This document discusses various topics related to muscle physiology, including: - The three types of muscle tissue and their differences - How calcium ions trigger muscle contraction and relaxation - The "sliding filament" theory of muscle contraction - Aerobic vs. anaerobic metabolism in muscle during exercise - Motor units and their role in fine vs. gross muscle movements - Factors that influence muscle strength - Phases of a muscle twitch contraction - Rigor mortis and the Treppe effect on athlete warmups

1. Muscular Physiology

2. What do you get when you
mix Muscles and Music???
Muscles + Music =

3. 1. Explain how skeletal muscles provide movement, heat,
and posture. Are all of these functions unique to
muscles? Explain your answer.
 Skeletal muscle moves bones by receiving
acetelecholine from a motor nerve that
triggers an action potential across the
muscle fibers. Muscle fibers contain actin
and myosin, which are the function
components of muscle contraction.
Essentially, movement of a bone occurs
when the muscle attached is being
shortened. The chemical reactions that
cause muscle contraction generate heat.
These functions are all unique to Skeletal
Muscle Cells.

4. 2. The characteristics of excitability are shared by what
other system? Relate contractility and Extensibility to the
concept of agonist and antagonist discussed in chapter
10.
 The characteristics of excitability are
shared with the Nervous System.
Contractility and Extensibility relate to
the concept of agonist and antagonist
because they both relate to the
movement of muscle. Agonist and
Antagonist are the muscles moving and
Contractility and Extensibility are the
actions of muscle movement.

5. 3. The Three types of muscle tissue:
skeletal, cardiac, smooth Differ in cell structure, body
location, function, and the means by which they are
activated to contract. Similar in that all are elongated and
contraction depends on 2 kinds of myofilaments.
1. .Skeletal Muscle Tissue - Packaged
into skeletal muscle that attach to and
cover the bony skeleton. Visually
obvious bands -- striations. Voluntary
control - subject to conscious control.
Can contract rapidly and vigorously but
tire easily. Can exert tremendous
power. Remarkably adaptable.

6. Continuation Muscle Tissue…
2. Cardiac Muscle 3. Smooth Muscle Tissue
Tissue - Found in walls of hollow organs
only in the heart. --
Striated and stomach, bladder, resp.
Involuntary. Gap tract, etc. Non-striated.
junctions allow Involuntary control.
rapid Contractions are slow
communication and sustained. Found in
between cells sheets of alternating
which circular and longitudinal
synchronizes cell layers; synchronized
contractions. contraction of the sheets
give rise to a wave of
contraction along the
hollow organ -

7. 4. Myofilament is the term for the chains of
(primarily) actin and myosin that pack a muscle
fiber. These are the force generating structures.
 Four different kinds of protein molecules
make up Myofilaments:
1.) myosin
2.) actin
3.) tropomyosin
4.) troponin.

8. 5. Explain how the sliding filament theory
allows for the shortening of a muscle fiber.
 The thin filaments are made of a
combination of three proteins:
actin, tropomyosin, and troponin. when
the muscle fiber is relaxed, the thin
filaments terminate at the outer edges of
the H zones. In contrast, the thick
myosin filaments do not attach directly
to the Zlines, and they extend only the
length of the A bands of the sarcomas.

9. 6. Compare and contrast the role of Ca++
in excitation, contraction, and relaxation of
a muscle cell.
 Contraction: the impulse, a temporary
electrical imbalance, is conducted over the
muscle fiber’s sarcolemma and inward along
the “T tubules”. The impulse in the T tubules
triggers the release of a flood of calcium ions
from the adjacent sacs of the SR. in the
sarcoplasm, the calcium ions combine with
troponin molecules in the thin filaments of the
myofibrils.
Relaxation: almost immediately after the SR
releases its flood of calcium ions into its sacs
once again.

