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Biology 241 > Locomotion > Flashcards

Locomotion Flashcards

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1
Q

What is a muscle?

A

A bundle of muscle fibres (muscle cells). Each muscle cell runs the entire length of the muscle; these muscle fibres are filled with bundles of myofibrils.

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2
Q

How are muscle cells formed?

A

During growth, hundreds of myoblasts fuse to form a long multi-nucleated cell

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3
Q

What are myofibrils?

A

Consist of stacks of thick and thin filaments, which are arranged along the length of the myofibril (called sarcomeres, functional unit of the skeletal muscle)

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4
Q

When do muscles contract?

A

When myosin filaments pull opposing actin filaments towards each other

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5
Q

What are the steps of the cross-bridge cycle?

A
  1. New ATP binds to myosin causing cross-bridge to release
  2. ATP hydrolysis (split into ADP and Pi) cocks myosin into position
  3. Myosin attaches to actin to form cross-bridge
  4. Myosin releases ADP and Pi causing a working stroke
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6
Q

What is a working stroke?

A

When the myosin head pivots and bends as it pulls on the actin filament

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7
Q

What do muscles generate?

A

Force flashback; generate force that causes skeleton to move

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8
Q

When is there more force?

A
  • When number of cross-bridges between actin and myosin in sarcomere increase
  • When number of muscle cells in the tissues increases (more muscle cells/fibres = more sarcomeres)
  • When length of the muscle tissue increases (longer muscle cells/fibres = more sarcomeres)
  • When muscle contracts more slowly (rapid contraction decreases number of cross-bridges)
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9
Q

What are the physiological limitations on energy production?

A
  • Limit rate of ATP production
  • Delivery of O2 to muscles (takes time)
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10
Q

What is slow switch (type 1) muscle fibres meant for?

A

Meant for longer duration or constant contractions with less force

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11
Q

What are the features of slow switch (type 1) muscle fibres?

A
  • Aerobic oxidative respiration
  • High mitochondria
  • High myoglobin (stores O2)
  • High vascularization
  • Low glycogen
  • Low power, endurance
  • Dark meat
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12
Q

What is fast switch (type 2) muscle fibres meant for?

A

Meant for fast and short bursts

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13
Q

What are the features of fast switch (type 2) muscle fibres?

A
  • Anaerobic glycolysis
  • Low mitochondria
  • Low myoglobin
  • Low vascularization
  • High glycogen
  • High power, bursts
  • White meat
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14
Q

What are the physiological limitations on MRmax and MRsus?

A
  • Pools of ATP stored in cells that provide instant energy, but gets used up fast
  • PCr is a backup pool of ATP
  • When PCr and ATP reserves get used up, we have glycolysis to quickly make ATP
  • Oxidative phosphorylation will eventually kick in to keep making ATP
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15
Q

What is the difference in scope/capacity in locomotion between endotherms and ectotherms?

A

The scope/capacity is roughly the same for both. However, absolute value of metabolism differs between them (metabolic rate for ectotherms is lower overall)

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16
Q

How is locomotion measured?

A

By mass specific metabolic rate (kJ/kg x h) and cost of transport (kJ/kg x km)

17
Q

What are the first two factors that affect locomotion?

A

Inertia and momentum increase mass.
Inertia: the tendancy of a mass to resist change in motion
Momentum: the tendancy of a moving mass to sustain velocity

18
Q

What is the third factor that affects locomotion?

A

Drag is the force generated in the opposite direction of an animal’s movement by density/viscosity of the medium. Large organisms spend less energy overcoming drag than small organisms.
Drag forces increase with mass and velocity, as velocity increases more energy has to go towards overcoming drag

19
Q

What are the forces acting on a runner?

A

Thrust: energy needed for forward motion (lots of energy from each step transferred to the ground)

Gravity: largest factor in activity budget

Drag: force generated in opposition to thrust (negligible in air)

Muscle action: constantly supporting our mass

20
Q

What is an additional thing that affects runners?

A

Mass also affects runners; cost of starting is higher for heavier runners. A small animal gets to top speed quickly but plateaus, a bigger animal gets to a higher top speed overall

21
Q

Why is less force generated in smaller animals?

A

It is more expensive to contract shorter muscles in a smaller animal

22
Q

In what ways does velocity affect runners?

A
  • As velocity increases, limbs move faster (muscles contract faster, more energy required)
  • Small runners have to work harder to move fast (limbs/muscles are shorter, stride is shorter so more contact with the ground (to overcome gravity))
  • As velocity increases, more energy is put towards generating forward motion (momentum increases, less contact with ground (less energy loss))
23
Q

As velocity increases, what happens to MRmax?

A

MRmax increases linearly for both runners. Though smaller animals have a steeper increase and higher overall MRmax.

24
Q

As velocity increases, what happens to cost of transport?

A

Cost of transport decreases linearly for both runners because of inertia, momentum, and decreased contact with the ground

25
Q

What is the relationship between mass and cost of transport?

A

The bigger you are (body mass), the lower the cost of transport

26
Q

What are the forces acting on a swimmer?

A

Thrust: energy needed for forward motion (body shape adopted to minimize drag)

Buoyancy: generate neutral buoyancy (swim bladders)

Drag: biggest cost to a swimmer (density/viscosity of water is greater than air)

Gravity: negligible factor in activity budget

27
Q

What are the different types of drag acting on a swimmer?

A

Viscous forces –> skin friction drag
Intertial forces –> pressure drag

Pressure drag: larger organisms create more turbulence which creates pressures that slow it down

Skin friction drag: single celled organisms (high SA to vol ratio) means that a lot of water sticks to skin and because of being small it has less mass and has better ability to generate force to overcome friction

28
Q

Why do larger swimming organisms have lower cost of transport?

A
  • Larger muscles
  • Ability to generate more force
  • Lower skin-friction drag
29
Q

What are the forces acting on a flier?

A

Thrust: energy needed for forward motion

Lift: force generated that counters gravity that increases with velocity

Drag: more important at high velocities

Gravity: more important at low velocities

30
Q

What is induced and parasite power?

A

Induced power: energy required to counter gravity

Parasite power: energy required to counter drag

Biology 241 (6 decks)

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