The skeleton provides a strong framework for the body and protects soft organs. It is made of bone and cartilage. Movement requires coordination of bones, muscles, tendons, and ligaments. Bones provide anchors for muscles and act as levers. Muscles contract to pull bones and cause movement, while tendons transmit force from muscles to bones and ligaments hold bones in place at joints. Nerves transmit signals to produce muscle contractions.

3. The skeleton provides a strong
framework that holds your body up
and maintains its shape
The skeleton also protects soft
organs and provides attachment
sites for your muscles
Cartilage, a type of connective
tissue that is softer than bone
and provides cushion between
bones in a joint.

4.  Movement is a complex coordination of
several parts of your body acting together,
each with a specific role:
TISSUE ROLE
BONES Provide anchorage for muscles. Act as levers. Provide support
MUSCLES As a muscle contracts, it pulls on the attached bone. Since
muscles can only pull, an opposing motion is needed to restore to
bone’s original position.
TENDONS Tough and dense connective tissue between muscle and bone.
Transmit the force generated by a muscle contraction.
LIGAMENTS Strong connective tissue that holds the bones in joints in their
place.
NERVES Transmit electrical signals to produce muscle contractions and
coordinate movement.

6.  An area where one bone
meets another bone is called
a joint.
 Immovable joints: connect
bones in a way that allows
little or no movement. Like
the ribs attached to the
vertebrae.
 Movable joints: allow you to
bend, twist, and rotate your
limbs, neck, and torso. The
bones in a movable joint are
held together by a strong,
fibrous connective tissue
called a ligament.

8.  A. Humerus (upper arm)
bone.
 B. Synovial membrane that
encloses the joint capsule and
produces synovial fluid.
 C. Synovial fluid (reduces
friction and absorbs
pressure).
 D. Ulna (radius) the levers in
the flexion and extension of
the arm.
 E. Cartilage (red) living tissue
that reduces the friction at
joints.
 F. Ligaments that connect
bone to bone and produce

9.  Knee Joint:
 The knee joint is an example
of a hinge joint.
 The pivot is the knee joint.
 The lever is the tibia and
fibula of the lower leg.
 A knee extension is powered
by the quadriceps muscles.
 A knee flexion is powered by
the hamstring muscles. Watch movement of knee joint:
 Movement is one plane only. http://www.youtube.com/watch?v=
wyiJw034ssA

10.  The Hip Joint:
 Rotation is in all planes and axis of movement.
 The lever is the femur and the fulcrum is the hip joint.
 The effort is provided by the muscles of quadriceps, hamstring and
gluteus.
 The shoulder is a ball and socket joint.
 The humerus is the lever.
 The shoulder (scapula and clavicle) form the pivot joint.
 Force is provided by the deltoids, trapezius and pectorals.
 Movement is in all planes.
Watch movement
of hip joint:
http://www.youtu
be.com/watch?v=s
PsyPwYZb6A&featu
re=related

11.  Antagonistic muscle pairs: Muscles must work in
pairs. For each skeletal muscle that is
contracting, there is an opposing muscle—one
that is relaxed but that can contract and pull the
bone back in the opposite direction.
A flexion like
this one is
called a
concentric
contraction
• One muscles bends the limb at the joint
(flexor) which in the elbow is the biceps.
• One muscles straightens the limb at the joint
(extensor) which in the elbow is the triceps.

12.  Taking a closer look, a skeletal muscle such as
your calf muscle consists of bundles of parallel
muscle fibers along with a supply of nerves and
blood vessels.

13. A muscle fiber is a single long cylindrical
muscle cell that contains many nuclei.
Inside a muscle fiber are
bundles of smaller units
called myofibrils.
Each myofibril has alternating light and
dark bands: striated muscle

14. Each sarcomere is composed of two kinds of filaments, thin filaments are
composed of the protein actin. The thick filaments are composed of the
protein myosin and have myosin crossbridges.
1. In each mini-
contraction, myosin
crossbridges first bind to
thin filaments.
2. Next, the crossbridges
bend, pulling the thin
filaments toward the
Watch muscle center of the sarcomere.
contraction: 3. ATP then binds to each
http://www.y crossbridge, releasing it
outube.com/ from the thin filament.
watch?v=83yN 4. The crossbridge is now
oEJyP6g free to attach at a new
spot and further pull the
thin filament along

