muscle physiology

Question 1

what are three characteristics of muscle tissue

Answer 1

excitable, contractile, elastic

Question 2

what are the three types of muscle tissue

Answer 2

smooth, cardiac, skeletal

Question 3

what are the parts of skeletal muscle

Answer 3

belly, origin, insertion

Question 4

what is the belly of skeletal muscle

Answer 4

the thickest part of the muscle

Question 5

what is the origin of skeletal muscle

Answer 5

proximal/less moveable end

Question 6

what is the insertion of skeletal muscle

Answer 6

proximal/less moveable end

Question 7

what is the endomysium

Answer 7

the connective tissue that is around each muscle cell/fiber

Question 8

what is the periomysium

Answer 8

the connective tissue that is around each fasicle (grouping)

Question 9

what is the epimysium

Answer 9

the connective tissue that is around the entire muscle

Question 10

where is internal tension

Answer 10

within cells

Question 11

where is external tension and what does it do

Answer 11

on the bones to move something

Question 12

what do muscles move

Answer 12

the skeleton, skin

Question 13

what does muscle tone maintain

Answer 13

posture, support joints

Question 14

what produces heat

Answer 14

muscle metabolism

Question 15

how much of the body’s heat is produced from muscle metabolism

Answer 15

80%

Question 16

what is sarcolemma

Answer 16

the muscle membrane

Question 17

what are transverse (T) tubules

Answer 17

pits that go deep off the membrane

Question 18

what is the sarcoplasm

Answer 18

muscle cytoplasm

Question 19

what are myofibrils

Answer 19

cylindrical subunits of contractile protein filaments

Question 20

what is a terminal cisternae

Answer 20

“end containers”
the widening of sacroplasmic reticulum near the t tubule

Question 21

what does the sarcoplasmic reticulum contain

Answer 21

smooth er, terminal cisternae, calcium ions

Question 22

what is glycogen

Answer 22

starch, chains of glucose

Question 23

what does myoglobin do

Answer 23

transfers oxygen

Question 24

do muscle cells have lots of mitochondria

Answer 24

yes

Question 25

where are muscle cell nuclei located

Answer 25

at/near the sarcolemma

Question 26

what is in thick myofilaments

Answer 26

myosin

Question 27

what are myofilaments made of

Answer 27

proteins

Question 28

what is in thin myofilaments

Answer 28

actin, tropomyosin, troponin

Question 29

what are the three parts of troponin

Answer 29

I, T, C (all polypeptides)

Question 30

what does the I polypeptide bind to

Answer 30

actin

Question 31

what does the T polypeptide bind to

Answer 31

tropomyosin

Question 32

what does the C polypeptide bind to

Answer 32

calcium

Question 33

what are A bands dark from

Answer 33

thick (myosin) filaments

Question 34

why is the H zone in A bands pale

Answer 34

there are no thin filaments

Question 35

why are I bands pale

Answer 35

there are no thick (myosin) filaments

Question 36

what is the Z disc/line

Answer 36

where thin filaments are connected to each other

Question 37

what is the sarcomere

Answer 37

the distancebetween adjacent Z disks

Question 38

what happens to I bands when there is contraction

Answer 38

they get smaller

Question 39

what happens to the H zone when there is contraction

Answer 39

it disappears

Question 40

what happens to A bands when there is contraction

Answer 40

they stay the same because it is the length of the thick filaments

Question 41

what happens to the sarcomere when there is contraction

Answer 41

it shortens

Question 42

what does the alpha motor neuron do

Answer 42

stimulates muscle fibers

Question 43

what is a motor unit

Answer 43

1 alpha motor neuron and all muscle fivers that it innerves

Question 44

how many and what type of motor neurons does fine control require

Answer 44

many small motor units

Question 45

how many and what type of motor neurons does gross control require

Answer 45

few large motor units

Question 46

what is the synaptic knob

Answer 46

a widened neuron ending

Question 47

where is acetylcholine (ACh) found

Answer 47

in membrane bound vesicles

Question 48

what is acetylchlinesterase (AChE)

Answer 48

an enzyme that breaks apart ACh

Question 49

where is the motor end plate

Answer 49

on muscle membranes (sarcolemma)

Question 50

what do junctional folds do

Answer 50

increase surface area

Question 51

where are ACh receptors

Answer 51

ACh gated ion channels

Question 52

what is the resting potential of muscle

Answer 52

-90 mV

Question 53

what is the resting potential of neurons

Answer 53

-70 mV

Question 54

why is there a membrane potential

Answer 54

because of the sodium-potassium pumps and gradient

Question 55

what is an action potential

Answer 55

a change in the membrane charge

Question 56

how does a muscle get stimulated by a neuron (8 steps)

Answer 56

1.) action potential from neuron reaches the synaptic knob 2.) the action potential in a neuron opens the voltage gates calcium channels in the neuron knob 3.) calcium diffuses into the neuron 4.) the increase in calcium induces exocytosis of ACh from neuron 5.) ACh diffuses to the ACh receptor on the sarcolemma 6.) ACh receptors allow sodium to diffuse into the cell and potassium to diffuse out of the cell 7.) the muscle cells creates an action potential 8.) the process stops by ACh being broken apart by AChE

Question 57

what are the steps to excitation-contraction coupling (8)

Answer 57

1.) action potential is recreated along the sarcolemma and down T tubules 2.) an action potential opens the voltage-gated calcium channels in the sarcoplasmic reticulum 3.) Calcium diffuses out of the sarcoplasmic reticulum, binding to troponin, and moving through tropomyosin, exposing binding sites on the actin filament 4.) myosin heads bind to actin 5.) myosin heads bend and release previously attached ADP and phosphate 6.) ATP attached to myosin head to release cross bridge 7.) the myosin head recocks 8.) the process continues as the action potential is releasing calcium around myofilaments and ATP is available

Question 58

what happens during rigor mortis

Answer 58

there is a lack of ATP causing the calcium pumps to stop working, calcium to increase around actin and myosin, exposing binding sites, and not releasing

Question 59

what is nerve gas

Answer 59

AChE is no longer working so ACh stays at the neurotransmitter junction, keeping the muscle contracted

Question 60

what is a muscle twitch

Answer 60

a rapid "jerk" response to a single stimulus

Question 61

what causes the muscle to twitch

Answer 61

a stimulus above the threshold

Question 62

what happens during the latent period of a muscle twitch

Answer 62

calcium releases from the sarcoplasmic reticulum, exposing binding sites at crossbridges

Question 63

what happens during the contraction period of a muscle twitch

Answer 63

actin and myosin interact and the muscle shortens

Question 64

what happens during the relaxation phase of a muscle twitch

Answer 64

there is no muscle action potential --> there is a decrease in calcium through the calcium pump --> cover binding sites and ATP is released --> the muscle stops contracting

Question 65

when does wave summation happen

Answer 65

when the stimulus frequency is changed

Question 66

what is tetanus

Answer 66

a sustained contraction

Question 67

why do contractions continue to grow

Answer 67

because calcium is maintained

Question 68

what is recruitment

Answer 68

multiple motor unit summation