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Chapter 6 Part I
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1. What are the characteristics of muscle tissues?
excitable/responsive; contractile; extensible; elastic
2. What are the f(x)s of muscles?
movementlocomotion & substances internally; maintain posture & body position;
stabilize joints; generate heathomeostasis
3. What is the importance of transverse tubules?
run around muscle fiberscontain extracellular fluidimp for nerve stimulation
4. Describe the structure of the endomysium.
endomysium surrounds the ind. muscle cells/fibers & connects adjacent fibers
contains capillary network=blood supply; contains satellite cellsembryonic stem
cells that help w/repair; contains nerve fibers that control the muscle
5. Define perimysium
perimysium=several muscle fibers are wrapped together by a coarser memb
6. Name, compare, & contrast the 3 types of muscles.
skeletal muscle fibers=packaged into organs called skeletal muscles; attach to
the skeleton; form large fibers, multinucleate; striated/striped & voluntary
smooth muscle=spindle shape; uninucleate; nonstriated & involuntary; us. only 2
layers; one circular & one longitudinal; ability to change sizes; found mainly in
the walls of hollow organs
cardiac muscle=forms the bulk of the heart; striated & involuntary; highly
branchedconnected
by
intercalated
discs;
have
a
spiral
arrangement;
intercalated discs & spiral arrangement allow heart activity to be closely
coordinated
7. What is a fascicle?
a bundle of muscle fibers
8. What is unique about the arrangement of smooth muscle?
2 layers=one circular & one longitudinal
9. What does the sarcoplasmic reticulum do?
modified version of the SER=holds lots of Ca2+ & encircles the myofibril
10.What are myofibrils?
tubes w/I muscle fibers that are resp for muscle contraction
11.What is muscle fatigue?
muscle is unable to contract even though it’s still being stimulated
12. What is oxygen debt?
muscle fatigue is caused by O2 debt which occurs during prolonged muscle
activity
13. Explain the differences b/t isotonic contractions & isometric contractions.
isotonic contractions=muscle shortens & movement occurs; ex bending the
knee/rotating the arms
isometric contractions=muscles do not shorten, tension increases; ex. pushing
against a walltriceps cannot shorten to straighten the elbows
14. Define epimysium
a group of fascicles are bound together by CT memb called an epimysiumcovers
the entire muscle
15. In general how do tendons & aponeuroses form? What is their f(x)?
at each end of the muscle epimysium, endomysium, & perimysium come together
to form tendons & aponeuroses=attach muscles directly to bones, cartilage, or
CT coverings
16. Compare & contrast the thin & thick filaments.
thin filaments contain 4 proteins: F actin; nebulin; tropomyosin; & troponin
repeating units of actin molecules twisted into a strand
ea actin molecule has active sites that enable it to interact w/myosin
thick filaments=contain myosin
has a heads & a tails; heads are arranged in spirals; tails point to the M-line
act as a motor; responsible for moving the actin
17. What does the A-band represent? What enzyme is present?
thick filaments; also contain ATPase enzymes; have small myosin projections
called cross bridges
18. List the components (7) of skeletal muscle activity?
stimulus; motor neuron; motor unit; axon; neuromuscular junction; synaptic cleft;
& AP
19. What does the I-band represent?
contains thin filaments; contains parts of 2 adjacent sarcomeres
20. What is required to create an action potential? movement of electrolytes
21. Describe the structure/arrangement of an axon & a sarcolemma.
when it reaches the muscle it branches=axon terminals; ea axon terminal forms a
junction w/ the sarcolemma of a diff muscle cell=neuromuscular junctions
the axon terminals & muscle cells do not touchgap b/t them=synaptic cleft
22. What is depolarization?
sarcolemma now has an excess of + ions on the i/s which reverses the electrical
conditions of the sarcolemma
23. What molecules cause ACh to be released? What is ACh?
Ca2+ causes synaptic vesicles to release ACh; neurotransmitter for muscles
24. What does ACh do?
as ACh levels increase the sarcolemma becomes temporarily more permeable to
Na+ & K+; Na+ rushes into the muscle cell; K+ rushes out of the muscle cell
25. What happens to ACh after the AP has moved on?
ACh is broken down into acetic acid & choline by acetylcholinesterase
26. Describe fused/complete tetanus.
muscle contraction is smooth & sustained
27. What is the all or principle of muscle contraction?
a muscle cell will contract to its fullest extent when it’s adequately
stimulatednever partially contracts
28. For muscles contractions, why is ATP important & what is a problem with ATP?
it’s the only source that can be used to directly power muscle activity; muscles
do not store large amts of ATP
29. Describe the 3 ways in which ATP is regenerated (be specific).
direct phosphorylation of ADP by creatine phosphate(CP)
interaction b/t CP & ADP causes a transfer of a phosphate grp from CP
to ADP=ATP
quickly regenerates ATP, but is depleted quickly
aerobic respiration/oxidative phosphorylationglucose is broken down to prod
32 ATP; req constant supply of oxygen
anaerobic glycolysis & lactic acid fermentation
pyruvic acid is converted to lactic acid=anaerobic glycolysis
30. What are problems with anaerobic glycolysis & lactic acid fermentation?
uses large amounts of glucose, but only prod a small amount of ATP &
accumulation of lactic acid
31. Describe the sliding filament theory of muscle contraction. Why is Ca2+
important?/
muscle is stimulated & Ca2+ triggers the binding of the actin to the myosin
activated myosin heads attach to thin filaments (actin) & begin to slide=cross
bridge formation
ea cross bridge attaches & detaches several times during contraction