Muscle Physiology

Question 1

Functions of the muscular system

Answer 1

1. move the body
2. maintain posture
3. produce body heat
4. respiration
5. communication
6. constriction of organs/vessels
7. heart beat

Question 2

muscle properties

Answer 2

1. contractility (ability to shorten)
2. excitability (how easily they react to stimuli)
3. extensibility (ability to be stretched beyond normal length)
4. elasticity (ability to recoil to original strength after stretching)

Question 3

smooth muscle

Answer 3

Involuntary muscle located in the walls of blood vessels and internal organs

Question 4

Cardiac Muscle

Answer 4

involuntary, striated muscle found only in the heart

Question 5

skeletal muscle

Answer 5

striated, voluntary muscle, over 400 in the body

Question 6

Skeletal muscle function

Answer 6

1. movement
2. breathing
3. postural support
4. heat production during cold stress

Question 7

what are the layers of skeletal muscle connective tissue?

Answer 7

epimysium- surrounds the entire muscle, continuous with tendons
perimysium- surrounds bundles of muscle fibers
endomysium- surrounds each individual muscle fiber

Question 7

sarcolemma

Answer 7

the muscle cell membrane, surrounds each muscle fiber, fuses with tendon

Question 8

myofibrils

Answer 8

contain contractile elements, divided into sarcomeres

Question 9

sarcoplasm

Answer 9

fluid part of muscle fiber separating myofibrils. contains myoglobin, which carries o2 in the muscle

Question 10

I-band

Answer 10

sarcomere region which contains actin, extends to end of myosin filament

Question 11

a-band

Answer 11

sarcomere region w/ overlapping actin and myosin

Question 12

h-zone

Answer 12

center of A band, contains only myosin, only visible in the resting state

Question 13

myofibrils

Answer 13

bundles of protein filament

Question 14

actin

Answer 14

the thin myofibril filament, attached to the z line, contains the active binding site for myosin

Question 15

myosin

Answer 15

the thick myofibril filament, made of 2 protein strands twisted together within the A-band, contains several protrusions called myosin heads

Question 16

tropomyosin

Answer 16

component of actin that covers the active binding site during rest

Question 17

troponin

Answer 17

component of actin that binds to ca2+

Question 18

how does myosin provide energy for contraction?

Answer 18

myosin heads contain ATPase, once myosin binds with ATP the ATPase splits the ATP to produce energy for the myosin to bind to actin

Question 19

Type IIa fiber

Answer 19

intermediate fast twitch/fast glycolytic

Question 20

Type IIb fiber

Answer 20

Fast twitch/ fast glycolytic, short, explosive activities

Question 21

what are the biomechanical properties of muscle fiber

Answer 21

oxidative capacity (determined by mitochondria and surrounding capillary amounts) and type of ATPase (fast twitch fibers = fast ATPase, and vice versa)

Question 22

Type I fiber

Answer 22

slow twitch, slow oxidative

Question 23

what are the contractile properties of muscle fiber

Answer 23

max force production, contraction speed (determined by speed at which ATP is broken), muscle fiber efficiency

Question 24

which muscle fiber type has a more developed sarcoplasmic reticulum, and why is it important?

Answer 24

Fast twitch, allows for Ca2+ to be delivered more readily into the muscle

Question 25

force is determined by (?), not (?)

Answer 25

number of fibers per motor unit, not amount of force generated per fiber

Question 26

which motor unit type reaches peak tension quicker and generates more force?

Answer 26

fast twitch

Question 27

selective recruitment

Answer 27

refers to the way motor units are recruited in order of size during an activity (smallest first) based on the requirements of that activity, not its speed

Question 28

agonist

Answer 28

prime mover muscle

Question 29

synergist

Answer 29

muscle that assists the prime movers, fine tunes movement

Question 30

antagonists

Answer 30

muscles that oppose the action of the prime movers, prevent overstretching/ overrecruitment

Question 31

Isotonic movement

Answer 31

dynamic movement, consists of concentric and eccentric

Question 32

concentric

Answer 32

muscles shorten during force production (ex: upwards phase of a curl)

Question 33

eccentric

Answer 33

muscles produce force, length increases (ex: lowering phase of curl)