10. 6. Continuation…
 Within a few milliseconds, much of the calcium
is recovered. Because the active transport
carriers of SR have greater affinity to calcium
than troponin and returned to sacs of SR. As
you might suspect, this shuts down the entire
process of contraction. Troponin without it’s
without its bound calcium allows the
tropomyosin to once again block actin’s active
sites.
Excitation: calcium is released from the SR
into the sarcoplasm, where it binds to troponin
molecules in thin myofilaments. Both
Excitation and contraction does this.

11. 7. People who exercise seiously are sometimes
told to work a muscle until they "feel the burn". In
terms of how muscle is able to release
energy, explain what is going on in the muscle
early in the exercise and when the muscle is
"burning."
 Muscle cells present a special case because they are
called upon for both sudden burst and long, sustained
periods of intense activity. During endurance
exercise, a muscle may utilize a hundred to a
thousand times as much ATP as it does during rest.
But ATP is utilized; it’s quickly replenished by the small
reserve energy stored as creatine phosphate. Creatine
phosphate very rapidly donates its high energy
phosphate to ADP to the moment ADP
forms, converting it back to ATP.
Right now, after 20-25 seconds of intense activity of
exercise, we are back in the same place- no ATP.

12. 7. Continuation…
 ”Aerobic Metabolism- Oxidative Phosphorylation”-
utilizes (fats) as well as glucose and glycogen, in
contrast to creatine phosphate or
glycolysis, “Aerobic Metabolism” is fairly slow, but
it is efficient and can provide energy for almost
unlimited durations, as long as the nutrients last.
Usually, it takes about 0.5 to 2 minutes for aerobic
metabolism to adjust to the increased demands of
exercise.
But also to supply energy at the beginning of long
term muscular activity before aerobic metabolism
becomes fully mobilized. Once this has
occurred, an exhausted runner may experience a
“second wind”.

13. 8. Describe the anatomical arrangement of
a motor unit. Contrast fine and gross motor
units.
1. Motor unit- consists of one somatic motor
neuron and the muscle fibers supplied by
its branches
Fine motor unit- in certain small
muscles, each motor unit includes only a
few muscle fibers and these muscles
produce precise movements
2. Gross motor unit- motor units in large
muscles that do not produce precise
movements are reported to include more
than a hundred muscle fivers each

14. 9. Using fiber types, design a muscle for a
marathon runner. and a different muscle for a
100-yard-dash Sprinter. Explain our choice.
 A muscle for a 100-meter-dash runner
would have quicker twitch contractions
than a marathon runner but a marathon
runner would require more oxygen
because during the course of the race
oxygen is able to reach his whole body.
A dash runner is only running for about
10 seconds so oxygen doesn’t have
time to reach the muscles in his legs

15. 10. Explain the meaning of a "unit of combined
cells" as it relates to cardiac Muscle. How does
the structure arrangement affect its function?
 The “unit combined cells” are
considered to be crystal cells and their
structure has everything to do with their
function. If one little thing is different in
the cells structure it has a completely
different function.

16. 11. Describe Rigor Mortis.
 If all the ATP is used up the myosin
heads will stay locked to the actin
filaments, meaning no sliding will take
place. The muscles become rigid and
resist both contraction and stretching;
this is what causes Rigor Mortis.

17. 12. Describe in detail the 4 factors that
influence the strength of muscle
contractions.
1. The number of muscle fibers stimulated
2. The relative size of the fibers
3. Frequency of stimulation
4. The degree of muscle strength

18. 13. What are the phases of a twitch
contraction? What molecular events occur
during each of these phases.
1. Latent Phase: Is the first phase where the
muscle begins to contract. Myofibrils are
the protein that helps the muscle contract.
2. Contraction Phase: The muscle fibers
shorten here. Myosin pulls the actin to
form crossbridges to make the muscle
contract.
3. Relaxation Phase: This is when the
muscle is going back to its original state
and lengthens. The Myosin is releasing
the actin.

19. 14. How does the Treppe Effect relate
to the warm-up exercises of athletes?
 The Treppe Effect causes the muscles
to be half has strong if a muscle has
been resting. This is important to
athletes because it goes to show that
they must warm up and get there
muscles moving so that their muscles
can be as strong as they can be.