muscle physiology 1

Question 1

________ is the the sliding of actin past myosin generates muscle tension

Answer 1

Sliding filament theory

Question 2

_______ is the smallest contractile unit of a muscle fiber

Answer 2

Sarcomere

Question 3

compare the bands and lines in a sarcomere (I, A, M, Z)

Answer 3

-I band: light portion made up of actin filaments (thin filament)
-A band: dark portion made up of myosin (thick filament)
-M line: in very middle
-Z line: where two neighboring I bands meet

Question 4

during a contraction how do the Z lines change?

Answer 4

the distance between the two Z-lines decreases because the Z-line moves toward the H-line

Question 5

does the length of the A band change during a contraction?

Answer 5

no

Question 6

does the length of the I band change during a contraction?

Answer 6

yes

Question 7

Crossbridge linkage between thick and thin filaments are achieved by what two things?

Answer 7

-Chemical and/or electrostatic linkages
-Force generation/ number of bonds between myosin and actin that are made in parallel

Question 8

______ cross bridges = more force

Answer 8

more

Question 9

what does in parallel vs in series mean?

Answer 9

-In Parallel: more than one sarcomere is contracting at the same time in different myofibrils. We assume that other myofibers are extending too
-In series: consecutive sarcomeres of one myofibril are contracting. We assume that one myofiber is contracting while others are not

Question 10

In parallel has ____ chance of producing muscle shortening, while series has _____ chance

Answer 10

GREATER, LESS

Question 11

Force generation is _____kg/cm2 cross-sectional area of muscle

Answer 11

3-4kg per cm2

Question 12

Skeletal muscle in males is _____% body weight, while in females muscle is only ____% body weight

Answer 12

40, 32

Question 13

Edible mussels generate _____ force in shell retractor

Answer 13

15kg/cm2

Question 14

do males and females generate the same force per cm2?

Answer 14

yes

Question 15

what is the lever ratio?

Answer 15

power arm of lever : load arm of lever

Question 16

What does it mean if there is a 1:7 lever ratio?

Answer 16

This means, for every 1cm the muscle (bicep) moves, the hand (or limb attached) will move 7 cm

Question 17

what is the tension to lift weight formula

Answer 17

Tension to lift weight = (weight)(1/ratio)

Question 18

Short distance of bicep contraction = ______ mvmt of hand with great speed

Answer 18

large

Question 19

Forceful exercise produces _______ that results in hypertrophy of myofibers. what does this mean?

Answer 19

hyperplasia of myofibrils
-myofibrils split forming more myofibrils within a myofiber

Question 20

does hyperplasia of myofibrils create more myofibrils in series or parallel?

Answer 20

parallel

Question 21

do long-distane runners experience hypertrophy?

Answer 21

no, because they are not exercising their muscles at maximal load

Question 22

sprinters experience ________ which adds myofibrils in parallel

Answer 22

myofiber hypertrophy

Question 23

why are bodybuilders so big?

Answer 23

-Muscles are larger due to more blood and interstitial fluid in the muscle and more water/sarcoplasmic fluid in each myofiber (sarcoplasmic hypertrophy)
NOT due to myofibril hyperplasia

Question 24

Negative mutation of _________ gene can increase muscle mass naturally

Answer 24

myostatin (Gdf8)

Question 25

________ is the amount of tension that is produced by a muscle as a feature of its length

Answer 25

Length tension

Question 26

when is max force of a muscle?

Answer 26

when greatest number of crossbridge bonds are made at parallel

Question 27

Range of muscle length is greatest within____ of 100% resting muscle length

Answer 27

+/-30%

Question 28

why is muscle not in a constant state of contraction?

Answer 28

because regulator proteins actively inhibit contraction

Question 29

________ sits on top of myosin binding sites on the actin helix.______ sits on top of tropomyosin

Answer 29

Tropomyosin, Troponin

Question 30

explain the relaxation/excitement cycle

Answer 30

-No Ca+ = no crossbridge binding, myosin binding site is covered by troponin/tropomyosin complex -ATP bound to myosin head -Ca+ enters -Ca+ binds to troponin -Troponin rotates on itself and pulls tropomyosin out of the way -Cross-bridge sites are now exposed -Binding of Myosin cross bridge to --Actin triggers the power stroke that pulls the thin filament inward during contraction -During power stroke, ATP hydrolyzed → ADP

Question 31

Myosin’s ATPase is active when ________

Answer 31

myosin is attached to actin

Question 32

There are __ heads on each myosin, and __ binding sites on each head

Answer 32

2,2

Question 33

what are the 2 binding sites on myosin heads?

Answer 33

-Myosin ATPase (where ATP → ADP + Pi) -Actin binding site

Question 34

Change of angle from one row to another = wedged ____ (every 3)

Answer 34

40* CCW