block 5 lecture 13 muscle physiology

Question 1

what does the muscle consist of?

Answer 1

muscle fibers, connective tissue, nerves and stem cells

Question 2

what are the muscle stem cells?

Answer 2

satellite cells

Question 3

when are satellite cells activated?

Answer 3

growth and muscle repair

Question 4

what is the facsia surrounding the skeletal muscle composed of?

Answer 4

adipose tissue and connective tissue

Question 5

what are the three layers of fascia?

Answer 5

outer epimysium
muscle fasicles surrounded by perimysium
muscle fibers are surrounded by endomysium

Question 6

what are myofibrils surrounded by?

Answer 6

sarcolemma

Question 7

what is the sarcolemma continuous with?

Answer 7

sarcoplasmic reticulum

Question 8

what is the epimysium continuous with?

Answer 8

tendons

Question 9

what is each muscle fiber made up of?

Answer 9

myofibrils

Question 10

what are the thick filaments?

Answer 10

myosin

Question 11

what are the thin filaments?

Answer 11

actin

Question 12

what are the contractile proteins?

Answer 12

actin and myosin

Question 13

what is the I band?

Answer 13

thin filaments (actin)

Question 14

what is the A band?

Answer 14

overlap of thick and thin

Question 15

what is the H band?

Answer 15

contains the M line - myosin filaments

Question 16

what is the Z disc?

Answer 16

1 sarcomere

Question 17

what causes the striation of skeletal muscle?

Answer 17

the different filaments

Question 18

what is myosin made up of?

Answer 18

2 heavy chains and some light chains
2 heads
hinge redgion

Question 19

what is myosin associated with?

Answer 19

actin filament

Question 20

what is the structure of the actin filament?

Answer 20

2 molecules form together to form a double strand
it is a helical polymer
there are groovs

Question 21

what is actin associated with?

Answer 21

tropomyosin

Question 22

what are the elements of tropomyosin?

Answer 22

troponin C
troponin T
troponin I

Question 23

what is the molecular mechanism of muscle contraction called?

Answer 23

sliding filament model

Question 24

what happends when actin binds to the myosin head?

Answer 24

cross bridge forms

Question 25

what does calcium release do to tropomyosin?

Answer 25

calcium binds to troponin C causing the molecule to undergo a conformational change

Question 26

what does ATP do during muscle contraction?

Answer 26

causes discosiation of myosin head to actin

Question 27

what does the myosin head act as in regard to the ATP?

Answer 27

ATP ase - hydrolyses ATP into adenosphene diphosphate and inorganic phosphate

Question 28

what happens to the hydrolyses ATP

Answer 28

it stays bound

Question 29

what happens when myosin head is bound to new actin molecule down the chain?

Answer 29

inorganic phosphate is released

Question 30

what causes the power stroke?

Answer 30

inorganic phosphate is release

Question 31

what happens to the ADP after the power stroke?

Answer 31

ADP is released and a new molecule of ATP comes along

Question 32

why do you get rigor mortis after death?

Answer 32

there is no ATP

Question 33

what are the receptors at the neuromuscular junction for acetylecholine?

Answer 33

nicotinic cholinergic receptors

Question 34

how is the neuromuscular junction specialised?

Answer 34

highly folded

Question 35

what happens when the motor neuron is depolarised?

Answer 35

voltage gated calcium ion channels are opened

Question 36

what happens after voltage gated calcium ion channels are opened?

Answer 36

there is an influx of calcium and the calcium binds to calmodulin

Question 37

what are on the presynaptic membrane for the vsicles containing acetylecholine?

Answer 37

docking receptors - snap and snare proteins

Question 38

what happens when the vesicles containing acetylcholine fuse with the presynaptic membrane?

Answer 38

exocytosis and the neurotransmitters diffuse across the cleft

Question 39

what happens after the neurotransmitters diffuse across the cleft?

Answer 39

acetylcholine binds to nicotinic cholinergic receptors

Question 40

what happens when acetylcholine binds to nicotinic cholinergic receptors?

Answer 40

sodium and potassium channels are opened

Question 41

what happens when the sodium channels are opened on the post synaptic membrane?

