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MBChB Glasgow Year 1 Phase 1 > PBL 6 > Flashcards

PBL 6 Flashcards

1
Q

What are the three types of muscle?

A

Skeletal, smooth and cardiac muscle

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2
Q

What type of muscle forms the majority of muscle tissue in the body

A

Skeletal muscle

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3
Q

How is skeletal muscle organised?

A

Parallel bundles of long, multinucleated fibers

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4
Q

What is the power/stamina of skeletal muscle like?

A

Skeletal muscle is capable of powerful contractions but can,however tire quickly

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5
Q

Where is skeletal muscle found?

A

Attached to the skeleton by either tendons or aponeurosis

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6
Q

What is an aponeurosis?

A

A thin sheet of connective tissue

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7
Q

What are the functions of skeletal muscle?

A

Moves bones and other structures

Provides support and gives form to the body

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8
Q

Is skeletal muscle controlled voluntarily or involuntarily?

A

Voluntarily but not always consciously

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9
Q

Where is the muscle belly found?

A

Between the origin and insertion

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10
Q

How many origins, insertions and bellies can muscles have?

A

Muscles can have multiple origins,insertions and bellies

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11
Q

What movements can skeletal muscles carry out?

A

They can contract, stretch beyond its normal length and revert to its original resting length

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12
Q

What are the constituent parts of skeletal muscle?

A

Muscle fascicles, Muscle fibers, myofibrils and myofilaments

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13
Q

What is a muscle fascicle?

A

Bundles of muscle fibers (muscle cells)

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14
Q

What is a muscle fiber?

A

Bundles of myofibrils

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15
Q

What is a myofibril?

A

Bundles of myofilaments

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16
Q

What are myofilaments?

A

The proteins responsible fro muscle contraction

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17
Q

What is the endomysium?

A

A thin layer of connective tissue that surrounds each muscle fiber

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18
Q

What is the perimysium?

A

A thick layer of connective tissue that surrounds each muscle fascicle

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19
Q

What is the function of the permysium?

A

To protect the fascicle from damage. It also contains capillaries and nerve fibers

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20
Q

What is the epimysium?

A

A sheet of thick connective tissue that surrounds the entirety of a skeletal muscle. It may continue at the end of the muscle belly as a tendon and thus become continuous with the periosteum

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21
Q

What is the function of epimysium?

A

To separate the muscle from surrounding tissues and organs.

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22
Q

What does each skeletal muscle fiber contain?

A

A plasma membrane (sarcolemma), cytoplasm (sarcoplasm), nuclei, sarcoplasmic reticulum and is composed of bundles of protein fibers

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23
Q

What is the sarcolemma?

A

The plasma membrane of a muscle fiber. It has invaginations to from the T tubules

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24
Q

What is the function of the sarcolemma?

A

To receive electrical stimuli and conduct an action potential to the internal structure of the muscle fiber (via the T tubules)

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25
Q

What is the sarcoplasmic reticulum?

A

A special type of smooth ER found only in skeletal muscle cells

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26
Q

What is the function of the sarcoplasmic reticulum?

A

Stores large, concentrated stores of calcium

27
Q

What is the sarcoplasm?

A

The cytoplasm of muscle cells

28
Q

What is the function of the sarcoplasm?

A

To store large amounts of glycogen and myoglobin.

  • Glycogen provides energy during muscle contraction
  • Myoglobin contains stored oxygen
29
Q

What are myofibrils?

A

Thread-like organelles 1-3 micro meters in diameter that extend the length of the muscle fiber

30
Q

What are the two general types of skeletal muscle fibers?

A

Slow-twitch (type 1) and fast - twitch (type 2)

31
Q

What is the structure of fast - twitch muscles like?

A

Fast twitch muscles are thicker and quicker to contract than slow twitch muscles.

32
Q

What is the endurance of slow twitch muscles like?

A

Slow twitch muscles have generally more endurance than fast twitch muscles

33
Q

Where is cardiac muscle found?

A

The walls of the heart

34
Q

What is special about cardiac muscle?

A

Cardiac muscle is resistant to fatigue and contracts without any external stimulation

35
Q

What is the word used to describe the nerves that stimulate cardiac muscle?

A

Autonomic

36
Q

What does autonomic mean?

A

The control is involuntary

37
Q

Where is smooth muscle found?

A

The walls of internal organs, such as otrgans of the digestive system, walls of blood vessels and the intrinsic muscles of the eye.

38
Q

What is the structure of smooth muscle?

A

Smooth muscle is non-striated. It consists of elongated or spindle-shaped fibres.

39
Q

What type of contractions are smooth muscles capable of?

A

slow, sustained contractions

40
Q

How is smooth muscle controlled?

A

Smooth muscle is able to contract without external stimulation, and is modified by the autonomic nervous system. It is under involuntary control and doesn’t fatigue

41
Q

What is the electrical excitability of a muscle?

A

The ability of a muscle to respond to stimuli

42
Q

What is the contractility of a muscle?

A

The ability of a muscle to shorten in response to an action potential

43
Q

What is the extensibility of a muscle?

A

the ability of a muscle to stretch

44
Q

What is the elasticity of a muscle?

A

the ability of a muscle to recover its original shape after contraction or extension

45
Q

How does muscle contribute to body movement?

A

The contraction and relaxation of muscles produce movement around various joints of the body

46
Q

How does muscle contribute to the stabilisation of joints?

A

Regulates the degree of movement possible at each joint

47
Q

How does muscle contribute to the maintenance of body positions?

A

Continuous or sporadic contraction of skeletal muscles around the body helps us to maintain our posture and position

48
Q

How does muscle contribute to storage of substances?

A

Contraction of smooth and skeletal muscle at specific points within the body enables certain substances to be kept within one place

49
Q

How does muscle contribute to the movement of substances?

A

Relaxtion of cardiac and smooth muscle at specific points within the body controls the movement of substances from one place to another

50
Q

How does muscle contribute to thermogenesis?

A

contracting muscles produce heat as a by-product, and this contributes to the maintenance of normal body temperature

51
Q

How does muscle contribute to communication?

A

Movement of muscles permits both verbal and non-verbal expression

52
Q

What is muscle atrophy?

A

The weakening and shrinking of a muscle

53
Q

What is muscle atrophy caused by?

A

Immobilisation or loss of neural stimulation

54
Q

What is muscle hypertrophy?

A

The enlargement of a muscle (cell size).

The muscle will develop more capillaries and more mitochondria

55
Q

What is muscle hypertrophy caused by?

A

Strenuous exercise or steroid hormones

56
Q

How does muscle hypertrophy occur?

A

When slow twitch muscle fibers become tired, fast twitch fibers take over which is when muscle mass will increase

57
Q

Why do men in general have more hypertrophied muscles than women?

A

They produce more steroid hormones

58
Q

What is muscle hyperplasia?

A

An increase in muscle cell numbers

59
Q

What type of muscle does hyperplasia occur in?

A

Smooth muscle is the only type of muscle capable of cell division

60
Q

Where does excitation-contraction coupling take place?

A

The sarcoplasm of a muscle fiber

61
Q

What is the concentration of calcium ions in the cytosol like in a relaxed muscle fiber?

A

Relatively low

62
Q

Where are a large number of calcium ions stored?

A

The sarcoplasmic reticulum

63
Q

When are the calcium ions released?

A

During contraction to mediate the process by binding to troponin

MBChB Glasgow Year 1 Phase 1 (10 decks)

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