SKELETAL PART 1

Question 1

what are the four functions of muscle tissue

Answer 1

produce movement, maintain posture and body position, stabilize joints, generate heat (as they contract)

Question 2

what are then four characteristics of muscle tissue

Answer 2

excitability, contractility, extensibility, elasticity

Question 3

does muscle need to be attached to bone to be moved

Answer 3

yes

Question 4

what are myotendinous junctions

Answer 4

where muscle fibers connect to tendons; prone to damage

Question 5

where are the primary sources of force transmission

Answer 5

myotendinous junctions

Question 6

what do myotendinous junctions allow for

Answer 6

allow force generated by muscle fibers to be applied through the tendons to the bones to produce desired movements

Question 7

describe three main traits of skeletal muscle fibers

Answer 7

multinucleated; technically differentiated; highly plastic

Question 8

describe the highly plastic part of skeletal muscle

Answer 8

load-driven size alterations; increase activity = hypertrophy; decrease activity = atrophy; activity-determined phenotype (I, IIa,IIx)

Question 9

describe the length of skeletal muscle fibers

Answer 9

varies considerably in human muscles; length + width affect force production potential

Question 10

differentiate between short and long muscle fibers

Answer 10

short fibers = more force, long fibers = higher velocities

Question 11

describe numbers of skeletal muscle fibers

Answer 11

several number fibers in small muscles to a million+ in large muscles; coordination and relaxation of many individual cues that occurs during standing, running, walking etc

Question 12

whats the sacrolemma

Answer 12

muscle fiber plasma membrane

Question 13

whats the sacroplasm

Answer 13

muscle fiber cytoplasm (contains proteins, minerals, fats, organelles, glycogen, myoglobin)

Question 14

what are the modified organelles for contractions

Answer 14

transverse tubules, sarcoplasmic reticulum, myofibrils

Question 15

what are transverse tubules

Answer 15

inholdings of sarcolemma that protrude inwards + conduct electrical impulses from surface of cell to terminal cisternae

Question 16

whats the sarcoplasmic reitculum

Answer 16

membranous channel parallel to myofibril and storage site for Ca2+ (basically smooth ER of muscle cells)

Question 17

describe myofibrils

Answer 17

roughly 80% of cellular volume and contain the contractile elements of muscle cells (myofilaments)

Question 18

what are striations

Answer 18

occur because of repeating series of dark A bands and light I bands

Question 19

what are the light I bands

Answer 19

actin

Question 20

how do the light and dark bands appear

Answer 20

dark because light can’t go through because of the myosin

Question 21

what are the two types of myofilaments

Answer 21

myosin (thick filaments) + actin (thin filaments)

Question 22

what are tropomyosin and troponin

Answer 22

regulatory proteins on actin

Question 23

describe the sacromere

Answer 23

smallest contractile unity; length-tension relationship; distance from one Z-disk to the next

Question 24

whats G-actin

Answer 24

individual subunits of F-actin; globular actin; actin monomers

Question 25

whats F-actin

Answer 25

filamentous actin; arranged in double helix; many G-actin come together to form

Question 26

describe actin

Answer 26

myosin binding site; exposed by removal of tropomyosin; attaches to myosin crossbridge

Question 27

whats myosin

Answer 27

~300 myosin molecules in one thick filament; important for muscular force and velocity of contraction; different myosin isoforms have diff force/velocity charcterstrics; different muscle types

Question 28

describe the different types of myosin heavy chains in animals

Answer 28

slow: type I fast: Type IIA Type IIX

Question 29

describe Type I fibers

Answer 29

endure low intensity activity (like sitting in a chair), slow contraction, high myoglobin, colored red

Question 30

describe Type IIA fibers

Answer 30

high force of contraction; cannot sustain effort for long time; fast contraction; high myoglobin; colored red to pink; fatigue more quickly

Question 31

describe Type IIX fibers

Answer 31

fast contraction, low myoglobin, colored white, tired out very quickly; strongest, quick/explosive movemenrs

Question 32

describe fiber recruitment

Answer 32

based on need for force production; recruit type I first and then move to type IIA and type IIX depending on needs

Question 33

why is Type I red

Answer 33

more capillaries in type I; some in Type IIA which is why its pink and none in Type IIX which is why its white

Question 34

what happens to muscle fiber content as people get more fit

Answer 34

Type I remains stable, Type IIA increases a ton and type Iix decreases a ton

Question 35

describe exercise + MHS content with age

Answer 35

as fit people age, their MHC IIA content increases and type Iix disappears