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The red muscle is used for slow
steady swimming strokes that barely bend the body of the
fish. In contrast, the white muscles are used for explosive
bursts of speed, such as the escape response.
White
muscles can generate much more power, but they fatigue much
more rapidly.
Q. What
else do white muscles generate?
- lactic acid.
Discussion
Question
The red blood cells of
certain fish contain multiple hemoglobins, one of which does
not show the Bohr effect. Under what circumstances would
this be an advantage?
- If a
fish has to use a tremendous anaerobic burst to escape a
preditor, its blood has high levels of lactic acid. But, it
has to keep swimming against the current, so it has to have
a hemoglobin that can load O2 and transport it to the
muscles, even at low pH.
Review:
ISP CD 49.3, muscle
contraction animation
1. What is muscle fatigue?
2. If
the blood flow to a skeletal muscle were disrupted, which
type of fiber will be affected first?
3. Will
a muscle contract in the absence of external Ca++ if
stimulated directly? How about if the the attached motor
neuron was stimulated?
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