15.  1. An action potential arrives at the end of a motor neuron, at the
neuromuscular junction.
 2. This causes the release of the neurotransmitter acetylcholine.
 3. This initiates an action potential in the muscle cell membrane.
 4. This action potential is carried quickly throughout the large
muscle cell by invaginations in the cell membrane called T-tubules.
 5. The action potential causes the sarcoplasmic reticulum (large
membrane vesicles) to release its store of calcium into the
myofibrils.
 6. Myosin filaments have cross bridge lateral extensions.
 7. Cross bridges include an ATPase which can oxidize ATP and release
energy.
 8. The cross bridges can link across to the parallel actin filaments.
 9. Actin polymer is associated with tropomyosin that occupies the
binding sites to which myosin binds in a contraction.
 10. When relaxed the tropomyosin sits on the outside of the actin
blocking the binding sites.
 11. Myosin cannot cross bridges with actin until the tropomyosin
moves into the groove.
 12. The calcium binds to troponin on the thin filament, which
changes shape, moving tropomyosin into the groove in the process.
 13. Myosin cross bridges can now attach and the cross bridge cycle
can take place.

16.  Cross Bridge Cycle:
 1. The cross bridge swings out from the thick filament and
attaches to the thin filament.
 2. The cross bridge changes shape and rotates through 45°,
causing the filaments to slide. The energy from ATP splitting
is used for this ―power stroke‖ step, and the products (ADP +
Pi) are released.
 3. A new ATP molecule binds to myosin and the cross bridge
detaches from the thin filament.
 4. The cross bridge changes back to its original shape, while
detached (so as not to push the filaments back again). It is
now ready to start a new cycle, but further along the thin
filament.

18. If electron micrographs of a relaxed and contracted myofibril are
compared it can be seen that:
Note that the filaments themselves don't get shorter, but as they slide
across one another, their overlap increases.
The sarcomere shortens (distance between Z-lines is smaller). The process
can continue until the sarcomere is fully contracted.
As the sarcomeres of many muscle fibers shorten together, the entire
muscle contracts.

19.  1.Explain the difference between Overlap of
a transverse
Actin only Myosin only
and a longitudinal section of a muscle. and
actin
 2. Deduce what part of the myofibril is during
myosin
muscle
represented by the drawings as small dots.
contraction
 3. Explain the differences between the
diagrams in the pattern of dots.

20.  Muscle contraction:
http://www.youtube.com/watch?v=83yNoEJy
P6g
 Krebs cycle:
 http://www.youtube.com/watch?v=WcRm3M
B3OKw

22. Breathing is not
the same as
respiration.
When we breathe
we exchange
gases (O2 and
CO2) with the
environment
Respiration
occurs at a
cellular level

23.  Total lung capacity: volume of air in the
lungs after a maximum inhalation.
 Vital capacity: maximum volume of air that
can be exhaled after a maximum inhalation.
 Tidal volume: volume of air taken in or out
with each inhalation or exhalation.
 Ventilation rate: number of inhalations or
exhalations per minute (this term is used,
not breathing rate).

24.  Any physical activity involves muscle
contraction, which requires energy in the
form of ATP.
 ATP can be supplied by aerobic cell
respiration
 Concentration gradients in the lungs have to
be maintained to ensure correct oxygen and
carbon dioxide diffusion and exchange

25.  If oxygen is available to a cell, pyruvate produced by
glycolysis can be oxidized to release more energy.
 Energy released from pyruvate oxidation is used to
produce ATP.
 Oxidation of pyruvate also involves the production of
CO2 and water. Watch the Krebs
cycle:http://www.yo
utube.com/watch?v=
WcRm3MB3OKw

26.  Oxygen diffuses into the body across the gas
exchange surface in the alveoli, and carbon
dioxide diffuses out.
 During gentle to moderate exercise, gases
exchange rapidly and O2 and CO2
concentration inside the body are restored.

27.  If the intensity of exercise increases, the
rate at which gas diffusion on the alveoli
surface occurs must also increase.
 If blood moves quicker to the lungs, CO2 can
be released quicker.
 It is also essential to bring more O2 from the
air outside.
 By breathing faster (increased ventilation
rate) and also deeper (increased tidal
volume) more air is present inside the lungs
for gas exchange.

