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physiology + pharmacology > muscles > Flashcards

muscles Flashcards

1
Q

what are muscles for

A

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

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2
Q

what is thermogenesis

A

production of heat - normal opperation

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3
Q

how do muscles achieve the things they do

A

contractility
electrical excitability
elasticity
extensibility

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4
Q

define contractability

A

the ability of muscle to contract forcefully

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5
Q

what is electrical excitability

A

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

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6
Q

what is elasticity

A

muscle returns to original length after contraction or
extension

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7
Q

what is extensibility

A

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

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8
Q

what is the structure of cardiac muscle tissue

A

striated

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9
Q

is cardiac muscle tissue voluntary or involuntary

A

involuntary

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10
Q

where is cardiac muscle tissue found in the body

A

forms myocardium of the heart

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11
Q

what is the structure of smooth muscle tissue

A

non striated / smooth

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12
Q

is smooth muscle tissue voluntary or involuntary

A

involuntary, sometimes auto-rhythmicity

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13
Q

where is smooth muscle found within the body

A

walls of internal structures like blood vessels

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14
Q

how are skeletal muscles controlled

A

by neurons via the neuromuscular junction

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15
Q

how many neuromuscular junctions do each muscle fibres have

A

1

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16
Q

how many muscles fibres do somatic motor neurons branch to innervate

A

150 avg

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17
Q

what are the typical measurements of a muscle fibre

A

diameter 10-100um
length 10-30cm

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18
Q

what is the sarcolemma

A

the plasma membrane of the muscle fibre

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19
Q

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

A

allows depolarisation to spread throughout the fibre

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20
Q

what is the sarcoplasm

A

interior of muscle fibre

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21
Q

what does sarcoplasm contain a lot of

A

glycogen and myoglobin

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22
Q

what are the 3 types of muscle proteins

A

contractile, regulatory and structural

23
Q

what is the role of contractile proteins

A

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

24
Q

what is the role of regulatory proteins

A

switch contraction on and off

25
Q

what is the role of structural proteins

A

hold contractile components in proper alignment. Allow elasticity and extensibility

26
Q

what lines do sarcomeres run from

A

z line to z line

27
Q

what is the m line

A

the centre of myosin

28
Q

what is the H zone

A

myosin alone

29
Q

what is the A band

A

myosin alone as well as actin and myosin overlap

30
Q

what is the I band

A

actin alone

31
Q

what happens to the lines and bands when muscles contract

A

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

32
Q

what is a power stroke in muscles

A

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

33
Q

is ATP hydrolysed or synthesised to reset the myosin head

A

hydrolysed

34
Q

what regulated contraction of muscles

A

excitation contraction coupling

35
Q

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

A

0.1u mole per litre

36
Q

where can calcium be released from to promote more muscular contractions

A

sarcoplasmic reticulum

37
Q

what is the sequence that results in muscular contraction

A

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

38
Q

what is Twitch Contraction

A

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

39
Q

what is Tetanic Contraction:

A

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

40
Q

what is an isometric muscle contraction

A

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

41
Q

what is an isotonic muscle contraction

A

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

42
Q

what does the muscle spindle receptor detect

A

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

43
Q

what does the Golgi tendon organ detect

A

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

44
Q

the heart has auto rhythmicity what does this mean

A

constant process of contraction and
relaxation.

45
Q

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

A

needs more energy so has more mitochondria

46
Q

what initiates contractions in smooth muscles

A

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

47
Q

what autonomic innervations do smooth muscles respond to

A

pH oxygen co2 hormones

48
Q

what does The distribution of myofilaments determine

A

the changes in cell shape associated with contraction
and relaxation

49
Q

why are smooth
muscle found orientated
longitudinally and transversely

A
50
Q

Smooth Muscle can also relax in response to?

A

chemicals cAMP
and cGMP (intracellular messengers)

51
Q

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

A

intracellular calcium ions

52
Q

what are the 2 main control mechanisms in smooth muscle control

A

electrochemical (membrane potential change)

53
Q

describe the stages of smooth muscle contraction mechanism

A
  • 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)
54
Q
A

physiology + pharmacology (12 decks)

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