BIOD43H3 Lecture Notes - Lecture 3: Myosin, Turkey Vulture, Myocyte
BIOD43 Lecture 3 Notes: Muscle Structure Part I
• Efficiency
- Metabolic efficiency is the amount of potential chemical energy that gets transformed
into mechanical work
- Efficiency is never 100%, some energy gets lost as heat
ex. Sometimes we want to do things that do not result in efficiency to get only heat, such
as when body is cold our muscles generate heat by contracting, this is why we shiver,
leading to a zero efficiency.
• “Costly” when displaying powerful behavior for a long period of time
Muscle as a Motor
• Muscles have diverse fiber types and motor units
• Muscles mass or volume do not scale in the same way as an animal’s size
• Tuna fish are one of the most active fish, as they need efficient respiratory and
circulatory systems to supply their needs.
I. --A Tuna fish swims with its mouth open, forcing water past its gills in a process
called ram ventilation. Its gills have up to 30 times more surface area than those of
other fish.
II. As a result, Tuna fish NEVER stop swim, they have much RED MUSCLES
• Groupers are slower swimming fish, but have powerful, burst attacks when predators are
around
I. Groupers have more active WHITE MUSCLES
• Birds also allow us to understand difference in performance
1. Type 1 Fiber type: Slow Oxidative, high mitochondria density, highly resistant
to fatigue ex. Turkey Vulture which soar and keep wings extended
2. Type 2AFiber: Fast Oxidative- Glycolytic, high mitochondria density, some
resistance to fatigue (can fly for a long time; migrating birds) ex. Mallard duck
(ducks which migrate have fast myosin heavy chain rich in red muscle)
3. Type 2B Fiber: Fast Glycolytic Rich in white muscle, low mitochondria density,
quick contraction velocity, very quick to get fatigue. Ex. Chicken (cannot fly for
miles, muscles not created for great distance)
• Muscle units are the unit of muscle recruitment.
• In aerobic fibers glycogen is important
• Bigger somas generate greater force to get motor neurons to fire
• Elite sprinters have smaller-slow twitches in their quadriceps muscles compared to elite
marathon runner.
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Document Summary
Biod43 lecture 3 notes: muscle structure part i: efficiency. Metabolic efficiency is the amount of potential chemical energy that gets transformed into mechanical work. Efficiency is never 100%, some energy gets lost as heat ex. -a tuna fish swims with its mouth open, forcing water past its gills in a process called ram ventilation. Its gills have up to 30 times more surface area than those of other fish. Turkey vulture which soar and keep wings extended: type 2afiber: fast oxidative- glycolytic, high mitochondria density, some resistance to fatigue (can fly for a long time; migrating birds) ex. Mallard duck (ducks which migrate have fast myosin heavy chain rich in red muscle: type 2b fiber: fast glycolytic rich in white muscle, low mitochondria density, quick contraction velocity, very quick to get fatigue. Chicken (cannot fly for miles, muscles not created for great distance)
