Module 16 - Muscle

Question 1

3 types of muscle cell

Answer 1

smooth
skeletal and cardiac (striated)

Question 2

2 functions of skeletal muscle

Answer 2

movement
heat generation

Question 3

what is muscle fiber

Answer 3

single muscle cell
smallest part of muscle tissue
aka a myocyte

Question 4

name of a bundle of muscle fibres

Answer 4

fascicle

Question 5

name the sheath of connective tissue surrounding bundle of muscle fibres

Answer 5

perimysium

Question 6

name of connective tissue that surrounds individual muscle fibres

Answer 6

endomysium

Question 7

name the outer layer of muscle

Answer 7

epimysium

Question 8

what is a triad made up of

Answer 8

T tubule
terminal cisternae

Question 9

what is the sarcolemma

Answer 9

cell memb of msucle fibre
NOT to be confused with endomysium which is connective tissue on top of this

Question 10

sarcomere sections in order left to right

Answer 10

Z line
I band (crosses over 2 sarcomeres)
A band
H zone
M line
see diagram

Question 11

what is thick filament made up of

Answer 11

myosin and titin

Question 12

what is thin filament made up of

Answer 12

actin and nebulin

Question 13

which of the filaments connects to the M line

Answer 13

thick filament

Question 14

what happens when muscle contracts to the filaments

Answer 14

thin move closer together
thick filaments have contractin in titin at the end

Question 15

cross section - what filaments are present in A band

Answer 15

thick and thin filaments

Question 16

cross section - what filaments are present in H zone

Answer 16

thick filaments

Question 17

cross section - what filaments are present in I band

Answer 17

thin filaments

Question 18

qhat is optimum srcomere length fro highest contrac force

Answer 18

1.1-1.2 micometres

Question 19

how many types of myosin

Answer 19

9
8 skeletal/cardiac
1 smooth
(myosin = hexamer, 2 heavy chains, 2 regulatory light chains, 2 heavy chains)

Question 20

what type of actin is found in muscle

Answer 20

filamentous actin

Question 21

tropomyosin structure

Answer 21

2 alpha helixes in coiled coil
1 for every 7 actin

Question 22

what are the 3 components of troponin and what do they do

Answer 22

T = binds with tropomyosin
C = binds Ca2+ during contraction
I = binds with actin and inhibits myosin by covering binding sites

Question 23

what happens when ATP binds to myosin

Answer 23

myosin dissociates froma actin
ATP hudrolysed to ADP and Pi
mysoin moves along
Pi dissociates
ADP dissociates

Question 24

what molecule regulates contration and how

Answer 24

Ca2+
binds to TnC = causes it to move and uncover binding sites on myosin

Question 25

name the channel in SR that allows main movement of Ca2+ into the cytoplasm

Answer 25

ryanodine receptor

Question 26

what channel acts as a voltage sensor and activates the ryanodine receptor

Answer 26

L type Ca channels (DHP) in the sarcolemma memb

Question 27

what receptor allows resotration of Ca balance

Answer 27

SERCA receptors in SR memb moves Ca frm cyto back into SR

Question 28

what triggers the DHP receptor to activate

Answer 28

depolarisation of sarcolemma memb via AP being passed down after nACh receptors are activated

Question 29

name process that occurs when neuron meets muscle fibre and neruomuscular junction

Answer 29

aborization basiclaly it just splits into branches

Question 30

what type of disease is myasthenia gravis

Answer 30

autoimmune disorder attacking skeletal muslce leading to muscle weakness and fatigue

Question 31

who is MG most common in

Answer 31

women 20-40

Question 32

how do we know thymus gland may be involved in MG

Answer 32

many have thymomas Removal of the thymus gland can prove beneficial for many patients

Question 33

where are the ACh binding sites in nACHr

Answer 33

between alpha and delta and alpha and epsilon on extracellular side

Question 34

what does 2nd TM domain of nAChr form

Answer 34

the inner lining of ion channel

Question 35

where to antibodies in MG target on nACHr

Answer 35

extracellular parts of alpha subunits aka the main immunogenic region MIR

Question 36

what are the 3 pathological mechanisms of MG

Answer 36

1 - antibody binding causes receptors to be internalised (endocytosis) 2 - end plate region destroyed/simplified by immune system 3 - antibodies can act as comp ant and dont allow Ach to bind (this is least important one, others have more effect)

Question 37

3 types of treatment for MG

Answer 37

AChesterase inhibitors (reversible) (end in -stigmine) Immunosuppressants (azathioprine) Plasma therapy/plasmapheris/plasma exchange (removes the autoantibodies form circ)

Question 38

name the irreverisble AChEsterase inhibitor

Answer 38

sarin vry deadly

Question 39

what AA does sarin bind to in AChEsterase that inhibits it

Answer 39

serine forms sarin-serin complex = cant be recycled

Question 40

2 reasons why sarin causes flaccid paralysis

Answer 40

- nAChr get desensitised after being exposed for long time - =memb constantly depolarise and Na+ channels get inactivated

Question 41

what 3 AAs control enzymatic activity of AChEsterase

Answer 41

serine glutamate histidine

Question 42

2 antidotes for sarin

Answer 42

injecting atropine as a muscarinic antagonist pralidoxime = recycles AChesterase (only effective if used quick)

Question 43

what tissue from electric fish is used to study nicotinic receptors

Answer 43

electroplaque Elecetrocytes has lots of nAChr orginally derived form msucle