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BIO2242 > Lecture 3 - Muscles > Flashcards

Lecture 3 - Muscles Flashcards

1
Q

Muscles can only generate force by shortening. True or False?

A

True

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2
Q

What is the difference between CIlia and Flagella?

A

Cilia are 0.2-0.5 um and are found in all animals except nematodes (and limited in some arthropods). Cilia beat asymmetrically. Fluid propelled parallel to surface.
Flagella are longer and beat symmetrically. Fluid propelled perpendicular to surface.

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3
Q

Functions of muscles

A

Posture, movement, peristalsis, generation of heat and electricity, sound, internal organ function

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4
Q

What are the four functional characteristics of muscle?

A

Contractility, excitability, extensibility, elasticity

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5
Q

Contractility

A

Muscles can forcefully shorten

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6
Q

Excitability

A

Muscles respond to a stimulus

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7
Q

Extensibility

A

Muscles can be stretched

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8
Q

Elasticity

A

Muscles recoil or bounce

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9
Q

What are the types of invertebrate muscle?

A

Smooth (bivalve adductor muscle - slow), striated (e.g. bivalve closure muscle - fast), fibrillar (e.g. insect flight, very fast)

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10
Q

Direct flight of insects

A

Muscles directly attach to wings

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11
Q

Indirect flight in insects

A

Muscles attach to the thorax, rather than to wings, and cause flight by movement of the thorax.

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12
Q

Types of vertebrate muscle

A

Smooth (gut and blood vessels)

Striated (skeletal and cardiac)

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13
Q

Skeletal muscle

A

Attached to skeleton
Responsible for movement and posture
Striated, many nuclei, transverse tubules
Voluntary control
Fast contraction, relaxes and tires quickly

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14
Q

Cardiac muscle

A

Located in walls of the heart
Role in the pumping of the heart
Striated, uninuclear, transverse tubules, intercalated discs
Involuntary control
Contracts as a unit, self-exciting, rhythmic

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15
Q

Smooth muscle

A

Located in walls of hollow viscera in gut
Role in movement and peristalsis
Not striated, uninuclear, no transverse tubules
Involuntary control
Contracts and relaxes slowly, self exciting, rhythmic contractions

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16
Q

True or false. Muscle can be attached to other muscle

A

True. e.g. Flehmen response

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17
Q

Power is affected by

A

Type of fiber
Muscle cross-sectional area
Type of leverage

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18
Q

Power formula

A

Force x speed

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19
Q

Components of a lever

A

Resistance, Fulcrum, Effort

20
Q

Mechanical Advantage

A

High MA = high force but low speed

Low MA = low force but high speed

21
Q

In a muscle/joint attachment, the muscle provides

A

The effort

22
Q

1st class lever

A

Fulcrum in the middle. E.g. neck atlantooccipital joint.

23
Q

2nd class lever

A

Resistance in the middle. Example; jaw joint.

24
Q

3rd class lever

A

Effort in the middle. Most joints in body.

25
Q

Antagonistic muscle pairs

A

Act against each other and balance each other out. When one is stimulated, the other is not.

26
Q

Spongy bone

A

Open interlacing framework of bony tissue, trebeculi, lots of blood vessels, red blood cells

27
Q

Compact bone

A

On the outside of shafts, stronger than spongy bone, dense, supports more weight.
Levers are usually attached to the spongy bone.

28
Q

Tendons

A

Attach muscle to bone

29
Q

Contraction of skeletal muscle

A

See slides. Actin and myosin filaments in a sarcomere (unit of a myofibril) slide towards each other due to the movement of the myosin head mediated by ATP.

30
Q

Contraction vs relaxation

A

Contraction requires energy. Relaxation is passive

31
Q

Muscle contraction requires

A

ATP, calcium, a stimulus

32
Q

Muscle contraction produces

A

Lactic acid

33
Q

Energy for muscle use is provided by

A

Cellular respiration, or anaerobic respiration with sustained use

34
Q

Motor unit

A

A neuron and all the muscle fibres it activates (a few to 2000).
Higher force is achieved with more motor units.

35
Q

Neural control of muscle

A

Neuron releases ACH
Fibre depolarises and relases Ca2+
Fibre contracts

36
Q

Vertebrate vs invertebrate muscle force

A

Vertebrate is an all-or-nothing response, where a threshold is met and then the muscle fibers contract.
Invertebrate muscles can contract gradually.

37
Q

Vertebrate vs invertebrate muscle force

A

Vertebrate is an all-or-nothing response, where a threshold is met and then the muscle fibers contract.
Invertebrate muscles can contract gradually.

38
Q

Variables in muscle performance

A

The trade-off between force and velocity
The proportion of fast and slow-twitch fibres
Physiological cross-sectional area
Energy storage by tendons.

39
Q

Vmax

A

Occurs when there is no weight. The fastest rate of contraction.

40
Q

Type 1

A

Slow fibres which fatigue slowly, are well vascularised and have large oxygen stores

41
Q

Type IIa

A

Fast fibres - little force, slow fatigue, aerobic function

42
Q

Type IIb

A

Fast fibres - large force, fatigue quickly, can function unaerobically

43
Q

Fast-twitch vs slow twitch

A

Fast-twitch has higher Vmax, generates more force, but requires more energy.

44
Q

Compared with contraction at Vmax, biceps contracting at half Vmax generate

A

More force

45
Q

What occurs during a muscle contraction?

A

Generation of heat
Shortening of sarcomeres
Thickening of muscle due to contraction

BIO2242 (33 decks)

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