
| less movable muscle attachment |
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Term
| Muscle attachments: Insertion |
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Definition
| more movable muscle attachment, insertion is pulled toward origin |
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Definition
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Term
| Muscle attachments: Direct attachment |
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Definition
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Term
| Muscle attachments: Indirect attachment |
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Definition
| CT extends beyond muscle to form tendon OR aponeurosis (flat sheet) A few tendons or aponeroses attach to skin, cartilage, sheets of fascia, or raphe |
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Definition
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Term
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Definition
| Strong band of CT that binds a group of tendons. |
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Term
| Macroscopic to microscopic |
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Definition
| Muscle, Fasciculus, Muscle cell, myofibrils, sarcomeres. |
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Term
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Definition
| Strand of regularly arranged threadlike fibers that extend entire length of muscle, densely packed, contain myofilaments (actin and myosin), basically a chain of sarcomeres. |
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Term
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Definition
| Found in striated muscle (skeletal and cardiac)- due to arrangement of myofilaments. The basic unit of structure and function in muscle. |
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Term
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Definition
| Thin filaments, a protein that is 6 nm in diameter. |
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Term
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Definition
| Thick filaments, a protein that is 16 nm in diameter. |
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Term
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Definition
| contraction- filaments slide over each other, myosin heads attach to active sites on actin (sliding filament theory) |
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Term
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Definition
At ends of sarcomere (one sarcomere goes z line to z line)
Place where actin is attached |
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Term
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Definition
Middle of sarcomere
Where myosin is anchored |
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Term
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Definition
Has bright appearance
ONLY myosin exists there (no overlap with actin)
Includes M-line |
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Term
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Definition
Includes ANYWHERE there is myosin, including where it overlaps with actin
Includes M-line and H zone
Appearance is dark bands |
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Term
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Definition
| ONLY actin exists there (NO myosin) |
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Term
| Muscle contraction: Crossbridge formation |
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Definition
Myosin binds to actin, requires calcium from SR (sarcoplasmic reticulum)
Trigger for calcium release is (efferent) motor neuron impulse |
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Term
| Muscle contraction: Crossbridge movement |
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Definition
Z lines are pulled toward M-line
Myosin attaches to actin and pulls actin toward center of sarcomere
Requires ATP hydrolysis |
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Term
| Muscle contraction: Crossbridge release |
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Definition
| Requires binding of fresh ATP |
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Term
| Regional changes during concentric contraction |
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Definition
Entire sarcomere = shortens
Z lines = shorten, pulled in toward M-line
H zone = shortens
A bands = DOES NOT shorten (myosin’s length itself doesn’t shorten)
I bands = shorten |
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Term
| Fiber length and Contraction force |
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Definition
Ideal resting length for muscle fibers is that at which they can generate the most force
The greatest force is produced when the fiber starts out slightly stretched |
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Term
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Definition
| protein that prevents overstretching; runs from Z line to M line |
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Term
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Definition
smooth ER with interconnecting tubules that surround myofibrils
Stores Ca++, which is released for muscle contraction – diffuses to thin filaments
Ca++ Pumped back into SR after contraction |
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Term
| T tubules: invaginations of sarcolemma |
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Definition
Reach deepest regions of cell
Conduct nerve impulses |
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Term
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Definition
Located in region of muscle cell membrane (is a receptor)
Electrical current causes release of neurotransmitter (acetylcholine) from nerve terminals onto muscle
Ach hooks up to the motor endplate on the sarcolemma
Binding of Ach causes another electrical current across muscle cell membrane and into t-tubule, causes calcium release from SR |
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Term
| Motor endplate: What is the type of receptor? |
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Definition
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Term
| One motor unit only contains... |
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Definition
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| Skeletal muscle fiber types: Overview |
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Definition
There is actually a wide continuum of fiber types that have various mechanical and enzymatic properties.
Fiber types are often referred to in terms contraction speed (fast vs. slow; Type I vs. Type II) but are also categorized in terms of how they manufacture ATP (oxidative vs. glycolytic) |
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| Skeletal Muscle gender stats |
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Definition
The average man, woman, child (regardless of race) has about 50 5% slow, and 50 5% fast (equal percentage of IIA, IIB)
There are NO significant gender differences in fiber types that would ALONE account for any gender differences in sport performance |
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Term
| Skeletal Muscle Fiber Types: Individual differences |
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Definition
| There are INTER (among different people)-individual differences in fiber type distribution, so my biceps might have 45% ST and yours might have 55% ST |
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Term
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Definition
Heart wall muscle, arranged in bundles
Striated and uses sliding filament
Cells are single (not fused like skeletal), separated by endomysium |
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Term
| Cardiac Muscle: Each cell is...called a fiber? |
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Definition
| NOT, fiber is a row of joined cells. |
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Term
| Cardiac Muscle: Typical... are present? |
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Definition
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| Cardiac Muscle: Myofibrils are... |
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Definition
| difficult to discern because they are branched (many mitochondria) |
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Term
| Cardiac Muscle: Role of Ca++ |
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Definition
Triggered by Ca++ but simpler SR and less T tubules
Ca++ from extracellular fluid triggers Ca++ release – diffusion into sarcomeres |
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Term
| Cardiac Muscle: Each cell can... |
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Definition
| rhythmically contract without innervation |
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Term
| Cardiac muscle: Cells stay slightly... |
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Definition
| shorter than optimal length so that they can stretch due to greater volumes of blood returned to heart (increases contraction force) |
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Term
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Definition
Sliding filament mechanism for contraction (not as well understood)
Spindle-shaped cells, separated by endomysium |
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Term
| Smooth muscle: Locations where found |
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Definition
| Inside eye, walls of circulatory vessels, respiratory tubes, digestive tubes, urinary organs, reproductive organs |
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Term
| Smooth muscle: In walls of hollow viscera... |
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Definition
| fibers are grouped in sheets – often 2 sheets (longitudinal layer and circular layer) |
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Term
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Definition
| No striations, no sarcomeres – but there are thin and thick filaments |
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Term
| Smooth muscle: Myofilaments move muscle by... |
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Definition
| interacting with cytoskeleton elements (intermediate filaments that have dense bodies, which anchor thin filaments) |
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Term
| Smooth Muscle: Ca++ stimulates... |
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Definition
| contraction – different from skeletal (no T tubules) |
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Term
| Smooth Muscle: Contractions are... |
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Definition
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Term
| Smooth muscle: Involuntary control |
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Definition
| only a few cells in each sheet are innervated – impulse spreads through adjacent fibers |
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Term
| Muscle disorders: Smooth muscle |
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Definition
| has few problems – mostly due to irritants |
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Term
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Definition
Inherited muscle-destroying diseases (group), usually appear in childhood
Muscle fibers degenerate |
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Term
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Definition
Chronic pain of unknown cause
Severe musculoskeletal pain, fatigue, sleep abnormalities, and headache |
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Term
| Development of muscle: Overview |
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Definition
Most muscle develops from myoblasts
Fuse together to make skeletal muscle
Do not fuse to make cardiac, smooth muscle |
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Term
| Development of muscle: Skeletal muscle... |
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Definition
| strength is generally greater in men, mostly due to testosterone levels |
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Term
| Development of muscle: With age... |
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Definition
| amount of CT in muscle increases, # of muscle fibers decreases, and muscles become stringier |
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Term
| Development of muscle: Body weight... |
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Definition
| declines due to loss of muscle mass, leads to decline in strength (sarcopenia = muscle wasting) |
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