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Flashcards in Muscles 1 Deck (55):
1

What are the functions of muscle?

The functions of muscle are:

Generate force and movement

Allow us to express and regulate ourselves

2

What are the 3 types of muscle?

The 3 types of muscle are:

Skeletal

Smooth

Cardiac

3

What kinds of muscle is striated?

Skeletal and cardiac muscle is striated

4

What can you say about the nucleus of skeletal muscle?

Skeletal muscle is multinucleated

5

What do myoblasts not do?

Myoblasts do not replace cells if they are damaged

6

What does skeletal muscle form from?

Skeletal muscle forms in utero from mononucleate myoblasts

7

What happens to skeletal muscle during growth?

During growth skeletal muscle increases fibre size

8

What is muscle?

Muscle is bundles of fibres enclosed in connective tissue sheaths

9

What are muscles attached to the bone by?

Muscles are attached to the bone by tendons

10

What do satellite cells do?

Satellite cells replace cells during injury

11

What cell replaces cells during injury?

Satellite cells replace cells during injury

12

How do satellite cells replace cells during injury?

Satellite cells differentiate to form new muscle fibres

13

What can muscle fibres that cannot completely recover undergo?

Muscle fibre that cannot completely recover can undergo hypertrophy to compensate

14

What is hypertrophy?

Hypertrophy is the increase in size of skeletal muscles due to the growth of its component cells

15

What is striated muscle?

Striated muscle is muscle tissue that is marked by transverse dark and light bands

16

What does the structure of striated muscle look like?

17

What are the compartments of myofibril?

Myofibril is split into:

I band

A band

Z line

18

What is a sacromere?

A sacromere is the basic unit of striated muscle, between the Z lines

19

What is the sarcomere composed of?

The sarcomere is composed of:

Myosin filament (thick)

Actin filament (thin)

20

What does the structure of a sacromere look like?

21

What are the thick myosin filaments surrounded by?

The thick myosin filaments are surrounded by a hexagon of thin actin filaments throughout the structure

22

What is contraction caused by?

Contraction is caused by sliding filaments

23

What happens when the muscle is shortened compared to relaxed?

When the muscle is shortened:

A band is unchanged

I band is reduced

H zone is reduced

24

What causes the muscle to contract?

The cross bridge causes the muscle to contract

25

What does the cross bridge contain?

The cross bridge contains:

Actin binding sites

ATP binding sites

Light chains

Heavy chains

26

Describe the process of the cross chain cycle?

The process of the cross chain cycle is:

  1. Cross bridge binds to actin
  2. [Ca2+] rises
  3. Cross bridge moves
  4. ATP binds to myosin causing the cross bridge to detach 
  5. Hydrolysis of ATP energizes the cross bridge

27

Why does an increase in [Ca2+] cause the cross bridge to move?

An increase in [Ca2+] causes the cross bridge to move because:

Tropomyosin partially covers myosin binding site, which is held in position by troponin

Calcium binds to troponin, changing conformation pulling tropomyosin away

ATP can bind to myosin

28

What is tropomyosin partially covering myosin binding site and being held in position by troponin known as?

Cooperative blocking

29

What happens when calcium is removed?

When calcium is removed the myosin binding site becomes blocked by tropomyosin again

30

What is excitation/contraction coupling?

Excitation/contraction coupling is the conversion of electrical stimulis into a mechanical response

31

What is the process of excitation/contraction coupling?

The process of excitation/contraction coupling is:

  1. Muscle action potential propogated
  2. Ca2+ released
  3. Binds to troponin, removing blocking action by tropomyosin
  4. ATP binds to the myosin of the cross bridge
  5. Ca2+ taken up
  6. Tropomyosin blocking action restored

32

What is a motor unit?

A motor unit is a motor neuron and a collection of muscle fibres working together

33

How may muscle fibres within a motor uni be arranged?

Muscle fibres within a motor unit may be scattered throughout the muscle

34

What is tension?

Tension is the load exerted by a muscle

35

What is load?

Load is the force exerted on a muscle

36

What is isometric?

Isometric is a contraction with a constant contraction length

37

What is an example of a sport that uses isometric contraction?

Weightlifting is an example of a sport that uses isometric contraction

38

What is isotonic?

Isotonic is a contraction with a shortening muscle length

39

What is an example of an isotonic contraction?

An example of an isotonic contraction is running

40

What is lengthening?

Lengthening is a contraction with increasing length

41

What is an example of a lengthening contraction?

An example of a lengthening contraction is sitting down

42

What are twitch contractions shown by?

Twitch contractions are shown by:

Single AP → Muscle fibre → Twitch

43

What is the latent period?

The latent period is the time before excitation contraction starts

44

What is the contraction time?

Contraction time is the time between the start of tension and the peak of the tension

45

What does muscle fibre contraction time depend on?

Muscle fibre contraction time depends on:

Fibre type

[Ca2+]

46

Which type of contaction has the shorter latent period but the longer contraction event?

Isometric contraction has the shorter latent period by the longer contraction event

47

What happens as load increases?

As load increases:

Contraction velocity decreases

Distance shortended decreases

48

What is tetanus?

Tetanus is muscle spasms because AP is only 1-2ms long but the twitch lasts for up to 100ms so more APs may occur in this time, causing summation of APs

49

Why is tetanus tension greater than twitch tension?

Tetanus tension is greater than twitch tension because [Ca2+] never gets low enough to allow reblocking of myolin binding sites

50

What does the length-tension relationship look like?

51

Why does the length-tension relationship look the way it does?

The length-tension relationship looks like this because:

Less overlap of filament is less tension

Too much overlap and filaments interfere with each other

52

What is the optimal length (lo)?

The optimal length is the muscle length for the greatest isometric tension

53

What does movement around a limb require?

Movement around a limb requires 2 antagonistic groups of muscles:

One flexes

One extends

54

Why are muscles arranged in a lever system?

Muscles are arranged in a lever system to amplify muscle shortening velocity to produce increases maneuverability

55

Do muscles exert or support muscle force?

Muscles tend to exert more force than they support