28.  Training is a program of exercise designed to
develop a particular type of fitness and to
improve performance. By training, the
pulmonary system is affected:
 The ventilation rate at rest can be reduced by 10
- 15% (from about 14 to 12 bpm), because the
efficiency of gas exchange is increased
 The maximum ventilation rate can be increased
from about 40 to 45 bpm or more, due to the
strengthening of the diaphragm and the
intercostal muscles.
 Vital capacity may increase slightly (about 5%)

30.  Heart rate: number of contractions of the
heart per minute.
 Stroke volume: volume of blood pumped out
with each contraction of the heart.
 Cardiac output: volume of blood pumped out
by the heart per minute.
 Venous return: volume of blood returning to
the heart via the veins per minute.

31.  Explain the changes in cardiac output and
venous return during exercise.
 When the body’s overall cell respiration rate
rises (to produce more energy), for example
during exercise, the CO2 content of the blood
rises.
 Receptor cells detect a lowered blood pH
(because of a high CO2 concentration) and
causes impulses to be sent by the brain to
the pacemaker, increasing cardiac output
(because heart rate and stroke volume
increase).

32.  Many veins are located between or adjacent
to muscles that are used during exercise.
 Contraction of muscles used during exercise
squeezes blood in adjacent veins, increasing
blood pressure and flow rate, therefore
increasing venous return. Valves in veins
ensure that blood only flows in one direction.

33.  Compare the distribution of blood flow at
rest and during exercise:
 Blood flow to the brain is unchanged during
exercise.
 Blood flow to the skin is increased for
temperature regulation.
 Blood flow to the heart wall, and skeletal
muscles is increased.
 Blood flow to the kidneys, stomach,
intestines and other abdominal organs is
reduced, as their functions can be reduced
during periods of exercise.

34.  Training can make the heart bigger: thicker
ventricle walls (stronger contractions that
can squeeze out more blood) and larger
ventricular volumes (more blood fits inside
the heart to be pumped out). Therefore
more blood can be pumped out with each
heartbeat = maximum stroke rate is higher.
 Training does not significantly affect the
maximum heart rate, but the maximum
cardiac output is greater.
 This means muscle contractions can be more
frequent and more powerful.

35. AT REST DURING EXERCISE
Cardiac output is not Increase in stroke volume,
significantly altered therefore more blood can be
supplied with fewer heartbeats.
Lower resting heart rate Lower exercising heart rate
Intensity of exercise can be
increased. The trained athlete
can run, swim or cycle faster.

36.  Evaluate the risks and benefits of using EPO
(erythropoietin) and blood transfusions to
improve performance in sports:
 There are clear ethical issues involved in the
use of performance-enhancing drugs.
 Human blood varies in the relative amounts
of cells and plasma.
 The higher the cell volume, the greater the
oxygen-carrying capacity of the blood,
allowing more intense exercise to be
sustained by aerobic cell respiration.

37.  Erythropoietin (EPO) is a hormone that
stimulates the production of red blood cells.
 Another method is to transfuse blood shortly
before the event.
 Benefit:
 Increase performance during events involving
intense exercise (100m race, swimming, etc.)
 Risk:
 Significant increases in the risk of strokes and
heart attacks as a result of blood clot formation
(cardiac arrest during sleep)

39.  VO2 : the volume of oxygen that is absorbed by
the body per minute and supplied to the tissues.
 VO2 max : the maximum rate at which oxygen can
be absorbed by the body and supplied to the
tissues.
 Aerobic cell respiration can only occur if oxygen
is available.
 If the intensity of exercise increases, the
pulmonary system absorbs more oxygen and the
cardiovascular system transports the increased
amounts.
 If the intensity of exercise continues to rise, we
reach VO2 max and the rate of oxygen supply is
less than the rate of use.

40.  Outline the roles of glycogen and myoglobin
in muscle fibres.
 Myoglobin is used to store oxygen in some
muscle fibers.
 Each molecule of myoglobin can store one
molecule of oxygen.
 Myoglobin releases oxygen during periods of
intense exercise to allow aerobic respiration
to fuel ATP production for a little longer.
 After the oxygen stored in myoglobin is used
up, aerobic cell respiration can only happen
as quickly as oxygen is supplied by the heart
and lungs.

