Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pe- Anatomy and Physiology > Muscle anatomy and function > Flashcards

Muscle anatomy and function Flashcards

1
Q

Myofibril

A

A cylindrical organelle running the length of the muscle fibre, containing actin and myosin filaments.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Sarcomere

A

The contractile unit of the myofibril, divided into I, A and H bands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What proteins does the myofibril contain?

A

Myosin
Actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Actin

A

A thin, contractile protein filament containing ‘active’ or ‘binding’ sites.
- They overlap the myosin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Myosin

A

A thick contractile protein filament with protrusions known as myosin heads.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What band does myosin appear on?

A
  • It appears as a dark band
  • ‘H’ band
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What band does actin appear on?

A
  • It appears as a light band
  • ‘I’ band
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is it at the end of each sarcomere?

A

Z line- actin is attatched to the z line
Sarcomeres are joined together lengthways at the z line.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What region is the middle of the sarcomere?

A

M line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does the A band refer to?

A

The dark A band identifies where both actin and myosin exist

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the cell membrane of muscle cells called?

A

Sarcolemma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the cytoplasm of muscle cells called?

A

Sarcoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How are the transverse (T) tubules created and what do they do?

A
  • Sarcolemma folds into the sarcoplasm
  • Help to spread electrical impulses throughout the cell by passing message to sarcoplasmic reticulum to release calcium ions.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Sarcoplasmic reticulum

A
  • They store calcium ions which causes contraction
  • Each myofibril is enveloped in it
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is skeletal muscle fibre also known as?

A

Striated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How many actin filaments surround 1 myosin filament?

A

6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the name of the nerve that stimulates a muscle to contract by carrying nerve impulses?

A

Motor neurone which controls a number of muscle fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is sliding filament theory?

A
  • It explains the sequence of events leading up to skeletal muscle contraction.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens during muscle contraction?

A

The thin actin filaments slide inwards over the thicker myosin filaments causing a shortening of each sarcomere along the entire length of the myofibril.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens to the H zone during the sarcomeres contracted state?

A

It disappears

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Whats happening at rest with the protein tropomysosin?

A

The protein tropomyosin (on the thin filament- actin) blocks the binding site as it covers the actin-myosin binding site and it is held in place by troponin.

22
Q

What happens when the muscle fibre relaxes?

A

The myofilaments slide away from eachother and move further apart lengthening the sarcomere.

23
Q

What is the region on actin where myosin binds called?

A

Actin-myosin binding site

24
Q

Sliding filament theory (stages)

A
  1. Electrical impulse reaches the muscle fibre
  2. Calcium ions released from sarcoplasmic reticulum
  3. Calcium binds to troponin and tropomyosin uncovers it’s myosin binding sites on the actin filament.
  4. Cross bridge formation (myosin attatches to actin)
  5. ATP energy is released
  6. Cross bridge ‘rachet’ (actin is pulled over the myosin so the muscle shortens)
  7. Stimulation stops, calcium ions are reabsorbed into the sarcoplasmic reticulum causing relaxation of the muscle.
25
Q

What is a motor unit?

A

A group of fibres and it’s motor neurone

26
Q

What is the motor end plate?

A

The point at which the nerve reaches the muscle fibre
(transfer impulse from motor neurone to muscle fibre)

27
Q

Components of a motor neurone?

A
  • Dendrites
  • Axon
  • Nodes of ranvier
  • Myelin sheath
28
Q

Dendrites

A

Receives electrical impulse

29
Q

Axon

A

Transmits the electrical impulse

30
Q

Nodes of ranvier

A

Allows impulses to jump so increases their speed

31
Q

Myelin sheath

A

Insulates and so speeds up the conduction

32
Q

What is the nerve action potential?

