muscles

Question 1

what are muscles for

Answer 1

whole body movements and localised movements
holding joints in place, maintaining posture
movement of substances within the body
thermogenesis

Question 2

what is thermogenesis

Answer 2

production of heat - normal opperation

Question 3

how do muscles achieve the things they do

Answer 3

contractility
electrical excitability
elasticity
extensibility

Question 4

define contractability

Answer 4

the ability of muscle to contract forcefully

Question 5

what is electrical excitability

Answer 5

can produce electrical signals which
allow regulation of contraction via excitation contraction
coupling – Control

Question 6

what is elasticity

Answer 6

muscle returns to original length after contraction or
extension

Question 7

what is extensibility

Answer 7

can stretch without being damaged – allows
contraction even after stretching e.g. cardiac muscle after filling
of heart, digestive tract after meal

Question 8

what is the structure of cardiac muscle tissue

Answer 8

striated

Question 9

is cardiac muscle tissue voluntary or involuntary

Answer 9

involuntary

Question 10

where is cardiac muscle tissue found in the body

Answer 10

forms myocardium of the heart

Question 11

what is the structure of smooth muscle tissue

Answer 11

non striated / smooth

Question 12

is smooth muscle tissue voluntary or involuntary

Answer 12

involuntary, sometimes auto-rhythmicity

Question 13

where is smooth muscle found within the body

Answer 13

walls of internal structures like blood vessels

Question 14

how are skeletal muscles controlled

Answer 14

by neurons via the neuromuscular junction

Question 15

how many neuromuscular junctions do each muscle fibres have

Answer 15

1

Question 16

how many muscles fibres do somatic motor neurons branch to innervate

Answer 16

150 avg

Question 17

what are the typical measurements of a muscle fibre

Answer 17

diameter 10-100um
length 10-30cm

Question 18

what is the sarcolemma

Answer 18

the plasma membrane of the muscle fibre

Question 19

what is the role interstitial fluid in transverse tubules that move into the muscle fibre from the sarcolemma

Answer 19

allows depolarisation to spread throughout the fibre

Question 20

what is the sarcoplasm

Answer 20

interior of muscle fibre

Question 21

what does sarcoplasm contain a lot of

Answer 21

glycogen and myoglobin

Question 22

what are the 3 types of muscle proteins

Answer 22

contractile, regulatory and structural

Question 23

what is the role of contractile proteins

Answer 23

generate force during contraction (actin and myosin, motor protein)

Question 24

what is the role of regulatory proteins

Answer 24

switch contraction on and off

Question 25

what is the role of structural proteins

Answer 25

hold contractile components in proper alignment. Allow elasticity and extensibility

Question 26

what lines do sarcomeres run from

Answer 26

z line to z line

Question 27

what is the m line

Answer 27

the centre of myosin

Question 28

what is the H zone

Answer 28

myosin alone

Question 29

what is the A band

Answer 29

myosin alone as well as actin and myosin overlap

Question 30

what is the I band

Answer 30

actin alone

Question 31

what happens to the lines and bands when muscles contract

Answer 31

M line - no change Z line - move closer I and H zone shorten A bands stay the same

Question 32

what is a power stroke in muscles

Answer 32

the formation of a cross bridge between filaments causing a change in shape of cross bridge - twisting motion - which in turn moves actin along

Question 33

is ATP hydrolysed or synthesised to reset the myosin head

Answer 33

hydrolysed

Question 34

what regulated contraction of muscles

Answer 34

excitation contraction coupling

Question 35

what is the concentration of calcium like in cell cytosol at rest

Answer 35

0.1u mole per litre

Question 36

where can calcium be released from to promote more muscular contractions

Answer 36

sarcoplasmic reticulum

Question 37

what is the sequence that results in muscular contraction

Answer 37

activation of NMJ causes action potential - this propagates along sarcolemma and into T tubules - depolarisation causes opening of calcium release channels- calcium released into cystol - calcium binds to troponin which changes the conformation of the troponin-tropomyosin complex - which clears the actin-myosin binding site

Question 38

what is Twitch Contraction

Answer 38

Brief contraction of a motor unit. Stimulate nerve and muscle depolarises.

Question 39

what is Tetanic Contraction:

Answer 39

Once refractory period is over, contractions can summate if inadequate time for relaxation

Question 40

what is an isometric muscle contraction

Answer 40

◦ Muscle exerts force without changing length ◦ Pulling against immovable object ◦ Postural muscles

Question 41

what is an isotonic muscle contraction

Answer 41

◦ Concentric - Muscle shortens during force production ◦ Eccentric - Muscle produces force but length increases

Question 42

what does the muscle spindle receptor detect

Answer 42

◦ Detect dynamic and static changes in muscle length ◦ Stretch reflex ◦ Stretch on muscle causes reflex contraction

Question 43

what does the Golgi tendon organ detect

Answer 43

◦ Monitor tension developed in muscle ◦ Prevents damage during excessive force generation ◦ Stimulation results in reflex relaxation of muscle

Question 44

the heart has auto rhythmicity what does this mean

Answer 44

constant process of contraction and relaxation.

Question 45

what does an organ with auto rhythmicity require and have more than others

Answer 45

needs more energy so has more mitochondria

Question 46

what initiates contractions in smooth muscles

Answer 46

binding calcium binding to calmodulin and activating myosin light chain kinase. which phosphorylates myosin head making it active

Question 47

what autonomic innervations do smooth muscles respond to

Answer 47

pH oxygen co2 hormones

Question 48

what does The distribution of myofilaments determine

Answer 48

the changes in cell shape associated with contraction and relaxation

Question 49

why are smooth muscle found orientated longitudinally and transversely

Question 50

Smooth Muscle can also relax in response to?

Answer 50

chemicals cAMP and cGMP (intracellular messengers)

Question 51

Skeletal Muscle, Cardiac Muscle and Smooth Muscle all contract in response to the presence of ?

Answer 51

intracellular calcium ions

Question 52

what are the 2 main control mechanisms in smooth muscle control

Answer 52

electrochemical (membrane potential change)

Question 53

describe the stages of smooth muscle contraction mechanism

Answer 53

* Calcium enters the smooth muscle cell * Calcium binds calmodulin * Activation of MLCK (myosin light chain kinase) * Phosphorylation of myosin leading to contraction * If calcium drops, loose phosphorylation, muscle relaxes * Cyclic nucleotides can reduce calcium levels in the cell (interplay with cell signalling pathways)