Anatomy And Physiology Ch 10 (Skeletal Muscle Structure / Contraction Of Skeletal Muscle)

Front 1

neuromuscular junction

Back 1

axon terminals and a skeletal muscle fiber

Front 2

synaptic cleft

Back 2

space between the synaptic end bulb and the sarcolemma where acetylcholine diffuses to the motor end plate

Front 3

synaptic end bulb

Back 3

branching divisions off the end of an axon terminal

Front 4

motor unit

Back 4

a somatic motor neuron and all the skeletal muscle fibers it ennervates

Front 5

synaptic vesicles

Back 5

vesicles within the synaptic end bulb that are filled with acetylcholine

Front 6

acetylcholine

Back 6

neurotransmitter molecules

Front 7

motor end plate

Back 7

region of the sarcolemma directly across from the synaptic end bulb
contains ACh receptors

Front 8

sarcolemma

Back 8

plasma membrane of a skeletal muscle fiber

Front 9

somatic motor neurons

Back 9

neurons that stimulate skeletal muscles to contract

Front 10

electromyography

Back 10

the detection, amplification, and recording of changes in skin voltage produced by underlying skeletal muscle contraction
(electrical impulses generated and conducted by muscle fibers)

Front 11

force or strength of a contraction depends on:

Back 11

frequency of motor neuron impulses
number of motor units activated
(motor unit recruitment)

Front 12

tonus

Back 12

state of slight tension in resting skeletal muscles that maintains the muscle in a state of readiness

Front 13

grading

Back 13

changing the strenth of a muscle contraciton in proportion to the load placed on it

Front 14

primary function of muscle

Back 14

to convert chemical energy to mechanical work
(muscle contracting)

Front 15

endomysium

Back 15

layer of areolar connective tissue surrounding
skeletal muscle fibers

Front 16

fascicles

Back 16

bundles of skeletal muscle fibers

Front 17

perimysium

Back 17

layer of dense regular connective tissue surrounding fascicles

Front 18

muscle

Back 18

bundles of fascicles

Front 19

epimysium

Back 19

layer of dense regular connective tissue surrounding a muscle

Front 20

tendons

Back 20

formed from endomysium, perimysium and epimysium that extend beyond each skeletal muscle fiber

Front 21

sarcoplasmic reticulum

Back 21

endoplasmic reticulum in skeletal muscle fibers that specializes in storing calcium

Front 22

myofibrils

Back 22

bundles of thick and thin filaments that contain different proteins
movement of myofibrils causes muscle contraction

Front 23

sarcomeres

Back 23

orderly arrangement of thick and thin filaments
the smallest structural and contractile unit of a muscle myofibril

Front 24

composition of thin filament

Back 24

actin (binding site for myosin)
tropomyosin (nestled between the actin molecules)
tropin (molecules that bind at precise intervals along the tropomyosin strand)

Front 25

T tubules

Back 25

tubelike invaginations in the sarcolemma that transmit the action potential to terminal cisternae

Front 26

terminal cisternae

Back 26

widened areas of the sarcoplasmic reticulum

Front 27

triad

Back 27

two terminal cisternae with
a T tubule between them

Front 28

composition of thick filaments

Back 28

myosin molecules (twisted golfclubs)
the tails form the thick filament
heads (crossbridges) project toward the thin filaments

Front 29

Z discs

Back 29

narrow, plate-shaped regions of dense material that separate one sarcomere from another and secure the thin filaments

Front 30

I bands

Back 30

lighter, less dense areas that contain only thin filaments
stripes are Z discs

Front 31

A bands

Back 31

darker middle part of each sarcomere
extends the entire length of the thick filaments

Front 32

M line

Back 32

supporting proteins that hold the thick filaments together at the center of the H zone

Front 33

H zone

Back 33

narrow center of each A band
cotains only thick filaments

Front 34

Fast Glygolytic Fibers (cells)
FG

Back 34

large diameter
lower myoglobin & blood supply
lighter in color (white)
produce ATP by glycolysis
(fast but not enduring)

Front 35

Slow Oxidative Fibers (cells)
SO

Back 35

smaller in diameter
more myoglobin & blood supply
darker in color (red)
produce ATP by aerobic cellular respiration
(slow but more enduring)

Front 36

Fast Oxidative Glycolytic Fibers
FOG

Back 36

medium diameter
medium color (pink)
produces ATP by both methods

Front 37

4 steps of a muscle contraction

Back 37

1. ATP hydrolysis energizes the myosin head
2. Myosin attaches to actin to form crossbridge - phosphate is released
3. Power stroke initiated by release of phosphate - ADP is released
4. Another ATP binds to myosin binding poscket of actin releasing the myosin head - return to step 1 as long as there is calcium and ATP available