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ROLE OF ATP
 ATP (provided by mitochondria)
 When a phosphate bond is broken off, this yields - energy plus leftover
ADP
ATP > ADP + P + ENERGY
 Energy supplies (in the order that they are used by the
muscles)
 ATP (stored) – is quickly used (within about 5 seconds)
 Phosphorylation – using Creatine Phosphate (which is
made by the body and stored within muscle) to supply a
phosphate to the leftover ADP from the previous step. It is
quickly used (within about 5 more seconds)
Glucose/Glycogen – stored form of glucose, in
the liver.
When broken down (glycolysis), it releases 2 ATP’s
and 2 molecules of pyruvic acid.
Anaerobic activity-pyruvic acids turns to lactic
acid and contribute to fatigue and soreness in the
muscles. Activity can only be sustained for about
60 seconds.
Aerobic activity- pyruvic acids enter into the
citric acid cycle (in the mitochondria), which leads
to the production of 36 ATP’s
Fat – provides the most energy, but is a last resort
Synthesis of Adenosine Triphosphate
Direct Phosphorylation
Glycolysis
Creatine Phosphate
Splitting glucose
(C6H12O6)
Stored in the
muscle
Duration of action
5~10 seconds
Adds Phosphate to ADP
(recharging ATP)
2 ATP
2 Pyruvic Acids
O2
O2
1 ATP
Replenished at rest
Anaerobic Respiration
Duration of action
45 – 60 seconds
1. From blood stream
2. Carried by myoglobin
Aerobic Respiration
(citric acid cycle -within
mitochondria)
2 Lactic acids
Direct Phosphorylation – 1 ATP
Glycolysis/Anaerobic Respiration – 2 ATP
Aerobic Respiration – 36 ATP
Remember
2 ATP are needed to “prime the pump”
TOTAL USABLE ATP - 36
Duration of action
HOURS
Muscle fatigue
and cramping
CO2
36 ATP
H2O
O2 SUPPLY AND CELL RESPIRATION

 hemoglobin – pigment responsible for carrying O2 molecules in the
blood and giving blood its color
 myoglobin – pigment in muscle, responsible for storing O2, gives
muscle its color (dark meat in poultry and fish)
 lactic acid – a by-product of muscle activity (contributes to soreness,
-
fatigue in muscles)
can be converted into glucose when combined with O2
but O2 is not available during exercise b/c the body cannot
metabolize it from the
air fast enough
lactic acid accumulates in the muscles
must wait until after exercise (when O2 is available) to convert it
into glucose
this whole process is known as Oxygen Debt
MUSCULAR RESPONSES
Twitch- Response of a single muscle fiber to the Ach released
by a single action potential.
 Short delay following to Stimulus [Ach]
 Result from higher stimulus intensity
Muscle Contraction Length
 -affects force of contraction
 Too stretched out= actin/myosin can’t reach and no
contraction
 Too close [sarcomere compressed]= no more shortening
CHARACTERISTICS OF TWO TYPES
OF MUSCLE FIBERS
 Type I (slow-twitch; oxidative; red)
 endurance activities
 found in muscles with high amounts of myoglobin (pigment that stores
oxygen in the muscles) - makes the muscle appear a darker red color
(dark meat in poultry)
 Rich in mitochondria
 Type II ( fast-twitch, glycolytic, white)
 quick, explosive, sprint-type activities
 not much myoglobin - makes the muscle appear a lighter color (white
meat in poultry), fewer mitochondria
 Accumulate lactic acid
CONNECTION BETWEEN DIFFERENT SYSTEMS
(ENDOCRINE - SKELETAL - MUSCULAR) OF THE BODY
Thyroid gland [Endocrine]
 - produces calcitonin, which encourages movement of
calcium from bloodstream into the bones [Skeletal]
 - if thyroid is overactive - too much calcium into the bones
lowers blood calcium so that the muscles could potentially
be deprived of calcium, which means they may not be able
to contract properly [Muscular]
