Studied by 1 person
What indicates degree of control
the size of motor unit
for Precise movements such as muscles of the eye the motor unit contains ______fibers per neuron; however gross movements such as muscles in the leg, Motor units contain up to ________muscle fibers per neuron
few(4-6); 2000
What is recruitment?
The activation of more and more motor units resulting in an increase in muscle tension to create movement
Which motor units are recruited first?
smaller motor units
What is the result of recruitment
smooth, steady increase in muscle tension
when is peak tension produced
when all motor units are recruited and contracting in complete tetanus
some motor units in skeletal muscle are always on but their contractions are NOT enough to produce tension for movement BUT they do tense and firm the muscle. What is this referring to?
muscle tone
What is muscle tone?
resting tension in a skeletal muscle
what is the purpose of muscle tone
maintain posture, stabilize joints, keep muscles firm and healthy
When muscle is not regularly stimulated by motor neuron what occurs
atrophy
what happens to muscle fibers as a result of atrophy
they become smaller and weaker
atrophy can be obsered after ______ when cast comes off
fracture
when is atrophy reversible
if caused by temporary reduction in use
are Dying muscle fibers ever replaced
no
In Isotonic contraction, _____________ changes but ________remains constant until relaxation
length(shortenin); tension
examples of isotonic contraction
lifting a book, walking
In isometric contraction, __________stays the same, but _____________is produced(does not exceed load)
muscle length; tension
tension produced by isometric contraction does not __________the load
exceed
exmples of isometric contraction
pushing against a wall
In order for muscle to return back to a pre-contracted, elongated state no ___________mechanism is needed
active
skeletal muscle RELAXATION is a ______________process involving elastic forces, Movements of opposing muscles, Gravity
passive
_____________________muscle fiber generates more ATP than needed
RESTING
When Excess ATP transfers energy to creatine, what forms?
creatine phosphate (CP)
creatine phosphate (CP) stores energy in ___________
muscles
At rest what does muscle have more of? CP or ATP
CP
Cp is created when muscles are at ___________--
rest
During contraction, each cross-bridge breaks down ATP into _________and a __________
ADP; PHOSPHATE GROUP
what is used to recharge ADP back to ATP in a reverse rxn
energy stored in CP
What enzyme is needed for the reverse reaction of creatine phosphate
creatine phosphokinase(CPK or CK)
creatine phosphokinase(CPK or CK) catylzes the conversion of
ADP and creatine phosphate to ATP and creatine
What are kinases?
Kinases are enzymes that transfer the phosphate group of ATP to a specialized molecule.
High levels of CPK in the blood can indicate ________________
serious muscle damage
when energy reserves become exhausted after 15 sec atp must be generated by different means such as ________________ and _________________
aerobic metabolism and anaerobic glycolysis
aerobic metabolism provides _________% of resting muscle cell's ATP needs
95
All stages of cellular Respiration except glycolysis occur in the _________
MITOCHONDRIA
Aerobic metabolism Involves breaking down of ___________, _______________, and ______________- into smaller components
carbohydrates, lipids, and proteins
aerobic metabolism end products
ATP, water, and carbon dioxide
Where does glycolysis occur?
cytoplasm
What are the products of glycolysis?
2 pyruvate, 2 ATP, 2 NADH
NADH is an _______________which carries electrons from glycolysis to ETC(electron transport chain)
electron shuttle
ETC occurs in the
inner mitochondrial membrane
energy from electrons is used by ETC to create ________________
H+ gradient
The H+ gradient refers to __________________distribution of H+ across across inner mitochondrial membrane
equal
The H+ gradient is used by enyme ________________--to make ATP from ADP and phosphate
ATP synthase
each NADH leads to the production of how many ATP by chemiosmosis
2.5
What is the second stage of aerobic respiration
pyruvate oxidation
Where does pyruvate oxidation occur?
mitochondrial matrix(outside cytoplasm)
pyruvate uses 2 molecules of pyruvate to produce
2 acetyle Co-A, 2 NADH, and 2 CO2
Like pyruvate oxidation, the krebs cycle occurs in_____________
mitochondrial matrix
Krebs cycle uses 2 molecules of acetyl Co-A to produce(TWICE)
6 NADH, 2 FADH2, 4CO2, 2ATP
Aside from NADH, which of the following is an electron shuttle
FADH2
FADH2 delivers electrons to___________which creates H+ gradient
ETC
each FADH2 leads to the production of _________( how many )ATP by ___________
1.5; chemiosmosis
oxidative phosphorylation includes
ETC and chemiosmosis
Where does oxidative phosphorylation occur?
