WEEK 5 - muscle physiology Flashcards
what is the structure function breakdown of the muscle ?
- muscle
- mundle of muscle fibers
- single muscle fiber (cell)
- myofibril
- sarcomere
where is the muscle fiber ?
in the muscle belly
where do muscle fibrils run ?
throughout the whole length (is the contracting unit)
TRUE OR FALSE
muscle fibre = muscle cell
TRUE
TRUE OR FALSE
muscle fibers have the same functional parts of the muscle cell
TRUE
what are the parts of the sarcomere ?
- thick and thin filament
- z-disk
- a-band
-I-band
what do crossbridges allow ?
allows muscle to change length (amount go overlap either increases or decreases) ; shortening or lengthening
what are the stricture function steps of the skeletal muscle ?
→ crossbridge binds → crossbridge rotates → crossbridge unbinds → crossbridge resets
what does each crossbridge contain ?
- 1 ATP
- 3.4 pN force
- 10nm length change
define muscular strength :
force a muscle or muscle group can exert in one maximal effort
define muscular endurance :
ability of muscles or muscle groups to perform repeated or sustained contractions
what is muscular strength determined by ?
muscle size and neural drive
what does bigger muscle = ?
more crossbridges
what does more crossbridges = ?
more force
what is muscle endurance determined primarily by ?
- increased capillarization (more blood flow)
- increased mitochondria dir density/function
what does endurance do ?
maintain those muscle contractions (need oxygen; provides the muscle with ATP) ; how well can we utilize oxygen to make ATP
what does increased mitochondria density / function lead to ?
- increased ATP
- increased crossbridges
- increased density
what is contractile function of muscle dependent on ?
fiber type
in humans, what are skeletal muscle characterized by ?
fast and slow twitch muscle fibers
what are the two types of fast (type 2) :
- type IIx (fastest)
- type IIa (fast)
define the fatigue resistance of type I (slow) :
high
define the fatigue resistance of type IIa :
moderate
define the fatigue resistance of type IIx :
low
define the ATPase activity of type I (slow) :
low
define the ATPase activity of type IIa :
high
define the ATPase activity of type IIx :
high(er)
define the contraction speed of type I (slow) :
slow
define the contraction speed of type IIa :
moderately fast
define the contraction speed of type IIx :
fast
define the mitochondria density of type I (slow) :
high
define the mitochondria density of type IIa :
moderate
define the mitochondria density of type IIx :
low
define the myoglobin of type I (slow) :
high
define the myoglobin of type IIa :
moderate
define the myoglobin of type IIx :
low
define the force output of type I (slow) :
low
define the force output of type IIa :
moderate
define the force output of type IIx :
high
FILL IN THE BLANK
slow muscles has (greater or lesser) capillary and mitochondrial density, which supports aerobic metabolism and (improves or fails) fatigue resistance ?
greater & improves
FILL IN THE BLANK
replacement of contractile tissue with non-contractile material (mitochondria, capillary, etc) decrease _____ ___________
force potential
talk about the “tale of two breasts: chicken vs duck” :
- despite having a similar build and size, the two animals preform different
- duck = more red (high myoglobin content)
- duck = slow twitch (endurance)
- chicken = fast twitch (sprint)
- duck = 8 hrs, 800 miles
- chicken = 13 secs, 300 ft
what are the two ways tissues can grow ?
hypertrophy and / or hyperplasia
what is hypertrophy ?
increase in the size of individual muscle fibers
what is hyperplasia ?
increase in the number of muscle fibers
between hypertrophy and hyperplasia, which is more difficult to grow # of cells ?
hyperplasia
FILL IN THE BLANK
predominance (>95%) of muscle growth attributed to _________
hypertrophy
how is muscle growth accomplished (in regards to anatomy) ?
accomplished with an increased number of myofibrils per fiber
TRUE OR FALSE
tissues can grow through hypertrophy and / or hyperplasia
TRUE
what is hypertrophy ?
increase in the size of individual muscle fibers
what is hyperplasia ?
increase in the number of muscle fibers
what are amino acids that are delivered to the muscle used to form ?
amino acids delivered to muscle are used to form muscle proteins that comprise new myofibril s
what is the myonuclear domain theory ?
each nucleus of a muscle cell is responsible for a finite volume of cell space
in order for a muscle fiber to grow (hypertrophy), what much increase ?
the number of nuclei needs to increase
what are satellite cells ?
quiescent cells that activate and enter the fiber
myogenic stem cells responsible for muscle regeneration throughout the lifespan
what do satellite cells aid in ?
aid in tissue repair
what do satellite cells donate ?
their nuclei
TRUE OR FASE
satellite cells are similar to stem cells ?
TRUE
what is the stimulus of muscle growth ?
exercise
what is the adaptation of muscle growth ?
- muscle protein synthesis generates new myofibrils within existing fibers (muscle hypertrophy)
- satellite cells proliferate and differentiate to form new nuclei to support cell processes of now bigger fibers
what does muscle respond (in specific ways) in response to ?
overload
what do muscle growth stimulus responds to ?
- metabolic accumulation
- mechanical forces
- immune signalling (inflammation)
what is muscular strength based on ?
muscle size and activation
what is muscular endurance based on ?
capillary and mitochondria density
FINISH THE SENTENCE …
muscles adapt to exercise stimulus by _________________________________
generation of myofibril muscle protein and satellite cell differentiation into nuclei
what are muscle adaptation stimulated by ?
accumulation of metabolites, detection of mechanical forces and inflammation