A
  • Following an impulse derived from the brain/CNS an impulse will travel along the motor neurone where the dendrites receives the impulse.
  • Impulse will travel along the axon where it’s insulated by a myelin sheath and has nodes of ranvier which will speed up delivery of the impulse until it arrives at the motor end plate.
33
Q

Motor neurone activity (stages)

A
  • A nerve action potential/ impulse arrives at a muscle fibre travelling down a motor neurone and reaches the motor end plate.
  • As the NAP reaches the motor end plate a neuro-chemical transmitter known as acetyl choline (Ach) transports the signal over the synpase where the receptor cells on the sarcolemma recives it.
  • It is now known as muscle action potential as the impulse is now located in the myofibril.
  • Spread of muscle action potential via the T tubules
  • Muscle contraction
34
Q

What is the ‘all or none law’?

A

If a motor impulse is of sufficient intensity the motor unit is stimulated and all the muscle fibres within it will contract to their maximum possible extent.

35
Q

What is total force output affected by?

A

The number of motor units recruited.

36
Q

What is unit summation?

A

The bodies recruitment of motor units depends on how much total force it wishes to create.
(increased by recruiting more motor units)

37
Q

How does the muscle vary it’s strength production?

A

The strength of the muscle contraction can be altered by recruiting more or less motor units.
Maximal contractions will recruit all motor units within a muscle but weaker contractions will only recruit a few motor units.

38
Q

What is wave summation?

A

The ability to vary the total force of contraction within the motor unit by varying the speed and frequency of nerve impulses.

39
Q

How can the force of contraction increase (wave summation)?

A
  • Force of contraction increases if a second impulse arrives before the first twitch has had time to relax so force is likely to escalate as it builds on top of the first twitch before it’s had time to relax.
  • Closer the impulses are the greater the wave summation
  • Frequency with which the impulse arrives at the muscle fibre affects the contraction force.
40
Q

What is spatial summation?

A

During sub-maximal, contraction, units will work together to share the force production across the muscle so reduce fatigue.
- It does it by activating different units at different times.

41
Q

What are the types of skeletal muscle fibres?

A
  • Type 1 slow twitch
  • Type 2 fast twitch
  • Type 2a (fast twitch)- fast oxidative glycolytic
  • Type 2x (fast twitch)- fast twitch glycolytic fibres
42
Q

Slow twitch fibres

A
  • Contract more slowly
  • Highly resistant to fatigue
  • Favoured by endurance athletes
  • More aerobic
43
Q

Fast twitch fibres

A
  • Contract more rapidly
  • Generating greater forces
  • More liable to fatigue
  • More prevalent in sprinters and power athletes.
  • More anaerobic
44
Q

Characteristics of slow twitch fibres (type 1)

A
  • Slow speed of contraction
  • Very resistant to fatigue
  • High aerobic capacity
  • High mitochondrial density
  • High capillary density
45
Q

Characteristics of type 2a (fast oxidative glycolytic)

A
  • Fast speed of contraction
  • High anaerobic capacity
  • More resistant to fatigue rather than type 2b
  • Moderate mitochondrial density
  • Moderate capillary density
  • High pc store
46
Q

Characteristics of type 2b (fast twitch glycolytic fibres)

A
  • Fast speed of contraction
  • High anaerobic capacity
  • Lower resistant to fatigue compared to type 2a
  • Low mitochondrial density
  • High pc store
47
Q

Muscle spindle

A
  • Detects muscle movement (proprioceptor) - muscle spindle apparatus
  • When it lengthens it causes contraction of a few fibres in the centre of the muscle (intrafusal fibres)
  • Called a stretch reflex (in response to a lengthening in the muscle)
48
Q

What are the 3 phases of the stretch shortening cycle?

A
  • Eccentric stage
  • Amortization phase
  • Concentric phase
49
Q

Eccentric phase

A
  • Pre-load
  • Muscle spindle apparatus sends signal to brain as they have detected movement
50
Q

Amortization phase

A
  • Between eccentric and concentric phase
  • Pause period
  • Intrafusal muscles contract (stretch reflex)
51
Q

Concentric phase

A
  • Muscles shorten

Pe- Anatomy and Physiology (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions