CH 9 MUSCULAR SYSTEM

Question 1

List three muscle types

Answer 1

Skeletal, Cardiac, Smooth

Question 2

Skeletal muscle definition

Answer 2

attached to bones voluntary control striated multi-nucleated limited regeneration

Question 3

Cardiac muscle definition

Answer 3

in heart walls involuntary striated short no regeneration controlled by pacemakers within heart intercalated discs autonomic nervous system regulation

Question 4

Smooth muscle definition

Answer 4

in the walls of the hollow organs involuntary not striated spindle shaped fast regeneration autonomic nervous system regulation

Question 5

Voltage

Answer 5

gated channels open when membrane potential changes

Question 6

Ligand

Answer 6

gated channels open when chemicals(such as neurotransmitters) attach to them

Question 7

ion channels

Answer 7

allow ions to diffuse across the cell membrane

Question 8

gated channels

Answer 8

these open and close, when closed do not allow any diffusion of ions

Question 9

Myosin

Answer 9

protein shaped like a double headed golf club

Question 10

Each thick filament contains _____ ______ molecules

Answer 10

300 myosin

Question 11

Central position of thick filament is ____, but its ends are _____ with a staggered array of myosin heads

Answer 11

smooth, studded

Question 12

thin filaments of muscle is made of ___

Answer 12

actin

Question 13

Actin

Answer 13

2 thin strands of protein that wind around each other and contains myosin binding sites (that the myosin heads attach to)

Question 14

When muscle is relaxed, ______ blocks myosin binding site on actin

Answer 14

tropomyosin

Question 15

Smooth muscle gross anatomy

Answer 15

arranged in layers in walls of hollow organs, cells in adjacent layers have opposite orientation

Question 16

Longitudinal layer

Answer 16

muscle fibers run parallel to the long axis of the organ. when the muscle contracts, the organ dilates and shortens

Question 17

Circular layer

Answer 17

fibers run around the circumference of the organ. Contraction of this layer constricts the lumen of the organ and causes the organ to elongate.

Question 18

Varicosity

Answer 18

large bulb-like swelling in the neuron

Question 19

Stimulation for contraction may be _______ innervation, _______, _____ conditions

Answer 19

autonomic, hormonal, local

Question 20

Skeleton muscles has 3 connective tissue sheaths ( all continuous with one another) which are

Answer 20

Epimysium, Perimysium, Endomysium

Question 21

Epimysium

Answer 21

dense connective tissue, surrounds whole muscle

Question 22

Perimysium

Answer 22

fibrous connective tissue, surrounds fascicles

Question 23

Endomysium

Answer 23

Sheath of fine areolar connective tissue with reticular fibers, surrounds each muscle fiber (cell)

Question 24

Sacroplasm

Answer 24

stores glycogen, myglobin, and creatine phosphate all are related to energy needs

Question 25

Nucleus

Answer 25

Multinucleated because they originate from fusion of several myoblast cells nuclei are pushed to side

Question 26

Myofibril

Answer 26

Rod-like structures that fill the cell contains bundles of proteins that compose the contractile units, about 2 micrometers in diameter, extend the entire length of the muscle fiber

Question 27

Thick/thin filaments

Answer 27

the proteins of the myofibrils

Question 28

Sacromere

Answer 28

the contractile units formed by the thick and thin filaments of the myofibril

Question 29

Muscle-atrophy

Answer 29

wasting away of muscles, individual muscle fibers decrease in size due to lack of use, or disturbance of nerve supply.in about 6 months to 2 years, the muscle will be a quarter of its original size, and will be replaced by fibrous c.t. a process that when complete cant be reversed

Question 30

4 types of attachments

Answer 30

origin, insertion, direct(fleshy), indirect

Question 31

Origin

Answer 31

attachment to bone that does not move during contraction

Question 32

Insertion

Answer 32

attachment to bone that moves during contraction

Question 33

Direct

Answer 33

epimysium of muscle fused to periosteum of bone or perichondrium of cartilage

Question 34

indirect

Answer 34

muscles connective tissue wrappings extend beyond muscle as a ropelike tendon or aponeurosis. indirect is much more common due to durability and small size.

Question 35

4 steps of skeletal muscle contraction- relaxation

Answer 35

excitation, excitation-contraction coupling, contraction (with power stroke), relaxation, cardiac muscle contraction is very similar to skeletal muscle contraction

Question 36

muscle cells typically have a ____ resting membrane potential

Answer 36

-70mv

Question 37

each muscle fiber has only one ___________ junction, located midway along the fibers length

Answer 37

neuromuscular

Question 38

list the steps for excitation

Answer 38

nerve impulse reaches axon –> ACh is released into cleft –> ACh attaches to receptors (ligand gated ion channels) –> Na floods more quickly than K into the cell and the sarcolemma depolarizes –> Action potential

Question 39

Excitation- contraction coupling neighboring voltage gatedd Na channels open and …..

Answer 39

depolarization sweeps across sacrolemma and into T-Tubules –> causes Ca to be released from terminal cisternae into cytoplasm –> ca attaches to troponin –> troponin changes shape and pulls the tropomyosin off the myosin binding sites on the actin –> myosin heads bind to the exposed binding sites

Question 40

muscle contraction- power stroke steps

Answer 40

when cell is resting, ca levels in the cell are low and myosin binding sites on actin are physically blocked by tropomyosin. when terminal cisterns releases ca into cytoplasm –> calcium attaches to tropinin –> troponin/tropomyosin complex moves which opens the myosin binding sites on the actin –> power strokes occur

Question 41

Contraction is the result of ______ shortening

Answer 41

sacromeres

Question 42

T or F: when relaxed the think and thick filaments overlap slightly

Answer 42

TRUE

Question 43

Contractio cycle (4 steps) (continuous until relaxation)

Answer 43

1. ATP hydrolysis
2. attachment of myosin to actin to form crossbridges
3. power stroke
4. detachment of myosin from actin

Question 44

Contraction- relaxation steps

Answer 44

cycle repeats to shorten sacromeres (muscle contracts) –> cycle is broken when calcium is reabsorbed into terminal cisterns –> tropinin/tropomyosin move back to cover myosin binding sites on actin –> sacromeres return to original length (muscle relaxes)

Question 45

Autorhythmic cells-pacemaker cells-

Answer 45

set heart rate 70bpm, auto or self generate action potentials and stimulate neighboring cells to generate and propagate action potentials