Answer 41

the membrane is depolarised creating an end plate potential

Question 42

what breaks down acetylcholine?

Answer 42

acetylecholine esterase

Question 43

what does acetylecholine esterase break acetylecholine into?

Answer 43

acetate and choline

Question 44

what happens to the choline produces by the action of acetylcholine?

Answer 44

taken back to the nerve terminal for reuse

Question 45

what happens to the acetate produces by the action of acetylcholine?

Answer 45

enters the krebs cycle

Question 46

what is succinylcholine? and when is it used?

Answer 46

muscle relaxant, used in surgery, block nicotinic cholinergic receptors

Question 47

what does botulinum do?

Answer 47

inhibits the snap and snare proteins inhibiting vesicle release

Question 48

what does peridostigmine do?

Answer 48

inhibits acetylcholine esterase

Question 49

what do snakes release?

Answer 49

alphabungero toxin, binds avidly to nicotinic cholinergic receptors

Question 50

what is the potential of skeletal muscle at rest?

Answer 50

-90mv

Question 51

what is the threshold of skeletal muscle?

Answer 51

-50mv

Question 52

what is the end plate potential?

Answer 52

-15mv

Question 53

what are either side of the of the T tubules?

Answer 53

terminal cisternae

Question 54

what do the T tubule and the terminal cisternae form?

Answer 54

triad

Question 55

what does the sarcoplasmic reticulum store that is needed for moving troponin?

Answer 55

calcium ions

Question 56

what receptors are found in the T tubules?

Answer 56

dihydropyrodine receptors

Question 57

what are dihydropyrodine receptors?

Answer 57

L type calcium channels, they are voltage sensors

Question 58

what are voltage sensory connected to?

Answer 58

ryanodine receptors

Question 59

what does muscle membrane depolarisation cause?

Answer 59

opens L type calcium channels

Question 60

what causes the release of calcium in muscle cells?

Answer 60

L type calcium channels are coupled with calcium release channels

Question 61

what happens during relaxation?

Answer 61

Na/Ca exchanges the ions | calcium ions are bound in the sarcoplasmic reticulum by calrecticulin and calsequestrin

Question 62

what happens in rigor mortis?

Answer 62

calcium ions diffuse out of the sarcoplasmic reticulum allowing the myosin heads to bind to actin, there is no ATP synthesis so cross bridges cant detatch

Question 63

what are the three phases of muscle twitch

Answer 63

1. lag phase 2. contraction phase 3. relaxation phase

Question 64

what is a motor unit?

Answer 64

motor nerve and the fibers it innervates

Question 65

what is the innervation ratio

Answer 65

number of muscle fibers innervated by a motor nerve

Question 66

what are the types of contraction?

Answer 66

isometric and isotonic

Question 67

what happens in isometric contraction?

Answer 67

no change in length - tendons take up stretch

Question 68

what happens in isotonic contraction?

Answer 68

muscle shortens

Question 69

what are the three muscle types involved in twitch?

Answer 69

type 1 - slow twitch type 2a - fast glycolytic twitch type 2b - fast twitch fatigue resistant

Question 70

what are the features of the type 1 slow twitch?

Answer 70

always oxidative, resistant to fatigue, maintain posture, good blood supply, most myoglobin, red

Question 71

what are the features of the type 2a fast twitch?

Answer 71

white fibers, poor blood supply, sucseptible to fatigue

Question 72

what are the features of the type 2b fast twitch?

Answer 72

oxidative, intermediate myoglobin, intermediate fibers, fatigue resistant

Question 73

what are the three sources of ATP

Answer 73

creatine phosphate anaerobic respiration aerobic respiration

Question 74

what is myopathy?

Answer 74

any muscle diseae

Question 75

what is myositis?

Answer 75

inflammatory problem

Question 76

what is muscular dystropy?

Answer 76

inherited, progressive

Question 77

what is myotonia?

Answer 77

failure of relaxation

Question 78

what is myasthenia

Answer 78

weakness on excersize

Question 79

what is channelopathies?

Answer 79

abnormal Na/K/Cl channels