41.  All muscles are composed of specialized muscle
fibers. Muscle fibers have certain key physical
distinctions that create two distinct kinds of
fibers, fast-twitch (type II fibers) and slow-
twitch (type I fibers).
 Whether a muscle fiber functions as a fast-
twitch or slow-twitch fiber is subject to a
number of physical and neurological factors.
 Slow-twitch fibers are governed by slow
conduction neurons, the relay switch of the
nervous system that governs a group of muscle
fibers ranging in size from as few as 10 to as
many as 2,000 fibers.
 Fast-twitch fibers are governed by fast-acting
neurons, which are capable of transmitting or
firing the nerve impulses that command
movements by the muscle 10 times more
frequently than the slow-twitch neurons will
fire.

42.  Fast-twitch fibers store glycogen within the
cells of the muscle fiber.
 Glycogen, the storage form of glucose, is
then utilized at the muscle in the cycle of
electrochemical reactions that produce ATP,
the source of energy within the muscle.
 The muscles store glycogen in quantities that
total approximately 1% of the muscle mass, a
reserve that is quickly depleted through
intense exercise; for an approximate
maximum of 90 seconds.
 Anaerobic cell respiration is used to provide
ATP in muscles during high-intesity exercise
when oxygen cannot be supplied rapidly
enough for aerobic cell respiration.

43.  Only glucose can be used as a substrate and
lactate is produced.
 Lactate accumulates in muscles and blood
and the body can only tolerate a limited
amount, so anaerobic cell respiration can
only be used for short periods of intense
exercise.

44.  Outline the method of ATP production used
by muscle fibres during exercise of varying
intensity and duration:
 Creatine phosphate can be used to
regenerate ATP for 8–10 seconds of intense
exercise. Beyond 10 seconds, ATP is produced
entirely by cell respiration.
 As the intensity of exercise decreases and
the duration increases, the percentage of
anaerobic cell respiration decreases and
aerobic cell respiration increases.

45.  Evaluate the effectiveness of dietary
supplements containing creatine phosphate in
enhancing performance:
creatine phosphate + ADP  creatine + ATP
 Creatine phosphate is absorbed in the intestines,
but the concentration of creatine phosphate in
the muscles only increases by a small amount.
 There is some evidence of an increase in the
maximum intensity of exercise over short time
periods, but performance in endurance events is
not improved.
 There is some evidence of creatine phosphate
causing increased fluid retention, which would
increase body mass and decrease athletic
performance.

46.  Outline the relationship between the
intensity of exercise, VO2 and the
proportions of carbohydrate and fat used in
respiration.
 As the intensity of exercise increases, VO2
rises until it reaches VO2 max. Use of fat in
respiration falls and use of carbohydrate
rises until it reaches 100%.

47.  Statethat lactate produced by anaerobic cell
respiration is passed to the liver and creates
an oxygen debt.

48.  Outline how oxygen debt is repaid.
 Lactate is turned into pyruvate, which is
converted to glucose or used in aerobic
respiration in the mitochondrion, using
oxygen taken in during deep ventilations
after exercise.

51.  Define fitness.

52.  Discuss speed and stamina as measures of
fitness.

53.  Distinguish between fast and slow muscle
fibres.
 Fast muscle fibres (typical of sprinters) have
greater oxygen needs, low myoglobin levels
and provide a maximum work rate over
shorter periods (strength).
 Slow muscle fibres (typical of marathon
athletes) have a very good blood supply,
plenty of myoglobin and are capable of
sustained activity (stamina) and high rates of
aerobic respiration.

54.  Distinguish between the effects of moderate-
intensity and high-intensity exercise on fast
and slow muscle fibres.
 Moderate-intensity exercise stimulates the
development of slow muscle fibres. High-
intensity exercise stimulates the
development of fast muscle fibres.

55.  Discussthe ethics of using performance-
enhancing substances, including anabolic
steroids.

57.  Discuss the need for warm-up routines.
 TOK: There is almost universal belief in the
need for warm-up and sometimes also warm-
down routines, but much of the evidence for
these theories is at best anecdotal and at
worst non-existent. The difficulty of
conducting controlled trials without a
placebo effect could be discussed. The
willingness of athletes to believe what they
are told, without questioning it, could also
be considered.

58.  Describeinjuries to muscles and joints,
including sprains, torn muscles, torn
ligaments, dislocation of joints and
intervertebral disc damage.