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Anatomy > Muscle > Flashcards

Flashcards in Muscle Deck (49):
1

Functions of muscle tissue

Body movement/
maintenance of posture.
Protection and support.
Storage and movement of materials.
heat production

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Characteristics of Muscle tissue

Excitability:cells can respond to stimulation (neurotransmitter-gated channels)
Conductivity: cells can conduct electrical charge.
Contractility: muscle fibers can shorten to generate tension.
Elasticity: ability to recoil (connection)
Extensibility: muscle can lengthen

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Tendon

Dense regular CT

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Deep fascia

Dense Irregular CT. Separates individual muscles, bind muscles with similar functions

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Epimysium

Dense irregular CT surround entire individual muscle.

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Perimysium

Dense irregular CT. Surround fascicle

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Endomysium

Areolar CT. isolate and electrially insulate muscle fiber

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Aponeurosis:

sheet-like dense reg CT.

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levels of gross muscle

cell=muscle fiber< fasicle< skeletal muscle

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Development of muscle

myoblast fuse together to form fiber. Multinucleated and amitotic.
Satalite cells

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Resting membrane potential

Relative difference in charge across a plasma membrane. always negative.

determined by number of K+/Na+ pumps and leak channels

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Na+ vs K+

More K in cell. More Na outside cell

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Depolarization

Inside of cell becomes more positive due to opening of VGNaC allowing NA+ to rush in.

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Repolarization

K+ exits cell to get back to RMP

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action potential

wave of depolarization followed by repolarization

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Muscle fibers (micro anatomy)

made of myofibrils, which are made of myofilaments

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Sarcolemma

plasma membrane of muscle cell. Contains voltage gated channels that allow for excitability and conductivity. It spans length of muscle fiber

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T-Tubules

extensions of sarcoma that extend into myofibrils. It contains Na+ and K+ pumps and leak channels

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Terminal cisternae:

flank t-tubules. enlarged regions of sarcoplasmic reticulum that contain Ca2+. Open in response to depolarization to release Ca2+

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Sarcoplasmic reticulum

specialized ER that holds Ca2+.

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Myofilaments

contractile proteins. Thick and thin

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Thick myofilaments

made of proteins called myosin that contains actin binding and ATP binding site.

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Thin fillaments

Made of actin and tropomyosin which wrap and block myosin binding site. When Ca2+ binds to troponin, it moves the tropomyosin so filaments can interact.

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Sarcomere

Unit of contraction

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z-disc

arrangement of proteins running perpendicular to longitudinal axis to muscle. The thin filament are attached towards M-line

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M-line

Center line, thick filaments are anchored with myosin ears towards z-disc

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I-Band

Light. spans 2 sarcomeres. contains only actin

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A-Band

Dark. Both myosin and actin

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H-Zone

Only myosin

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Motor Unit

single motor neuron and all the fibers it innervates

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neuromuscular junction

where motor neuron meets muscle fiber
1. synaptic knob: contains vesicles of neurotransmitters
2. synaptic cleft: space between knob and fiber
3. motor end plate: contains ACh gated Na+ channels

32

Excitation

1. action potential travels down neuron to synaptic knob. AP stimulates opening of VGCaC
2. Ca enters synaptic knob and binds with vesicles allowing them to fuse with plasma membrane
3. ACh is released by exocytosis into synaptic cleft
4. ACh bind to ACh receptors on the motor end plate. Movement of Na ions create positive charge in cell and begin the End plate potential

33

Excitation-contraction coupling

1. EPP stimulates opening of VGNaC which open to depolarize sarcolemma. NA rushes in.
2. Depolarization moves down T-tubules and sarcolemma. Na rushes in
3. depolarazion is followed by depolarization as VGKC open and K flows out.
4. AP spreads to T-tubules, depolarizeation opens VGCaC in terminal cisternae and SR.

34

Cross bridge cycling

1. Ca from SR interact with thin filaments, Ca binds to troponin, shifting the tropomyosin off of actin which expose myosin head binding site.
2. Cross bridge is formed as myosin binds too myosin head binding site on actin
3. Myosin performs power stroke, pulling towards M-line
4. Myosin releases (ATP)
5. myosin resets to repeat.

35

Twitch

occurs when voltage used to stimulate muscle reaches threshold. Delay is the latent period between stimulus and contraction. (enough time for excitation-contraction coupling to occur and Ca release from SR.)
Contaction occurs with power strokes from thick an thin filaments. , shortening the sarcomeres. Then period of relaxation

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What happens when stimulus intensity increases?

more motor units are involved with increase of stimulus until all the motor units are being used creating maximum contractions

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What happens with increased stimulation?

Muscle tension increase because there isn't enough time to relax, between stimulations, creating treppe

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tetany

maximum contraction until you run out of ATP or Ca2+

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Isometric contraction

muscle tension is less than resistance

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Isotonic Contraction

Tension is greater than resistance

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Cardiac muscle tissue

Striated, branched
intercalated discs with gap junctions and desmosomes for coordinated contractions.

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Smooth muscle

hollow organs, not striated, involuntary, same proteins contracting but in a different orientation

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muscles Can be named by

action, body region, muscle attachment, muscle shape, size, number of heads or tendons

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Axial muscle functions

Support and move head.
Chewing, non-verbal communication
Aid in breathing.
Support and protect abdominal muscles

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Appendicular muscles functions

control movement of upper and lower limbs
control movement of pectoral and pelvic girdles

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Agonist

Prime mover

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Antagonist

oppose action of prime mover

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Synergist

2 or more muscles working together for movement

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synergist fixators

hold join still to stabilize prime mover