inner mitochondrial membrane
inner mitochondrial membrane seperates mitochondrial matrix from___________
intermembrane space
How many molecules of ATP does oxidative phosphorylation produce
28
overall ____ atp are produced ____atp from glycolysis, _____atp from krebs cycle, __________from oxidative phosphoraltion
30, 2, 2, 28
The 30 ATP are used to transport ___(how many) glycolytic NADH (produced during glycolysis) from the cytoplasm to mitochondrion
2
In the presence of oxygen (aerobic) the cell produces _____molecules of atp by using _________ molecule of glucose
30; 1
it is also true to say that ___molecules of pyruvate lead to the production of 30 molecucles of ATP
2
at rest skeletal muscle cells rely on ______________to make atp
aerobic metabolism
Triglycerides are broken down into
fatty acids and glycerol
what enzymes catalyze the break down of fats to fatty acids and glycerol
lipases
skeletal muscles cell use fatty acids to produce _____________, _______________ , and____________in the ____________during a process called fatty acid(beta) oxidaton
acetyl CoA, NADH, FADH2; mitochondrial matrix
acetyl CoA is needed for _________ to happen; NADH and FADH2 are needed for ________ to work
krebs cycle; ETC
the generated atp is used by skeletal muscle cells to convert excess glucose into ______________
glycogen
conversion of glucose to glycogen in the presence of ATP
anabolism
at moderate activity, the demand for ___increases. the rate of _____________use also increases
atp; oxygen
at moderate activity glycogen is broken down into ______________ in a catabolic process
glucose
during moderate activity the atp produced is used to power ___________--
contration
only when ________is present can skeletal muscle make 30 atp/ glucose
oxygen
when does peak activity occur
during severe or extended periods of exercise
at peak activity, skeletal muscles run out of __________and rely on _________to produce only ___molecules of ATP
oxygen; glycolysis; 2
During glycolysis, glucose is broken down into
2 molecules of pyruvate;
Glycolysis produces how many ATP?
2 ATP
2 molecules of pyruvate are used by skeletal muscle cells to produce TWO molecules of
lactate(aka lactic acid)
lactic acid fermentation
The conversion of pyruvate to lactate with no oxygen.
Where does lactic acid fermentation occur?
cytoplasm of skeletal muscle cells
in the presence of oxygen hydrogen ions are___________ by mitochondria In the absence of oxygen hydrogen ions _____________with lactic acid
absorbed; accumulate
what happens to the pH of our muscles when hydrogen ions accumulate with lactic acid
decreases!!
as a result of pH decreasing, what happens to muscles?
muscle FATIGUE; metabolic(lactic) acidosis
Where is the majority of ATP produced during PEAK activity?
glycolysis(w/ acetate and H+ as biproducts)
During muscle fatigue, the muscle will no longer perform at required level EVEN if _____________
stimulated
why does muscle fatigue affect sprinters more quickly
they rapidly build uo lactic acid
how does muscle fatigue affect the muscles of marathon runners?
after using stores of glycoge and lipids(depletion of energy reserves)
What is the recovery period?
time required after exertion for muscles to return to normal
How is the recovery period carried out
restoring oxygen levels, removing lactic acid, replacing intracellular energy reserves, Losing heat produced during contraction
how is the removal of lactic acid after exercise(recovery period) carried out?
releasd into blood, sent to liver, converted to glucose in liver (energy source)
liver uses extra glucose to make _________
glycogen
AT rest our muscles have more ____________than ATP
CP(creatine phosphate)
At rest, the rate of heat loss________
increases(blood flow increases and sweat gland secretions increase)
How is muscle performance measured?
force and endurance
what is force
max amt of tension produced by muscle or muscle group
what is endurance
the amount of time an activity can be sustained
What two factors determine performance
Types of fibers in muscle (fast-twitch and slow-twitch)
Physical conditioning or training
Wat is the most common type of fibers in our muscles
fast twitch fibers
why are they called fast(fast twitch) fibers
they reach peak tension very quickly
fast(fast twitch) fibers have a large _________ and ______________
diameter, glycogen reserves
Why do fast(fast twitch) fibers rely on glycolysis
bc they have few mitochondria
Note 
Flashcard (108)